The Pennsylvania State University

The Graduate School

College of Engineering

DEVELOPMENT OF FRAGILITY INFORMATION FOR BUILDING

LIGHT-FRAME AND ENVELOPE SYSTEMS FOR

PERFORMANCE-BASED SEISMIC DESIGN

A Thesis in

Civil Engineering

by

Yizhi Zhu

© 2016 Yizhi Zhu

Submitted in Partial Fulfillment

of the Requirements

for the Degree of

Master of Science

December 2016

ii

The thesis of Yizhi Zhu was reviewed and approved* by the following:

Ali M. Memari

Professor of Architectural Engineering and Civil Engineering

Hankin Chair of Residential Building Construction

Thesis Advisor

Aly M. Said

Associate Professor of Architectural Engineering

Konstantinos Papakonstantinou

Assistant Professor of Civil Engineering

Patrick Fox

Professor of Civil Engineering

Head of the Department of Civil Engineering

* Signatures are on file in the Graduate School

iii

ABSTRACT

Performance-based seismic design (PBSD) has been introduced since 1990s, and a

second-generation performance-based design approach has been carried out by the

Pacific Earthquake Engineering Research (PEER) in 2000 to address the limitations in

current PBSD. Thus, Federal Emergency Management Agency (FEMA) initiated a series

of projects for development of the new performance-based seismic design procedure.

The objective of this study is to make contribution to the second-generation performance-

based design by generating fragility data for light frame system such as structural

insulated panels (SIPs), and envelope systems such as brick veneer panels and rounded

corner glazing panels. These fragility data are all developed based on past experimental

testing of the components.

A case study of comparing wood-frame structure and SIPs structure with and without

brick veneer panels using the performance-based design approach is also presented in this

study. The structural analysis and modeling of the structure is completed with the used of

software SAPwood. Software PACT provided by FEMA is used for evaluating the

performance (probability of exceedance of repair cost) of structures.

iv

Table of Contents

List of Figures .....................................................................................................................v

List of Tables ................................................................................................................... vii

Acknowledgements ........................................................................................................ viii

Chapter 1: Introduction ....................................................................................................1

1.1 Background information ............................................................................................1

1.2 Objectives ..................................................................................................................2

1.3 Research approach .....................................................................................................4

Chapter 2: Literature review related to testing ..............................................................5

2.1 Introduction ................................................................................................................5

2.2 SIPs ............................................................................................................................6

2.3 Brick veneer panels ..................................................................................................14

2.4 Glass panels .............................................................................................................29

2.5 Summary ..................................................................................................................22

Chapter 3: Fragility function development methodology & PBD approach..............23

3.1 Fragility function development methodology ..........................................................23

3.2 PBD approach ..........................................................................................................27

Chapter 4: Fragility function development for selected systems.................................36

4.1 Structural insulated panels ........................................................................................36

4.2 Brick veneer panels...................................................................................................38

4.3 Glass panels with rounded corners ...........................................................................40

Chapter 5: Computer modeling and analysis ................................................................46

5.1 Shear wall modeling .................................................................................................46

5.2 Structure analysis ......................................................................................................54

Chapter 6: PBD case study..............................................................................................64

6.1 Repair cost data.........................................................................................................65

6.2 Performance group assembly ....................................................................................70

6.3 Collapse fragility development ................................................................................72

6.4 Building performance results ....................................................................................75

Chapter 7: Conclusion .....................................................................................................79

7.1 Summary ...................................................................................................................79

7.2 Limitations ................................................................................................................81

References .........................................................................................................................82

v

LIST OF FIGURES

Figure 1: Wall panel elevation section, and loading condition (Terentiuk and Memari,

2012) ....................................................................................................................................8

Figure 2: CUREE loading protocol......................................................................................9

Figure 3: Cyclic load displacement curve (Terentiuk and Memari, 2012) ........................10

Figure 4: (Terentiuk and Memari, 2012) – (a) Staple shear (A3); (b) Panel disjointed

(A4); (c) screw shear (A4); (d) nail withdraw along spline (A1); (e) sheathing damage

(A1); (f) Panel separation ..................................................................................................11

Figure 5: Wall panel and loading condition (Kermani and Hairstans, 2006) ....................12

Figure 6: SIP test set-up (Mosalam et al., 2008)................................................................13

Figure 7: Out-of-plane load test set up of the brick veneer panels (Reneckis and LaFave,

2004) ..................................................................................................................................16

Figure 8: (a) tie fracture; (b) nail pull out; (c) partial tie failure (Reneckis and LaFave,

2012) ..................................................................................................................................18

Figure 9: failure of brick veneer panels (Reneckis and LaFave, 2012) ............................18

Figure 10: Cracking of rounded corner glass ....................................................................21

Figure 11: Flowchart of loss analysis using FEMA methodology ....................................27

Figure 12: Example of repair cost function (FEMA, 2012a) .............................................28

Figure 13: Components of a single-story wood-frame structure (Folz and Filiatrault,

2004) ..................................................................................................................................30

Figure 14: Single story wood-frame structure model (Folz and Filiatrault, 2004) ............30

Figure 15: 10-parameter model (Pei and Van de Lindt, 2010) ..........................................31

Figure 16: Process of performance assessment under each realization (FEMA, 2012a) ...33

Figure 17: Fragility curve for Panel 1 – 4 ..........................................................................38

Figure 18: Fragility curve of brick veneer panels for three damage states ........................39

Figure 19: Fragility curve of glass panels ..........................................................................41

Figure 20: Nail location of wood-frame shear wall ...........................................................45

Figure 21: Cyclic loading protocol ....................................................................................46

Figure 22: Cyclic results from SAPwood ..........................................................................46

Figure 23: nail location of SIPs .........................................................................................47

Figure 24: Load displacement curve results from SAPwood ............................................48

vi

Figure 25: Load-displacement curve of panel 1 (Terentiuk and Memari, 2012) ...............48

Figure 26: One-story residential building ..........................................................................50

Figure 27: Story level information .....................................................................................50

Figure 28: Design response spectrum ................................................................................52

Figure 29: One-story building with brick veneer walls .....................................................53

Figure 30: Building Drift ratio results for wood-frame .....................................................54

Figure 31: Peak story acceleration for wood-frame ...........................................................54

Figure 32: Building Drift ratio results for SIPs building ...................................................55

Figure 33: Peak story acceleration for SIPs building .........................................................55

Figure 34: Building Drift ratio results for wood-frame with brick veneer ........................57

Figure 35: Peak story acceleration for wood-frame with brick veneer .............................57

Figure 36: Building Drift ratio results for SIPs building with brick veneer ......................58

Figure 37: Peak story acceleration for SIPs building with brick veneer ...........................58

Figure 38: PACT interface .................................................................................................61

Figure 39: PACT interface (performance group) ...............................................................68

Figure 40: IDA results of Wood-frame building ...............................................................70

Figure 41: IDA results of SIPs building ............................................................................70

Figure 42: IDA results of wood-frame with BV ................................................................71

Figure 43: IDA results of SIPs with BV ............................................................................71

Figure 44: Wood-frame building w/o brick veneer repair cost..........................................73

Figure 45: Wood-frame building with brick veneer repair cost ........................................73

Figure 46: SIPs building w/o brick veneer repair cost .......................................................74

Figure 47: SIPs building with brick veneer repair cost......................................................74

vii

LIST OF TABLES

Table 1: Description of test specimens of SIPs (In-plane) ..................................................7

Table 2: SIPs testing results under racking load (Terentiuk and Memari, 2012) ................9

Table 3: In-plane SIP test results (Kermani and Hairstans, 2006) .....................................12

Table 4: SIP test results (Mosalam et al., 2008) ................................................................14

Table 5: Description of brick veneer panel (out-of-plane) ................................................15

Table 6: Test results of elastic phase (Reneckis and LaFave, 2004) .................................17

Table 7: Test results of intermediate phase (Reneckis and LaFave, 2004) .......................17

Table 8: Test results of ultimate phase (Reneckis, 2004) ..................................................17

Table 9: Test Specimen (Memari et al, 2006) ....................................................................20

Table 10: Test Results in drift (Memari, 2006) .................................................................21

Table 11: method name and data used (Porter et al., 2007) ...............................................25

Table 12: Fragility data of SIPs (in-plane) ........................................................................37

Table 13: Fragility data of brick veneer panel (out-of-plane) ............................................39

Table 14: Fragility data of glass panels with rounded corners (in-plane) ..........................40

Table 15: SIPs description (Terentiuk and Memari, 2012) ................................................43

Table 16: Wood-frame wall panel description (FEMA, 2012) ..........................................44

Table 17: Sheathing to framing connector hysteretic parameters (FEMA, 2009) .............44

Table 18: Shear wall hysteretic parameters .......................................................................49

Table 19: Earthquake information (FEMA, 2009) ............................................................51

Table 20: Period and spectral acceleration for each building system ................................56

Table 21: Median structure response .................................................................................59

Table 22: Median residual drift ..........................................................................................60

Table 23: repair cost breakdown for damage state 1 (brick veneer) ..................................63

Table 24: repair cost breakdown for damage state 2 (brick veneer) ..................................64

Table 25: repair cost breakdown for damage state 3 (brick veneer) ..................................65

Table 26: Repair cost for SIPs ...........................................................................................66

Table 27: Nonstructural component list .............................................................................67

viii

ACKNOWLEDGEMENTS

First, I would like to thank my parents for all the support financially and mentally, and

without them, these would all be impossible. I would also like to thank my thesis advisor,

Professor Ali M. Memari for his valuable comments and suggestions throughout the

research. This research could not have been completed absence of his guidance.

1

Chapter 1: Introduction

1.1 Background

Serious damage can be inflicted on structural and nonstructural components of buildings

during a seismic event. Failure of nonstructural components such as building facade can

cause costly damages and injuries or casualties and is therefore a serious life safety

concern. In order to better predict earthquake consequences, including repair costs and

downtime, and to help engineers achieve desired performance objectives, a second

generation performance-based earthquake engineering approach has been developed by

the Pacific Earthquake Engineering Research (PEER) center (FEMA, 2012a). Using this

methodology as basis, the Applied Technology Council (ATC) initiated a series of

projects known as ATC-58 in 2001 (FEMA, 2012a). In 2012, ATC prepared two seismic

performance assessment documents for Federal Emergency Management Agency

(FEMA) as part of the ATC 58 projects, FEMA P-58-1 and FEMA P-58-2, which include

the methodology and implementation approach for buildings (FEMA, 2012a&b). While

Volume 1 of FEMA document explains the methodology used to assess building

performance, Volume 2 of FEMA 58 provides detailed procedure and examples that

apply the methodology to individual structural or nonstructural component.

As a document that provides the procedure to assess probable seismic performance of

building components, FEMA 58 has gathered fragility data on some types of structural

systems, including RC moment frames, shear walls, slab systems, masonry walls, steel

moment frames, and braced frames. Some nonstructural systems, such as interior

partitions, ceilings, and stairs are also covered in this report. Although this report and

other relevant literatures provide some fragility function information related to certain

2

structural and nonstructural components, there is still a large knowledge gaps on fragility

data for various types of building components for use in the performance-based design

(PBD) procedure. For example, Structural Insulated Panels (SIPs) that are used as

structural load bearing components in light-frame buildings (e.g., residential) are

vulnerable to seismic related damage, yet no published fragility functions are readily

available. Similarly, brick veneer wall systems that are widely used as building facade of

various types of commercial and residential buildings have shown to have the potential

for life-safety hazard upon failure in an earthquake event, but no attempt have been made

to develop fragility functions for PBD application. Finally, although some efforts have

been made to develop fragility functions for certain types of glazing systems used as

curtain walls or windows (O’Brien et al., 2012), there are still several other types of

glazing systems that merit such development to allow their use in the PBD process. The

three mentioned systems (SIPs, Brick Veneer, and Glazing) have been studied

experimentally with test results available in open literature. This study has identified the

need for development of fragility function for the three selected wall and/or cladding

systems. Because the application of PBD method to buildings required all the structural

and nonstructural component types to be designed for a building already have fragility

function available.

1.2 Objectives

While the goal of this study is to contribute to performance-based seismic design of

buildings, the main objective of this study is to generate fragility data for some light-

frame systems such as structural insulated panels, and envelope systems such as brick

veneer wall and glazing systems. The results of this work will help supplement fragility

3

information available in the FEMA report (FEMA, 2012) and other relevant literature.

Building performance in terms of probability of repair cost for conventional wood-frame

buildings with and without brick veneer walls are also developed for comparison with

SIP systems under seismic event as a PBD case study.

This study initially presents a review of several past experimental test programs

(including specimens and data) that were used to develop the fragility curves. The

loading conditions and damage states of the specimens are included in the review. The

key references related to selected test results used in this study are described in Chapter 2,

which discusses the literature in detail. The fragility function development methodology

and PBD approach using fragility data are described in Chapter 3, while fragility function

development for selected systems is discussed in Chapter 4. Chapter 5 presents the

computer modeling and analysis of SIPs and wood-frame building using SAPwood.

Chapter 6 presents the PBD case study using fragility data developed, and Chapter 7

summarizes the results from this study.

The major tasks that were carried out in order to satisfy the objective are as follows:

Gather in-plane racking test results for structural insulated panels and glazing

system, and out-of-plane test results for brick veneer panels from previous

experimental studies and identify damage states and demand parameters for

specimens tested

Develop fragility functions for identified damage states of SIPs, brick veneer

panels and glazing systems

As a case study, create computer modeling of a simplified wood-frame and SIPs

building using SAPwood software and perform nonlinear analysis

Evaluate and compare performance of both wood-frame and SIPs building with

and without brick veneer panels using FEMA P-58 methodology

4

1.3 Research approach

In order to accomplish these research tasks and satisfy the stated objective, the

methodology and procedure used in this study were adopted from those provided by the

FEMA P-58 document (Seismic Performance Assessment of Buildings). Because

performing original tests was not in the scope of this study, it was necessary to identify

test data on SIPs, brick veneer panels, and selected glazing systems from previous

experiments and other published literature. Three racking test evaluation on SIPs

including previous work done at Penn State (Terentiuk and Memari, 2012; Kermani,

2006; Mosalam et al., 2008), one out-of-plane experiments done on brick veneers that

were found in literature, and some recent tests done at Penn State on glazing panels with

rounded corners were chosen as the data source for this study. With these available test

results, the data recorded served as engineering demand parameters (EDP) associated

with relevant damage states for fragility functions. Since fragility data was developed

from different testing facilities, the units were converted to keep consistency and for

comparison of the results from different test set-ups. For developing fragility information,

MATLAB was used to generate results in both graphic and numeric format. The PACT

software package published by FEMA was used to evaluate building performance using

the developed fragility data and other building information, while computer modeling and

structural analysis were performed by using SAPwood software (Pei and Van de Lindt,

2010).

5

Chapter 2: Literature Review Related to Testing

2.1 Introduction

In this chapter, selected literature related to testing different building envelope system

used for developing fragility data is discussed. The objective of this literature review is to

present the background needed to develop the fragility functions. The building envelope

and light-frame systems that are discussed in this chapter include brick veneer panels,

glass curtain walls, and structural insulated panels. These are all commonly used building

envelope or panelized light-frame systems for which some full-scale lateral load

experimental test results available. Major references that are used as sources of data to

develop fragility information and discussed in this Chapter include the following:

SIPs:

1. Racking resistance of SIPs (Kermani and Hairstans, 2006)

2. Seismic evaluation of SIPs (Mosalam et al., 2008)

3. In-Plane monotonic and cyclic racking load testing of SIPs (Terentiuk and

Memari, 2012)

Brick Veneer Panels:

1. Out-of-plane performance of brick veneer walls on wood frame construction

(Reneckis et al., 2004)

Glazing system:

1. Architectural glass panels with rounded corners to mitigate earthquake damage

(Memari et al., 2006)

6

2.2 Structural insulated panels (SIPs)

Background information

Structural insulated panels are widely used as a highly thermally insulated load bearing

light-frame wall systems in residential and light commercial structures. The prefabricated

panels are constructed with an insulating foam core sandwiched between two structural

sheathing boards, such as plywood or more widely used oriented strand board (OSB).

The panels have inherently high overall strength due to the sandwich construction with an

important advantage of reducing the need for on-site structural framing, thus minimizing

associated labor cost. Under out-of-plane loading conditions, a SIP panel behaves

structurally like an I-beam, where the core acts as the web and the OSB boards act as

flanges. (Kermani, 2006). Due to the use of rigid insulation layer, SIPs are also normally

known for their superior thermal energy efficiency compared to conventional wood-

frames. For this research, three relevant test programs were found to serve as the main

source of data to develop fragility functions. A total of six types of SIPs were found from

three different test programs that include monotonic and cyclic racking tests on SIPs.

Table 1 summarizes the SIPs test specimens from different sources under in-plane

loading. Panels 1-4 were constructed with external hold downs, while panels 5 and 6

were constructed without hold-downs. The hold-downs used in Terentiuk’s work were

United Steel products PHD6, and attached to both end posts of SIPs.

7

Table 1: Summary of test specimens of SIPs (In-plane)

Literature

SIP

Panel

Panel

ID

Panel-Panel

connection

Top

plate

Bottom

plate

End

posts

Fastener

Fastener

spacing

Hold-

down

In-plane

racking load

testing of

structural

insulated

panels

(Terentiuk

and Memari,

2012)

2400 x

2400 x

114mm

(8ft x 8ft

x 4.5in)

1

11.1 x

76.2mm (7/16

x 3 in) OSB

surface spline

single

38

x89mm

(2 x 4)

single

38

x89mm

(2 x 4)

double

38x89mm

(2 x 4)

8d common

nails

[3.3mm

(0.131 in)

diameter]

152mm

(6 in) o.c external

2

11.1 x

76.2mm (7/16

x 3 in) OSB

surface spline

single

38

x89mm

(2 x 4)

single

38

x89mm

(2 x 4)

double

38x89mm

(2 x 4)

16 gauge

staple

[1.6mm

(0.0625-in

dia) &

38mm (1.5-

in) long]

152mm

(6 in) o.c external

3

11.1 x

76.2mm (7/16

x 3 in) OSB

surface spline

single

38

x89mm

(2 x 4)

single

38

x89mm

(2 x 4)

double

38x89mm

(2 x 4)

No. 6

screws

[3.5mm

(0.138-in)

dia &

31.75mm

(1.25-in)

long]

152mm

(6 in) o.c external

4

Double 38 x

89mm (2 x 4)

spline

single

38

x89mm

(2 x 4)

single

38

x89mm

(2 x 4)

double

38x89mm

(2 x 4)

8d common

nails

[3.3mm

(0.131 in)

diameter]

152mm

(6 in) o.c external

Racking

performance

of SIPs

(Kermani

and

Hairstans,

2006)

2400 x

2400 x

117mm

(8ft x 8ft

x 4.6in)

5

Lapping 23.5

mm of OSB

boards over a

wall stud

Single

47 x

95mm

(1.85 x

3.75in)

Single

47 x

95mm

(1.85 x

3.75in)

Single 47

x 95mm

(1.85 x

3.75in)

2.65mm

(0.1in) dia

screws,

35mm

(1.4in) long

250mm

(9.8in)

o.c

None

eismic

evaluation of

SIPs

(Mosalam et

al., 2008)

2400 x

1200

x111mm

(8ft x 4ft

x 4-

3/8in)

6

Only one

panel was

tested

single

38

x89mm

(2 x 4)

single

38

x89mm

(2 x 4)

N/A

8d common

nails

[3.3mm

(0.131 in)

diameter]

152mm

(6 in) o.c None

8

2.2.1 In-Plane monotonic and cyclic racking load testing of structural insulated

panels (Terentiuk and Memari, 2012)

Loading protocol

In tests carried out by Terentiuk and Memari (2012), the bottom plate of the specimen

was attached to a sliding steel tube through cap screws spaced at 0.3 m, and the top of the

specimen where load is applied was attached with a MC8x20 steel channel that connects

to the top sliding steel tube. The cyclic loading protocol used was based on CUREE-

Caltech wood frame project that includes incrementally increasing amplitudes

(Krawinkler et al., 2001). Figure 1 shows the racking loading facility and the test

specimen setup. Figure 2 shows a plot of the loading protocol. Engineering demand

parameter measured during the test includes peak load and associated drift; the latter is

used in this study in developing fragility data. For panel specimen Types 1 and 2, each

type was tested twice (two specimens), and for panel specimen Types 3 and 4, three

cyclic tests were carried out (three specimens).

Figure 1: Wall panel elevation section, and loading condition (Terentiuk and Memari,

2012)

9

Figure 2: CUREE loading protocol

Test results

Four types of specimen configurations with external hold-down anchors were tested

under cyclic racking load, and the lateral drift was measured when maximum load was

achieved. The resulting test data are shown in Table 2. Figure 3 shows the load

displacement curve for specimen A3-1C.

Table 2: SIPs testing results under racking load (Terentiuk and Memari, 2012)

Panel ID Specimen Ultimate lateral drift mm(in) drift ratio (rad)

1 A1-1C 127(5) 0.0529

A1-2C 131(5.11) 0.0546

2 A3-1C 92(3.64) 0.0383

A3-2C 80(3.15) 0.0333

3

A4-1C 93(3.65) 0.0388

A4-2C 83(3.28) 0.0346

A4-3C 89(3.51) 0.0371

4

B-1C 131(5.15) 0.0546

B-2C 127(5) 0.0529

B-3C 137(5.4) 0.0571

10

Figure 3: Cyclic load displacement curve (Terentiuk and Memari, 2012)

Failure mode

According to Terentiuk and Memari (2012), the failure mode observed for Specimens A1

that used OSB spline with nail fasteners consisted of nail withdrawal along the spline and

at top and bottom plates. The OSB sheathing was also damaged on inner corners.

Specimens A3 that used OSB spline with staple fasteners experienced staple shear failure

along the spline, followed with staple shear failure along top and bottom plates.

Specimens A4 that used OSB spline and screw fasteners experienced screw shear failure

along the spline, and top and bottom plates, followed by pulling away from the top plate.

Specimens B that used double 38 mm x 89 mm spline with nail fasteners experienced

spline split failure and nail withdraw. Figure 4 shows the failure modes of these

11

specimens

(a) (b) (c)

(d) (e) (f)

Figure 4 (Terentiuk and Memari, 2012): (a) Staple shear (A3); (b) Panel disjointed (A4);

(c) screw shear (A4); (d) nail withdraw along spline (A1); (e) sheathing damage (A1); (f)

Panel separation

2.2.2 Racking resistance of structural insulated panels (Kermani and Hairstans,

2006)

Loading protocol

In tests carried out by Kermani and Hairstans (2006), racking loading was applied at a

constant rate of movement to the panels through a compression jacking device at the top

of the panel. Maximum load was measured at failure, which was prescribed as either

panel collapse or displacement of panels reaching 100 mm (Kermani and Hairstans,

2006). Since displacement record was not available, the peak force is used in this study as

EDP to develop fragility data.

12

Figure 5: Wall panel and loading condition (Kermani and Hairstans, 2006)

Test results and failure modes

Three specimens were constructed for each panel type, with test results presented in

Table 3 below. The failure mode for all three specimens was observed to be disjointing of

OSB panels from the soleplate.

Table 3: In-plane SIP test results (Kermani and Hairstans, 2006)

Panel ID Specimen Test ultmiate load(KN) Failure mode

5

Wall 1 11.5 OSB panels disjointed

from the soleplate Wall 2 12.5

Wall 3 12.8

13

2.2.3 Seismic evaluation of SIPs (Mosalam et al., 2008)

Loading protocol

In the tests carried out by Mosalam et al. (2008), three specimens were made for different

test procedures following the CUREE loading protocol (Krawinkler et al., 2001).

Specimen 1 was a test run before applying the full cyclic motion applied, and a number

of smaller amplitude cycles with loading rate at 1-3 in/sec. Specimen 2 was applied with

loading rate at 0.03-0.9 in/sec range and a reference displacement of 3 in was used.

Specimen 3 was tested with the loading rate of 0.15 in/sec, and the same reference

displacement 3 in. Peak load and displacement associated with it for each specimen were

measured. The displacement is used in this study as the EDP to develop fragility data.

Figure 6 shows the test set-up.

Figure 6: SIP test set-up (Mosalam et al., 2008)

14

Test results and failure mode

Three specimens were constructed and tested under cyclic loading. For each specimen,

the peak load observed and the associated displacement were recorded. At failure, all

three panels experienced OSB splitting, nail pull-out and foam crushing. Table 4

summarizes the test results.

Table 4: SIP test results (Mosalam et al., 2008)

Panel ID Specimen max load(KN) displacement(mm) drift ratio (rad) Failure mode

6

1 17.4 24.9 0.0102 OSB splitting at

connection, nail

pull-out and

foam crushing

2 9.8 47.7 0.0196

3 11.7 50.5 0.0207

2.3 Dynamic Out-of-Plane Performance of Brick Veneers Background Information

Brick veneer wall is a commonly used type of building envelope system in the US for

residential and commercial buildings. Such walls are normally considered nonstructural

components, which are not intended to carry the structural gravity or resist building in-

plane lateral loads. However, because of their function as exterior building envelope, they

are expected to resist out-of-plane wind load and their own seismic induced inertial loads

and transfer the reactions to the structural system; these walls as other envelope systems

are also expected to accommodate in-plane inter-story drifts. Another role of brick veneer

as an envelope system is to physically separate the building interior and exterior, which

provides resistance against air, water, heat, light, and noise effects to the building. Since

brick veneer is a nonstructural component, its function is to transfer the lateral load to the

structural frame of the building. During earthquake events, brick facade may have poor

performance in resisting out-of-plane inertial loads due to potential deterioration of

masonry metal ties. In-plane seismic induced drift conditions may pose potential hazard

15

due to possible damage and failure of the brick masonry panel. In the study reported by

Reneckis et al. (2004), dynamic out-of-plane performance of brick veneer panels was

evaluated through experimental testing. Experimental data were obtained through a series

of tests, which allows us to better understand more about the performance of brick veneer

under seismic loads.

Test Specimens

In the study reported by Reneckis et al. (2004), panels with wood-frame back up system

were tested for out-of-plane loading conditions for a wall system in a typical residential

house. The wall panel had dimensions of 3.37 m long and 2.87 m tall, and the wood

frame back up consisted of 38 mm x 89 mm wood stud spaced at 406 mm o.c. with OSB

sheathing. The wood frame was also attached to concrete foundation and floor framing on

top. The bricks used for constructing veneer were 89 mm x 194 mm x 57 mm modular

with type N mortar. Corrugated sheet metal ties were used to connect brick veneer and

the wood frame backup wall, and each tie was attached to the backup through 8d nails.

Figure 7 shows an elevation view of the test set up.

Table 5: Description of brick veneer panel (out-of-plane)

Reference

Wall

Panel

Panel

ID

Wood-frame

backup

Brick Veneer

wall Connection Spacing

Out-of-plane

performance

of brick

veneer walls

on wood-

frame

construction

(Reneckis et

al., 2004)

3370 long

x 2870 tall

mm ( 11 x

9.4 ft)

1

38 x 89mm wood

stud spacing at

406 mm with

OSB sheathing

89 x 194 x 57 mm

modular bricks

with type N

mortar

Corrugated sheet

metal ties and 8d

nails

406 mm

horizontally

and 610 mm

vertically

16

Figure7: Out-of-plane load test set up of the brick veneer panels (Reneckis et al.,

2004)

Test Method

A total of two wall specimens were tested on a shaking table facility in Reneckis et al.

(2004) study. Three earthquake records, M10, M2, and Nahanni with Richter magnitudes

of 6.7, 8.0, and 6.9 respectively, were selected for this test, including two synthetic

motion and one real earthquake data. The displacement and acceleration at top of the

brick veneer panels were measured throughout the test.

Test Results

The results were recorded through different levels of earthquake input and specimen

response. There were three levels of response, including elastic phase where no visible

damage occurred, intermediate phase where tie and veneer started to sustain damage, and

ultimate phase where tie damage was sufficient to cause veneer collapse.

17

Table 6: Test results of elastic phase (Reneckis et al., 2004)

Elastic Phase

wall 1

Top of brick veneer

PGA

(g) Acc. (g) Displ.

(mm) Drift Ratio (rad)

0.19 -0.38 1 0.0003

0.22 -0.47 1.6 0.0006

0.37 0.84 3.8 0.0013

wall 2

0.19 0.79 7.2 0.0025

0.23 1.52 9.3 0.0032

Table 7: Test results of intermediate phase (Reneckis et al., 2004)

Intermediate Phase

wall 1

Top of brick veneer

PGA

(g)

Acc.

(g) Displ.

(mm) Drift Ratio (rad)

0.51 1.09 7.3 0.0025

0.58 - - -

0.3 1.39 7.7 0.0027

wall 2

0.2 0.68 6.2 0.0022

0.22 -0.91 7.8 0.0027

0.24 0.75 7.8 0.0027

Table 8: Test results of ultimate phase (Reneckis et al., 2004)

Ultimate Phase

wall 1

Top of brick veneer

PGA

(g)

Acc.

(g) Displ.

(mm) Drift Ratio (rad)

0.66 2.19 17.5 0.0061

0.64 -5.01 42.9 0.0149

Wall2

0.3 1.07 11.4 0.0040

0.3 0.98 9.7 0.0034

0.41 1.63 13.2 0.0046

0.31 1.23 11.9 0.0041

0.49 -2.98 46.9 0.0163

18

Failure mode

During the elastic phase of the test, no visible damage occurred until the end of this phase

where cracks were seen at mortar to concrete foundation interface. During the

intermediate phase, ties and nails that were used to connect the veneer panel and back up

wall started to fail, but not sufficient to cause collapse of the whole panel. During the

ultimate phase, the connection failure became large enough and could no longer hold the

brick veneer panels. The panel collapsed as shown in Figure 9 when it moved away from

the backup wall.

Figure 8: (a) tie fracture; (b) nail pull out; (c) partial tie failure (Reneckis et al., 2004)

Figure 9: failure of brick veneer panels (Reneckis et al., 2004)

19

2.4 Dynamic racking tests of curtain wall glass elements

Background Information

Due to potential life safety hazard posed by glass curtain wall failure under earthquake

conditions, better understanding of seismic performance of this type of nonstructural

component building façade is needed. Also, studies have shown that up to 40 percent of

replacement value of a building is from nonstructural building elements (Pantelides et al,

1993). Below is a description of an in-plane racking test program to simulate seismic

effect on a certain type of curtain wall system that includes glass panels with rounded

corners (Memari et al, 2006).

Test Specimen and loading condition

In the study reported by Memari et al (2006), 14 types of monolithic glass panels were

tested as listed in Table 9, including annealed, heat-strengthened, and fully tempered. The

configuration of the glass panels for all tests is 1.52 m x 1.83 m x 6 mm, and corner and

edge finish for each type is also described below. The glass panels were all installed

within a dry-glazed wall system, where rubber gaskets are used to anchor the glass

perimeters with aluminum frame.

Dynamic racking crescendo tests were performed on the specimens with mullions

anchored to sliding steel tubes. The loading protocol included a series of increasing

amplitude intervals, with each interval having four sinusoidal cycles at 0.8 Hz for drift

from 0 to 76mm and 0.4 Hz for drift from 76mm to 152mm (Memari et al, 2006).

20

Table 9: Test Specimen (Memari et al, 2006)

Literature Glazing

panel

Panel

ID

Monolothic

glass type

Corner radius

mm(in)

Edge

finish Corner finish

Glazing

panels with

rounded

corners

(Memari et

al., 2006)

6mm (thick)

x 1.52m

(wide) x

1.83m

(high)

[0.25in x 5ft

x 6ft]

1 6 mm AN 0 (square) Cut Cut

2 6 mm AN 13 (0.5) Cut Ground

3 6 mm AN 19 (0.75) Cut Ground

4 6 mm AN

25 (1)

Cut Ground

5 6 mm AN 76 (3) Cut Ground

6 6 mm AN 25 (1) Seamed Ground

7 6 mm AN 19 (0.75) Flat Polish Flat Polish

8 6 mm AN 25 (1) Flat Polish Flat Polish

9 6 mm HS 0 (square) Seamed Seamed

10 6 mm HS 19 (0.75) Flat Polish Flat Polish

11 6 mm FT 0 (square) Seamed Seamed

12 6 mm FT 25 (1) Seamed Rough Ground

13 6 mm FT 0 (square) Flat Polish Flat Polish

14 6 mm FT 25 (1) Flat Polish Flat Polish

Test Results and Failure Mode

Two damage states observed in this study included glass cracking and glass fallout.

Cracking drift is the horizontal displacement at which cracking of the specimen occurs,

and fallout drift is the displacement at which a glass fragment larger than 645 mm2 falls

from the specimen.

For annealed specimens, average cracking drift for rounded corner glass panel was 32%

larger than for square corners, and fallout drift was 24% larger. The positive effect of

rounded corners can also be seen in HS and FT glasses. For HS glass specimens, a 49%

increase in cracking drift and a 43% improvements of fallout capacity was observed.

Table 10 list the test data recorded for each specimen and Figure 10 shows an example of

glass cracking.

21

Table 10: Test Results in drift (Memari, 2006)

Panel

ID

No. of

specimens cracking drift (mm) fallout drift (mm)

1 6 [38.1,38.1,38.1,38.1,38.1,44.5] [44.5,44.5,44.5,44.5,44.5,44.5]

2 4 [63.5,50.8,50.8,57.2] [69.9,50.8,50.8,63.5]

3 3 [57.2,44.5,50.8] [57.2,50.8,57.2]

4 2 [50.8,44.5] [50.8,50.8]

5 1 [44.5] [50.8]

6 3 [76.2,69.9,76.2] [82.6,69.9,82.6]

7 1 [44.5] [63.5]

8 1 [50.8] [63.5]

9 8 [76.2,57.2,57.2,50.8,63.5,57.2,69.9,63.5] [82.6,57.2,57.2,63.5,63.5,57.2,69.9,63.5]

10 2 [88.9,95.3] [88.9,95.3]

11 7 [76.2,57.2,69.9,88.9,69.9,76.2] [76.2,57.2,69.9,88.9,69.9,76.2]

12 4 [50.8,44.5,44.5,44.5] [50.8,44.5,44.5,44.5]

13 3 [82.6,82.6,82.6] [82.6,82.6,82.6]

14 6 [108,108,120.7,95.3,120.7,108] [108,108,120.7,95.3,120.7,108]

Figure 10: Cracking of rounded corner glass

22

2.5 Summary

A considerable number of in-plane racking tests and out-of-plane loading tests has been

carried out on various type of building envelope systems to predict their performance

under seismic loading conditions. There is also some research available on developing

fragility curve for the structural and nonstructural component systems. However, very

few of these tests have been used to develop the fragility curve of these building façades.

An example of fragility development for glazing systems is presented by O’Brien et al.

(2012). Due to the lack of information on fragility curves of nonstructural elements like

building facade, this research took advantage of existing test results and would follow the

approach by O’Brien et al. (2012) to develop fragility functions of structural insulated

panels, curtain wall system with rounded corner glass, and brick veneer panels.

Resources used related to testing have been presented in this chapter. The literature

review and study revealed that SIP systems and brick veneer wall systems have been

studied extensively for testing, as these systems are widely used in building construction.

The rounded corner glass curtain wall system was also chosen as a system that has been

developed with potential for seismic damage mitigation; the fragilities to be developed

for this system will complement the work done by O’Brien et al. (2012). Furthermore,

using the fragility data developed in this study, loss analysis was performed on a typical

residential building to show an example application of fragility information. A baseline

conventional wood-frame system commonly used for residential buildings was also used

for better evaluation of the performance of the structural insulated panel system; both SIP

and wood-frame systems with brick veneer attached are considered in this study.

23

Chapter 3: Fragility function development methodology & PBD

approach

In this chapter, the methodology and procedure used to develop fragility functions are

described. PBD approach and procedure that utilizes fragility data developed in this study

are also presented in detail. In this study, PBD procedure discussed in FEMA P-58 for

evaluating building performance is followed and presented in this chapter. Computer

software SAPwood is used for structural modeling and analysis in this study; and its

major function and the basis of numerical modeling of the software are also explained in

this chapter.

3.1 Fragility function development methodology

According to FEMA (2012a), “Fragility functions are statistical distributions used to

indicate the probability that a component, element, or system will be damaged as a

function of a single predictive demand parameter, such as story drift or floor

acceleration” (FEMA, 2012a). As the primary goal of this study, fragility data were

developed for selected building system types that are widely used but lack fragility

information derived based on experimental test results.

The method to create fragility functions for performance-based earthquake engineering

has been extensively discussed by Porter et al (2007), and later it was adopted and

implemented in the PACT software (FEMA, 2012a). According to the FEMA document,

“the fragility functions are statistical distributions that indicate the conditional

probability of incurring damage at a given value of demand”. In this research study, both

structural and nonstructural components were considered in developing fragility curves.

24

Some of the information and data that is required for development of fragility functions

are as follows:

1. Details of specimens: for a given building, it is necessary to know the types of

building components, and their configurations, and the types of materials and

their properties. In addition, the number of times specimens were tested and the

boundary conditions for each test need to be stated.

2. Loading details and EDP: The excitation to which the specimen is subjected to

should be described in detail. Engineering demand parameters (EDP) should be

defined based on previous test results with values at identified and recorded

damage states. The engineering demand parameter such as velocity, acceleration,

deformation or force can be either measured or derived from other measured

parameters recorded during the tests.

3. Damage state: The type of damage the building component is expected to

experience needs to be addressed as the fragility curve is developed based on

damage states such as cracking and fallout failure of the envelope system.

4. Test data summary and fragility determination method: The process that is used to

determine the method for developing fragility function and its description are

discussed in detail by Porter et al. (2007). Six methods have been suggested, with

each method depending on the level of details provided. Table 11 shows the

method associated with each type or level of corresponding data (Porter et al.,

2007). Later in the study, each data source will be listed and the manner in which

the associated method is used to develop fragility curve for that data will be

described.

25

Table 11: Method name and data used for developing fragility function (Porter et

al., 2007)

Method name Data used

A. Actual failure EDP All specimens failed at observed values of EDP

B. Bounding EDP Some specimens failed; maximum EDP for each is known

C. Capable EDP No specimens failed; maximum EDP for each is known

D. Derived fragility Fragility functions produced analytically

E. Expert opinion Expert judgement is used

U. Updating Enhance existing fragility functions with new method-B data

The primary function used for fragility of a damage state is denoted as Fdm(edp), a

function of engineering demand parameter. At a given EDP, this function will give the

probability the structural or nonstructural component reaches or exceeds that damage

state. In this study, the components for fragility development will be structural insulated

panels, brick veneer panels, and rounded corner glass curtain wall system. A fragility

function Fdm(edp) that describes a cumulative distribution is defined as follows.

Fdm(edp)=P[DM≥dm│EDP=edp] (1)

Fdm(edp)= Φ (ln(

𝑒𝑑𝑝

𝑋𝑚)

𝛽) (2)

In these equations, the results of which can be calculated and plotted in Microsoft Excel or

MATLAB, Xm represents the median value of the distribution, and β represents the

logarithmic standard deviation. EDP denotes an engineering demand parameter, dm

denotes damage states, while Φ stands for the standard normal cumulative distribution

function. With the general equation given, in order to calculate the fragility function, both

Xm and 𝛽 are needed. The method to determine these two parameters depends on the

availability and informative level of the data gathered.

26

Method A: Actual failure EDP

Method A may be used if an informative set of data is available and the exact demand

parameter is recorded at the defined damage states. In this case, a force or displacement

(e.g., cracking of the panels) may have been recorded for a damage. Other failure criteria

such as collapse condition or a certain displacement of the panel can also be defined. This

method (Method A) was chosen in this research study since the tests selected have EDP

recorded at each damage state desired. In order to account for the uncertainty of variability

of tests and accuracy of dispersion from test results due to limited number of test sample,

Equation (5) presents the total dispersion for fragility function. The value 0.25 was used in

this case as recommended by FEMA P-58 (2012a). The test results used matched the

conditions described in using 0.25 as additional uncertainty: (1) Test specimen equal or

fewer than five (2) All specimens tested were in the same configuration.

𝑋𝑚 = exp (1

𝑀∑ 𝐿𝑛(𝑅𝑖))𝑀

𝑖=1 (3)

𝛽 = √1

𝑀−1∑ (𝐿𝑛 (

𝑟𝑖

𝑋𝑚)) ^2𝑀

𝑖=1 (4)

𝑇𝑜𝑡𝑎𝑙 𝛽 = √𝛽2 + 0.252 (5)

M = number of specimens tested to failure

I = index of specimens

Ri = EDP recorded when damage occurred for specimen i

27

3.2 PBD approach

Figure 11: Flowchart of loss analysis using FEMA methodology

In this study, a PBD case study was developed to present the application of fragility data

generated consistent with the PBD procedure defined by FEMA. The new PBD (second

generation) was initiated by FEMA for several reasons, including reliability of available

techniques to predict building response, conservatism of current procedure, and the need

for communicating performance with other stakeholders (FEMA, 2012a). As part of

FEMA’s effort to facilitate the use of PBSD, FEMA P-58 focuses on seismic

performance assessment of buildings, and a detailed guideline and procedure on assessing

performance was provided. With this procedure available, the case study presented in this

thesis focused on evaluating seismic performance of a residential building in terms of

probability of repair cost which is an important part of the performance-based design

process. Details of the procedure and approach of this methodology are explained in

detail in this section.

Figure 11 shows a flow chart of the process of loss analysis in order to determine

building performance in terms of repair cost, i.e., the probability of repair cost for a

building. The procedure includes developing building model and computer analysis in

28

SAPwood, determining fragility data and repair cost data for SIPs, brick veneer panels,

and wood-frame walls, and how probability of repair cost are determined.

3.2.1 Repair Cost Development Methodology

The repair cost includes estimation of labor cost, material cost and collateral labor work

such as scaffolding when doing the repair work. In order to take into account the

uncertainty, the dispersion of repair cost is determined from cost data at 10th, 50th and 90th

percentile of construction cost which is based on judgement as suggested in FEMA P-58.

Like the fragility curve, the repair cost also has a median cost and dispersion for each

quantity. Unit cost associated with lower bound and upper bound quantities also needs to

be addressed. The final repair cost for each component is determined based on quantities

needed and its dispersion. Figure 12 shows a typical example of repair cost function

where the unit cost would decrease as the quantity increases. In this study, repair costs

were developed based on cost data found from literature.

Figure 12: Example of repair cost function (FEMA, 2012a)

29

3.2.2 Computer Modeling Using SAPwood

As a structural component like conventional wood-frame, structural insulated panels have

an inhomogeneous characteristic, large variability in mechanical properties, and

nonlinear connection response (Folz and Filiatrault, 2004). To be able to model light-

frame wood buildings with consideration of such aspects, Pei and Van de lindt developed

SAPwood through a four-year NEESwood project (Pei and Van de Lindt, 2010). In the

study presented here, SIPs and wood-frame models will be developed and nonlinear

analysis will be performed using SAPwood (Pei and Van de Lindt, 2010).

Structural model of SAPwood

In SAPwood, both nonlinear time-history analysis and nonlinear pushover analysis can be

performed taking into account the hysteretic behavior of the structure components. The

authors of the SAPwood program adopted the concept of Seismic Analysis of

Woodframe Structures (SAWS) and the computer program for the Cyclic Analysis of

SHEar Walls (CASHEW) developed by Folz and Filiatrault (Folz and Filiatrault, 2004).

In this software, building elements that can be modeled include shear walls, interior

partition walls, floor, and roof diaphragms. Both roof and floor diaphragms are modeled

as rigid elements for analysis. Three-dimensional buildings can be modeled as planar

model with no overturning effect so that shear walls act like nonlinear spring model,

which connect horizontal diaphragms to assumed rigid foundation. In this study, all SIP

panels are assumed to be equivalent SDOF nonlinear shear elements as shown in Figure

14. The sloping roof is modeled as rigid diaphragm as well in this program. The 10-

parameter model as shown in Figure 15 describes, a hysteretic model for seismic analysis

of shear walls, that can be used to model the load-displacement behavior of shear wall

30

elements under earthquake motion in SAPwood program. The rigid diaphragm

assumption is based on the aspect ratio of 2:1. The limitation to this model is that it does

not account for the effect of overturning and in-plane flexural behavior of shear walls.

However in low-rise wood frame building, these effects are not very significant compare

to shear. (Folz and Filiatrault, 2004)

Figure 13: Components of a single-story wood-frame structure (Folz and Filiatrault,

2004)

Figure 14: Single story wood-frame structure model (Folz and Filiatrault, 2004)

31

Figure 15: 10-parameter model (Pei and Van de Lindt, 2010)

32

3.2.3 Building performance evaluation procedure

As discussed earlier, test results for SIP and brick veneer are used in this study to develop

fragility data, and repair cost for chosen damage states are estimated as well. The use of

SAPwood software can help us determine collapse fragility and building response. After

determining the building response under 11 different seismic excitation (as suggested by

Huang et al., 2008), responses (e.g., drift ratio, floor acceleration) are organized in a

demand parameter matrix automatically in software PACT. Additional model uncertainty

that accounts for accuracy of model, which is a value based on judgement are also

provided by FEMA document and as an input to the PACT program. The PACT program

accounts for the additional uncertainty and generates a new demand set that better fits the

actual response of a building would experience. With these inputs, three main targets are

to be defined, performance group, building response, and collapse fragility of the

building. As the final outcome, building performance is expressed in terms of probability

of repair cost for a specified ground intensity for different types of SIPs with and without

brick veneer, and is compared to wood-frame buildings with and without brick veneer.

The probability distribution is determined by repeating calculation of damage and repair

cost for a large number of realization. Realization is a term that defines one possible

outcome of the building for a particular seismic intensity, and thus it represents one

repetition of performance assessment. Figure 16 shows the process of how building

performance is assessed under each realization. After a large number of realizations are

performed, the performances in terms of repair cost for each realization are determined

and outcome are sorted in ascending order. For example, if 1000 realizations are

performed, the repair cost that has 50% probability of exceedance is the 500th largest cost

33

in those 1000 realizations. Since 1000 repair costs are generated through 1000

realizations, and 500th largest cost among 1000 repair costs means there are 500 repair

costs in those 1000 that are larger than this cost. In probabilistic terms, one can then say

there is 50 percent of chance that repair cost will be likely more than this number in real

life.

Figure 16: Process of performance assessment under each realization (FEMA, 2012a)

Performance group assembly: Performance group includes both structural and

nonstructural components such as exterior windows and doors and MEP systems.

Applicable nonstructural components are estimated using the spreadsheet provided by

FEMA. The fragility data and consequence data for SIPs and brick veneer panels are

developed in this study. Fragility and repair cost data for wood-frame system as a

34

structural component and nonstructural component such as MEP, doors and windows are

already developed and adopted in FEMA database which is in PACT software.

Building response: Building response is determined by performing nonlinear dynamic

analysis using SAPwood. As mentioned earlier, 11 earthquake ground motion are used,

and nonlinear wall models are developed based on previous test results from Terentiuk

and Memari (2012). According to FEMA document, 11 earthquake motion record is

recommended when chosen with random selection, and can provide a reasonable estimate

of median response (+/-20%) (FEMA, 2012a). This value is obtained from previous

research of using 11 earthquake motion records from Huang (Huang et al., 2008). The

demand parameters calculated from SAPwood will then be used to determine damage and

repair cost.

Collapse fragility: Collapse fragility defines the probability of collapse of a building, and

this is determined by performing incremental dynamic analysis. For each realization, the

response of the building is determined as collapsed or not collapsed at a specified

earthquake intensity. In each realization, the system will generate a random number from

1 to 100; if the number is larger than probability of collapse, then the building is

considered collapsed, otherwise, it is not expected to collapse. If collapsed, repair cost is

the total replacement cost of the building. If not collapsed, damage and repair cost is then

be calculated.

Residual drift: Residual drift is an important factor in determining whether the building is

repairable after earthquake. Large residual drift can lead to safety concern for repairing

due to instability of structure, and economical concern if the repair cost is almost the

same as the cost of replacing the building. In this study, residual drift is estimated using

35

equation provided by FEMA document, as described below. ∆ represents the story drift,

∆y represents the yield drift and ∆r is the residual drift. In this study, the median residual

drifts for both wood-frame and SIPs building are estimated, and a dispersion of 0.8 is

applied as suggested in FEMA document. The irreparable residual drift is set at 1%

residual drift ratio with a default dispersion of 0.3 (FEMA, 2012).

∆r = 0 for ∆ ≤ ∆y (6)

∆r = 0.3 (∆ - ∆y) for ∆y < ∆ < 4∆y (7)

∆r = (∆ - 3∆y) for ∆ ≥ 4∆y (8)

36

Chapter 4: Fragility Function Development for Selected Systems

Test results and the methodology used for developing fragility data have been discussed

in detail in previous chapters. This chapter presents the fragility data developed for those

systems including structural insulated panels, brick veneer panels, and glass panels with

rounded corners. The results are in tabular format with median response, dispersion value

and damage state described for each panel; the fragility curves are also plotted for brick

veneer panels, glass panels and selected SIPs. For SIPs and glass panels, multiple test set-

ups from different sources were used to develop fragility data; thus, one can choose to

use these data that is closest to actual condition in the field.

4.1 Structural Insulated Panels

Based on test results from past experimental studies, and data processed using

methodology described earlier, Table 12 summarizes the fragility data for all SIP types

considered under in-plane loading. Damage states for each panel type are also included in

the tables. A sample fragility curve plotted using MATLAB is shown in Figure 17, which

presents the probability of failure for each type of SIPs considered. The figure shows that

structural insulated panels with 8d nails fasteners have a significant advantage in racking

performance compared to the ones with screw or staple fasteners. At drift ratio of 0.4 rad,

the probability of failure is only 10%, while with screw or staple fasteners, the probability

increases to 70%. Panel 6 had similar set-up as Panels 1 and 4, but it only had half their

length, so it is reasonable to see its median response at failure is slightly lower than half

of the value from Panel 1 and 4.

37

Table 12: Fragility data of SIPs (in-plane)

Reference

(in-plane)

Panel

ID Xm β Damage state

(Terentiuk and

Memari, 2012)

1 0.0537

(rad) 0.25 Initial nail withdrawal along spline, and top and bottom plates;

sheathing damage on inner corners of panels

2 0.0357

(rad) 0.269 Staple shear along spline and top plate, and withdraw along

base plate

3 0.0368

(rad) 0.257 screw shear along spline and top and bottom plates; top plate

pulled away from sheathing

4 0.0548

(rad) 0.253 double 2 x 4 split apart; nail withdrawal and sheathing failure

along top and bottom plate

(Kermani and

Hairstans, 2006) 5

12.25

(kN) 0.256 OSB panels were disjointed from sole panel

(Mosalam et al,

2008) 6

0.0201

(rad) 0.253

OSB split at top and bottom connections where nails pull out;

foam crushing at the end of panels

38

Figure 17: Fragility curve for Panel 1 – 4

4.2 Brick Veneer Panels

For fragility development of brick veneer panels, out-of-plane test results carried out by

Reneckis et al. (2004) were used. Two wall samples were tested on a shaking table, and

acceleration at top of the veneer was measured for different stages during the test. Thus,

in this case acceleration was used as EDP to develop fragility data for the following three

damage states: initial tie fracture, further tie failure, and veneer collapse. Table 13

presents the fragility data along with description of damage states; details of the testing

can be found in literature review presented in Chapter 2.

0 0.02 0.04 0.06 0.08 0.1 0.120

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

drift ratio (rad)

pro

babili

ty o

f fa

ilure

(%

)

Fragility Curve for Structural Insulated Panels with different connections at failure

spline connection with 8d nails(Panel 1)

spline connection with staples(Panel 2)

spline connection with screws(Panel 3)

double 2x4 connection with 8d nails(Panel 4)

39

Table 13: Fragility data of brick veneer panel (out-of-plane)

Reference (out-of-plane) Panel

ID

Acc

(g) β Damage state

Brick Veneer Walls (Reneckis et

al., 2004) 1

0.98 0.4 Initial tie fracture in the left corner of top row of the

tie connection

1.43 0.438 Further tie failure in upper row of connection

(fracture and nail pullout)

3.86 0.444 Veneer collapse about horizontal crack at around

mid-height of wall panel including all upper row

ties

Figure 18: Fragility curve of brick veneer panels for three damage states

40

4.3 Glass panels with rounded corners

For fragility development of glass panels with rounded corners, the results of tests carried

out by Memari et al. (2006) was used. Under in-plane cyclic testing, drift was measured

for glass cracking and fallout for 14 glass types including rounded corner glasses and

square corner glasses. For fragility development, drift ratio was used as EDP, and

fragility data can be found in Table 14. In development of fragility curve, for better

comparison, fragility data are organized into three groups which are annealed glass, heat-

strengthened glass and fully tempered glass, as shown in Figure 19.

Table 14: Fragility data of glass panels with rounded corners (in-plane)

Reference (in-plane)

Panel

ID

Glass Cracking Glass Fallout

Xm (rad) β Xm (rad) β

Glazing panels with rounded corners

(Memari et al., 2006)

1 0.0213 0.258 0.0243 0.25

2 0.0303 0.272 0.0318 0.297

3 0.0277 0.28 0.03 0.259

4 0.026 0.268 0.0278 0.25

5 0.0243 0.25 0.0278 0.25

6 0.0404 0.255 0.0427 0.268

7 0.0243 0.25 0.0347 0.25

8 0.0278 0.25 0.0347 0.25

9 0.0336 0.28 0.0349 0.28

10 0.05 0.255 0.05 0.255

11 0.04 0.289 0.0396 0.289

12 0.0251 0.259 0.0251 0.259

13 0.0451 0.25 0.0451 0.25

14 0.06 0.265 0.06 0.265

41

42

43

Figure 19: Fragility curves for rounded corner glass panels

44

Summary

The fragility data and fragility curve are presented and listed in this chapter for six types

of SIPs (In-Plane), one type of brick veneer facade (Out-of-Plane) and fourteen types of

glass panels. The damage states considered for glass panels are cracking and fallout,

while multiple stage of damage including final failure damage state are considered for

brick veneer walls, and failure damage state is studied for SIPs.

For SIPs of size 2400x2400 (mm), the failure median drift ratio ranges from 0.035 to

0.055 based on different connection used. SIPs of 1200x2400 (mm) has a median failure

drift ratio of 0.02 which is about 50% of the average value of a full size SIPs. When nails

are used as connectors, the 2400x2400 (mm) SIPs could increase its failure drift by 50%

compared to staple or screw connectors. Other than the failure at connections, the damage

state for each panel is very similar, that are connection failure at top and bottom plate,

and sheathing and insulation damage at corners.

For brick veneer facade, acceleration is used as EDP for evaluating fragility data at three

damage states including veneer collapse as final failure damage. The results showed that

this type of nonstructural component could sustain a high acceleration before major

damage would occur. The median acceleration for veneer collapse is 3.86g, which means

for this set-up of brick veneer walls, they are very unlikely to collapse during seismic

event.

Fourteen types of glass panels are studied and fragility data are developed. The results

showed that the drift at where glass crack are very close to the drift when glass fallout for

most of the types, and the difference are within 10% of the drift. The exceptions are type

7 and 8, which are 6mm annealed panels with corner radius of 19 mm and 25 mm

45

accordingly. The finish of the corners are flat polish, while other edge finish of the same

type does not have a significant gap between glass fallout and glass cracking. The glass

panels for these two types can sustain 40% more drift after the glass cracked until

reaching fallout failure.

All of the fragility data developed in this study are based on experimental testing and

results from published literatures. These data can be used towards performance-based

design, and a case study using the fragility data is also presented in later chapters in this

study.

46

Chapter 5: Computer modeling and analysis

In this research, computer modeling is used in order to determine the response of SIPs

and wood-frame buildings under seismic load that will later be used with fragility data

and repair cost data to evaluate building performance. Fragility data defines the

probability of damage under a specified demand parameter such as story drift, while

computer modeling and analysis simulate the demand parameter for a building. The goal

of this chapter is to determine the building response in terms of the chosen demand

parameter, and relate it to a probable damage and repair cost associate with it. In this

chapter, each step of the model development will be presented with screenshots from the

software, along with figures and tables.

5.1 Shear Wall Modeling

SIPs and a conventional wood-frame wall were modeled in SAPwood program (Pei and

Van de Lindt, 2010). Table 15 presents the SIPs wall detail used for structural modeling

in this study, while Table 16 presents the wood-frame wall detail that is going to be

modeled in SAPwood; the information is provided by FEMA document wherein fragility

and repair cost data are already available for this wall panel.

Table 15: SIPs description (Terentiuk and Memari, 2012)

SIP

Panel Panel-Panel connection

Top

plate

Bottom

plate

End

posts fastener

fastener

spacing

Type-

1

11.1 * 76.2 mm (7/16 *

3 in.) OSB surface

spline

single 2

x 4

single 2 x

4

double 2

x 4

8d common

nails (0.131

in. diameter)

152 mm (6

in.) o.c

47

Table 16: Wood-frame wall panel description (FEMA, 2012b)

Wood-frame wall panel Wall description Panel fastener

fastener

spacing studs

Light frame wood walls

with structural panel

sheathing, gypsum

wallboard with hold-

downs

2400mm by 2400 mm (8ft

by 8ft) without doors or

windows opening, double

top plate, single bottom

plate, no hold-down

3/8 in

OSB or

15/32 in

plywood

8d box

nails

100mm (4in)

to 150 mm(6

inch) o.c.

along edge,

300mm(12

in) o.c. field

nailing

DF #2 2x4

Wood-frame shear wall

NP analysis tool is a function in SAPwood that helps modeling shear walls defined by

user with components (studs and panels) and fasteners (nail, screw) information, and

perform monotonic and cyclic loading analysis on the shear wall models. The SAPwood

program relies on the NP analysis tool to model wood frame wall sections defined by

user for displacement – controlled loading protocol analysis. The NP analysis enables

nonlinear hysteretic behavior of the wall section to be defined and used later in the

building model level. Both 16-parameter hysteretic model and the 10-parameter SAWS

type hysteretic model are available for nonlinear analysis in this program. (Pei and Van

de Lindt, 2010). Table 17 lists the hysteretic parameters for fasteners that were used to

develop wood-frame shear wall model, and were obtained from FEMA P-695.

Table 17: Sheathing to framing fastener hysteretic parameters (FEMA, 2009)

Connector Type K0

(N/mm) F0 (N) F1 (N) r1 r2 r3 r4

∆u

(mm) α β

7/16" OSB - 8d common nails

1163 1014 142 0.026 -0.039 1 0.008 13 0.7 1.2

48

The wood-frame shear wall model developed represents a 2400mm by 2400mm (8ft by

8ft) panel with 11.1mm (7/16 in.’’) OSB sheathing and studs at 406mm (16 in.) O.C, and

a top and bottom plate. The edge nails were spaced at 6 in, while the field nails were

spaced at 12 in. Figure 20 shows the screenshot from the program interface for

developing the model. With the shear wall model, the hysteretic parameter was then

determined using a displacement-controlled loading protocol defined in the software. The

wood-frame shear wall model using the connection hysteretic parameters has been

proved to have a good accuracy compared to experimental results in FEMA P-695

(FEAM, 2009). Figure 21 shows the loading protocol used to test the shear wall model,

and Figure 22 shows the cyclic results generated from SAPwood.

Figure 20: Nail location of wood-frame shear wall

49

Figure 21: Cyclic loading protocol

Figure 22: Cyclic results from SAPwood

This cyclic result had a peak force of about 27 KN (6000 lb) when 41 mm (1.6 in.) of

displacement is reached, and this is identical to the results from experimental testing for

an identical set-up of shear wall (Line et al., 2008).

-30000

-20000

-10000

0

10000

20000

30000

-80 -60 -40 -20 0 20 40 60 80 100Forc

e (N

)

Displacement (mm)

Wood-frame cyclic results

50

SIPs wall model

SIPs wall model is also developed using SAPwood in this study. The procedure is

basically the same as for developing wood-frame model. The model represents an

2400mm by 2400mm (8ft by 8ft) SIP panel with vertical studs spaced at 1219 mm (48 in)

and nail spaced at 152 mm (6 in.) o.c., which is Panel Type 1 in this study. Figure 23

shows the stud and nail locations for the model. Since SIPs has sheathing on both sides,

and it is not available in the program to model on both sides, the nail spacing in the

model was reduced to 76 mm (3 in.) to represent nail spacing at 152 mm (6 in.) on both

sides.

Figure 23: Nail location of SIPs

51

Figure 24: Load displacement curve results from SAPwood

Figure 25: Load-displacement curve of panel 1 (Terentiuk and Memari, 2012)

It can be seen from the results above that the actual SIPs wall can bear load up to 71,172

N (16,000 lb), while the numerical model shows they can only bear a peak load of about

35,586 N (8,000 lb). For structural insulated panels, although it is a wood structure and

0

5000

10000

15000

20000

25000

30000

35000

40000

0 20 40 60 80 100 120 140

Forc

e (N

)

Displacement (mm)

Monotonic results of SIPs

52

can be modelled in SAPwood, the software is incapable in modeling the second sheathing

and take into account the insulation material which can contribute to the strength to the

shear wall. The additional sheathing and insulation core of SIPs increase the strength of

SIPs and shows good structural performance of the panel. Therefore, in this study, the

hysteretic parameters for SIPs were determined through the actual cyclic test data

acquired which were listed in literature review chapter instead of NP analysis. The

parameters can be determined by manually fitting the real load-displacement response.

The fitting step that requires original experimental data output was performed by

Donovan at Penn State (Donovan, 2014). Table 18 summarize the hysteretic parameters

for both SIP and wood-frame shear walls with hold-downs.

Table 18: Shear wall hysteretic parameters

SIP

Panel

ID

K0

(N/mm) F0 (N) F1 (N) r1 r2 r3 r4 ∆u (mm) α β

1 1191 809576 9341 0.05 -0.09 1 0.09 127 0.9 1.2

Wood-

frame 2592 23224 3870 0.01 -0.08 1 0.02 50 0.75 1.1

53

In this research, a one-story residential building was modeled in SAPwood to determine

the structural response of the building with different shear walls (SIPs and wood-frame).

The building has a dimension of 12.2 meters (480 in) long and 7.6 m (300 in) wide, with

a total area of 93 square meter (1000 square feet). Figure 26 shows a plan view of the

building and Figure 27 is the story information in SAPwood. The model was built by

assigning shear wall properties and location for each story. At story level, both

concentrated mass and distributed mass can be added. In this study, only distributed mass

was used.

Figure 26: One-story residential building

Figure 27: Story level information

54

5.2 Structure analysis

After SIP and wood-frame building system were modeled in the program, including

generation of hysteretic parameters, structure analysis for a residential building was

performed using SAPwood. A total of 11 earthquake ground motion records were used as

suggested in FEMA document to produce a reasonable median building response. The

performance response also includes uncertainty of the model which comes from the

model itself and material property variation; the uncertainty value were selected based on

judgement value from FEMA P-58 document. Table 29 shows the 11 earthquake input

used which were selected from FEAM P-695.

Table 19: Earthquake information (FEAM, 2009)

ID

No

Earthquake Recording station

M Year Name Name

1 6.7 1994 Northridge Beverly Hills - Mulhol

2 6.7 1994 Northridge Canyon Country - WLC

3 7.1 1999 Duzce, Turkey Bolu

4 7.1 1999 Hector Mine Hector

5 6.5 1979 Imperial Valley Delta

6 6.5 1979 Imperial Valley El Centro Array #11

7 6.9 1995 Kobe, Japan Nishi-Akashi

8 6.9 1995 Kobe, Japan Shin-Osaka

9 7.5 1999 Kocaeli, Turkey Duzce

10 7.5 1999 Kocaeli, Turkey Arcelik

11 7.3 1992 Landers Yermo Fire Station

After selecting earthquake ground motions, a target response spectrum was determined to

which these earthquake ground motions were scaled to. The residential building in this

study is assumed to be located in Los Angeles area, with risk category I and site class D.

The response spectrum was then determined using the USGS ground motion parameter

calculator, and shown in Figure 28.

55

Figure 28: Design response spectrum

The building was then subjected to a random earthquake motion to determine the

fundamental period, with a damping ratio of 0.05 chosen. The outcome of the

fundamental period for Wood-frame building without brick veneer is 0.31 sec and 0.45

sec for SIPs building. SIPs is much more ductile and stronger than wood-frame shear

wall, and wood-frame shear wall has a larger initial stiffness. So, even SIPs is stronger in

strength, its stiffness is weaker which cause it to have larger period. At this period, the

spectral acceleration is 1.59 g, and all earthquake ground motions were scaled to this SA

for both wood-frame and SIPs building without brick veneer wall.

56

Figure 29: One-story building model with and without brick veneer walls

First, the building without brick veneer was evaluated. Each earthquake record was

applied to the building twice, with the peak ground acceleration reversed in direction the

second time. Therefore, a total of 22 analyses were performed and peak drift ratio and

accleration for the building in both direction were recorded as shown from figure 30-33.

As shown in Figure 29, building without brick veneer on the left and building with brick

veneer on the right, Direction 1 is the long end of the building, and Direction 2 represents

the shorter end of the building. Direction 2 only had two shear walls resisting the

earthquake load while direction 1 had a total of four shear walls, so its peak drift was

significantly higher than direction 1. Peak acceleration was also recorded for each

analysis, it is shown that for Wood-frame building, acceleration in direction 1 is slightly

higher than direction 2. However, the acceleration is almost identical for SIPs building.

57

Figure 30: Building Drift ratio results for wood-frame

Figure 31: Peak story acceleration for wood-frame

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

1 2 3 4 5 6 7 8 9 10111213141516171819202122

Dri

ft r

atio

(ra

d)

Earthquake motion No.

Peak drift ratio results (Wood-frame)

direction 1

direction 2

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

Sto

ry a

ccel

erat

ion

(g)

Earthquake motion No.

Peak story acceleration (Wood-frame)

direction 1

direction 2

58

Figure 32: Building Drift ratio results for SIPs building

Figure 33: Peak story acceleration for SIPs building

Of interest in this study is comparison of the results of buildings with and without brick

veneer. The building with brick veneer is shown in figure 29 on the right. Therefore,

structural analysis and building model were developed for wood-frame and SIPs building

with brick veneer walls too. To be conservative, the strength and stiffness of brick veneer

0

0.01

0.02

0.03

0.04

0.05

0.06

1 2 3 4 5 6 7 8 9 10111213141516171819202122

Dri

ft r

atio

(ra

d)

Earthquake motion No.

Peak drift ratio results (SIPs)

direction 1

direction 2

0

1

2

3

4

5

6

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

Sto

ry a

ccel

erat

ion

(g)

Earthquake motion No.

Peak story acceleration (SIPs)

direction 1

direction 2

59

were not taken into account, so that the hysteretic behavior of the shear walls remain the

same. However, since the weight of brick veneer is significant enough and can change the

structure response in an earthquake, a 2.4 KPa (50psf) weight of brick veneer is added to

the shear wall. Since the EDP used for brick veneer fragility data in this study is out-of-

plane acceleration. The damage determined for brick veneer walls is the acceleration of

shear walls from analysis which is perpendicular to the brick veneer walls. So if the

damage of brick veneer wall along direction 1 is to be estimated, the EDP used is the

acceleration of shear walls along direction 2 because the in-plane acceleration in direction

2 would cause the walls along direction 1 to move out-of-plane.

Table 20: Period and spectral acceleration for each building system

Period

(s) SA (g)

Wood-frame w/o brick veneer 0.31 1.59

Wood-frame with brick

veneer 0.45 1.59

SIPs w/o brick veneer 0.45 1.59

SIPs with brick veneer 0.64 1.25

With the change of the weight, the period of the system also changed and listed in table

21 above. The wood-frame building with brick veneer has a period of 0.45 second that is

0.14 second more than one without brick veneer wall, but the SA still remains the same

according to the spectrum plot. The SIPs building increase its period from 0.45 second to

0.64 second, which result in a different SA at 1.25g.

60

Figure 34: Building drift ratio results for wood-frame with brick veneer

Figure 35: Peak story acceleration for wood-frame with brick veneer

0

0.2

0.4

0.6

0.8

1

1.2

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

Dri

ft r

atio

(ra

d)

Earthquake motion No.

Peak drift ratio results (Wood-frame with brick veneer)

direction 1

direction 2

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

Sto

ry a

ccel

erat

ion

(g)

Earthquake motion No.

Peak story acceleration (Wood-frame with brick veneer)

direction 1

direction 2

61

Figure 36: Building drift ratio results for SIPs building with brick veneer

Figure 37: Peak story acceleration for SIPs building with brick veneer

0

0.02

0.04

0.06

0.08

0.1

0.12

1 2 3 4 5 6 7 8 9 10111213141516171819202122

Dri

ft r

atio

(ra

d)

Earthquake motion No.

Peak drift ratio results (SIPs with brick veneer)

direction 1

direction 2

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

Sto

ry a

ccel

erat

ion

(g)

Earthquake motion No.

Peak story acceleration (SIPs with brick veneer)

direction 1

direction 2

62

Table 21: Median structure response

Wood-

frame SIPs

Wood-

frame (with

bv)

SIPs

(with bv)

drift ratio

(rad)

direction 1 0.014 0.02 0.08 0.03

direction 2 0.03 0.037 0.11 0.04

acceleration

(g)

direction 1 0.99 1.23 0.93 1.01

direction 2 0.86 1.33 0.8 0.87

Table 21 summarizes the median structure response from 22 analyse. For wood-frame

building, the additional weight of brick veneer increased the fundamental period but did

not affect the spectral acceleration. So the scaling of earthquake motion for both wood-

frame system was the same (1.59 g), and the peak story acceleration results are almost

identical which showed its consistency with spectral acceleration. However, with the

mass of the building system increased, and acceleration remained identical, the results

showed a significant increase in drift ratio. This increase in drift resulted in drift ratio

calculated by the software that is not possible for wood-frame shear wall to reach before

collapse because the story force was significantly larger than the shear wall capacity. The

results for wood-frame with BV, even though it is very large, it can still be used to assess

building damage because those large responses are considered as failure of shear walls.

For SIPs building, the additional weight of brick veneer resulted in a change in period

that associated with a smaller SA (1.25 g). Thus, the peak acceleration response for SIPs

with BV is smaller. Even with smaller acceleration, the additional mass still pushed the

building more than one without brick veneer. Both SIPs building showed drift response in

the reasonable range of its behavior.

63

After structure response for both SIPs and wood-frame building were determined, the

residual drift can be estimated through the equation discussed in Chapter 3 for each

analysis. The yield drift for wood-frame shear wall is 6 mm (0.24 inches) according to

APA cyclic shear wall testing (Line et al., 2008). The yield drift for SIPs is obtained from

actual tests done by Terentiuk and Memari, which is 109 mm (4.3 inches) for this

particular type of SIPs that is modeled in this study. Yield drift for different types of SIPs

and wood-frame may vary. The resulting median residual drift is presented in Table 22.

SIPs has a median residual drift of almost zero because it has a much higher yield drift

than wood-frame shear wall, which made it more likely to be repairable after an

earthquake.

Table 22: Median residual drift

Median residual drift (mm)

Wood-frame SIPs Wood-frame with bv SIPs with bv

direction 1 8.4 (0.33 in) 0 175.3 (6.9 in) 0

direction 2 47.2 (1.86 in) 0 251.5 (9.9 in) 0.08 (0.003 in)

64

Chapter 6: Performance-based design case study

The main objective of this study is to gather test data and develop new fragility

information for SIPs, brick veneer panels, and a selected type of glass curtain wall

system. As an example application of fragility information, comparison of the

performance of SIPs and wood-frame with brick veneer panels for residential building

under seismic event were also developed. The methodology for evaluating building

performance has been discussed in Chapter 3. This chapter presents the step-by-step

procedure for using fragility data to develop performance assessment. The final outcome

of loss analysis presents the direct economic loss in a residential building in terms of

probability of exceedance of repair cost under seismic event. In this study, software

PACT provided by FEMA is used to assess the building performance. Figure below

shows the main interface of the PACT software for building modeler.

Figure 38: PACT interface

65

The information needed for assessing performance includes component fragilities

(fragility data and repair cost data), performance groups including structural group and

nonstructural group, collapse fragility and residual fragility of the building, and structural

analysis results. The program can also assess life losses for which additional information

about population would be needed; however, this study only focuses on assessing the

performance in terms of repair cost. The structure results and residual drift results are

presented in Chapter 5; this chapter demonstrates the rest of the information for

evaluating performance.

6.1 Repair cost data

In this section, the repair cost data of SIPs and brick veneer panels for each damage state

are estimated and presented. Just like fragility data, repair cost data are constructed with a

mean repair cost and an uncertainty value. This study focused on estimating the mean

cost. Since in actual construction, costs can have a significant uncertainty from the

estimation, a logarithmic standard deviation of 20% is used in repair cost data. (Porter

and Beck, 2002) The process of estimation is by determining the unit cost of labor and

material needed, and multiply by the quantities needed to be repaired. The cost data in

this research is found from other reliable literature and online sources, such as national

building cost manual (Moselle, 2015), loss estimation for wood-frame buildings (Porter

&Beck, 2002). The replacement cost of constructing a new building, is based on national

building cost manual 2015. To build an average quality four corner family residence, the

cost is estimated around $150,000 for a 93 square meter (1000 SF) of area (Moselle,

2015).

66

Brick veneer panels

For initial tie fracture, repairs recommended is to remove brick veneer of the top row

which has lost strength in connection, and reinstall them. Since the whole panel is

assumed to have an area of 9.3 square meter (100 square feet), a 2.3 square meter (25

square feet) of repair area is conservatively chosen for initial tie fracture repair

estimation. The supplies in the table represent the general cost of materials and supplies

used to construct brick veneer.

Table 23: Repair cost breakdown for damage state 1 (brick veneer)

Damage State: Initial tie fracture in top row of panel

Cost breakdown Mean cost ($)

Labor

Demolition: Remove brick veneer and

connection (2.3 square meter) 30 per sm 68.75

Install new brick veneer (2.3 square

meter)

209 per

sm 485.5

Material

Brick veneer (2.3 square meter) 129 per

sm 300

Supplies 18.55

Total mean cost 854.25

67

For further tie fracture and nail pull out damage, repairs recommended involves drywall

repair in addition to fixing brick veneer panel since nail pull out can cause damage and

cracks to the sheathing. In this case, a total repair area of 4.6 square meter (50 square

feet) is chosen.

Table 24: Repair cost breakdown for damage state 2 (brick veneer)

Damage State: tie fracture and nail pull out in upper row of panel

Cost breakdown Mean cost ($)

Labor

Demolition: Remove brick veneer and

connection (4.6 square meter (sm)) 30 per sm 137.5

Install new brick veneer (4.6 square

meter)

209 per

sm 971

drywall repair 78

Material

Drywall 10

brick veneer 129 per

sm 600

supplies 18.55

Total mean cost 1709

68

The last damage state which is veneer collapse, the repair cost is the cost to install a new

wall. The total mean cost is around $3230 for building a new panel.

Table 25: Repair cost breakdown for damage state 3 (brick veneer)

Damage State: Veneer collapse

Cost breakdown Mean cost ($)

Labor

brick veneer wall labor (9.3 square meter) 1942

Material

Brick veneer wall materials and supplies 19

Equipment allowance 68

brick veneer wall cost (9.3 square meter) 1200

Total mean cost 3228

Structural insulated panels

Unlike conventional wood-frame structures, the sheathing of structural insulated panels

on both sides are structural component and carry load in both horizontal and vertical

directions. Although it is a prefabricated component and thus easier to install during

construction, the OSB sheathing cannot normally be removed. In this study, the damage

state of SIPs that is modeled experienced nail pull-out along spline, top and bottom plate.

The sheathing is also damaged on the inner corners. At such damage after an earthquake,

it is recommended that the whole panel be replaced; therefore, the repair cost of structural

insulated panels for that damage state consists of the demolition cost of the damaged SIP

69

panels and their replacement cost. Accordingly, the brick veneer attached to SIPs (if any)

also has to be reconstructed since the whole wall is to be replaced. Therefore, if brick

veneer is used as the facade of the building, its repair cost has to be taken into account

when the back-up walls need to be replaced, as is the case in this study.

According to RS means (2006), “Labor costs for a 6 ½ inch SIPs wall are $0.97/square

foot, while a conventional wall is expected to have a labor cost of $2.37/square foot”.

Although the test specimen in this example is 114mm (4.5 in), it is assumed that labor

cost remains the same. The cost of a 1200x 2400 mm SIPs is around $150 ($49 per SM),

so the panel cost for a 2400 x 2400 mm shear wall is around $300.

Table 26: Repair cost for SIPs

Damage State: nail withdraw along spline, top and bottom plate,

sheathing damage on inner corners of panels

Cost breakdown Mean cost ($)

Labor

Demolition: Remove the wall panel 30/SM 176

Install new SIP wall (5.9 SM) 10.4/SM 62

Painting 12.2/SM 72

Plaster 38.7/SM 230

Material

SIP wall (two 1200 x 2400 mm) 300

Plaster 8/SM 48

Total mean cost 889

70

6.2 Performance group assembly

In PACT software, both structural and nonstructural components need to be assigned a

quantity and distributed to each direction and floor of the building. For this study, only

shear walls were considered as structural component since foundation and slabs were

considered rigid and not vulnerable to earthquake event. Nonstructural components of the

building were estimated through a supporting excel document provided by FEMA. This

tool (FEMA, 2012), normative quantity estimation tool, allows you to estimate

nonstructural component and their quantities based on the occupancy use and area of the

building. Table 27 blow shows the nonstructural components, and Figure 39 shows

components assemblies for Direction 1 in PACT software

Table 27: Nonstructural component list

Fragility

group Nonstructural component direction

B2022.001 Curtain Walls 1,2

B3011.011 Concrete tile roof none

C1011.001a Wall Partition 1,2

D2021.011a Cold Water Piping none

D2022.011a Hot Water Piping none

D2031.011b Sanitary Waste Piping none

D3041.011a HVAC Galvanized Sheet Metal Ducting none

D3041.031a HVAC Drops / Diffusers none

D3041.041a Variable Air Volume (VAV) box none

D4011.021a Fire Sprinkler Water Piping none

D4011.031a Fire Sprinkler Drop Standard Threaded Steel none

71

Figure 39: PACT interface (performance group)

72

6.3 Collapse fragility development

Collapse fragility is determined through incremental dynamic analysis in this study, and

the goal is to develop a collapse fragility curve which has a median value and a

dispersion to represent the probability of collapse of the structure. The collapse fragility

curve uses spectral acceleration at first mode period of the structure as the engineering

demand parameter. The sample building was subjected to 11 earthquake motion. The

earthquake motion was applied in both directions, so a total of 22 analyse were

performed. Figures 40-43 below presents the incremental dynamic analysis (IDA) results.

Figure 40 and 41 presents the IDA results for wood-frame building and SIPs building

without brick veneer, and the median collapse spectral acceleration (SA) are 1.4g and

2.35g respectively. Each line in the figure represents a simulation under one earthquake

motion, and there are 22 lines for each figure. The figure shows that at each level of

spectral acceleration, what the displacement of the one-story building is. The collapse

displacement is determined from the shear wall model developed, which is around 3

inches for wood-frame shear wall and 5 inches for SIPs shear wall. The collapse SA is

then determined associated with this collapse displacement. Figure 42 and 43 presents the

results for buildings with brick veneer attached, and the median collapse SA are 0.8g for

wood-frame building and 1.6g for SIPs building.

73

Figure 40: IDA results of wood-frame building

Figure 41: IDA results of SIPs building

0

0.5

1

1.5

2

2.5

3

3.5

4

0.00E+00 5.00E-01 1.00E+001.50E+002.00E+002.50E+003.00E+003.50E+004.00E+00

SA(g

)

Displacement (in)

Incremental dynamic analysis results (Wood-frame)

EQ1(x)EQ1(y)EQ2(x)EQ2(y)EQ3(x)EQ3(y)EQ4(x)EQ4(y)EQ5(x)EQ5(y)EQ6(x)EQ6(y)EQ7(x)EQ7(y)EQ8(x)EQ8(y)EQ9(x)EQ9(y)EQ10(x)EQ10(y)EQ11(x)EQ11(y)Sa(median)

Median = 1.4 g

0

0.5

1

1.5

2

2.5

3

3.5

4

0.00E+00 1.00E+00 2.00E+00 3.00E+00 4.00E+00 5.00E+00 6.00E+00

SA(g

)

Displacement (in)

Incremental dynamic analysis results (SIPs)EQ1(x)EQ1(y)EQ2(x)EQ2(y)EQ3(x)EQ3(y)EQ4(x)EQ4(y)EQ5(x)EQ5(y)EQ6(x)EQ6(y)EQ7(x)EQ7(y)EQ8(x)EQ8(y)EQ9(x)EQ9(y)EQ10(x)EQ10(y)EQ11(x)EQ11(y)Sa(median)

Median = 2.35 g

74

Figure 42: IDA results of wood-frame with BV

Figure 43: IDA results of SIPs with BV

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

0.00E+005.00E-011.00E+001.50E+002.00E+002.50E+003.00E+003.50E+004.00E+00

SA(g

)

Displacement (in)

Incremental dynamic analysis results (Wood-frame with BV)EQ1(x)EQ1(y)EQ2(x)EQ2(y)EQ3(x)EQ3(y)EQ4(x)EQ4(y)EQ5(x)EQ5(y)EQ6(x)EQ6(y)EQ7(x)EQ7(y)EQ8(x)EQ8(y)EQ9(x)EQ9(y)EQ10(x)EQ10(y)EQ11(x)EQ11(y)Sa(median)

Median = 0.8 g

0

0.5

1

1.5

2

2.5

3

0.00E+00 1.00E+00 2.00E+00 3.00E+00 4.00E+00 5.00E+00 6.00E+00

SA(g

)

Displacement (in)

Incremental dynamic analysis results (SIPs with BV)

EQ1(x)EQ1(y)EQ2(x)EQ2(y)EQ3(x)EQ3(y)EQ4(x)EQ4(y)EQ5(x)EQ5(y)EQ6(x)EQ6(y)EQ7(x)EQ7(y)EQ8(x)EQ8(y)EQ9(x)EQ9(y)EQ10(x)EQ10(y)EQ11(x)EQ11(y)Sa(median)

Median = 1.6 g

75

It can be seen from the results that SIPs building is overall stronger than wood-frame

building, and thus requires larger spectral acceleration to cause failure. For both wood-

frame and SIPs building, the presence of brick veneer facade would make both system

weaker. This aligns with the expectations since the additional weight of brick veneer is

significant for light-frame systems, which would cause larger inertia force. For all

collapse fragility data, a dispersion of 0.6 is suggested by FEMA and thus used in this

study.

6.4 Building performance results

In this study, the evaluation of building performance was determined through PACT, and

as stated in the beginning of this chapter, information gathered in chapter 6.1 to 6.3 and

structural analysis of the building serve as the input in the software. These information

includes component fragilities and performance groups, collapse fragility data, structural

analysis results, and residual drift value.

With these information provided for the software, the evaluation can be determined

through PACT. The performance of four systems have been evaluated in this report and

results are presented below, Wood-frame building with and w/o brick veneer wall, and

SIPs building with and w/o brick veneer wall.

76

Figure 44: Wood-frame building w/o brick veneer repair cost

Figure 45: Wood-frame building with brick veneer repair cost

77

Figure 46: SIPs building w/o brick veneer repair cost

Figure 47: SIPs building with brick veneer repair cost

As shown in Figure 44, the median repair cost for wood-frame building w/o brick veneer

is around $16,000, which is about 10% of the total repair cost. While with brick veneer

shown in figure 45, the median cost is equal to the replacement cost at $150,000, which

means the type of wood-frame building in this study is very unlikely to survive with all

78

the weight attached to it. The results based on repair cost coincide with the structural

analysis results. The drift ratio for wood-frame building without brick veneer is within its

shear wall capacity, so no major damage would occur to the shear wall system. While the

drift ratio for wood-frame building with brick veneer are significant, which cause the

building to have large residual drift and irreparable, or the drift ratio exceeds the major

damage state which would be costly to repair.

SIPs building has a significantly better performance compared to wood-frame. Due to its

high yield drift and strength capacity, the building hardly reaches yield point and thus can

come back to its original position after earthquake. Damage is also unnoticeable

compared to wood-frame system. The median repair cost for SIPs system w/o brick

veneer as shown in figure 46 is only $3,500, while the median cost for including brick

veneer is only $11,000. Such good performance can be foreseen from the structural

analysis as well, for both SIPs system, with and without brick veneer, the median drift

ratio does not even reach the yield point, which means very low residual drift and low

damage to the shear wall. The acceleration is also not significant enough for the system to

experience fallout of brick veneer.

79

Chapter 7: Conclusion

7.1 Summary

This research has been focused on developing fragilities of various types of building

components through actual testing data, and an application of using developed fragilities

in performance-based seismic design using FEMA P-58 procedure was presented.

Fragility development of structural component included six different types of structural

insulated panels. The nonstructural component fragilities developed included one type of

brick veneer facade and fourteen types of glazing panels.

For SIPs, the failure damage state was used to when determining the fragility data, and

the average value of median failure drift ratio for all types of 2400 x2400 mm panel is

0.045 which is 110 mm (4.34 in.) in drift. The median drift ratio for 1200 x2400 mm

panel is about half of the full size panel, which is 0.02, and the damage state is very

similar, top and bottom plate connection failure and sheathing damage at corners, except

for that the full size panel has connection failure at middle for connecting two small

panels.

For brick veneer walls, the fragility data shows that the nonstructural component can

withstand a high acceleration before major damage would occur. The median acceleration

for veneer collapse is 3.86g for this particular set-up of brick veneer walls, which shows

that they are unlikely to fallout during seismic event due to connection failure. However,

the collapse of back-up wall would still cause the failure of brick veneer walls.

For glass panels, it is discovered that the glass fallout drift are close to the value of glass

cracking drift for 12 out of 14 types, and the differences are within 10%. The exceptions

80

are the 6mm annealed panels with corner radius of 19mm and 25mm with flat polished

finishes. For these two types, the glass panels could sustain 40% more drift until glass

fallout when cracking drift reached.

Some key findings for the fragility data are listed below:

Average value of median failure drift ratio for 2400 x 2400 mm SIPs is 0.045

(110 mm), and 0.02 (49 mm) for 1200 x 2400 mm SIPs

Median acceleration of 3.86g for damage state of veneer collapse

High acceleration capacity (3.86g) for connections of brick veneer facade in low-

rise residential building (floor acceleration less than 1.5g)

Glass fallout drift are very close to the value of glass cracking, within 10% for

most glass panel types among the 14 types in this study

For 6mm annealed panels with corner radius of 19mm and 25mm and flat polish

finishes, fallout drift is 40% more of the cracking drift, which is significant

compare to other types, which only have 10%.

With these developed fragilities, the seismic performance of buildings that include these

building components then was evaluated. A compare study of SIPs building and wood-

frame building with and without brick veneer attached was presented. The Sapwood

software was used for structural analysis and incremental dynamic analysis in this

research, and the software PACT was used for evaluating the probability of repair cost of

each building type.

The following are the key findings for the case study in this research:

81

The median repair cost for the type of wood-frame building in this study without

brick veneer in this study is $16,000 (10% of the total replacement cost), and for

wood-frame building with brick veneer is $150,000

The median repair cost for the type of SIPs building in this study is $3,500 (2.5%

of the total replacement cost) without brick veneer walls, and $11,000 (7.5% of

total replacement cost) for SIPs building with brick veneer walls

Without the presence of brick veneer walls, the difference of the repair cost of

SIPs building and wood-frame building in this study is 7.5% of total replacement

cost, which is not very significant

The type of wood-frame building in this study performed poorly with the presence

of brick veneer facade because the additional weight makes it vulnerable in

seismic event

7.2 Limitations

The fragility data developed in this study highly relies on the availability of previous

experimental testing. For SIPs, only one failure damage state was evaluated for fragility

data, however, other damage might have occurred before that final damage state.

Additional testing could be developed in observing damage states when experiencing

the cyclic loading of SIPs.

In addition, the numerical model developed for SIPs shear wall is based on the

experimental data points, which might not reflect the actual condition in the field. Since

the testing of SIPs did not take into account the effect of gravity load. The numerical

model could be refined with more knowledge of the behavior of SIPs under actual

condition.

82

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