Instrumented Moment Frame Steel Buildings Models

Erol Kalkan, PhDCalifornia Geological Survey

PEER-GMSM First Work Shop, Berkeley Oct-27 2006PEER-GMSM First Work Shop, Berkeley Oct-27 2006

PEER GMSM 2

Moment Frame Existing Steel Buildings

Analytical Model in Two-DimensionAnalytical Model in Two-Dimension 6-Story Building [Burbank, CA]6-Story Building [Burbank, CA] 13-Story Building [Los Angeles, CA]13-Story Building [Los Angeles, CA]

Analytical Model in Three-DimensionAnalytical Model in Three-Dimension 19-Story Building [Los Angeles, CA]19-Story Building [Los Angeles, CA]

PEER GMSM 3

6-story Instrumented Moment Frame Steel Building at Burbank, CA

Moment resisting steel frames on perimeter walls.

Designed in 1976 as per the 1973 UBC requirements

PEER GMSM 4

Structural Details

The structural system is essentially symmetrical. Moment continuity of each of the perimeter frames is

interrupted at the ends where a simple shear connection is used to connect to the weak column axis.

4

7

6

5

3

2

1

BA

6@6.

1 m

DC E GF

6@6.1 m 6@ 6.1m

5@4m

5.3m

3rdFloor

2ndFloor

1st Floor

4th Floor

5th Floor

Roof

W14

x176

W14

x90

W14

x132

W24x68

W24x84

W24x68

W24x68

W27x102

W30x116

A C E F GDB

Moment resisting connection

Moment resisting connectionSimple hinge connection

PEER GMSM 5

Analytical Modeling in OpenSEES

One half of the total building mass was applied to the frame distributed proportionally to the floor nodes.

The simulation of special features such as local connection fracture did not accounted for; consequently, the modeling of the members and connections was based on the assumption of stable hysteresis derived from a bilinear stress-strain model with 3 percent strain hardening.

The columns were assumed to be fixed at the base level.

A force-based nonlinear beam-column element that utilizes a layered ‘fiber’ section is utilized to model all components.

Centerline dimensions were used in the element modeling.

PEER GMSM 6

Recorded Earthquake Data from 6-Story Building

Earthquake1994 Northridge 6.7 22 0.35 0.49

1992 Bigbear 6.5 137 0.04 0.111992 Landers 7.3 172 0.05 0.22

1991 Sierra Madre 5.8 30 0.11 0.161987 Whittier 6.1 26 0.22 0.30

Magnitude (Mw)

Epicentral Distance (km)

PGA Base Level (g)

PGA Roof Level (g)

The building performed well in all these earthquakes with no visible signs of damage. Recorded data indicates an essentially elastic response in each case.

-12

0

12

0 10 20 30 40 50 60Time (sec)

Dis

p. (

cm

)

RecordedSimulated

6-Story Bld.Roof

PEER GMSM 7

Dynamic Characteristics of 6-Story Building

6-Story Building Mode-1 Mode-2 Mode-3Modal Periods (sec), Tn 1.39 0.51 0.31

Modal Participation Factors, Gn 2.58 0.96 0.46Mass Participation Factors, an 0.85 0.12 0.03

Elastic Modes

0

1

2

3

4

5

6

0.00 0.02 0.04 0.06

IDR

Sto

ry L

evel

0

1

2

3

4

5

6

0.00 0.01 0.02 0.03 0.04

IDR

Sto

ry L

evel

0

1

2

3

4

5

6

0 2 4

Story Ductility

Sto

ry L

evel

0

1

2

3

4

5

6

0 2 4 6

Story Ductility

Sto

ry L

evel

Dominant Higher ModeDominant First Mode

PEER GMSM 8

13-story Instrumented Moment Frame Steel Building at Los Angeles, CA

Moment resisting steel frames on perimeter walls. Located in South San Fernando Valley. It was built in 1975 on a design based on the 1973 UBC code designed in 1976 as per the 1973 UBC requirements

PEER GMSM 9

Structural Details

The exterior frames of the building are the moment resisting frames and interior frames are for load bearing.

The foundation consists of piles, pile caps and grade beams. The corner columns of outer frames are composed of box sections.

5@9.76 = 48.8 m

5

E

F

G

C

D

B

4

5@9.

76 =

48.

8 m

86 7 9

Moment resisting connection

(a) Plan view of perimeter frames

(b) Elevation

W33x118

W27x84

W33x141

W33x130

W33x130

W33x152

W33x152

W33x152

W33x141

W33x118

W36x230

W33x152

W33x152

W33x194

W14

x314

W14

x426

W14

x500

W14

x398

W14

x246

W14

x287

W14

x167

6th Floor

5th Floor

1st Floor

2nd Floor

3rd Floor

Plaza Level

4th Floor

12th Floor

Roof

9th Floor

10th Floor

11th Floor

7th Floor

8th Floor

12@

4.01

3 =

48.

2 m

4.88

4.42

5@9.75 = 48.8 m

Moment resisting connectionSimple hinge connection

PEER GMSM 10

Analytical Modeling in OpenSEES

One half of the total building mass was applied to the frame distributed proportionally to the floor nodes.

The simulation of special features such as local connection fracture did not accounted for; consequently, the modeling of the members and connections was based on the assumption of stable hysteresis derived from a bilinear stress-strain model with 2 percent strain hardening.

The columns were assumed to be fixed at the base level.

Raleigh damping of 5 percent for the first and third vibration modes was utilized.

A force-based nonlinear beam-column element that utilizes a layered ‘fiber’ section is utilized to model all components.

Centerline dimensions were used in the element modeling.

PEER GMSM 11

Recorded Earthquake Data from 13-Story Building

Approximately 12% of the connections on the west perimeter of the North-South frame fractured during the Northridge earthquake.

Earthquake1994 Northridge 6.7 32 0.18 0.37

1991 Sierra Madre 5.8 33 0.17 0.18

Magnitude (Mw)

Epicentral Distance (km)

PGA Base Level (g)

PGA Roof Level (g)

-40

0

40

0 10 20 30

Dis

p. (

cm)

6th Floor -40

0

40

0 5 10 15 20 25 30Time (sec)

Dis

p. (

cm

) 13-Story Bld.Roof

13-Story Building Mode-1 Mode-2 Mode-3Modal Periods (sec), Tn 3.03 1.08 0.65

Modal Participation Factors, Gn 5.57 2.13 1.29Mass Participation Factors, an 0.77 0.11 0.04

Elastic Modes

PEER GMSM 12

19-story Instrumented Moment Frame Steel Building at Los Angeles, CA The building was design in 1967. Has 19 stories above ground and 4 parking levels below ground. Instrumented in 1992 with 15 accelerometers on 5 levels in the building.

Structure has 4 ductile frame along E-W and 5 X-braced frame in N-S direction.

PEER GMSM 13

Structural Details

Moment resisting steel frames in the longitudinal and X-braced steel frames in the transverse direction.

The diagonal members of the cross frames are composed of built-up steel sections of two or four back-to-back angles.

Pin connections fasten the diagonal members of the cross frames to the columns. The foundation consists of 72 ft (21.9 m) long, driven, steel I-beam piles.

PEER GMSM 14

Analytical Modeling in OpenSEES

Rigid diaphragm was assumed. Centerline dimensions were used in the element

modeling. Mass was distributed proportionally to the floor

nodes. The modeling of the members and connections

was based on the assumption of stable hysteresis derived from a bilinear stress-strain model with 3 percent strain hardening.

The columns were assumed to be fixed at the base level.

Raleigh damping of 3 percent for the first and third vibration modes was utilized.

3D Model was created in OpenSEES including 19+4 stories. Braces were modeled as truss elements. A force-based nonlinear beam-column element that utilizes a layered

‘fiber’ section was utilized to model all beam and columns.

PEER GMSM 15

Recorded Earthquake Data from 19-Story Building

Earthquake1994 Northridge 6.7 20 0.32 0.65

Magnitude (Mw)

Epicentral Distance (km)

PGA Base Level (g)

PGA Roof Level (g)

19-Story Building Mode-1 Mode-2 Mode-3Modal Periods (sec), Tn 3.68 3.38 3.08

Torsional Longitudional Transverse

Elastic Modes

After Northridge earthquake, no structural damage was reported. A more accurate match of the recorded response was obtained with both lateral components of the earthquake applied simultaneously.

0 5 10 15 20 25 30 35 40 45 50-1

-0.5

0

0.5

1

Acc

eler

atio

n (g

)

Time (sec)

OpenSeesObserved

0 5 10 15 20 25 30 35 40 45 50-20

-10

0

10

20

Dis

plac

emen

t (in

)

Duration (sec)

OpenSeesObserved

PEER GMSM 16

Nonlinear Transient Analyses

The following response parameters are recorded: Peak and residual roof displacements Peak and residual interstory drift ratios Floor accelerations Beam plastic rotations (interior/exterior) Column plastic rotations

(interior/exterior) Time steps of non-convergence (if exist)