NEESR-SG: Controlled Rocking of Steel-Framed Buildings with Replaceable Energy Dissipating Fuses Greg Deierlein, Paul Cordova, Eric Borchers, Xiang Ma, Sarah

Billington, & Helmut Krawinkler, Stanford University

Jerome Hajjar & Kerry Hall, University of Illinois

Mitsumasa Midorikawa, Hokkaido University

David Mar, Tipping & Mar Associates

Shortcomings of Current Approaches

Throw-away technology:Structure and Architecture absorbs energy through damage

Large Inter-story Drifts:Result in architectural & structural damage

High Accelerations:Result in content damage& loss of function

Deformed Section – Eccentric Braced Frame

Objective

Develop a new structural building system that employs self-centering rocking action and replaceable* fuses to

provide safe and cost effective earthquake resistance.

*Key Concept – design for repair

PT Cables

“Fuse” Panel

Leveraging previous research …

Self-Centering Concepts rocking frame/wall systems post-tensioned frames

Energy Dissipating Shear Panels ductile fiber cementitous composites slit steel shear walls

Performance-Based Engineering (PEER/ATC) damage & collapse limit states economic losses & life-cycle assessment simulation tools

Scope System Design Development

- parametric design studies

- shear panel fuse design and testing

- building simulation studies

Subassembly Frame/Fuse Tests- quasi-static cyclic loading

- PT rocking frame details & response

- panel/frame interaction

- model calibration

Shake Table System Tests- proof-of-concept

- validation of simulation models

NEES - Illinois

E-Defense

Stanford

H

A B A

Pivoting Fuse Braced Frames

Replaceable Fuse

Shear Strains = /H x A/B

Pivoting Fuse System with Backup MRF

Elastic restoring force Reduce damage in

fuse Reduce residual

deformations

Provides redundancyFraming Plan

Framing Elevation

deck/slab

Figure 1a

Figure 1a

Moment Resisting Frames

Bas

e Sh

ear

Drift

MRF

Pivoting Fuse

Combined

“Rocking” Braced Frames

Gravity load overturning resistance

Force

Displacement

No Permanent Displacement

Midorikawa, M., Azuhata, T., Ishihara, T. and Wada, A. (2003)

Orinda City OfficesArchitect: Siegel and Strain Architects

Rocking Braced Frame w/Post Tensioning

Controlled Rocking Braced Frame with Fuses

A B A

Post-tensioning (PT) Tendons

Structural Fuse

Steel Braced Frame

Yielding of Structural Fuse

PT Cables & Braces remain elastic

Could potentially employ additional fuse at base of column

Bas

e S

hea

r

Drift

a

b c

d

f

g

Combined System

Origin-a – frame strain + small distortions in fusea – frame lift off, elongation of PTb – fuse yield (+)c – load reversald – zero force in fusee – fuse yield (-)f – frame contactf-g – frame relaxationg – strain energy left in frame and fuse, small residual displacement

Fuse System

Bas

e S

hea

r

Drift

a

b c

d

efg

Fuse Strength Eff. FuseStiffness

PT Strength

PT – Fuse Strength

Pretension/Brace SystemB

ase

Sh

ear

Drift

a,f b

cde

g PT Strength

Frame Stiffness

e

2x FuseStrength

Energy Dissipating Fuse Options

Attributes of Fuse high initial stiffness large strain capacity hysteretic energy dissipation

Candidate Fuse Materials & Designs ductile fiber cementitious

composites** steel panels with slits** low-yield steel mixed sandwich panels

Ductile Fiber Reinforced Cemetitious Panels

Tapered Flexural/Shear Links

- Designed for distributed plasticity

- Similar in concept to a “butterfly” link beam

HPFRCC Flexural Panel Tests by Kesner & Billington 2005

Steel Shear Wall with Slits

Hitaka et al., 2004

OpenSees Simulation Model

Elastic Truss Members

EPP Post-Tensioning

Tendons

Nonlinear Truss Members

Uplift Spring

-0.08 -0.06 -0.04 -0.02 0 0.02 0.04 0.06

-500

-400

-300

-200

-100

0

100

200

300

400

500

Link Strain

Axia

l F

orc

e (

kN

)

4% shear strain cap

Pinching

50% residual

Cyclic Response

A B A

DESIGN with R = 8.0Vd = 0.125WPT = 1055kN, Vp,fuse = 1687kNr = 1.0

PD Fuse Behavior

-0.06 -0.04 -0.02 0 0.02 0.04 0.06-2500

-2000

-1500

-1000

-500

0

500

1000

1500

2000

2500

RDR

Base S

hear

(kN

)

3-story Frame

Hardening = 0PostCap Softening = -0.02Strength Det. = 0Unloading Stiff Det. = 0Accelerated Stiff. Det. = 0PostCap Strength Det. = 0

Global Behavior

PT YieldingRDR = 3%

Bilinear vs. Pinching Fuse

-0.06 -0.04 -0.02 0 0.02 0.04 0.06-2500

-2000

-1500

-1000

-500

0

500

1000

1500

2000

2500

RDRB

ase

She

ar (

kN)

3-story Frame

Hardening = 0PostCap Softening = -0.02Strength Det. = 0Unloading Stiff Det. = 0Accelerated Stiff. Det. = 0PostCap Strength Det. = 0

-0.06 -0.04 -0.02 0 0.02 0.04 0.06-3000

-2000

-1000

0

1000

2000

3000

RDR

Bas

e S

hear

(kN

)

3-story Frame

PT Strength = Fuse Strength(2PT*A) / (Vp,fuse (A+B)) = 1.0

RestoringNotRestoring

0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.160

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Maximum IDR

Sa(

T1)

(g)

10/50 Level

2/50 Level

The yellow squares represent the median, 16th and 84th percentile response.

1.6%

2.7%

Unscaled records

PT Yielding

Maximum Interstory Drift vs. Sa(T1)

Inelastic Time History Analyses:

• 20 EQ record pairs, scaled to increasing intensities

• Primary EDP: interstory drift

• structural limit states

- column lift-off (rocking)

- fuse yielding/damage

- PT yielding

Subassembly Frame Tests (NEES-Illinois) Test Configuration

2/3 scale planar rocking frame with realistic details

quasi-static

System Response

structural details & PT

various fuse types

indeterminate shear-fuse/frame interaction

Simulation model validation

NEES - Illinois

Shake Table Validation Test (E-Defense) Large-scale frame

assembly

Validation of dynamic response and simulation

Proof-of-Concept

construction details

re-centering behavior

fuse replacement

Collaboration & Payload Projects

3 @

2.8

m =

8.4

m

2.5 m2.5 m 1 m

3 @ 6 m = 18 m

W 360 (typ)

2 @

2 m

= 4

m

W 300 (typ)

85 mm slab on75 mm deck

E-Defense Testbed Structure

Plan View

shaking direction

Section

E-Defense

Collaboration Opportunities

Alternative Fuse Designs Alternative Rocking Systems

rocking column base details hydraulically actuated self-centering

Industrial Collaboration Steel manufacturers/fabricators Design practitioners

Related Japanese “Steel Project” Related US Initiatives

PEER Building Benchmarking ATC 58 & 63

Rocking Frame

Seismic & Green Design

Design Decision Matrix

$-

$10,000

$20,000

$30,000

$40,000

$50,000

$60,000

$70,000

$80,000

Woodw /conventional

partitions

Steelw /conventional

partitions

Steelw /improved

partitions

Expected Annual Loss

$-$20,000$40,000$60,000$80,000

$100,000$120,000$140,000$160,000$180,000$200,000

Woodw /conventional

partitions

Steelw /conventional

partitions

Steelw /improved

partitions

Annualized Lifecycle Cost

Life-cycle Financial Assessment