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Buckling Restrained Steel Shear Walls for Seismic Protection

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This presentation covers the use of ANSYS to develop a new system of seismic lateral load resisting system for tall buildings. Steel shear walls can be a safe economic model to resist seismic forces in skyscraper design. However, current steel shear walls can buckle under relatively small lateral forces. The innovative buckling restrained steel shear walls under development, using ANSYS to reduce the cost of construction and increase the capacity of the wall by preventing wall buckling.
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1 © 2014 ANSYS, Inc. May 19, 2014 ANSYS Confidential Buckling Restrained Steel Shear Walls for Seismic Protection X. Qian and A. Astaneh-Asl University of California, Berkeley
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Page 1: Buckling Restrained Steel Shear Walls for Seismic Protection

1 © 2014 ANSYS, Inc. May 19, 2014 ANSYS Confidential

Buckling Restrained Steel Shear Walls for Seismic Protection

X. Qian and A. Astaneh-Asl University of California, Berkeley

Page 2: Buckling Restrained Steel Shear Walls for Seismic Protection

2 © 2014 ANSYS, Inc. May 19, 2014 ANSYS Confidential

Earthquakes create horizontal inertia forces in buildings

Horizontal inertia forces need to be resisted by lateral load resisting system

Lateral load resisting systems also resist lateral loads due to wind

Seismic Protection of Tall Buildings

Page 3: Buckling Restrained Steel Shear Walls for Seismic Protection

3 © 2014 ANSYS, Inc. May 19, 2014 ANSYS Confidential

Lateral Load Resisting Systems:

Shear Walls Braced Frames Moment Frames

Page 4: Buckling Restrained Steel Shear Walls for Seismic Protection

4 © 2014 ANSYS, Inc. May 19, 2014 ANSYS Confidential

Lateral Load Resisting Systems:

Braced Frames

http://www.aviewoncities.com/

Moment Frames

www.toptenepic.com/

Shear Walls

www.timgriffith.com

Page 5: Buckling Restrained Steel Shear Walls for Seismic Protection

5 © 2014 ANSYS, Inc. May 19, 2014 ANSYS Confidential 19/05/2014 5

What is a Steel Shear Wall?

The main role of a steel shear wall is to collect the lateral forces of earthquakes or winds in a building and transfer those forces, in shear, to the foundations and the ground.

• Steel shear walls studied here are steel plates welded to beams and columns in a building.

www.timgriffith.com

Page 6: Buckling Restrained Steel Shear Walls for Seismic Protection

6 © 2014 ANSYS, Inc. May 19, 2014 ANSYS Confidential 6

Stiffened Steel Plate

Used in Japan Unstiffened Steel Plate

Used in U.S.A Steel plate shear walls are either “unstiffened” or “stiffened” . Stiffened steel shear walls have horizontal and vertical stiffeners to divide the plate to smaller panels that will not buckle until the entire plate has yielded in shear.

Types of Steel Shear Wall Panels:

Page 7: Buckling Restrained Steel Shear Walls for Seismic Protection

7 © 2014 ANSYS, Inc. May 19, 2014 ANSYS Confidential

30-story Steel Shear Wall Building in Kobe Japan

After the 1995 Kobe Earthquake

1996

After the 1996 retrofit

Steel Shear Wall Building

Page 8: Buckling Restrained Steel Shear Walls for Seismic Protection

8 © 2014 ANSYS, Inc. May 19, 2014 ANSYS Confidential

Seismic Studies of an Innovative Steel Shear Wall System

Objective: To develop an innovative steel plate shear wall system for wind and seismic lateral force resisting

Performance objective: limit the failure to first buckling under frequent earthquakes and design wind load, while allowing yielding of the shear wall system under maximum considered earthquake.

Page 9: Buckling Restrained Steel Shear Walls for Seismic Protection

9 © 2014 ANSYS, Inc. May 19, 2014 ANSYS Confidential

RESEARCH METHODOLOGY

First Stage Current Focus

Conduct literature survey

Validate computational tools (ANSYS)

Establish seismic demand on the innovative system (ANSYS)

Optimize the system (ANSYS)

Develop tentative seismic design recommendations based on analysis

Apply the design guidelines to design steel shear walls for low-, mid- and high-rise buildings and possibly bridge applications

Conduct time history analysis of structures subjected to ground motions as well as wind effects using ANSYS and refine the design procedure

Design two specimens representing traditional and innovative shear walls and perform pre-test analysis of behavior under cyclic loading up to fracture failure using ANSYS

Fabricate and conduct cyclic tests of two 1/2 scale specimens that are designed using the proposed design procedures and based on their behavior further refine and finalize the design procedures.

Page 10: Buckling Restrained Steel Shear Walls for Seismic Protection

10 © 2014 ANSYS, Inc. May 19, 2014 ANSYS Confidential

ANSYS ANALYSIS PLANS

• Validate FEA simulation – Use ANSYS to model existing test specimens and loading and compare its prediction of behavior of specimens to actual test results. (this presentation)

• Case Study Model: Jinta Tower in Tianjing, China • Designed by S.O.M.

• Test by Tsinghua University

• Generic Low-, mid-, and high-rise structures using proposed innovative “buckling restrained” steel shear walls

Page 11: Buckling Restrained Steel Shear Walls for Seismic Protection

11 © 2014 ANSYS, Inc. May 19, 2014 ANSYS Confidential

VERIFICATION OF ANALYSIS SOFTWARE AND MODELING ISSUES

Tested specimen used in simulation:

from: Lubell, 1997)

Page 12: Buckling Restrained Steel Shear Walls for Seismic Protection

12 © 2014 ANSYS, Inc. May 19, 2014 ANSYS Confidential

VERIFICATION OF ANALYSIS SOFTWARE AND MODELING ISSUES

Simulation of actual behavior of tested steel shear wall specimens using ANSYS:

(Photo: Curtsey of C. Ventura)) (Curves from: Lubell, 1997)

Page 13: Buckling Restrained Steel Shear Walls for Seismic Protection

13 © 2014 ANSYS, Inc. May 19, 2014 ANSYS Confidential

CASE STUDY 1: 10 Scale Test Specimen

Page 14: Buckling Restrained Steel Shear Walls for Seismic Protection

14 © 2014 ANSYS, Inc. May 19, 2014 ANSYS Confidential

Mesh The ANSYS

shell181 element

is used for infill

plates and

boundary

elements. Mapped

mesh is used .

Page 15: Buckling Restrained Steel Shear Walls for Seismic Protection

15 © 2014 ANSYS, Inc. May 19, 2014 ANSYS Confidential

Boundary Conditions

Top Beams

and

Loading

Actuators

Page 16: Buckling Restrained Steel Shear Walls for Seismic Protection

16 © 2014 ANSYS, Inc. May 19, 2014 ANSYS Confidential

Boundary Conditions

Bottom

Beam

Support

Page 17: Buckling Restrained Steel Shear Walls for Seismic Protection

17 © 2014 ANSYS, Inc. May 19, 2014 ANSYS Confidential

Results Comparison between ANSYS Simulation and Test Results

Page 18: Buckling Restrained Steel Shear Walls for Seismic Protection

18 © 2014 ANSYS, Inc. May 19, 2014 ANSYS Confidential

Results

Comparison between ANSYS Simulation and Test Results

Page 19: Buckling Restrained Steel Shear Walls for Seismic Protection

19 © 2014 ANSYS, Inc. May 19, 2014 ANSYS Confidential

Results

The Problem with Plate Buckling and Column Bending

Page 20: Buckling Restrained Steel Shear Walls for Seismic Protection

20 © 2014 ANSYS, Inc. May 19, 2014 ANSYS Confidential

Buckling of Plate and Bending of Columns

Page 21: Buckling Restrained Steel Shear Walls for Seismic Protection

21 © 2014 ANSYS, Inc. May 19, 2014 ANSYS Confidential

Innovative Buckling Restraining Stiffeners

Page 22: Buckling Restrained Steel Shear Walls for Seismic Protection

22 © 2014 ANSYS, Inc. May 19, 2014 ANSYS Confidential

ANSYS ANALYSIS PLANS

• Validate FEA simulation – Use ANSYS to model existing test specimens and loading and compare its prediction of behavior of specimens to actual test results. (this presentation)

• Case Study Model: Jinta Tower in Tianjing, China • Designed by S.O.M.

• Test by Tsinghua University

• Generic Low-, mid-, and high-rise structures using proposed innovative “buckling restrained” steel shear walls

Page 23: Buckling Restrained Steel Shear Walls for Seismic Protection

23 © 2014 ANSYS, Inc. May 19, 2014 ANSYS Confidential

ANSYS ANALYSIS PLANS • Case Study Model: Jinta Tower in Tianjing, China

• Designed by S.O.M.

• Test by Tsinghua University

www.timgriffith.com

Page 24: Buckling Restrained Steel Shear Walls for Seismic Protection

24 © 2014 ANSYS, Inc. May 19, 2014 ANSYS Confidential

Test details

Reference: Nie et al(2013)

Page 25: Buckling Restrained Steel Shear Walls for Seismic Protection

25 © 2014 ANSYS, Inc. May 19, 2014 ANSYS Confidential

Test details cont.

SPSW1 (Not Buckling Restrained)

Total lateral load vs overall drift

Inter-story lateral load vs inter-story drift

SPSW2 (Buckling Restrained)

Page 26: Buckling Restrained Steel Shear Walls for Seismic Protection

26 © 2014 ANSYS, Inc. May 19, 2014 ANSYS Confidential

• Using ANSYS we were able to simulate buckling behavior of two test specimens of steel shear walls.

• Also, using ANSYS, we simulated behavior of steel shear walls with vertical stiffeners acting as buckling restraining elements.

• This was our use of ANSYS and now we are embarking on simulating fracture crack initiation and propagation as well as cyclic yielding and buckling behavior simulation using ANSYS.

• The goal is to use ANSYS in developing an innovative buckling restrained steel shear wall for buildings to resist wind and seismic lateral forces.

Concluding Remarks

Page 27: Buckling Restrained Steel Shear Walls for Seismic Protection

27 © 2014 ANSYS, Inc. May 19, 2014 ANSYS Confidential

We acknowledge and appreciate very valuable support and technical assistance received from Casey Heydari, Chris Cowan, and Cassandra Casteel , all of Ozen Engineering Inc.

Also, we appreciate the time and professional care that Ian Lockley and Ming Yao Ding, both of ANSYS Inc. spent with us in guiding us in our preparation of this presentation.

Acknowledgements


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