Develop a state-of-the-art computational model and perform nonlinear dynamic analysis of the UC-Berkeley Life Sciences building using the OpenSees simulation platform to demonstrate PEER performance-based earthquake engineering assessment and design methodologies. The project has dual objectives:
- Testbed for simulation in OpenSees using actual buildings, and
- Developing floor displacement and acceleration time histories to be utilized in testing building contents
The project is a realistic demonstration for the computational platform
of PEER, namely OpenSees. Moreover, through the simulations, assessment
of the importance of a number of uncertain variables will be conducted.
This includes not only ground shaking details but also mass, damping, modeling
assumptions (e.g. 2-D versus 3-D) and component force-deformation behavior
of the selected building.
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Collect information about the structural system of the testbed, including member sizes, foundation type, material properties, and configuration and layout of any non-structural components.
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Survey available modeling options in OpenSees for representing structural elements including current nonlinear elements for geometric and material effects. This survey considered modeling issues related to soil conditions and interfaces between structural and non-structural elements.
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Develop a 2-D model where emphasis is on the structural system and boundary conditions using the available options in OpenSees.
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Conduct time history analysis of the several available ground motions developed for the building site to address uncertainty in the ground motion details.
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Generate floor time histories of relative and absolute displacements and accelerations for use by the researchers (at UCB and UCI) conducting the shake table experiments on the LSA building contents.
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Extend the structural model to 3-D to account for multi-directional ground motion effects and have more realistic distribution of mass and lateral stiffness.
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Simulate the 3-D model of the building with different properties addressing variability in mass, damping, and force-deformation relations of the different structural components comprising the 3-D model.
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Explore the application of the finite element response sensitivity analysis for LSA using OpenSees-Reliability developed by T. Haukaas & A. Der Kiureghian.
Figure 3: Description of ENT material to simulate soil behavior in OpenSees
Larger View
Figure 4: Spring forces in soil springs due to 50% in
50 years Coyote Lake earthquake
Larger View
Figure 5: Relative displacements of Roof due to 50%
in 50 years, Coyote earthquake
Larger View
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2-D working nonlinear model in OpenSees of the coupled shear wall lateral load-resisting system in the transverse direction (normal to the Hayward fault) as shown in Figures 1 and 2 (Year 5).
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Account for modeling foundation and soil conditions of the 2-D model, refer to Figures 3 and 4 (Year 5).
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Develop floor accelerations and deformation to be used for the shake table tests of the building equipments using several ground motions developed by other researchers for the building site, sample results (one simulation out of thirty) are given in Figures 5, 6, and 7 (years 5 and 6).
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Perform deterministic sensitivity study (Year 6) where probabilistic hazard curve is used to determine the intensity measures in terms of spectral accelerations. This is followed by determining representative ground motion profiles. Finally, several sources of uncertainties were accounted for using their swings in the form of Tornado diagrams as shown in Figure 8.
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Simulate the 3-D model of the building with different properties addressing variability in mass, damping, and force-deformation relations of the different structural components comprising the 3-D model, Figure 9 (Year 6).
Figure 6: Relative accelerations of Roof due to 50% in 50 years, Coyote
earthquake
Larger View
Figure 7: Absolute displacement of Roof due to 50% in 50 years, Coyote
earthquake
Larger View
Figure 8: Tornado diagrams for different engineering demand parameters to demonstrate the importance of different sources of uncertainties
Larger View
Further
account of uncertainties in ground motion and modeling and developing
means of reducing them should be pursued. One major issue is
the development of EDP’s for the performance of building
content. This should be pursued in light of the tests conducted
at UC-Berkeley
and UC-Irvine. With this set of test results, possible development
of representative limit states of the performance of the building
content can be formulated and utilized with the developed computational
model of the building to investigate losses due to damage to
the building content. One specific issue is to develop tornado
diagrams
in terms of design variables (related to building content and
non-structural components).
The project main milestones are:
- May 2002: Complete the 2-D model of the building and its associated simulations
- Sept 2002: Identify the important uncertain variables based on the 2-D working model
- March 2002: Finalize the deterministic sensitivity analysis using the 2-D model
- April 2003: Complete the simulations using the 3-D model and investigate the important uncertainties
- June 2003: Address the modeling issues related to any non-structural components, such as partitions or building contents
- Sept 2003: Summarize results and produce the final report
The project main deliverables include:
- A working 2-D model of the building
- A working 3-D model of the building
- A complete suite of time histories of displacements and accelerations for the building floors under the effect of the developed ground motions for the site.
Results of the deterministic sensitivity analyses from the 2-D and 3-D models with ordering of importance of the different sources of the uncertainties affecting the structural performance of the building and its contents