Project Title/ID Number Van Nuys Testbed Simulation—3272002
Start/End Dates 10/1/02—9/30/03
Project Leader Laura Lowes (UW/Faculty)
Team Members Chaitanya Paspuleti (UW/Grad Student), Nilanjan Mitra (UW/Grad Student)
Project goals and objectives

The primary objective of the proposed research effort is the development of state-of-the-art numerical modeling techniques for use in simulating the earthquake performance of older reinforced concrete buildings. The OpenSees analysis platform will be used as a basis for model development and the Nuys Testbed Building will be used as an example structure. The Year 6 research effort will building on a previously developed model of the Van Nuys building to 1) improve simulation of inelastic structural response, 2) enable prediction of structural and non-structural damage and economic loss, and 3) predict the impact of the FEMA 356 retrofit scheme on damage and loss.
Role of this project in supporting PEER’s vision
The results of this project support the PEER research effort in several ways. First this study uses the OpenSees platform to simulate the earthquake response of an older reinforced concrete building frame and thereby contributes to evaluation, verification and advancement of the OpenSees platform. This analysis platform is central to the PEER research effort. Second, this study uses multiple component models developed by various researchers to predict response and thereby contributes to the evaluation, verification and advancement of these component models. Third, the results of this study define the relationship between intensity measure and engineering demand parameters for the Van Nuys testbed building. By quantifying the uncertainty in EDPs associated with modeling decision, the results of this investigation contribute to modeling of the uncertainty of the IM-EDP relationship. Fourth, this project is required to demonstrate the application of the PEER loss-assessment methodology to the Van Nuys testbed building.
Methodology employed

Classical methods for nonlinear, dynamic, structural analysis were employed to generate simulated response histories. Classical statistical methods will be employed to quantify variability in EDPs associated with epistemic and alleatory uncertainty in model parameters.
Brief description of past year’s accomplishments and more detail on expected Year 6 accomplishments

Year 5 accomplishments include the following:

  1. the development of a parameterized model of the Van Nuys building using the OpenSees platform, this approach facilitates investigation of the impact on predicted EDPs of alleatory uncertainty using a Monte Carlo approach and epistemic uncertainty using a decision-tree approach,
  2. development/identification of a baseline model of the Van Nuys building that provides representation of column splice failure, column shear failure and limited flexural ductility of beams and columns,
  3. use of the baseline model to generate EDPs for three earthquake hazard levels,
  4. evaluation of the impact of modeling decisions such as concrete material model parameters, column shear strength model, level of mesh refinement, damping, column plastic-hinge length, etc. on prediction of EDP (Figures 1 and 2).

 
Figure 1: Base shear versus roof displacement for one exterior and one interior frame of the Van Nuys Holiday Inn building. Different response histories are shown for models of the structure that include different representations of column shear and splice strength.
Larger View


Figure 3a: Maximum story drifts for a the baseline model of the Van Nuys building subjected to an earthquake ground motion record with 10% probability of exceedance in 50 years. Different maximum drift values correspond to different models of the structure that include different levels of damping (x = 2%-M1, x=8%-M2), different concrete compressive strength (fc = design strength-M14), different beam-column element formulation (nlbc-M5), different column hinge length (lp=0.5d-M6), different effective slab width (_=0.22-M7) and different column shear strength values (computed shear strength is reduced 10% - M16 and computed shear strength is increased by 10% - M17).
Larger View



Figure 2: Base shear versus roof displacement for one exterior and one interior frame of the Van Nuys Holiday Inn building. Different response histories are shown for models of the structure that include different beam-column element formulation (nlbc-M5), different column hinge length (lp=0.5d-M6), different effective slab width (_=0.22-M7) and different joint flexibility (flexible-M8).
Larger View



Figure 3b: Maximum story drifts for a model of the Van Nuys building, which does not include simulation of column shear failure, subjected to an earthquake ground motion record with 10% probability of exceedance in 50 years. Different maximum drift values correspond to different models of the structure that include different levels of damping (x = 2%-M1, x=8%-M2), different concrete compressive strength (fc = design strength-M14), different beam-column element formulation (nlbc-M5), different column hinge length (lp=0.5d-M6) and different effective slab width (_=0.22-M7).
Larger View

  

Year 6 accomplishments will include the following:

  1. Introduction of three beam-column joint models into the OpenSees model of the Van Nuys building, evaluation of these models and the impact of modeling joint deformation on building frame response.
  2. Introduction of an improved shear-critical column model (the model developed by Moehle and Elwood will be used) into the OpenSees model of the Van Nuys building, evaluation and further development of this model as is necessary, and assessment of the impact of model formulation and model parameters on prediction of EDPs.
  3. Introduction into of foundation elements into the model and assessment of the impact of these elements on predicted EDPs.
  4. A formal sensitivity study to quantify the uncertainty in the IM-EDP relationship associated with modeling decision.
  5. In collaboration with other PEER researchers, the results of the Van Nuys simulation will be use to predict economic loss resulting from earthquake ground motion.
Other similar work being conducted within and outside PEER and how this project differs
 
Plans for Year 7 if this project is expected to be continued
 
Describe any instances where you are aware that your results have been used in industry
 
Expected milestones

Milestones mirror the Year 6 accomplishments identified above.
Deliverables

Deliverables associated with Year 6 accomplishments identified above:

  1. Simulated EDPs for the suite of Van Nuys ground motion records, including joint load and deformation demands, for a single beam-column joint element formulation
  2. Simulated EDPs for the Van Nuys ground motion records
  3. Simulated EDPs for the Van Nuys ground motion records, including foundation load and deformation demands
  4. Sensitivities
  5. Economic loss predictions for three earthquake hazard levels