Project Title/ID Number Benchmarking Performance of New RC Frames Building—3362003
Start/End Dates 10/1/03—9/30/04
Project Leader Gregory Deierlein (Stanford/F)
Team Members Curt Haselton (Stanford/PD), Arash Altoontash (Stanford/PD)

F=faculty; GS=graduate student; US=undergraduate student; PD=post-doc; I=industrial collaborator; O=other

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1. Project Goals/Objectives:

The concept for this project grew out of discussions among researchers and BIP members at the PEER 2003 Annual Meeting. The overall objective of the project is to apply the PEER PBEE methodology and tools to assess the performance of ductile RC frame buildings, which conform to current design standards. Within this global objective are three specific goals to:

  1. Benchmark the performance of code-compliant RC buildings using the PEER PBEE methodology. This goal extends the previous testbed studies to consider generic buildings designed according to current building codes. Thus, the exercise is as much an evaluation of code provisions, as specific buildings designed and assessed in this project.
  2. Contribute to development and “packaging” of the PBEE methodology and enabling data and technologies through their application to the benchmarking exercise.
  3. Conduct preliminary studies to use PBEE assessment tools to ascertain how building performance is affected by key design criteria for minimum strength, stiffness, and ductility. Included within this goal is consideration of the uncertainties in these design parameters, which are subject to the minimum requirements of building code provisions but are uncertain in the sense of how they are defined for a specific project.

2. Role of this project in supporting PEER’s mission (vision):

This project is a key activity to develop and demonstrate a comprehensive PBEE approach to assessing the performance of reinforced concrete buildings. The project is inspired by the success of the PEER building testbeds to integrate and focus the multidisciplinary research spanning from engineering seismology, through structural and geotechnical engineering, and ultimately to loss modeling. Beginning in Year 8, the benchmarking research begun in this project will become a central effort of the realigned Thrust Area I on Building Systems.

3. Methodology Employed:

The scope and project plan for the coming year involve the following components:

  1. Solicit input from practicing engineers on typical RC moment frame building construction in the western US (occupancy, floor plans, height, framing layout, typical design considerations/constraints, etc.)
  2. Develop a detailing planning/scoping document, which outlines
    1. Key design, construction, and structural behavior considerations in the benchmark investigation,
    2. Details for implementing and applying the PBEE methodology to the benchmark buildings,
    3. A matrix of descriptors for the benchmark buildings, and
    4. A timeline for conducting the study and reporting results.
  3. Develop design of a benchmark RC building, including definition of the structural system and major nonstructural components and contents.
  4. Perform nonlinear structural simulations using OpenSees to develop data for the PBEE assessment. These will include Incremented Dynamic Analyses of the median design to assess collapse, sensitivity studies of selected design and modeling parameters at discrete hazard levels, and additional analyses as necessary to describe the response in a probabilistic sense as input for the loss modeling.
  5. Coordinate with Beck and Porter to integrate structural EDPs with loss models to determine DMs and DVs the benchmark building(s)
Resulting from the study will be a probabilistic description of building performance in terms of key decision variables, including mean annual probabilities of collapse, downtime, and repair costs. In addition to the results for this particular class of building, the study will serve to articulate a step-by-step methodology for such studies and to collect and begin packaging of the data and tools (simulation models, loss models, etc.) necessary to conduct the study.

4. Brief Description of past year’s accomplishments (Year 6) & more detail on expected Year 7 accomplishments:

A new PhD graduate research assistant (Curt Haselton) has been working on the project since October 2003 and has been familiarizing himself with the nonlinear simulation tools of OpenSees and the overall PEER PBEE framework and loss models. We have met with practicing engineers and collected building plans for modern office buildings and parking structures designed with RC moment frame systems. We then conducted independent design reviews of these structures to develop data on uncertainties in design parameters, i.e., to what extent do typical designs vary from the minimum requirements of the building code. Based on this preliminary work, a prototype four-story office building has been designed according to current design standards (ASCE/SEI 2002 and related provisions from ACI-318). Through meetings with our collaborators at Caltech (Beck and Porter), we have developed a specification for an SQL database to exchange information between the structural simulations (IM-EDP) and loss modeling (EDP-DM-DV). We have similarly coordinated with Stewart at UCLA to develop earthquake hazard information for the assessment (including selection of ground motions) and to develop a plan to jointly investigate soil-foundation-structure interactions. We are on track to complete an assessment of the benchmark building by October 2004.

5. Other Similar Work Being Conducted Within and Outside PEER and How This Project Differs:

Synthesizing and “packaging” of the methodology and tools for this project is being done in consultation with several PEER investigators, including: Beck/Porter (loss modeling); Miranda (loss modeling and non-structural components); May (articulation of performance metrics), Krawinkler (assessment and design methodology), Cornell (assessment methodology), Stewart (soil-structure interaction effects), Lehman/Lowes (simulation and performance of beam-column joints), Eberhard (simulation and performance of beam-columns), and others.

The benchmark studies involve direct collaboration with projects by Beck/Porter at Caltech “Building Loss Modeling and Benchmarking - EDP to DV” and Stewart at UCLA “Soil-structure Interaction Effects and Their Influence on Input Ground Motions.” All three teams are collaborating on planning details of the research, with the Stanford effort focusing on the IM-EDP aspects, the Caltech group focusing on EDP-DV, and the UCLA group is developing the site hazard information and input ground motions, including the effects of soil-foundation interaction.

The PI is not aware of similar benchmarking efforts of this type being applied to reinforced concrete frames. The project bears some similarity to a series of assessment studies of steel moment frame buildings conducted through the SAC joint venture. As the PEER methodology is building upon concepts first developed in SAC, the RC building benchmarking study will take advantage of the prior SAC work.

6. Plans for Year 8 if project is expected to be continued:

This project is envisioned as a multi-year effort, which will begin with assessment studies that are anticipated to evolve into research on performance based design (design being distinct from assessment). The project was begun in Year 7, and the goal for the first year is to synthesize the necessary models and information and complete a benchmark assessment of a four story RC building. Plans for Year 8 are to extend the study to evaluate a broader range of RC buildings and to improve the underlying assessment procedures, depending on what gaps and problems arise during Year 7.

7. Describe any actual instances where you are aware your results have been used in industry:

PEER’s PBEE assessment framework has been adopted as a model by the ATC 58 project to codify performance-based procedures for application to engineering practice. This project will contribute to the interactions between PEER and the ATC 58 group by demonstrating the application of the PEER PBEE method for assessment of RC moment frame buildings.

8. Expected Milestones & Deliverables:

The primary deliverable of this project will be a report and a journal paper that document the PEER PBEE assessment procedure, including guidelines for developing the simulation and loss models necessary for the procedures. These are expected to be completed by October 2004.

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