1. Project Goals/Objectives:

The goal of this project is to develop validation data and nonlinear models for nonlinear response, component failure mechanisms, and internal force redistribution as collapse occurs in a building frame representative of older concrete construction.

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

This project supports the PEER strategic plan by providing performance data, validation tests, and nonlinear models to advance the simulation capabilities of OpenSees. Performance data and simulation are central to the PEER mission of developing performance-based earthquake engineering methodologies.

3. Methodology Employed:

This project is conducting analyses and experiments on the nonlinear dynamic response of components and substructures sustaining shear and axial load failures. These tests provide validation data for simulation models being developed in OpenSees. Additional work includes development of mechanical models for shear and axial failure and implementation of those models in OpenSees.

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

We previously have completed pseudo-static and dynamic shaking table tests of specimens sustaining shear and axial-load failures. These serve as the basis for development of analytical models as well as computational procedure.

Models for shear strength have been developed and checked against available data for representative columns tested both within PEER and by other organizations. Models for axial-load failure following shear failure also have been developed and compared with available data. These models show a correlation between axial load, transverse reinforcement, and drift at failure. We have implemented the model in OpenSees and have validated it against results of earthquake simulation tests conducted previously within this project. Additional details can be found at http://peer.berkeley.edu/%7Eelwood/research/dissertation.htm.

We have found that simulation of axial failure in building frames requires accurate simulations of displacement response of systems with degrading strength. Analytical studies suggest that peak displacement is strongly affected by in-cycle strength degradation, but little data exists to verify this. We are planning a series of earthquake simulator tests to validate these models, with tests planned for summer 2004. Another set of tests for later in the year extends the study to multi-story systems.

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

Researchers in Japan and Taiwan have carried out similar work. The details and configurations used in those tests are different from those considered common and most critical for existing US buildings. However, we remain in close contact with our counterparts in other countries so that we can take advantage of their conceptual thinking, data, and analysis models. Within PEER, we are collaborating with developers in OpenSees to ensure optimal development of analytical models and simulation modules. A companion project in PEER (PI Mosalam) will collaborate in developing analytical models.

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

We anticipate completing earthquake simulator tests during Years 7 and into Year 8. We propose to continue work in this general direction with emphasis on the development of nonlinear models/simulation strategies for systems with strength degradation.

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

 

8. Expected Milestones & Deliverables: