RC Frame Validation Tests - 4282005

Project goals and objectives

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

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.

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.

Brief Description of previous year's achievements, with emphasis on accomplishments during last year (Year 8)

This past year we completed shaking table tests to collapse on twelve one-story, one-bay frames and one three-story, three-bay frame. The one-story frame specimens comprised various combinations of ductile and nonductile concrete columns with varied axial loads and either long- duration ground motion or short-duration impulsive motion. Behavior generally was consistent with models for shear and axial failure developed in earlier phases of this research, an also was consistent with pre-test dynamic simulations. The three-story frame was subjected to the long- duration ground motion. The indeterminate framing apparently enabled redistribution of internal forces following initial failures, such that collapse of the frame system was delayed beyond initial expectations.

Continuing work on these projects will study the following:

• - Load-deformation characteristics of shear-critical columns subjected to loadings resulting in shear and axial failures.
• - Computational procedures for response simulation of strength-degrading systems.
• - Parameter studies to identify sensitivity of results to variations in ground motions and component properties.
• - Extrapolation of results using simulation tools to understand implications for seismic assessment of existing buildings.

Other similar work being conducted within and outside PEER and how this project differs

Researchers in Japan and Taiwan have carried out similar work, and we have arranged an extensive collaboration with leading researchers in both countries for Years 9 and 10. 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.

Describe any instances where you are aware that your results have been used in industry

Our results have been used by Degenkolb and Rutherford & Chekene for assessment of collapse potential of existing buildings. The results were presented in the EERI/PEER seminar in January and February 2006, as well as the 2006 Earthquake Conference, where they reached nearly 400 engineers. Results have been incorporated by reference into the ASCE-41 guidelines for seismic rehabilitation of existing buildings.

Expected milestones & deliverables

Complete analyses of test results and write final report.

Member company benefits

Useable data and models for assessment of existing buildings, as well as invitations to view tests.