- Author
- El-Bahy, A. | Kunnath, S. K. | Stone, W. C. | Taylor, A. W.
- Title
- Cumulative Seismic Damage of Circular Bridge Columns: Benchmark and Low-Cycle Fatigue Tests.
- Coporate
- Tilden Lobnitz, Cooper, FL University of Central Florida, Orlando National Institute of Standards and Technology, Gaithersburg, MD KPFF Consulting Engineers, Seattle, WA
- Journal
- ACI Structural Journal, Vol. 96, No. 4, 633-641, July/August 1999
- Keywords
- bridges (structures) | damage | reinforced concretes | piers | earthquakes | fatigue (materials) | structures | cyclic loads | ductility | material properties
- Identifiers
- earthquake-resistant structures; details of prototype and model; summary of reinforcing bar characteristics; benchmark tests; low-cycle fatigue tests; fatigue life relationship
- Abstract
- An experimental study was undertaken to investigate cumulative damage in reinforced concrete circular bridge piers subjected to a series of earthquake excitations. Twelve identical quarter-scale bridge columns, designed in accordance with current AASHTO specifications, were fabricated and tested to failure. This paper summarizes the results of Phase 1 testing that consisted of benchmark tests to establish the monotonic force-deformation envelope and the energy capacity under standard cyclic loads, and constant amplitude tests to determine the low-cycle fatigue characteristics of typical flexural bridge columns. A companion paper will present the results of variable amplitude testing that focused on the effects of load path on cumulative damage. Test observations indicate two potential failure modes: low cycle fatigue of the longitudinal reinforcing bars; and confinement failure due to rupture of the confining spirals. The former failure mode is associated with relatively large displacements amplitudes in excess of 4 percent lateral drift, while the latter is associated with a larger number of smaller amplitude cycles. A fatigue life expression is developed that can be used in damage-based seismic design of circular, flexural bridge columns.