Effect of Load History on Performance Limit States of Bridge Columns

AUTC project number: 410002

PI(s):

Mervyn Kowalsky (NCSU)

Funding:
  • US Department of Transportation (RITA)
  • Alaska Department of Transportation & Public Facilities
  • Start Date: Jul 1, 2010
  • End Date: Aug 15, 2012

Project Summary

This project investigates the impact of seismic loading history on the design of reinforced concrete bridge columns typical of those used in Alaska. Currently, structural engineers use concrete and steel strain limit states in seismic design, which have minimal experimental or theoretical basis. The overall objective of this project is to propose strain limit states that account for regional seismic loading histories in Alaska, and to relate these proposed strain limits to displacement limits. Project goals will be met through a combination of analytical and experimental studies. A key requirement of the experimental work is the ability to measure large strains (up to 12%). The seismic loading histories to which the test specimens will be subjected will be determined from a data set developed by researchers at the University of Alaska Anchorage. Results from both frame-type and fiber-based analyses using ground motions from the data set will guide the initial selection of specimen design variables. A total of nine tests on essentially full-scale circular bridge columns will be performed. Given the limited number of tests, it is important to learn as much as possible from each test before designing and conducting additional 9 tests. These nine test units will be subjected to load histories with varying characteristics, but typical of those experienced in Alaska. The primary benefit of this project will be a better understanding of how seismic load history influences the performance of reinforced concrete bridges in Alaska. ADOT&PF engineers will be provided with tools to refine bridge designs, optimizing for regional seismicity and ensuring that bridges in Alaska remain safe in major earthquakes and serviceable in smaller earthquakes.