Report No.: CCEER-98-1

Title: Cyclic Behavior of "As-Built" Laced Members with End Gusset Plates on the San Francisco-Oakland Bay Bridge

Authors: Ahmad M. Itani, Timothy D. Vesco, and Adrianne M. Dietrich

Date: March 1998

Performing Organization:
Department of Civil Engineering/258
University of Nevada, Reno
Reno, NV 89557


This report presents results of an experimental program to evaluate the cyclic behavior of the San Francisco-Oakland Bay Bridge tower diagonals. The objectives of the study were to:

  1. Determine the cyclic behavior of built-up laced members with their end connections.
  2. Evaluate the ultimate tensile/compressive capacity and post buckling behavior of laced members with their end connections.

A one-half scale specimen that represented the diagonal member, B9WG, of Pier E9, Eastern Spans, was tested under severe cyclic loading. The test results showed the laced member suffered premature buckling at its end connections at a load less than 40% of its code predicted capacity. Individual components of the built-up section experienced out-of-plane buckling at the ends of the stay plates. Extending the stay plates through the double gusset plates exposed the out-of-plane edge buckling of gusset plates. The tensile capacity of the laced member was equal to one half of the code predicated value of the built-up section.

The AISC LRFD relationships between individual component buckling and section buckling can be used to predict the ultimate capacity of laced members. The stay plates of laced members should be extended as much as possible into the double gusset plate connections (Abstract by authors).