Report No.: CCEER-02-6

Title: Cyclic Behavior of Shear Links and Tower Shaft Assembly of San Francisco-Oakland Bay Bridge Tower

Authors: P. Dusicka, A. Itani, and I. Buckle

Date: July 2002

Sponsoring Agency: California Department of Transportation (CalTrans)

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


The single steel tower of the suspension cable span for the replacement of the East Span of the San Francisco Oakland Bay Bridge consists of four individual shafts that are connected by links. Two experiments were conducted at the University of Nevada, Reno, to quantify the behavior of the shear links and links-to-tower shaft assembly using half-scale replicas of the tower assembly typical for the transverse and longitudinal directions of the bridge. The specimen fabrication and erection procedures are outlined. The results of the cyclic experiments showed ductile behavior. The maximum rotational capacity of the link deformable length, measured at 0.13 rad shear deformation in both types of links, exceeded that of the code specified maximum allowable demand value of 0.08 rad. The ultimate strengths of the links were found to be significantly higher than those recommended by the code, which was reflected in the overstrength ratio of 2.48 and 2.24 for the longitudinal and transverse experiments respectively. The plastic deformations and ultimate failure of the assembly was concentrated in the deformable length of the links. All failures were initiated by web tearing, which were found at the toe of the stiffener to the web weld closest to the flange. No distress or inelastic strains were found in the shaft or link-to-shaft connections.