Cyclic Behavior of Corroded Fuse-Type Dissipaters for Posttensioned Rocking Bridges

Abstract

This article presents the observed cyclic responses of three types of metal hysteretic, axial dissipative devices (typically used with dissipative controlled rocking bridge piers) under varying degrees of corrosion. Dissipative controlled rocking bridge piers employ a combination of unbonded posttensioning tendons and external replaceable dissipaters. Unbonded posttensioning provides the ability to self-center, and dissipaters absorb seismic energy. The quality and properties of dissipaters decrease over time as a result of corrosion, which needs to be considered for capacity evaluations. The effects of chloride-induced corrosion on the hysteretic and cyclic response of these dissipaters were studied experimentally. To save time, the dissipaters, having equal length and cross-sectional area in the reduced area, were corroded using an accelerated corrosion technique called the impressed current method at a corrosion rate of 8 μA/cm2. Cyclic (tensile-compression) tests for 36 dissipaters in total were conducted under three levels of corrosion and two different deformation rates. This investigation has resulted in clear quantification of the relationship between the degree of corrosion and both cyclic and hysteretic properties of the dissipaters studied.