Seismic Behavior of Shear-Critical Hollow Bridge Columns

Abstract

The high-speed rail project to improve Taiwan’s transportation systems is an effort by the Taiwanese government to further the island’s economic development. The planned route is 345 km long, and the viaducts and bridges are approximately 207 km long. Hence, there are many bridge piers in the project. To maximize structural efficiency in terms of the strength/mass and stiffness/mass ratios and to reduce the mass contribution of the pier to seismic response, it is desirable to use a hollow section for the piers. To consider both the ductility and constructability, a hollow section with special confinement reinforcement has been used in the bridge piers in the high-speed rail project of Taiwan. During the past three decades, various studies on the confinement effects of lateral reinforcement in columns have been conducted, and the analytical models have been proposed. It is not clear that if any of the stress-strain models of confined concrete proposed in the past is appropriate for the hollow sections used in Taiwan. Therefore, such hollow sections need to be studied by both tests and analysis. The seismic performance of rectangular hollow bridge piers is a significant issue of the high-speed rail project in Taiwan, because the shear capacity of such piers with the configuration of lateral reinforcement used in Taiwan is not clear. Such piers were tested under a constant axial load and a cyclically reversed horizontal load to investigate their seismic behavior (Yeh and Mo 1999; Yeh, Mo and Yang 2001). This paper presents the experimental results of three specimens of such piers. The parameter of the test program was the height to width ratio of the piers. The seismic behavior of the piers, including flexural ductility, dissipated energy, and shear capacity is presented. On the other hand, shear research at the University of Houston performed over the past two decades resulted in a series of constitutive models. The Cyclic Softened Membrane Model (CSMM) (Mansour and Hsu 2005a, 2005b) is the latest developed STRUCTURES 2006