Cyclic tests of modular CFT bridge piers

Abstract

Digital manufacturing and fast construction using machinery need standard design models and connection methods of prefabricated modules. Modular bridge substructures with concrete-filled steel tube (CFT) columns and composite pier caps were suggested to realize accelerated bridge construction. Column modules have bracings to connect each other and use standard tube products. Each bridge pier has four or six CFT columns which connect to the pier cap. From the cyclic test of a modular bridge pier, connection failure due to low cycle fatigue was observed. In order to solve the problem, four types of the connection for the enhancement of energy dissipation were fabricated and tested to derive moment-rotation curves. Using the curves, seismic behavior of CFT bridge piers with the connections was investigated. Intentional plastic hinge connection provided ductile behavior without premature failure of the connection. A prototype modular bridge pier was constructed and cyclic tests were performed. Incremental cyclic tests showed that the connections between column modules provided plastic hinge at the bottom part of CFT columns after yielding of bracing connection parts without connection failure. Through the cyclic test, design concepts of column modules, connection of bracings and pier cap module were verified.