Experimental Study on Steel Jacket-Concrete Composite Connections

Steel-concrete composite frame bridges have larger structural stiffness, lower cost, and faster construction speed than traditional bridges because a combination of steel-concrete composite girders, concrete piers, and steel-concrete composite connections is used. In this type of composite bridge, the most important part is the connection joint between the steel-concrete composite girder and the concrete pier, which is formed by a steel plate, core concrete, shear connectors, and rebars. Taking a five-opening (110 m × 5) steel-concrete composite frame bridge with five 40-m-high piers as a prototype structure, three specimens, including two steel jacket-concrete composite connections with different construction details and one traditional rebar connection, were designed to study the load transfer mechanism in different types of composite connections. Results of the reversed cyclic load tests on the three specimens indicated that the steel jacket composite connections have better structural performance than the rebar connection, and bending moments in steel-concrete composite girders can be directly transferred to concrete piers via steel jackets. Furthermore, the interrelationship between the anchorage length of longitudinal rebars in the core concrete and the length of the steel jacket is revealed by strains measured by strain gauges, from which the design method of the steel jacket-concrete composite connections is recommended.