Experimental study on seismic behavior of T-joints of composite shell system with prefabricated underground pipe gallery

The prefabricated assembly structure adopts a new joint structure and construction method, which has the advantages of low environmental pollution, high construction quality, and less traffic interference. At present, prefabricated structures have been widely used in the field of building construction and bridge engineering, but less in the application of underground comprehensive pipe gallery. In view of this, this paper proposed a new type of assembled composite shell system underground comprehensive pipe gallery structure. The formwork is made of high-performance materials, and connectors are set between the formwork, and the load-bearing reinforcement of the composite shell pipe gallery component was set outside the formwork. Quasi static tests were carried out on 6 specimens of composite shell pipe gallery T-joints to study the mechanical properties of the joints and the integrity of the connection interface. The results show that the bearing capacity, stiffness and ductility of composite shell T-joints are basically equivalent to those of cast-in-place (CIP) reinforced concrete shear walls, which verifies the good seismic performance of fabricated joints. When the specimen is in the yield and bearing capacity state, the joint surface between the formwork and the post cast concrete is good, which can effectively ensure that the formwork and the concrete maintain the common force. The bearing capacity of upper and lower T-joints of composite shell with shear reinforcement is 10 similar to 15% higher than that of CIP structure. In addition, a calculation formula for the bearing capacity of the T-shaped joint of the composite shell was proposed and its accuracy was verified through test results. This study can provide technical support for seismic design of prefabricated underground pipe gallery.