EXPERIMENTAL RESEARCH ON MECHANICAL PERFORMANCE OF MONOLITHIC PRECAST BEAMS USING CAST-IN-PLACE LOW-SHRINKAGE ENGINEERED CEMENTITIOUS COMPOSITE

This paper proposes two kinds of monolithic precast frame joint schemes based on a new type of ECC material, named high-toughness low-shrinkage ECC (LSECC), to achieve high aseismic performance and simple reinforcement details in high earthquake intensity regions. According to the joint schemes, five assembled monolithic precast LSECC beams are constructed and tested under static monotonic loading. Based on the analysis of loading capacity, stiffness, failure mode and cracking behavior, the feasibility and advantages of application of LSECC in monolithic assembled joints are preliminarily verified. The critical problem such as interface details (including hot and cold connections) and longitudinal bar anchorage are carefully studied, and proper construction details are proposed, which effectively guides the subsequent study on the aseismic performance of large-scale monolithic precast beam-column joints. The test results show that the loading capacity and ductility of a monolithic assembled LSECC beam are equivalent with those of a cast-in-place beam while the crack width in ECC region is obviously smaller than concrete. The larger range of ECC used in the beam span leads to lower initial stiffness and slower stiffness degradation. Better deformation compatibility and higher bonding strength can be found between ECC and rebar, and the anchorage length is significantly reduced compared to the concrete joint. Therefore, the application of ECC in the assembled joints can ensure sufficient bonding and anchoring capacity. Proper reinforcement details can effectively improve the performance of the ECC-precast concrete interface, thus providing sufficient crack controlling capacity.