Experimental study on axial compression performance of unbonded prestressed mortise-tenon precast concrete mid joint

Abstract

This paper presents an unbonded prestressed mortise-tenon precast concrete (MTPC) structure, where the beam-column joints are connected by mortise and tenon construction and are tightly crimped using longitudinal prestressed steel strand. It has the advantages of no wet works, easy on-site assembly, short construction period and can be disassembled. First, the structure and assembly method of MTPC joints were introduced. Five full-scale models of MTPC mid joints and one full-scale model of cast-in-place joint were produced. Then the axial compression test was carried out on these models. According to the test results, the damage mode and axial bearing capacity of the MTPC mid joint were analyzed. The analysis results show that the mortise and tenon construction of MTPC joint can effectively transfer the axial compression load, and its axial compression load bearing capacity is about 37%–46% of that of the cast-in-place joint. Unlike cast-in-place joint, there is an obvious compaction stage in MTPC joint under the axial compression. The damage of MTPC joint is concentrated in the beam-column joint area, and the main damage mode is short column damage. The weakest part of the joint is the lower column mortise, which is weakened by the small cross-sectional area and shear-compression force state. The MTPC joint is sensitive to the construction error and assembly error, which will cause the joint to be in eccentric force state and lead to the decrease of its bearing capacity. Finally, this paper proposes a method to calculate the axial compression bearing capacity of MTPC mid joint.