Experimental Research on Fully-Dry Connections of Prestressed Concrete Columns Under Unidirectional Eccentric Compression

It is of great significance to perform the mechanical properties of connections of pre-stressed concrete columns for promoting the development of pre-stressed concrete frame structure which is a typical kind of assembled structure with fully-dry connections. In this paper, the mechanical properties of three kinds of connections of pre-stressed concrete columns were studied through quasi-static connection of loading tests. The quasi-static tests on the connection of unbonded pre-stressed concrete column (UBPC), bonded pre-stressed concrete column (BPC), and the connection between longitudinal rebar and unbonded pre-stressed concrete column (RUBPC) were carried out under unidirectional eccentric compression. The experimental results demonstrated a better ductility for the three connections. When the deformation of the columns reached 1/50 which was the elastic-plastic inter-story drift of RC frame structure, the maximum bearing capacity was still more than 85% of the ultimate bearing capacity for each specimen. For UBPC and BPC, the damage of precast column was effectively reduced due to the opening of the bonding surface at column bottom, while their ultimate bearing capacity was 15%~20% lower than that of RUBPC. In addition, the energy dissipation of UBPC and BPC was less than that of RUBPC. When Compared with RUBPC, UBPC and BPC presented better re-centering capacity and smaller residual deformation. Moreover, the steel rods remained elastic during tests for all the specimens, and their initial tensile forces in RUBPC and UBPC were decreased by 12% when the specimens were destroyed. Compared with UBPC, the BPC presented a larger bearing force and a better energy dissipation.