Experimental and analytical investigation on the in-plane mechanical property of discretely connected precast RC floor diaphragm

Abstract

Discretely connected precast reinforced concrete floor diaphragm (DCPCD) is a new-type untopped precast concrete floor system. Using slab joint connectors, instead of cast-in-situ concrete overlap layers on precast slab, to transmit slab joints inner forces caused by vertical and horizontal loads eliminates the need for wet works in construction site, thus leading to economical designs and high efficiency in installation. This paper presents the development and experimental evaluation of DCPCD subjected to in-plane low-cyclic reversed loading. Performance of the tested specimen was evaluated in terms of failure mode, in-plane deformation pattern, hysteretic curves, stiffness, ductility and energy dissipation capacity. The results show that DCPCD had high in-plane stiffness and good integrity, and the beam-to-slab connections and slab joints perform well during the test process. The ductility of the specimen is acceptable, while the energy dissipation is not that satisfactory, confirming that the elastic design method of precast RC diaphragms is rational. The shear and axial force distribution regularity of the tested specimen was analyzed, and the results indicate that internal force distribution is similar to that of the simply supported beam. The equivalent beam model theory was modified based on the measured tensile (compressive) stiffness of slab joint connectors and the actual load effect in the floor et al. It is demonstrated that the in-plane deformations determined by the modified calculation method agree well with the test results. Hence, the proposed in-plane stiffness analysis method is reliable and can be used for designing buildings adopting DCPCD.