TUDY ON THE BENDING STIFFNESS CALCULATION METHOD OF DCNPD IN THE ORTHOGONAL SLAB LAYING DIRECTION

In order to enhance the vertical bearing capacity and in-plane stiffness of discrete connected new-type precast RC floor diaphragms (DCNPD), slab joints and slab-beam joints are connected by mechanical connectors. The theoretical and numerical studies of bending stiffness in the orthogonal slab laying direction (OSLD) were conducted to reveal the vertical bearing capacity of DCNPD based on experimental results. The result shows that:the vertical bearing capacity of DCNPD is slightly smaller than that of cast-in-situ floor, but much higher than that of the precast floor without slab joint connectors, demonstrating that the connectors are effective in transferring the OSLD force in DCNPD. An analytical model for bending stiffness in OSLD was constructed and the bending stiffness calculation method (which was verified valid in the elastic analysis of DCNPD) in OSLD of DCNPD was proposed based on equivalent beam-model theory. Both slab numbers and connector numbers are main factors for the vertical bearing capacity of DCNPD, but slab numbers are more vital compared with connector numbers. It is proposed that wide-precast-slab plan should be preferred when the transportation and hoisting conditions are available. The results can provide a reference for further studies and project practices of DCNPD.