PEDESTRIAN LOAD TEST AND VIBRATION SERVICEABILITY ANALYSIS OF DISCRETELY CONNECTED PRECAST RC FLOORS

To study the dynamic characteristics of discretely connected precast RC diaphragms (DCPCDs) and the response to human-induced excitation, two DCPCD specimens and one cast-in-situ slab specimen were tested. All specimens were simply supported at four sides. The vibration response of the specimens under pedestrian load was analyzed considering the step frequency, walk path, load distribution form, number of pedestrians and distribution of loads. The results show that the plate seam reduces the vertical stiffness of the floor and increases the damping ratio. The second and the third mode shapes are anti-symmetric in the orthogonal slab laying direction (OSLD) and the slab laying direction (SLD), respectively. Increasing the number of connectors can effectively increase the natural frequency and reduce the vibration response of the DCPCDs. The peak acceleration increases with the increase of the step frequency and number of people. The peak acceleration when walking in the OSLD is greater than that when walking in the SLD and diagonal direction. The greater the load distribution density and the closer the load distribution is to the center of the floor, the greater the peak acceleration will be. The fundamental frequency of DCPCD specimens can meet the code requirements, but the acceleration varies significantly under different support conditions. The numerical calculation methods of the peak acceleration of DCPCD under standard single-footfall forces is proposed. The calculated values are well correlated with the test values. For serviceability, it is recommended that the stiffness ratio between the OSLD and SLD is between 0.3-0.75.