Analysis The Economic Span-depth Ratio Of The Assembly Box Concrete Hollow Floor In The Underground Garage Roof Engineering

The assembly hollow concrete floor is suitable for the underground garage roof engineering with large span and oversized loads,and has a great impact on the structural system and project cost. The assembly box as a new type of hollow membrane for concrete hollow floor system,the hollow ratio can reach 70%, which greatly reduced the structural weight. Being a combination box of precast reinforced concrete,the top and bottom of the assembled cabinet participate in the overall force of the floor. At the same time, the side panels can be used as templates around the rib beams. The span-depth ratio “λ”of the assembly hollow concrete floor refers to the ratio of the slab span and the height of the floor structure. According to the long side, the span is counted. And it is the key indicator to determine the floor deformation, stress and reinforcement. At the same time, it is also an important indicator of the impact of architecture rationality and the optimal economy.With the finite element analysis software STRAT,the floor model of underground garage roof of three kinds of span with these three column grid size 9m × 9m, 12 m × 12 m and 15 m × 15 m when λ for different values for 10,12,15,17.14,17.6,18 were discussed. Analyzing the impact of λ on the floor structure and the cost according to the rationality and economy of the structure, the applicable economic span-depth ratio were concluded. Furthermore, economic contrast with ordinary rib slab floor, the assembly box concrete hollow floor is more suitable for the underground garage roof engineering.