Experimental Research And Analysis Of Composite Floor Slab Crack

Superimposed slab are mainly two or three blocks of prefabricated plates are assembled together, a new bidirectional stress slab cast-in-place layer by pouring a certain thickness to stress. Is widely used laminated floor has been in Anhui, Jiangsu, Shaanxi and other places in the practical engineering. But the laminate according to the two direction force reinforcement analysis has not been applied to actual engineering. If the two-way force in consideration, can satisfy the laminated floor stress performance and application requirements, not only can save steel also can reduce certain thickness.In this paper, in order to continue the application of composite slab, the composite floor in the two board and three board case, according to a two-way plate theory for the reinforcement calculation and test. The test consists of a cast-in-situ slab, three pieces of two pieces of superposed slab and two pieces of three pieces of superposed slab,. The test mainly through the observation of cracking load, ultimate superimposed slab bearing capacity, failure mode, deformation and strain of the steel with the load change is in accordance with the development situation of cast-in-situ slab and laminated floor seams. The experimental phenomena and results show that the stress performance composite two-way slabs in all aspects are consistent with the cast-in-place slab is better, especially the two pieces of superposed slab can be basically equivalent cast-in-situ slab to consider. In carrying out the laminate joints crack is less than the maximum crack width corresponding loading plate bottom, namely the crack seams and not into the crack control of laminated slab.Through the theoretical analysis of the ultimate superimposed slab bearing capacity, crack spacing and maximum width, and were compared with the experimental value. Due to the existence and seams laminate unique lattice steel reinforcement is not continuous, so that the three spell limit superimposed slab is slightly lower than that of the cast-in-place board and two pieces of superposed slab bearing capacity. Through the limit line of plastic hinge method of bearing capacity and are close to the experimental results, and gives the calculation formula of estimating the stack type the ultimate bearing capacity of two-way slab, the plastic hinge line final location and angle are in line with the cast-in-place slab. But on the calculation of crack, can not be applied in cast-in-situ slab theory. Through the test data collection, are given to test the correction formula of superimposed slab crack spacing, and found that by comparison to calculate the final destruction of the maximum crack width and the experimental value has a little error with nevirapine-Orenstein formula. Finally superposed slab either two or three pieces are in line with the characteristics of all the bidirectional stress, experimental basis and theoretical results provide research and composite two-way slab crack resistance and the ultimate bearing capacity for the stack.