Study On The Basic Mechanical Behavior Of CFRP-concrete Composite Slab

The modernization of the construction industry is the main trend of the development of the construction industry,and the development of prefabricated buildings is a major measure to promote the industrialization of China’s construction.The composite concrete floor has the advantages of assembly and the good overall performance of the whole cast structure,which has been widely promoted and applied.In practical projects,the concrete double-sided composite floor slab is often split-jointed in the form of post-cast strip.When the overhanging steel bar is removed,the bearing capacity of the double-sided composite floor slab joint section decreases obviously,while the deformation and crack width increase.In order to solve this problem,this paper proposes to paste CFRP(Carbon Fiber Reinforced Plastics)on the bottom joint of common double-sided composite floor slab(the overhanging steel bar is eliminated)to form cfrp-concrete double-sided composite floor slab,and to carry out research on the basic mechanical properties of cfrp-concrete double-sided composite floor slab.The basic work is as follows:(1)Through the establishment of the flexural failure mode of cfrp-concrete compact bidirectional composite floor slab and the calculation formula of flexural bearing capacity,the influence of the amount of CFRP and the amount of additional reinforcement on the mechanical performance of cfrp-concrete compact bidirectional composite floor slab was analyzed.The results show that: 1)reasonable setting of CFRP,cfrp-concrete compact bidirectional composite building can reach the ultimate bending capacity of the whole cast plate;2)the CFRP pasted at the bottom of the plate to replace the tensile force,the bending force arm is larger,can reduce the use of additional steel bar,improve economic benefits;3)the CFRP at the plate bottom joint can meet the deformation requirements of the secondary stress of the cfrp-concrete compact bidirectional composite floor slab,and the secondary stress damage will not occur to the members.(2)Through the comparison test of static load between cfrp-concrete dense bidirectional composite floor slab and ordinary dense bidirectional composite floor slab,the influence of CFRP on the mechanical performance of composite floor slab with additional steel bar on the composite surface and at the plate bottom joint is studied.The results show that: 1)bidirectional force transmission can be achieved in the compact composite concrete slabs with simple supports on four sides,and no concentrated cracks appear at the joints.2)CFRP-concrete compact bidirectional composite floor slab can reach the ultimate flexural capacity of the cast plate;3)CFRP at plate bottom joint can improve the flexural capacity of composite floor slab and enhance the flexural efficiency of CFRP;4)CFRP can improve the stiffness of composite plates and slow down the development of joint width;5)improving the material resistance of CFRP can further reduce the crack width and mid-span deflection deformation,but the material cannot play a full role.(3)Through the static load comparison test of cfrp-concrete compact bidirectional composite floor slab,the influence of polymer mortar filled at the joint on the mechanical performance of compact composite floor slab was studied.The results show that the polymer mortar can reduce the crack width and mid-span deflection of composite floor slab.(4)By analyzing the failure patterns of test members,reasonable suggestions are put forward for the engineering application of cfrp-concrete compact bidirectional composite floor slab.