Theoretical And Experimental Research On Punching Shear Performance Of Concrete Slabs Reinforced With Cfrp Grids

Carbon fiber reinforced composite material(CFRP)is a lightweight,high-strength,excellent corrosion-resistant polymer composite material.Carbon fiber mesh bar is a new type of fiber composite material construction form,which has good overall stress performance and anti-slip performance.In recent years,it has been widely used in the field of structural reinforcement.The research on the punching resistance of concrete slabs is a focus issue in the field of structural engineering research.The punching failure of concrete slabs often occurs in structural systems such as beamless floors,bridges,pile foundation caps and independent foundations.Compared with the traditional method of reinforced concrete slabs,it is a new method to improve the mechanical properties of punching shear by configuring carbon fiber mesh bars in newly built concrete slabs.Based on the existing research,this paper carried out the punching test of 10 concrete slabs,including 9 concrete slabs with carbon fiber grids(test group)and 1 concrete slab with ordinary steel bars(control group).The key parameters such as the equivalent replacement parameters of the carbon fiber grid,the reinforcement ratio of the bent reinforcement at the bottom of the plate and the layout of the punching shear grid(“口” shaped,“米” shaped and“井” shaped)are studied.The results showed that:(1)The carbon fiber grid can replace the ordinary steel bar as the bending reinforcement of the concrete slab to resist punching action;the equivalent substitution parameter λ＿sub is about 0.85;(2)The reinforcement ratio of the bent ribs at the bottom of the slab has a direct impact on the punching failure mode and the punching bearing capacity of the concrete slab.’closely related.(3)Compared with the “口” shaped,“米” shaped anti-punching carbon fiber grid layout,the “井” shaped anti-punching grid is more helpful to improve the anti-punching of concrete slabs Carrying capacity and deformability.Based on the punching test of the concrete slab,the theoretical analysis of the punching resistance of the carbon fiber grid concrete slab was carried out,and the equivalent replacement parameters of the material between the carbon fiber material and the steel bar and the contribution factor of the carbon fiber punching grid bearing capacity The mechanical model of plastic strands suitable for low-reinforcement concrete slabs and the split-pressure zone splitting model for high-reinforcement concrete slabs were established.According to calculations,the theoretical values of the punching bearing capacity of the carbon fiber grid concrete slabs configured by the above two methods are in good agreement with the experimental values for the different reinforcement ratios and structural forms of the test pieces.The design of other similar tests And development have reference value.The ANSYS finite element software was used to numerically simulate the punching performance of concrete slabs with carbon fiber grids.The calculation results obtained by the finite element method are consistent with the test results.The distribution of the internal force and the bearing capacity level of the concrete slab obtained by the finite element method are not much different from the true stress distribution and bearing capacity level of the test member.The results of the three parts of the above-mentioned slab punching test,theoretical analysis and numerical simulation show that the configuration of carbon fiber grids can effectively improve the punching resistance and deformation capacity of concrete slabs.The configuration of carbon fiber grids in concrete slabs has engineering application value.