Study On The Performance Of CFRP-Concrete Two-way Composite Slab Under The Kinds Of Influence

With the rapid development of modern industrial technology and the advancement of construction industrialization,prefabricated building has become the main trend of the development of China’s construction industry.There are many kinds of connection forms between prefabricated concrete structural members.The diversity and complexity of component connection bring some difficulties to the site construction.Among them,the different connection ways between the prefabricated bottom plates of the two-way composite concrete floor have a great influence on the mechanical performance and construction quality of the floor.This paper aims to explore an effective connection way to realize the two-way force transmission and improve the construction efficiency Rate and quality.In the actual project,the construction problem can be solved by using the close jointed composite floor slab,but there are some problems such as the decrease of bearing capacity,the concentration of stress and strain at the joint,the large amount of additional tie bar in the cast-in-place surface layer,the large deformation at the joint and the increase of crack width.For this reason,the project team proposed the structural form of FRP-Concrete close jointed two-way composite floor,and carried out relevant theoretical analysis and experimental research.On this basis,the paper carried out in-depth the mechanical performance and service performance of FRP-Concrete close jointed two-way composite floor under the influence of many factors,such as slab thickness,amount of additional reinforcement,FRP paste method and amount,joint position,whether there is polymer mortar or not,Through the method of experimental research and numerical simulation analysis,the mechanical mechanism,bearing capacity,crack development,deflection and stiffness of the new composite floor are recognized,the relevant calculation model is established,and reasonable technical suggestions are put forward for the practical engineering application.The results show that:(1)failure mode: all specimens have two-way slab failure mode,and cracks perpendicular to the joint appear in the middle of the span,and extend outward.With the increase of the load,the cracks develop to the four corners of the composite plate until failure,but there is interlaminar slip on the plate side.(2)Bearing capacity: with the increase of the thickness of cast-in-place layer,the decrease of the distance between truss reinforcement and butt joint,the decrease of the distance between additional reinforcement,the number of bottom slab is 3 and the butt joint is not in the middle of the span,and the increase of the amount of CFRP,the cracking load of the component increases by 3.4%-27.8%,the ultimate load increases by 1.9%-8.4%,and the bending contribution rate of CFRP increases by 17.65%-77.5%.(3)Normal performance: with the increase of the thickness of cast-in-place layer,the decrease of the distance between truss reinforcement and butt joint,the decrease of the distance between additional reinforcement,the increase of CFRP dosage,the number of bottom plate is 3 and the butt joint is not in the middle of the span,the deflection of the member in the middle of the span decreases by 7%-58%,and the change value of the width of the butt joint decreases by 2.3%-20.7%.In conclusion,appropriately increasing the thickness of cast-in-place slab,reducing the distance between truss reinforcement and joint,reducing the distance between additional reinforcement,avoiding the midspan position of joint,and improving the CFRP strength can effectively improve the stiffness of components and reduce the change of joint width on the premise of ensuring the bearing capacity of components.