Experimental Study On Mechanical Property Of Composite Slab With Steel Fiber Reinforced Ceramsite Concrete Ribbed Panel

The precast concrete structure is one of the main promotion structure forms in the process of modernization construction industry,as an important part of the precast concrete structure,the composite floor slab has high bearing capacity,good integrity and seismic behavior,which can realize factorization,automation,modularization,and improve the overall prefabricated rate of the precast concrete structure.Therefore,in-depth study of mechanical property and calculation theory of composite slab plays an important influence on promoting the development of precast concrete structures.Based on previous study,a kind of composite slab with steel fiber reinforced ceramsite concrete ribbed panel(FCRP composite slab)is proposed,through the static loading experiment,studying on the mechanical properties of the composite slab under construction and serviceability stage,analying the effects of different precast panel’s materials and reinforced rib’s forms to the basic mechanical properties of the composite slab;Based on the experimental study,using nonlinear finite element numerical extension analysis,comparing the influence law of the key parameters on the mechanical properties of the composite slab;By the plain section assumption,the calculation formula of the short-term stiffness,deflection,cracking moment and bearing capacity of FCRP composite slab are established.1.Through the static loading test of 5 full-scale composite slabs and 1 full-scale precast panel,studying on the mechanical properties of the composite slab under construction and serviceability stage,analying the effects of different precast panel’s materials(Ordinary concrete,Steel fiber reinforced ceramsite concrete,Steel fiber recycled brick aggregate concrete)and reinforced rib’s forms(Single longitudinal ribs,Cross rib,Rib-free)to the basic mechanical properties of the composite slab.The experimental results show that: 1)In the construction stage,the composite slab is still in the elastic stage,and the deflection value is far less than the limit value of the code,which fully meets the construction requirements;2)under static loads,composite slabs are experienced elastic stage,cracking stage(also called elastoplastic stage)and failure stage,each stage basically obeys the plain section assumption;3)There is no horizontal crack in the composite surface,and the combination of the reinforced rib and the rough surface is considered to meet the shear requirement;4)The addition of steel fiber significantly improves the cracking load of the component,which plays a significant inhibitory effect on the development of cracks;5)Compared with different forms of reinforced rib,the bearing capacity and cracking load of composite slab with cross rib panel is the highest,its midspan deflection is minimum under the same level of load;6)Compared with different materials of precast panel,the bearing capacity of composite slab with steel fiber recycled brick aggregate concrete panel is the highest,the ductility of the composite slab with steel fiber reinforced ceramsite concrete panel is the best.2.The finite element numerical model of composite slab is established based on ABAQUS,and contrasting experimental results to verify its rationality;Carrying out the numerical analysis based on the change of key parameters to compare and analyze the influence law of the reinforced rib height(2 blocks)and the reinforced rib width(2 blocks)on the mechanical properties of FCRP composite slab.The results show that: 1)With the increase of the reinforced rib width,the stiffness of the composite slab increases and the deflection decreases,but the difference is slight.The rib width reduces 50 mm,the change range of the midspan deflection is 7.2%,the rib width increases 100 mm,the change range of the midspan deflection is 10.5%;2)With the increase of the reinforced rib height,the stiffness of the composite slab increases,the deflection showes a trend of decrease,and the difference is larger.The rib height reduces 10 mm,the change range of the midspan deflection is 24.6%,the rib height increases 10 mm,the change range of the midspan deflection is 22.8%.Obviously,the change of the reinforced rib’s height with respect to width is more significant to the mechanical properties of the composite slab.3.Based on the experimental results and numerical analysis,considering the effect of steel fiber,the short-term stiffness,deflection,cracking moment and bending bearing capacity of FCRP composite slab are established.Theoretical calculation and experimental results show that:1)By analyzing the effect of steel fiber to short-term stiffness of the composite slab,the short-term stiffness and deflection formula of the composite slab under construction and serviceability stage are deduced;2)The cracking moment of FCRP composite slab can be calculated according to the current《code for design of concrete structures》,but the basic value of the Section resistance moment plastic influence coefficient should be revised according to the results of this paper;3)The practical calculation formula of the normal section bending bearing capacity of FCRP composite slab is established,and the rationality of the formula is determined by comparison between theoretical and experimental values,which provides reference for practical engineering design.