Design And Experimental Study On Heavy-load Spancrete Hollow Core Composite Slab

In recent years,with the advancement and development of construction industrialization in China,Spancrete hollow core slab and Spancrete composite slab have broad prospects in industrial buildings and civil buildings.As a very mature technology,many studies have been done about Spancrete hollow core slab.However,There are still few studies on the performance of Spancrete composite slab,and the design method and performance analysis of Spancrete hollow core slab on heavy-load field are almost scarce.Taking heavy-load Spancrete hollow core composite slab as the study object,which integrates the technologies of Spancrete hollow core slab and cast-in-situ hollow slab,experiments and design methods combined with engineering experience are carried out to expand the application of Spancrete hollow core slab in the fields of common industrial and civil long-span buildings,as well as warehouses and equipment layers that need to be heavy-loaded.By taking theoretical analysis and experimental study in this paper,the main work and conclusions are as follows:(1)On the basis of sorting out and summarizing the design method of Spancrete hollow core slab,it is verified that updating the design method of Spancrete hollow core slab is necessary under certain conditions by comparing the design methods between new and old design code.(2)According to the two-period loading characteristics of composite slab,a more reasonable checking calculation for over-reinforcement and minimum reinforcement ratio are put forward.In view of the checking calculation of shearing for composite face of Spancrete composite slab,a new design method for shearing is presented by consulting the ACI318 Code in USA and the shear design method of the composite face of the composite beam in Code for Design of Steel Structures(GB50017-2003).Then some problems and its solutions for heavy-load Spancrete hollow core composite slab are discussed,such as the problems of over-reinforced precast slab,cracking after releasing and so on.(3)Through the bending tests of 7 heavy-load Spancrete hollow core composite slab,the failure modes,development of cracking,deflection and ductility of flexural specimens were observed and studied.The problem of short-term stiffness in different failure stages of Spancrete hollow core composite slab,and the effect of inserting reinforcement for shearing on preventing the composite face from peeling were also studied.Finally,it was reasonable in experiment that heavy-load Spancrete hollow core composite slab is treated as the overall slab to calculate ultimate bending bearing capacity and needs to consider the two-period loading characteristics of unsupported composite flexural member when calculating the cracking moment.(4)Through the shearing tests of 8 heavy-load Spancrete hollow core composite slab,the failure mechanisma and shearing bearing capacity of shearing specimens were observed and studied.A practical design method for inclined section shearing bearing capacity of composite hollow section member is put forward,which takes the effective rib width of the composite layer contributing to shearing bearing capacity of the overall slab,and then adds shearing bearing capacity of the precast slab.