Study On Bending Performance Of Composite Slab With Square Steel Tube Truss

Although the steel deck-concrete composite slabs and composite slabs made of rebar truss have been widely used,there are still a lot of work to be done in filed.Because the slab is heavy,it's not beneficial to the anti-seismic of structure and to reduce the foundation cost.Therefore,in recent years,the research on light-weight assembled composite slabs have attracted much attention.In this paper,a new kind of composite slab made of square steel tube truss is presented.The composite slab is composed of thin-walled steel tube and rebar.The steel truss system mainly bear the load.The surface of slab is made up of concrete,and the inner space is filled with EPS which can insulate the noise.The composite slab can be manufactured in the factory.It's light and requires no special fireproof and anti-rust treatment,which conforms to the development trend of the assembled building.In order to investigate the flexural properties of this new kind of composite slab,the following specific research work is carried out:1.The bending performance experiment of 11 composite slabs were carried out.The length of the slab is 3m,4.5m and 6m respectively.The results show ed that: the flexural process of the composite floor slab is divided into three stages:the bottom concrete cracked,the bottom chord reached the yield strength,the web member appears buckling failure which located the end of steel frame.All the failure form of slabs were the buckling failure of web member.Buckling of the web member caused big deformation which lead to the decline of load capacity.The stiffness and load capacity of the slab can satisfy the requirement.The load capacity is high enough to insure that composite slabs have sufficient safety storage.2.Finite element software Abaqus was used to simulate and analyze the bending performance of composite slabs.The simulated load-displacement curves are in good agreement with the test results.The analysis of the parameters shows that the reinforcement of web member located in the end of the steel frame can effectively avoid the destruction of the slab caused by the buckling of the web member,and also can improve the load capacity of the slab at the same time.The analysis of the natural frequency of composite slabs shows that the natural frequency of slabs are much larger than 5Hz,which can meet the requirements of comfort.3.Based on the results of experiment,the calculation method of the common concrete beam is modified.The theoretical calculation formulas of the crack moment and ultimate load capacity of the composite slab were put forward.According to the structure of the composite floor slab,the calculation formula of crack width and stiffness in the design code of Concrete structure(GB50010)was modified,and the new formulas were established.The theoretical calculation results fit well with test results.The correctness and reliability of the formulas were verified.Finally,based on the results of experiment and analysis,the design suggestions for the further optimization of slab were proposed.