Research On Imposed Load Test Of Full-scale Assembied Precast Shale-ceramsite Concrete Composite Slabs

Having the advantage of high construction speed,free templates,good entirety and high bearing capacity,composite floors are widely used in assembled pre-cast structures.Shale ceramsite concrete is a new type of lightweight aggregate concrete which has the advantage of light weight,good seismic performance and favorable insulation properties.Combining shale ceramsite concrete with composite floors can not only reduce structural weight but also improve the floor insulation performance.Under that situation,the experimental study on the mechanical properties of shale ceramsite concrete composite floors is carried out in this paper.In this paper,one-way and two-way bending performance of the new type of composite floor is studied,including stiffness,bearing capacity,crack resistance and slippage characteristics of combined interface.Specific studies are as follows:（1）Static load test was carried out on 2 one-way shale ceramsite concrete composite floors and the 4 two-way composite floors.The results showed that all specimens were in elastic stage under the standard live load,the mid span deflection was far less than the standard limit（l₀/200）,and the ultimate load was much higher than the standard live load.The composite floors have better rigidity and cracking resistance than the cast in place floors under the same conditions.（2）The slip characteristics of the combined surface were studied by analyzing the strain of concrete on the side of one-way composite floors.The results showed that shale ceramsite concrete composite floors with truss shear reinforcement had a good overall performance,and the failure of the combined surface was not occurred until the specimen failure.（3）The bending process simulation of one-way shale ceramsite concrete composite floors was obtained by using the numerical analysis software Matlab.The theoretical value of the midspan deflection of one-way composite floors was obtained then.（4）In this paper,the mid span deflection of the one way composite floors was calculated by using the short-term stiffness formula of the flexural member given by Code for design of concrete structures GB 50010-2010.The short-term stiffness formula of one-way shale ceramsite concrete composite floors was obtained by comparing experimental value with theoretical value.（5）The elastic bending stiffness formula of semi-ordinary-semi-ceramsite concrete composite floors was derived by taking the different Young’s modulus of precast and cast-in-place concrete into account.At the same time,the formula of the mid span deflection of the shale ceramsite concrete composite floors was given by considering the torsion effect of the side beams.The results were compared with the experimental values.It turned out that the formula had a high degree of coincidence of the cast-in-place shale ceramsite concrete floors,the relative error was less than10%.The stiffness of the composite floors was strengthened because of the additional structural steel bars and truss reinforcement.Therefore,it is necessary to multiply the stiffness amplification coefficient on the basis of the original formula.Based on the above research,this paper makes a detailed analysis of the mechanical properties of the shale ceramsite concrete composite floors,which can provide a reference for the following research and engineering design.