Study On Mechanical Behaviors Of Reinforced Concrete Superimposed Slabs With Steel Bar Truss

Reinforced concrete superimposed slabs with steel bar truss have a wide application prospect for its advantage of meeting the requirenments of energy conservation in building and housing industrialization.What is more,it is well accepted in national market and has achieved more and more applications.The existence of steel bar truss makes it stiffer than that of ordinaty superimposed slabs in the construction,even do not need the template and support during the construction phase.In this paper,mechanical performance of this superimposed slabs are comprehensively studied during the construction phase and the application phase respectively.Also,the computational methods of the short-term stiffness and the ultimate load of this kind of superimposed slabs are put forword.The specific contents are as follows:(1)The finite element software of ABAQUS was used to simulate the mechanical performance of the superimposed slabs with steel bar truss and ordinaty superimposed slabs during the construction phase.The results show that the steel bar truss can enhance the overall stiffness of the superimposed slabs effectively.The steel bar truss can improve the concrete cracking load and reduce the maximum deflection as well.Taking the effect of the height of the steel bar truss,the diameter of truss diagonal bar?the strength of the concrete?the thickness of the slabs and the length of the slabs into consideration,this paper simulated the mechanical performance of the superimposed slabs with steel bar truss.The results show that the thickness of the slabs?the strength of the concrete and the length of the slabs have greater effect.What is more,the mechanical performance of the superimposed slabs with support during the construction phase is simulated and some suggestions are put forword for the support settings.(2)Based on the existing theoretical calculation formula of member in bending,this paper present the short-term stiffness formula of superimposed slabs with steel bar truss,and compare the results of existing trial.It shows tha the formula has better calculation accuracy.(3)Through the finite element numerical simulation of the traditional two-way slab,two pieces of the superposed slab and three pieces of superposed slab,comparing the the deflection?stress and strain of steel and concrete with each other.It shows that the mechanical performance of the superposed slab is very similar to the traditional two-way slab.Based on it,exploring the effect of the thickness of the superposed slab?the seam height?the length and spacing of additional bars on the mechanical performance.The results show that the thickness of the superposed slab has the greatest influence on the mechanical performance,and when the length of the additional bars is over 200mm,it will have little impact on the mechanical performance.(4)The yield line theory is adopted to calculate the ultimate bearing capacity of superposed slabs.Compared to the ultimate bearing capacity of FEM,we find the deviation is small.Based on it,this paper calculates the ultimate bearing capacity of superposed slabs with different support constraint conditions.