| Reactive powder concrete(RPC)is a new type of cement-based composite material with high strength,high toughness and excellent durability,which has been widely concerned by scientific research institutions at home and abroad.However,at present,the research on RPC at home and abroad mainly focuses on the mechanical properties of materials,and there are relatively few researches on RPC components,especially on RPC-NC composite components.Therefore,this paper applies the RPC material to the prefabricated part of the composite slab with steel bar truss to make full use of the excellent tensile properties of the RPC.Takes the RPC-NC composite slab with steel bar truss as the research object,and carries on the anti-bending performance test research and the theoretical analysis under the static load mechanical.The main work and conclusions in this paper are as follows:(1)Three RPC-NC composite slabs with equal height but different proportion of RPC and one normal concrete(NC)contrast slab were fabricated and tested on simply supported static loading mechanical test in order to study the flexural behavior.Then the test phenomena were observed and recorded in detail.Their cracking load,fracture distribution and development,ultimate bearing capacity,deflection and deformation,section strain distribution and ultimate bearing capacity were obtained by experiments.The load-deflection curve was plotted by the measured data,and the results show that the development form of the load-deflection curves of RPC-NC composite slab with steel bar truss is similar to that of normal concrete flexural structures,which includes the elastic stage before concrete cracking,the stage of crack development and the failure stage after the yield of tension longitudinal tendon.Due to the different height of RPC,the elastic working stage before concrete cracking of RPC-NC composite slabs possesse from 30.2% to 44.3% of ultimate load and it is proportional to the increase of the proportion of RPC height,which is higher than the corresponding proportion of NC composite slab.It proves that the RPC-NC composite slab has better crack resistance.The strain measurement results accord with the assumption of flat section.(2)Based on the measured results and plane section assumption in the main,the contribution of steel fibers to the flexural capacity of RPC-NC steel truss composite slabs was reasonably considered.According to the measured flexural capacity of the cross section of composite slabs and the equilibrium equation of the force and moment,the formula of the equivalent coefficient k of the tensile stress of RPC prefabricated part was fitted with the ratio of the height of RPC as a variable.Different RPC heights will cause the change of the crack position of the composite slabs.The cracking moment of composite slabs was calculated and analyzed by simplifying the stress distribution calculation model with reference to other literatures and combining with the experimental data.The result shows that the crack moment calculated by the theoretical method is in good agreement with the experimental data.The short-term flexural stiffness of composite slab was calculated and analyzed by using the measured data,the moment-curvature relationship and the effective moment of inertia method based on the experimental data of specimens.A formula for calculating the stiffness of RPC-NC steel truss composite plate was obtained.(3)Nonlinear finite element software ABAQUS was used to simulate and analyze the test slab.Then the simulated moment-midspan displacement curve and the simulated ultimate moment were compared with the measured value.It is found that the curve has the same trend and is in good agreement with the experimental data,and the error of ultimate bending moment is less than 10%.It shows that the calculation of flexural capacity of RPC-NC composite slab with steel bar truss by ABAQUS is reliable,and the model adopted in this paper is very reasonable. |
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