Study On Spatial Truss Model Of The Bridge Pile Caps

The pile caps structure, because of its high bearing capacity and can adapt to thefoundation uneven settlement and good seismic performance, is widely used in theconstruction of railway bridges in recent years. Structure of caps as a connection of large sizeof the pier and small size of the pile foundation become a key point in the pile-caps-pilefoundation structural system. The upper structure of the transmission through the bridge loadto the pile caps, via the cap structure will load tap to pile foundation, the pile foundation andthe load to the foundation, pile caps is internal flow of disperse and its mechanicalperformance will be a focus in the study of this article in the whole process of loading force.Structure of pile caps is the internal struts-tie force model has become the mainstreamthought, this paper will continue to deeply research the force model, and the stress of the flowpassing the virtual space truss for actual reinforcement-configuration space steel truss, andthe configuration of the pile caps of steel truss structure of force transmission performanceanalysis. In this paper, the research contents and conclusions are as follows:By the nine pile caps structure applying operating load, limit load, through the finiteelement software MIDAS/FEA model of the pile foundation pile caps is numerical simulationanalysis, get the following conclusion:(1) Under operating load, the study analyzed theconcrete tie rod in pile caps, steel tie bar, pile stress and displacement of pile caps andreceived distribution law of displacement of the pile caps in flexible working state, the pilecaps appeared tie-compressive bar transmission system;(2) Through the truss modelparameters change trend diagram can be obtained directly structure in operating load,cracking load and ultimate load under the level of stress, displacement, and can be directly asa design reference. Tie-compressive bar stress analysis are obtained in structural damage, thetie-compressive bar is still carrying capacity, the destruction of the rod-compressive bar areassociated with cap structure fracture penetration and structure of the large deformationoccurring in the course, then pile caps is punching shear fracturing.Based on the bottom of the pile caps of steel fabric to striping equivalent configuration,with comparing analysis and getting: the equivalent effect is good. Cracking load of pile capswith the increase of reinforcement ratio increased slightly, but the overall trend changes,shows that the bottom of the pile caps of the reinforcement ratio influence of cracking lesseffected; The bearing capacity of the pile caps is along with the increase of reinforcementratio, but when the reinforcement ratio exceeds a certain value, simply by increasingreinforcement has not improve the bearing capacity of the pile caps.Inside the pile caps is configured with the pile caps of steel space steel truss model arestudied:(1) The configuration of steel truss model of pile caps is delayed fracturedevelopment in a strip of reinforced pile caps model; The ultimate load is greater than thestrip reinforcement, the bearing capacity of pile cap structure has improved.(2) Based on theworking condition of different reinforcement ratio and configuration of steel structure of the pile caps under the condition of the ultimate bearing capacity analysis of available:configuration overcomes the pile caps of steel truss structure under a strip of reinforcement ofstructure bearing capacity bottlenecks, make the structure of the carrying capacity of a stepup.The bottom of the pile caps of reinforced equivalent transformation process: uniformreinforcement-the strip of reinforcement-optimized the strip of reinforcement-arrangementof the steel truss.