Experimental Study On The Spatial Mechanical Performance Of Double-span Truss Composite Beams

The steel-concrete truss composite beam is a combination of tube truss and concrete slab to form a new type of combined structure.This new structure can give full play to the advantages of steel and concrete.The structure has strong integrity,large spatial rigidity,small cross-sectional size,reasonable stress,high bearing capacity,superior performance in earthquake resistance and dynamics,and the construction of the structure is more convenient.At present,some scholars have conducted corresponding experimental research on single-strength concrete-filled steel tube truss composite beams,which mainly include two aspects:(1)the bearing capacity and fatigue performance of the truss joints of the composite beam,(2)the overall mechanical performance of the composite beam.However,in many experimental analysis of space truss composite beams,there are few research results on the mechanical performance of double-strength truss composite beams.There are no detailed design theories and calculation formulas in the domestic and foreign codes concerning this type of composite structure.Only a few literatures have introduced relevant structures.And analysis,but only by simple simulation analysis with the help of finite element software,there is almost no experimental analysis of the mechanical performance of the structure,and the simulation and test results cannot be verified.Therefore,it is necessary to further study the mechanical performance of this new type of structure.In practice,double-strength truss composite beam bridges are more competitive for medium-span and large-span bridge structures,and have better engineering application prospects.The main work done in this article is basically as follows:(1)Make double-strength truss composite beam specimens with scale reduction,maintain them according to the requirements,make preparations for the early stage of the experiment,formulate eight test loading conditions,clarify the required data collection,arrange strain gauges at the corresponding positions of the specimens,and finally Load the test piece in the laboratory,collect data,and complete it.(2)ABAQUS finite element analysis software is used to establish the same specimen model,and the corresponding post-processing analysis calculations are carried out on the model under eight loading conditions such as double amplitude symmetric loading,double amplitude eccentric loading and single amplitude eccentric loading.And the test results are compared with the ABAQUS finite element software post-processing results,combined with the experimental measurement and model data to analyze the displacement of the specimen under each loading action,the longitudinal strain along the cross-sectional height,the longitudinal strain on the top of the concrete slab,the axial direction of the diagonal web The strain and the axial strain of the transverse connection vary with the development and distribution of the load.(3)The spatial stress analysis of the double-strength truss composite beam in the elastic stage,especially the distribution law of the shear lag effect along the transverse and longitudinal directions under different loading methods.For the unbalanced load case,analyze the lateral load characteristics,convert the cross section of the double-beam truss composite beam,and derive the corresponding formula for calculating the stress of the double-beam truss composite beam,and analyze the double-beam truss composite beam for ABAQUS modeling The ultimate failure characteristics under the action of single amplitude loading and double amplitude loading.