Study On Bearing Capacity Of Precast Prestressed Truss-Type Steel Reinforced Concrete Beams

With advancement of building industrialization,the steel reinforced concrete structure has been widely used in housing and bridge structures.The steel truss frame in pre-stressed truss-type steel reinforced concrete is to connect chord members,web members and gusset plates as a whole by welding,so as to impose pre-stressed on large span or in heavy load structure,which in turn becomes prefabricated pre-stressed truss type-steel reinforced concrete structure.This can be applied to the structural systems such as industrial plants,houses and bridges.The basic design concept is that the steel truss frame shall be able to bear dead load and various loads during construction phase.The pre-stressed steel bars are used to bear second-phase dead load and live load to improve the structural integrity and crack control requirements.Compared with reinforced concrete,it has higher load-bearing capacity and better seismic performance;compared with solid-type steel-reinforced concrete,it saves more steel with better anti-slip capability.Therefore,pre-stressed truss steel reinforced concrete can be properly applied in practical engineering.Truss steel structures have been extensively used in bridges and scaffolds,but there are only a few domestic and foreign theoretical design researches on the pre-stressed truss-type steel reinforced concrete structures.Therefore,the experimental study on the mechanical behavior of pre-stressed truss-type steel reinforced concrete beams is of profound practical significance.With reference to pre-stressed reinforced concrete beams,this paper implements experimental research and finite element modeling on the influence of steel content,pre-stress degree,web spacing and shear span ratio on the bearing capacity of beams,which contributes to perfecting design theory.In this paper,by means of combining with National Natural Science Foundation Project Research on Mechanical behavior of Prefabricated Pre-stressed Truss-type Steel Rib Frame,13 beams are designed for static test and theoretical analysis,so as to observe test process and its failure mode,and research the cracking load,crack development,yield load,ultimate load,etc.At the same time,based on the finite element software ABAQUS,the finite element nonlinear analysis was performed,and the finite element analysis results were compared with test results.The results show that:(1)The tension angle steel in the pure bend section of normal section test component firstly yielded,and then the concrete in compression zone was crushed and angle steel in pressed zone yielded when continuing loading.The members were destroyed presenting ductile failure;(2)Partial stressed web in members the central position of connection of oblique section test member bearing and load point were yielded,and finally web shear oblique fracture extended to the loading point and bearing of component,which all presented shear pressure failure mode(3)The component failure modes,ultimate loads and load-displacement curves obtained by finite element method were in good agreement with the test results,which showed that the mechanical behavior of the pre-stressed truss-type steel reinforced concrete beam was accurately simulated based on ABAQUS,and the accuracy of test results was verified;(4)Referring to the formula for the bearing capacity of pre-stressed reinforced concrete beams,the formula for the bearing capacity of the pre-stressed truss-type steel reinforced concrete beams that is applicable to this paper was deduced.The results showed that the calculation formula of established ultimate bearing capacity was applicable.