Flexural Test Of Precast Hybrid Steel-Concrete Beam

The existing prefabricated concrete frame structure still has the limitatons of large quantity of wet work,complicated joint connection,poor quality and uncontrollable yield mechanism.Therefore,it was of great significance to study a simple and reliable connecting method of between prefabricated concrete members to promote the development of prefabricated building technology in our country.Thus,an original precasted hybrid steel-concrete beam?PHB?system with a rigid connection was developed to overcome the limitations of conventional precasted concrete beam with wet connection between the precasted beam and by supported by columns.The developed PHB system has three different section along the length of hybrid steel-concrete beam:H-steel beam,concrete beam and steel-concrete composite part.To examine the efficiency of connection and mechanism performance of fixed-end hybrid steel-concrete beam,the flexural performance of fixed end hybrid steel-concrete beam were tested under monotonic one-point concentrated top loads at mid-span.The main research work and conclusions are summarized as follows:1)Experiments were conducted on the fixed-end hybrid steel-concrete beam with the monotonic loading at mid-span.The parameters include:the length of steel beam;the design flexural capacity ratio of between steel beam and concrete beam.The influences of these parameters on the flexural behavior,failure modes as well as working performance of composite part were analyzed.The test results showed that all specimens exhibited flexural failure mode.There were large crack width and development range in the mid-span of prefabricated hybrid beam than that of prefabricated ordinary concrete beam.The results showed that the descending section of load displacement curve was gentle and larger ultimate deformation capacity and displacement ductility.It was concluded that the precasted hybrid steel-concrete beam has a favorable ultimate resistance and flexural performance.Throughout the loading process,the steel-concrete beam composite part did not appear serious damage,the developed composite part connecting the steel and concrete beam can be regarded as rigid connection,resisting the applied moments.2)The flexural resistance of the fixed end hybrid steel-concrete beam was calculated based on the virtual work principle and structural mechanics,and the values calculated agree well with the test values.3)The three-dimensional finite element mode?FEM?have been developed by general commercial FE program ABAQUS to simulate the flexural behavior of fixed-end hybrid steel-concrete beam.The developed FEM considers the material and geometric nonlinearities of concrete and steel,and the solving technology of dynamic explicit?ABAQUS/Explicit?was used.Extensive validations of the FE analyses against the reported tests proved that the developed FEM offered reasonable simulations on flexural behaviors of hybrid beam in terms of flexural resistances,load-displacement curves,crack patterns and failure modes.4)Based on the validated FEM,a subsequence parametric study comprising 27cases to systematic investigate the influences of the length of steel beam and the design flexural capacity ratio of between steel beam and concrete on crack patterns,failure modes and ultimate resistance of hybrid steel-concrete beam.Finally,according to the parametric results,the steel beam working efficiency factor F_eff was proposed in order to determine the optimal design of steel beam of the hybrid steel-concrete beam.