Research On The Mechanical Properties Of A New Type Of Fabricated SRC Beam-column Connection

The steel reinforced concrete(SRC)structure has the characteristics of large stiffness and high bearing capacity,and the fabricated structure has the characteristics of energy conservation,environmental protection and short construction period.Under the background of vigorously promoting fabricated buildings in our country,fabricated steel reinforced concrete structure,as a building structure with the above characteristics,has a glorious application prospect.The connection node between prefabricated components is the weakest and key part of the fabricated steel reinforced concrete structure.Its mechanical properties affect the quality of the whole fabricated steel reinforced concrete building.In view of this,a dry-wet mixed beam-column connection suitable for steel reinforced concrete structure is proposed in this paper.The mechanical properties of the new joint are studied from two aspects of static performance and seismic performance.The main research results are as follows.(1)The research status of dry connection and wet connection in fabricated beam-column joints at home and abroad is summarized in this paper.On this basis,a new type of dry-wet mixed beam-column joint is proposed,and the structure and assembly process of the new joint are explained.In order to make the research results more convincing,this paper introduces the establishment process of nonlinear simulation model in detail,and ensures the accuracy and reliability of simulation model by comparing the existing test results.(2)According to the different steel strength grade,concrete strength grade,stirrup form,anchorage longitudinal bar diameter and channel steel end thickness,24 assembled joint specimens and one cast-in-situ joint specimen as a control are designed.The monotonic static loading simulation test is carried out on the new assembled SRC beam-column connection specimens proposed in this paper,and the stress mechanism and failure mode of each member in the joint are obtained.By analyzing the influence of different parameters on the initial stiffness The influence of bearing capacity and moment rotation relationship curve to further study the static performance of the new joint.The results show that the new joint has better bearing capacity than the cast-in-place joint due to the restraint effect of the end of channel steel on the post cast end of concrete;The main factors affecting the static performance of the new joint are the strength grade of beam section steel,the strength grade of beam channel steel end,the strength grade of beam concrete and the diameter of anchor longitudinal reinforcement;The influence laws of various parameters on the static performance of new joints are summarized,which can provide a theoretical basis for the further optimization design of new joints.(3)Four parameters that have the greatest impact on the static performance of new joints are selected.The new joint specimens with these parameters changed and the cast-in-situ joint specimens as the control are simulated under low cycle repeated loading.The failure characteristics,hysteretic performance,skeleton curve characteristic points,stiffness degradation,ductility and energy dissipation capacity of these joint specimens under low cycle repeated loading are analyzed,The seismic performance of the new fabricated SRC beam-column connection proposed in this paper is further studied.The results show that although the strength grade of beam channel steel end and beam concrete have a great influence on the static performance of the new joint,they hardly affect the seismic performance of the new joint;Increasing the strength grade of beam steel and the diameter of anchorage longitudinal bar can improve the seismic performance of the new joint.