Experimental Study On Mechanical Properties Under Axial Compression And Pure Bending Of Precast Fabricated Concrete Filled Steel Tubular Column

At present,vigorously developing prefabricated buildings has become the development trend of Chinese construction industry modernization.The concrete-filled steel tube structures are very suitable in prefabricated buildings for its characteristics.The fully prefabricated CFST columns used in prefabricated buildings(ie core concrete is also prefabricated at the factory)can effectively reduce on-site wet work and reduce fire risk at the construction sites,which also speed up construction progress.It is urgent to invent the form of connecting joints between the prefabricated column sections at the present stage for extension and application of full prefabricated concrete-filled steel tubular columns,which can not only meet the requirements of load transfer,but also meet the requirements of rapid installation and convenient construction on site.Therefore,three new types of joints between concrete-filled steel tubular columns are proposed.In this paper,the mechanical properties of prefabricated CFST columns under axial compression and pure bending load are studied by means of experimental research.The following aspects are specifically carried out:1.The research status of related topics at home and abroad are reviewed,including the connection mode and mechanical properties of the joints between the empty steel pipe columns,the prefabricated reinforced concrete column segments,and the joints between the existing prefabricated assembly concrete-filled steel tubular columns.2.Comparing with the stress performance of the cast-in-place test piece and regarding the node type as the main parameters,the axial pressure performance test of fourteen prefabricated CFST columns was carried out through comparative tests.The test results show that the three types of nodes can meet the stress requirements under the axial compression load,in which the bearing capacity of prefabricated test pieces connected with the side plate joints larger than that the cast-in-place test pieces.3.Comparing with the stress performance of the cast-in-place test piece and regarding the node type as the main parameter,the experimental study based on the pure bending mechanical properties of five prefabricated CFST columns was carried out through comparative tests.The test results show that the joint side plate joint test piece meets the design strength requirement,and the cross plate type joint test piece is lower than the design strength requirement.Improvement suggestions are proposed for different node types based on experimental results.4.Some practical design suggestions and improvement measures are proposed through this test,which provide reference for further research work and engineering practice in the future.