Experimental Study On Mechanical Performance Of New Type Of Non-template Short Columns Under Axial Compression

In order to adapt to the development trend of building industrialization and promote the development process of assembled monolithic building,this paper proposed a new type of non-template column that consisted of prefabricated concrete templates and cast-in-place reinforced concrete in core area.Prefabricated concrete templates are manufactured in bulk in the factory,transported to the construction site to assemble and form prefabricated concrete templates system,and finally pouring concrete into the core area to produce a non-template column.Through the experiment on mechanical performance of four non-template short columns and one cast-in-place short column under axial compression,the feasibility of construction technology of non-template short column as well as the collaborative performance between prefabricated concrete templates and cast-in-place reinforced concrete in the process of axial compression experiment was investigated.The cracks development process,destruction mechanism,load-displacement curve and the bearing capacity under axial compression of non-template short columns and cast-in-place short column were comparatively analyzed.Through the shear capacity experiment on three sets of non-template shear specimens,the influence of different strength of prefabricated concrete template and the existence of shear connector were investigated.The experiment phenomenon,destruction mechanism,load-displacement curve and the shear bearing capacity were comparatively analyzed.According to the phenomena and results of axial compression experiment and shear capacity experiment,some suggestions for the design and construction of non-template short columns are given.The results of axial compression experiment of non-template short columns showed that:(1)the manufacture of prefabricated concrete templates and the construction of non-template short columns are simple and feasible.There is no crack,swell and separation of prefabricated concrete templates during pouring and the prefabricated concrete templates can effectively resist lateral concrete pouring pressure.(2)The synergistic performance between prefabricated concrete templates and cast-in-place reinforced concrete behave well in the early stage of the experiment load.However,the crack width of the templates is larger and it falls off in the later stage of the experiment load.In order to promote the early application of the non-template column in the actual project,it is necessary to improve the performanceof bond surface.(3)The strength of prefabricated concrete template is not fully utilized,which weakens the bearing capacity of the non-template short column to some extent,but the influence is limited.(4)The influence of the reserved holes on the bearing capacity of the non-template short column is negligible.Prefabricated concrete templates can be assembled by split bolts or angle steel according to the situation.The results of shear capacity experiment of non-template shear specimens showed that:(1)The shear capacity of the bond interface increased with the strength of concrete of prefabricated template.(2)The shear connector can prevent the spalling of prefabricated concrete templates and improve the synergistic performance between prefabricated concrete templates and cast-in-place reinforced concrete.(3)In theory,the shear capacity of the bond interface is directly related to the roughness of the contact surface of the prefabricated concrete template and the layout of shear connector,which should be analyzed and discussed in the further research work.