| As a new type of concrete filled steel tube structure,corrugated-steel-tuberubberized-concrete composite column(CSTRC)can make full use of the energy dissipation and vibration reduction characteristics of rubberized concrete and the physical characteristics of corrugated steel tube,improve the active energy dissipation capacity of the structure,and effectively solve the debonding problem of the steel and concrete.The bearing capacity of the structure is also greatly improved by the restraining effect of the corrugated steel tube on the core rubberized concrete.The CSTRC piers can be prefabricated in the factory and assembled on site with the foundations by socket connections.The construction time can be substantially reduced by this kind of connection scheme on site.Meanwhile the tolerance of socket connections for construction is larger than that of the other connection schemes,which is conducive to construction.However,there are few studies on the joint of socket connections for CSTRC piers at home and abroad,which limits its development.In this paper,the side shear and punching shear properties of the joints with socket connection were first studied under vertical load,and the effects of various parameters on the side shear strength and punching shear strength were further analyzed by finite element calculation.On this basis,the mechanical properties of the structures were studied under combined vertical and horizontal load.The main work and conclusions are as follows:(1)A total of seven test specimens in two groups were completed,the side shear tests and punching shear tests were performed respectively.The test phenomena were observed,recorded and analyzed.The analysis results show that in terms of structural integrity performance,the socket connection is similar to the integral cast-in-place connection.Under vertical design load,the joint of the socket connection can provide sufficient side shear strength with no need for additional shear connectors.Under the action of punching shear failure load,the joint of the socket connection maintains good integrity condition,and the corrugated steel tube interface,joint and composite pier can be regarded as a whole.Further,the finite element calculation and analysis for the parameters of the socket connections were conducted and corresponding suggestions were given concerning the embedded length of the composite piers,waveforms of corrugated steel tubes,clear distance and material strength of the joint.(2)Considering the combined vertical-horizontal load condition,finite element models of the rubberized concrete-filled steel tube piers were,and the reliability of the solid element modeling method was verified by comparing with the existing test results.On this basis,the finite element calculation and analysis for the joint models of socket connections for CSTRC piers were carried out.Both the load-drift curves on the top of piers and the bending moment-curvature curves at the bottom of piers for socket connections and integral cast-in-place connections are equivalent to each other.With reference to the completed test and finite element analysis results,case study was conducted in terms of shape selection,joint design of socket connections for CSTRC piers.Calculation and analysis under the effect of load combination were carried out.The results show that when the embedded length reaches 1.0D(D is the inner diameter of the combined pier),the flexural bending capacity of the composite pier can be fully developed,with a 45 degree crack pattern developing at the foundation outside the corrugated steel tube.(3)Based on the test and finite element analysis results,and the domestic and foreign codes,the calculation formula of side shear capacity for the joints with socket connections was established.With reference to the cone failure mode and punching shear failure mode under the combined load condition,the formula of the minimum embedded length for the CSTRC piers and the minimum thickness of the end bearing concrete were derived and put forward. |
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