Study on Interfacial Bond-Slip Constitutive Model of Concrete-Filled Steel Tube Under Freeze-Thaw Cycles
In the cold area of north China,the concrete-filled steel tubular structure is eroded by freeze-thaw action,which causes the cracking of steel tube and the deterioration of mechanical properties of concrete-filled steel tubular structure.Aiming at the problem of interfacial bonding performance of concrete-filled steel tube under freeze-thaw erosion,freeze-thaw cycle test and push-out test of concrete-filled steel tube were carried out.Considering the different parameters such as the number of freeze-thaw cycles,concrete strength and the diameter-thickness ratio of steel tube,the distribution law and influencing factors of interfacial bonding force were analyzed,and the interfacial bond-slip constitutive relationship of concrete-filled steel tube under freeze-thaw cycles was studied.The average bond strength,peak bond strength and residual bond strength were determined.The results show that with the increase of the number of freeze-thaw cycles,the average interfacial bond strength decreases,the slip corresponding to the ultimate load increases gradually,while the residual bond strength decreases linearly,and the initial slip of the stable section increases exponentially.The peak bond strength and residual bond strength increase with the increase of concrete strength,and decrease with the increase of diameter-thickness ratio.By analyzing the strain distribution law measured by the dense strain gauges of the outer steel tube,it can be seen that the interfacial bond stress obeys exponential distribution.The bond stress distribution function derived from the load and slip combined energy method is compared and analyzed with good precision,which provides a new idea for the later experimental study of the interfacial bonding performance.A three-stage constitutive model of interfacial bond stress-slip after freeze-thaw cycles was constructed,and the corresponding eigenvalue calculation formula and constitutive model equation were proposed,which may provide reference for the design of concrete-filled steel tubular members considering freeze-thaw action.
concrete-filled steel tubefreeze-thaw actionpush-out testinterfacial bond stress-slip constitutive modelbond stress distribution function
万方数据
维普
