Study On Axial Compressive Behavior Of Square Steel Stub Column Filled With Demolished Concrete Blocks

Demolished concrete blocks is the large size lumps which can be acquired by thesimple process of crushing and screening, which can provides an effective way torecycle waste concrete. Demolished concrete lump can save more energy than thetraditional recycled aggregate concrete which was consumed during the workingprocess. But it has poorer structure performance than the ordinary concrete, themechanical behavior of steel stub column filled with demolished concrete lump were studied,Because the concrete-filled steel tubular can take advantages of the two kinds ofmaterials and it has high strength, good plasticity and convenience of erection, it canalso reduce the consumption of the cost of the construction. The following studies arecarried out:Experimental study of demolished concrete blocks under uniaxial compressionwas carried out in order to study the influence of varying mix ratio of demolishedconcrete on the mechanical behavior of the demolished concrete blocks. Test resultsshow that:(a) when the mix ratio increases from0%to13%, the compressionstrength of the specimen has a little increase, but when the mix ratio is greater than13%, with the increasing of the mix ratio, the compression strength of the specimendecreases.(b) when the mix ratio increases from0%to13%, the peak strain of of thespecimen has a little decrease, when the mix ratio is greater than13%, with theincreasing of the mix ratio, the peak strain of the specimen increases.(c) The ductilityof the specimens gradually deteriorate as the replacement rate increases.Experimental study of square steel stub column filled with demolished concreteblocks under axial compression was carried out in order to analyze the influence ofvarying mix ratio of demolished concrete on the mechanical behavior of stub columns.Test results show that:(a)The mix ratio has little effect on the bearing capacity of thespecimens as the mix ratio ranges from0%to26%. But as the mix ratio increases to39%, the bearing capacity of it decreases by20%compared to0%.(b)The ductilityfactor of the specimens gradually become larger overall as the mix ratio increases.(c)The optimal mix ratio of the specimens ranges from13%to26%.(d) The formulaof square steel stub column filled with demolished concrete blocks under axialloading is given by using the effective width method.Load-deformation relationship curves of the square steel stub column filled withdemolished concrete blocks under axial loading are analyzed by finite elementmethod. The predicted load versus deformation relationship curves are in goodagreement with those of tests. Based on this, the influence of width-thickness ratioconcrete strength and mix ratio on the mechanical behavior of stub columns areanalyzed.