Experimental Study On Shear Performance Of Cold-formed Thin-walled Square Steel Tube Skeleton Wall Filled With Phosphogypsu

With the development of cold-formed thin-wall steel structure to the demand of high-rise and the frequent occurrence of natural disasters such as hurricanes and earthquakes,the insufficient shear capacity of traditional cold-formed thin-wall steel composite wall has become increasingly prominent.Therefore,how to effectively improve the shear capacity of coldformed thin-wall steel composite wall is one of the urgent problems to be solved in the engineering field.In order to improve the shear performance of cold-formed thin-wall steel composite wall,a new type of cold-formed thin-wall steel composite wall--cold-formed thinwall square steel pipe skeleton wall filled with phosphogypsum is proposed in this paper.In this paper,the shear behavior and mechanical mechanism of the cold-formed thin-walled square steel tube skeleton wall filled with phosphogypsum are studied by means of experimental research,numerical simulation and theoretical analysis.The main contents are as follows:(1)A monotone loading test was carried out on 6 pieces of specimens filled with phosphogypsum for cold-formed thin-walled square steel tube skeleton wall.The influences of such factors as whether the specimens are filled with phosphogypsum,whether there is wall panel,the strength of phosphogypsum and the wall thickness of square steel tube on the shear properties of the specimens were explored.The failure characteristics and failure modes of the walls under monotone horizontal loading were investigated.The load-displacement curve,load and displacement characteristic values,lateral stiffness and other mechanical properties of the specimen were analyzed.The results show that the main failure characteristics of the coldformed thin-walled square steel tube skeleton wall filled with phosphogypsum include selftapping screw bending in the wall panel,screw hole extrusion failure,corner collapse of phosphogypsum and fiber cement board,local buckling of square steel tube column,etc.Filling only the square steel tube with phosphogypsum has little effect on the shear capacity of the wall,but has great effect on the opposing side stiffness.The shear strength and lateral stiffness of the specimens filled with phosphogypsum both inside the square steel pipe and between the wall frame columns are greatly improved.The wall slab has great influence on the shear capacity and lateral stiffness of the wall.(2)Using the finite element software ABAQUS,a finite element model of a cold-formed thin-walled square steel pipe skeleton wall filled with phosphogypsum was established and its shear properties were numerically simulated.The failure modes and load-displacement curves of the wall model were compared with those of the test wall.The results showed that the simulation results were in good agreement with the test results.On this basis,the shear properties of the wall are analyzed with variable parameters.The results show that the shear capacity and lateral stiffness of the wall increase with the increase of the phosphogypsum strength.The shear capacity and lateral stiffness of the wall can be significantly improved by increasing the wall thickness.With the increase of the thickness of the wall panel,the shear capacity and lateral stiffness of the wall are greatly increased.The strength grade of steel has great influence on the shear property of wall.(3)On the basis of experimental research and numerical simulation,according to the failure characteristics and failure mechanism of the wall,the simplified force model of the wall is established,and the calculation formula of the shear bearing capacity and lateral stiffness of the wall is proposed,and the shear bearing capacity and lateral stiffness of the wall are calculated by using the formula.The results show that the calculated values of the shear capacity of the wall are not much different from the experimental values and the finite element values,and the calculated values of the lateral stiffness of the wall are in good agreement with the experimental values.It shows that the formulas for calculating the shear capacity and lateral stiffness proposed in this paper have good accuracy.