Study On Mechanical Properties Mechanical Properties Two-end Linear String Truss Structure

The closed material yard structure usually has the characteristics of large span,high height and wide coverage area.At the same time,in order to satisfy the stacking and transportation of materials,the profile of the structure should also satisfy the arc operation envelope of the stacker-reclaimer.As a hybrid structure,string truss structure has good mechanical properties,super span ability and mature construction technology.Therefore,arc string truss structure has been widely used in large-span closed material yard project.It is found that the circular arc truss at the end of the structure has a larger section because of the large force.Aiming at this defect of traditional structure,this paper presents a two-end linear string truss structure,and makes a comparative analysis of the mechanical and economic performance of the two structures.Firstly,the finite element models of single traditional circular arc truss structure and two-end linear string truss structure at both ends are established.Comparing and analyzing the unit steel amount,the maximum combined displacement and the maximum horizontal reaction force.The results show that the two structures have good basic mechanical properties.In terms of economic performance,the unit pass steel of the two end linear string truss structures can be saved by about 7%-18% when the inclination angle is optimum,compared with the traditional circular arc string truss structures.From the two levels of the whole structure and the local components,the stress of the two structures is compared.Firstly,the equivalent steel arch finite element models of the two structures are established.And to study the effect of cables on the internal forces of structures,and the pure steel arch structure model without cables is established.The Strength-Stress ratio of the two structures and the stress state of the members are compared.The results show that the force acting on the two ends of the two-end linear string truss structure are more reasonable,and the structural cables can effectively improve the mechanical properties of the structure.Secondly,the calculating models of circular and linear members are established,and the internal force,stiffness and stability of the two components are compared.Because of the initial bending of the circular-arc members,the p-? effect of the members makes its stress more disadvantageous.Therefore,the mechanical properties of linear members are due to the circular-arc members,which is one of the reasons why the linear string truss structure has better mechanical properties.Using ANSYS finite element analysis software,the finite element models of two-end linear string truss and circular-arcstring truss structures are established respectively.The eigen value buckling analysis and non-linear buckling analysis of the two structures are carried out,and the buckling modes,eigen value buckling factors and non-linear buckling coefficients of the two structures are compared.The results show that the b uckling shapes of the two structures are similar,and the linear string structure has higher stability.The overall instability of the two structures is mainly due to the buckling of the lower chord members at the junction of the two ends.Therefore,the section of the lower chord members at the junction can be reasonably enlarged in order to improve the stability of the structures.