Mechanical Analysis Of Concrete Filled Double Skin Steel Tubular Columns With Mortise And Tenon Joint

In recent years, China has the rapid development in construction field, a lot of kinds of high-rise and super high-rise continue to emerge, the concrete filled steel tube with its high bearing capacity and good plastic and toughness are gradually appreciated by engineers. Concrete filled double skin steel tubular (CFDSST) is developed on the basis of the concrete filled steel tube, it deducted the core part of concrete, not only can reduce the weight but also makes the section for more to use and can improve the bending stiffness of structure form, as an excellent mechanical properties has already caused the attention of the academic circles at home and abroad. But there is little about its application in practical engineering, the reasons are as following:firstly, did not have the appropriate form of nodes and the detailed research work; secondly, difficult construction, how to ensure the accurate positioning of the inner and the outer steel pipe construction, how to ensure the concrete pouring and compacting. These are what this kind of new structure has to face.In view of the existing problems, this paper presents a new type of mortise and tenon joints, the new node can connect the CFDSST and steel beam to form a frame structure system that has the characteristics of assembly type construction, effectively solve the practical problems that are facing. This paper uses the finite element software ABAQUS to compare the members performance under mortice and tenon joints node and ordinary node, in contrast to the two node constraints members under the axial compression mechanical properties analysis of short column, bias in the long column and low cyclic loading. Specifically the following aspects of work:1.Axial compression:The members under two node constraints have the same bearing capacity and deformation, the calculation method of the CFDSST is also applicable to that under the new node.2.Eccentrically-loaded:The new node can increase the bearing capacity and reduce the lateral deflection of the CFDSST; the length of the mortise and χ are the main factors to effect the new node’s constraint. When the χ=0.54 and the mortise length l=0.2L, which have obvious advantages of the new node; the conclusion is also proved by Euler formula to get the theoretical verification.3.Horizontal low cyclic effects:Comparing with the skeleton curve of the two kind of nodes, we can conclude that the new node can increase the horizontal bearing capacity of the members, and with the increasing of axial compression ratio, the new node can increase more; comparing with the stress cloud and failure pattern we can conclude that the members under two nodes have different damage of concrete with different positions, the new node can protect root of the members from damage; the ductility is better than that of normal node.