Research On Bearing Capacity Of Welded Hollow Spherical Joint Connected With Reduced-diameter Steel Pipe

Welding hollow spherical joints with its advantages of simple structure, convenient connection, no joint eccentricity, is widely used in grid structure. In recent years, with the increase of the spatial span, modelling of increasingly complex, welding hollow spherical joints also develop in the direction of large size, seriously affected the beautiful of the grid structure, and the bearing capacity of large diameter also lack reliable theoretical and experimental research.In this paper, a form of welded hollow spherical joint connected with reduced-diameter steel pipe is presented, combining of the characteristics of welded hollow spherical joints and bolt-sphere joints. This joint form possesses the advantages of general welding hollow spherical joints, and effectively reduces the diameter of welding hollow spherical. Ensuring the bearing capacity of the welding hollow spherical and the beautiful of grid structure, the same diameter of welding hollow spherical can be concurrent more bar. Series designed welding cone can also make it realize batch processing in factory, and effectively reduce the length of the welding which make it more convenient to construction.Useing the ANSYS finite element analysis software, the typical steel tube reducing Welded Hollow Spherical Joint is modeling analysied. further study of the geometric nonlinear effect on the bearing capacity of joint has be done. load- displacement curve of the joint under unidirectional tensile and compressive load has been compared. By analyzing the development process of the stress of joint, the steel tube reducing welding mechanical performance and failure mechanism of the welding hollow spherical joint is been understanded.This article through to 194 groups of the one-way axial force of steel tube reducing welding hollow spherical joints finite element analysis, investigates the steel tube reducing ball diameter ratio, and the diameter of the hollow ball after diameter-thickness ratio and the hollow ball diameter, to the influence of the bearing capacity of joint, and put forward the limited bearing capacity of steel tube reducing welding hollow spherical joints formula. To consider the hollow ball multidirectional stress effect on the bearing capacity of the node, in 180 set of nodes by the bi-directional stress finite element analysis, the bearing capacity of node in return out of the hollow ball unidirectional compression bearing capacity formula of basic quality to a two-way pressure reduction factor calculation, the coefficient and steel pipe after reducing diameter and the ratio of ball diameter, tube and director of the axial force ratio, ratio of hollow ball diameter to thickness, the coefficient decreases with the increase of the ratio, the final regression analysis get the calculation formula of the reduction factor.In this paper, to make welded hollow spherical joint connected with reduced-diameter steel pipe practical, referencing common steel models,a series of specific dimensions of welding cone and welding hollow ball is designed, and studied its capacity, ompared its quality, carrying capacity and site welding weld length with straight pipe welded hollow spherical joints. With the aid of an actual grid roof engineering, image intuitive to steel tube reducing welding and welding hollow ball straight steel tube hollow spherical joints were compared, for design of steel tube reducing welding hollow ball node series has carried on the preliminary explore practical. Results show that this joint form, on the premise of guaranteing the bearing capacity, reduces the diameter of the hollow ball, reduces the weight of the joint, save the steel, reduce the workload of field welding, saving labor and make it more convenient to constructe, basically achieved the desired effect.