Mechanical Performance Of Socket Joint And Stability Of Single-layer Reticulated Domes

The socket joint, which is a typical semi-rigid joint system, can be assembled through the bolts. It has a bright prospect of application because of its high construction speed and excellent appearance. However, during the design process of a single-layer reticulated dome, the weld-joints are usually considered as rigid-joint system and the bolt-ball joint, such as socket joint system and bolt-ball joint, are generally considered as pin-joint system, so, few of single-layer latticed domes with a semi-rigid joint system are actually used in reality. In fact,the socket joint system with partial bend-bearing capacity is a typical semi-rigid joint system, and a single-layer latticed dome with socket joints can be used in actual space structures. As a matter of fact, it is worthwhile to carry out the study on the mechanical performance of semi-rigid socket joint system and the stability of the single-layer latticed dome with socket joints.The bending moment-rotation curve of socket joint is not only one of the most significant factor to estimate the mechanical performance of joint, but also the foundation to analyze a single-layer latticed domes with socket joints. The finite element analysis model used to conduct a numerical analysis of socket joint system is developed to make an accurate and efficient investigation into the overall mechanical behavior of the joint. The numerical simulation method is experimentally verified through the obtained moment-rotation relationship and failure mode of the joint.Using the numerical simulation model established in this paper, the influence of diameters of bolt and outer washer, value of pre-tension force and the ratio of bending moment and compressive axial force on the bending stiffness are studied in detail. The investigation into the effect of the input parameters of the model, such as the diameters of bolt and outer washer, value of pre-tension force and the ratio of bending moment and compressive axial force, on the bending stiffness of the joint is carried out in detail. By means of the power-law model with three parameters established by Kishi-Chen for semi-rigid column-beam joints in steel forms, a formula has been developed for predicting the bending stiffness of socket joint; and a good agreement has been achieved between the formula and the experimental results.Based on the moment-rotation curves established for the socket joints through the simulation in ANSYS, the elasto-plastic stability of Schwedler single-layer latticed domes with socket joints is carried out. The influence of several different parameters on the critical loads and buckling modes of the Schwedler single-layer domes, such as bend-stiffness, ratio of rise to span, asymmetric load distribution, tube section, support condition and initial imperfection, are investigated in detail. Based on the comprehensive parametric analysis, the stability of the Schwedler single-layer dome is mastered.