The Behavior Of The Multi-bar Cast-steel Joint

With the rise of large-span structure in China, the steel-tube construction has been widely used in structural engineering. The nodes in large span steel-tube construction system directly related to stability and security of the structure, so it is the key of the structural system. Due to the cast steel joint has a advantages of design flexibility, high capacity, and wide applicability, it is gradually used in large span steel-tube construction by structure design personnel.According to Changfeng Group Headquarters Building (Administr-ative Center) pipe-truss structure cast steel joint static test data, this paper choose one of the cast steel joint, do some numerical analysis to the joint by using finite element analysis software. This paper use elastic-plastic constitutive relation theory in analysis and consider the material nonlinearity and the geometric nonlinear. We change all bar cross-section for circular tube. By changing the wall thickness and chamfer, we establishes a variety of cast steel joint model for the normal use load cases and the limit load cases of ANSYS finite element analysis, to study the joint force by change the fillet radius and wall thickness at the same time. The main research contents:(1) The experimental design can simulate actual situation of the joint well, the data of the joint analysised by ANSYS is in the control range. Under the load of1.1times the design value, the joint did not get damaged or local failure.(2) Comparisons of test data and ANSYS analysis results, the trends of stress-strain in experiments are consistent with the finite element simulation by ANSYS, the measured stress-strain data is a little deviated, but at the same level, confirmed the feasibility of ANSYS analysis.(3) Using ANSYS to analyze the model by changing the wall thickness and chamfer radius, find that there’s an optimum value at the chamfer radius in the cast steel joint at the intersection under the normal use loads. The stress at the chamfer is significantly increases when the chamfer radius is greater or less than the optimum value.(4) Wall thickness has a big impact on ultimate bearing capacity of the weak parts in cast steel joint, wall thickness for each additional5mm ultimate bearing capacity increased by16%and10%respectively. The chamfer radius has a certain influence on ultimate bearing capacity, due to the model and analysis limitation, the difference in chamfer radius is not obviously influenced ultimate bearing capacity in the weak parts in this paper.The research on cast steel joint in this paper provides experimental data and guidance model for further study in the field in the future, and also provides a certain basis and learn in cast steel joint for optimization design.