The paper presents the numerical study of tubular square T-joints under fire conditions. The sequentially coupled thermal-displacement numerical model was proposed to examine the performance of square hollow section (SHS) joints. The developed finite element (FE) model was validated against available experimental test results and applied to study the influence of dimensionless parameters on the strength of SHS tubular T-joints at elevated temperatures. These parameters include brace-to-chord width ratio β, chord-width-to-thickness ratio γ, chord-to-brace thickness ratio τ and loading ratio n_F. The obtained results show that the critical temperature of T-joints is mostly influenced by the loading ratio n_F and β parameter. Different methods to obtain the joint resistance are presented. The strength of the joint obtained based on EN 1993-1-8 was compared with FE analysis, which showed that the decrease in the joint resistance in brace axial compression follows the curve of Young's modulus reduction factors. Finally, the strength of the joint was calculated based on the component method, with a temperature increase specified for each individual component. This method gave higher results in joint strength, when the non-uniform temperature distribution within the joint was taken into account.

本文介绍了在火灾条件下管状方形T型接头的数值研究。提出了相继耦合的热位移数值模型，以检验方形空心截面（SHS）接头的性能。针对现有的实验测试结果验证了开发的有限元（FE）模型，并将其用于研究无量纲参数对高温下SHS管状T形接头强度的影响。这些参数包括杆条-弦宽度比β，弦宽度与厚度比γ，弦长与支架厚度比τ和负载率Ñ _˚F。获得的结果表明，T型接头的临界温度主要受载荷比n _F的影响。和β参数。提出了获得关节阻力的不同方法。将根据EN 1993-1-8获得的接头强度与有限元分析进行比较，结果表明，在支撑轴向压缩时，接头阻力的减小遵循杨氏模量降低因子的曲线。最后，根据零部件方法计算接头的强度，并为每个单独的零部件指定温度升高。当考虑到接头内温度的不均匀性时，该方法在接头强度方面给出了更高的结果。