The material reduction factor of rectangular hollow section (RHS) joints in a new version of Eurocode 3 part 1–8 is validate for steel with the nominal yield strength up to 700 MPa. In this paper, finite element simulations of gap K-joints are conducted to investigate effects of material properties, gap size of the joint, the brace to chord width ratio and welds type on the secondary bending stresses and the resistance. The governing failure mode considered for all the FE models is the chord face failure followed by brace sidewall failure. The ratio of axial stresses to the nominal stress was lower in the compressive brace made of higher strength steel grades compared to the mild strength grades. The maximum secondary bending stresses is 0.12–0.32 yield strength. The secondary bending stresses are increasing with the increase of the steel grade and the brace to chord width ratio and with reducing the gap size. The level of secondary bending stresses varied between 38% and 56% of the average normal axial stress. The secondary bending stresses of fillet-welded joints are larger than the butt-welded joints. The yield line model is used to predict the ultimate load and good agreement is obtained compared with FE results.

在新版的Eurocode 3第1-8部分中，矩形空心截面（RHS）接头的材料减少系数适用于标称屈服强度高达700 MPa的钢。本文对缝隙K型接头进行了有限元模拟，以研究材料性能，缝隙尺寸，支撑与弦宽之比以及焊缝类型对次级弯曲应力和阻力的影响。对于所有有限元模型考虑的主要失效模式是弦面失效，然后是支撑侧壁失效。与中等强度等级相比，由高强度等级钢制成的压缩支架的轴向应力与标称应力之比较低。最大二次弯曲应力为0.12-0.32屈服强度。二次弯曲应力随着钢种的增加和支撑与弦的宽度比的增加以及间隙尺寸的减小而增加。次级弯曲应力的水平在平均法向轴向应力的38％至56％之间变化。角焊缝的二次弯曲应力大于对焊缝的二次弯曲应力。屈服线模型用于预测最终载荷，并且与有限元结果相比具有良好的一致性。