These joints are used when the designer and contractor anticipate difficulties during the construction of overlap joints. They were not included in the PN EN 1993‒1‒8 in full scale. Resistance assessment of such joints is presented in accordance with standard rules. The results were compared with the experimental studies carried out at the “Mostostal” Centre; while the former research activities and the legitimacy of the proposed method of assessing the resistance of these joints was confirmed. This is an example of an overlap joint calculation.

The basis for calculating of resistance of welded RHS connections is provided by codes and international guidebooks. In the matter of calculation of the resistance of welded joints, the European standard contains very general recommendations without specifying the detailed calculation procedures, which (the) designers could use in their work. Estimation of resistance of welded semi-rigid joints is a complex issue because it requires determining of effective lengths of welds, their placement on the member walls with their different rigidity, and distribution of components of the load acting on each section of welds in various joint areas. In this paper an approximate assessment is suggested of the resistance of the welded connection in the overlapped K type joints, made of rectangular hollow sections.

In calculating the resistance of welds within the connections between hollow sections in EN 1993‒1‒8, very general information is given without presenting specific calculations. The chief recommendations indicate that the resistance of the welds connecting the wall to the second element should not be less than the resistance of the cross section of the wall. In addition, assessment of the welds’ resistance based on the effective lengths is viable in cases when forces in the braces are smaller than the resistance of the joint, though the detailed method was not specified. The objective of this paper is to present the most up-to-date information about the design of overlap welded joints with a reinforcing rib plate.