Static load capacity of welded, high-strength hollow section joints – presentation of the FOSTA research association HOCHFEST: projects “High-strength hollow section joints”. Truss structures made of directly welded hollow sections under predominantly static loading are used in many areas of structural steel engineering and infrastructure, such as pedestrian bridges, as well as in plant- or mobile crane constructions. The use of high-strength steels can lead to economical lightweight structures with high load-bearing capacities and wide spans. In order to use this potential of hollow section joints, normative rules are required that enable economic design. The current design rules were validated semi-empirically by tests on joints of normal strength steels. These tests on normal-strength hollow section joints showed that through plasticising local stress peaks are compensated and secondary bending moments are redistributed. Compared to normal strength steels, high-strength steels have a reduced plastic redistribution capacity. This behaviour is considered in the design rules by reduction factors, which are conservatively defined because of lack of test results and have not yet been sufficiently experimentally validated for high-strength hollow sections. The projects on “High-strength hollow sections joints” in the FOSTA research association HOCHFEST are intended to derive differentiated and validated design rules that meet the safety requirements and enable the economical and resource-saving use of high-strength steels in hollow section structures.