High strength long span structures (HILONG) : final report

HILONG investigated innovative cross-sections and structural arrangements which enable the benefit of high strength to be maximised by suppressing buckling and reducing deflection. The study focussed on long span applications, such as trusses for stadia, exhibition halls etc. The strengths studied were between S460 and S690. Tests and numerical studies on stub columns, beams and beam-columns confirmed current guidelines in Eurocode 3 and also led to the development of a less conservative deformation-based design method. The performance of different types of joints in two HSS trusses was investigated. One truss comprised conventional tubular sections and the other a U-shaped bottom chord and semi-closed polygonal top chords; these innovative crosssections facilitate easier fabrication of the joints compared to conventional tubular joints. Tests were also carried out on a crocodile nose connection, which is a novel type of connection suitable for joining tubular diagonal members to a gusset plate. The performance of prestressed stayed columns and prestressed trusses was studied experimentally and numerically to assess the extent to which they enable a greater proportion of the higher strength to be utilised by suppressing buckling and limiting deflection. Vibration tests explored the dynamic response of these prestressed systems. Two case studies (a long span roof truss and a prestressed cable stayed column) demonstrated the potential for savings in weight, cost and environmental impacts through the use of HSS and the technologies studied in HILONG. The studies clearly demonstrated the potential advantages of HSS structural systems, but careful design is required to maximise these advantages.