Stub column tests of fabricated square and triangular sections utilizing very high strength steel tubes

Abstract

This paper describes a series of stub column tests carried out on fabricated square and triangular sections (FSTSs) utilizing very high strength (VHS) circular steel tubes with a nominal yield stress of 1350 MPa. The VHS tubes are placed at each corner of the section and welded to Grade 350 steel plates. Two different nominal diameter-to-thickness ratios of 15.9 and 23.8 were chosen for the VHS tubes. Five different nominal width-to-thickness ratios ranging from 40 to 133 were chosen for the steel plates. The geometric imperfection of the fabricated sections was measured. Twelve tests on VHS columns, with the same length as that for corresponding FSTS specimens, were tested for comparison purpose. The load carrying capacity of the FSTSs utilizing VHS tubes was found to be 3.5 times the calculated nominal section capacity of a corresponding welded square or triangular box section without tubes. The load carrying capacity of the FSTSs was found to be up to 3.8 times that of the corresponding VHS columns without the plates and a length of 1200 mm. Two design models were proposed. One is based on the simple superposition of the capacities of VHS tubes and steel plates. The other is based on the capacity of steel plates with a newly derived plate element yield slenderness limit.