Column base connections under compression and biaxial moments: Experimental and numerical investigations

Abstract

Very little guidance exists on the design of steel column base connections subjected to axial compression and biaxial bending moment. In order to develop a design method, an experimental program of 32 tests to failure was carried out to determine the effects of various factors that affect the failure modes, strength and behaviour of unstiffened column base connections under biaxial bending moment. Plate thickness, bolt diameter and axial compression force were set to low and high values in a full factorial experimental design chosen to bring about different failure modes. The program was completed with detailed finite element analyses calibrated with the experimental results. The investigations provide a clearer understanding of the failure modes, strength and behaviour of baseplates under biaxial bending moment. Increases in plate thickness, holding-down bolt diameter and axial force were found to increase the connection strength. The welds at the flange tips of corner bolted base connections under biaxial bending were shown to be vulnerable to premature failure, and the work showed that existing design codes are conservative for the uniaxial bending case.