COMPRESSION BEHAVIOUR OF BI-ANGLED BUILT-UP CRUCIFORMS LOADED THROUGH ONE ANGLE

Abstract

Angles are popularly used in built-up steel sections. The behaviour of common sections built-up by angles such as boxes and tees are established, and design provisions are available in design codes. The cruciform arrangement, consisting of vertex-to-vertex connected angles, has been studied recently as a strengthening arrangement for lattice tower primary members, where the load is not applied through the centroid on the built-up section, like in common built-up sections. The behaviour of such cruciforms need to be studied further for establishing their efficiency as compression members. This study consists of experimental tests followed by numerical parametric study of such cruciforms. Experimental tests on cruciform of slenderness 80, 100 and 120 were performed followed by numerical finite element analysis for validation. A parametric study was conducted on 36 bi-angled cruciforms with slenderness, connector spacing, number of bolts and angle width-thickness ratio as the chosen parameters. Predictions by national design codes were compared with the numerical results. The influence of these parameters on the load sharing rate between the angle sections were observed and it is seen that slenderness has the highest influence while the number of bolts per connector has least influence. Equal load sharing was achieved for cruciforms of lesser slenderness, showing that the arrangement can be an efficient strengthening arrangement.