Cyclic testing of built-up, extended end plated replaceable links for more cost-effective weld design

Abstract

Experimental cyclic tests were performed on four pairs of built-up, extended end plated replaceable links with a range of welded connections, one representing current design practice and three others with more cost-efficient weld designs. For the latter welds, the traction stress method is used to determine the critical failure plane for both their flange to web and end plate fillet welds. An improved sizing criterion was then proposed for these joints, demonstrating up to a 25% reduction in their sizes. The use of more economical effective full penetration butt welds, in lieu of complete penetration butt welds and larger fillet welds, is also investigated for the link flange to end plate joints. Of the four tests conducted, three were on specimens with flanges and web to endplate fillet welds of 6 – 10 mm and one with flange to end plate effective full penetration butt welds. The links all exhibited ductile and repeatable behaviour through to failure, developing overstrengths of over 1.37 and peak plastic rotation angles of 0.071 - 0.075 rad at the actuator’s maximum capacity. The failure mode across the links was via local buckling of the web under positive shear, coupled with tensile tearing of the link under negative shear. No instances of failure in the weld metal were observed across the four tests. Based on the test findings, an improved sizing criterion for the flange to web and end plate fillet welds in such links is proposed. Recommendations for the use of reinforced partial penetration butt welds are also proposed.