Influence of Tension Loading Protocol on Crack Cycling Tests on Undercut Anchors

Crack cycling tests govern the seismic approvals of most of the mechanical anchors. Currently, the guidelines recommend performing crack cycling tests with constant tension load for simplification of test setup. This assumption is deemed conservative. In this work, crack cycling tests on undercut anchors are performed with three different extremities of tension loading protocols-namely, 1) constant load during crack cycling; 2) load cycling in-phase with crack cycling; and 3) load cycling out-of-hase with crack cycling. The tests are performed on two different types of undercut anchors and are principally compared with the tests on headed studs available in literature. The results indicate that depending on the anchor type, the assumption of constant load during crack cycling may not always be conservative considering the displacement demands on the anchor. The in-phase crack and load cycling test is more realistic while being conservative from induced displacements viewpoint.