Block shear strength and design of coped beams with double bolt-line connections

Abstract

Available test data on block shear behaviour of coped beams with double bolt-line connections are quite limited, and earlier investigations found that the test block shear capacities could not be accurately predicted by existing design rules which deal with this failure mode in an inconsistent manner. To address this, a comprehensive investigation focusing on the block shear behaviour of coped beams with double bolt-line connections was reported in this paper. The research commenced with 17 full-scale tests considering the test parameters of web block aspect ratio, out-of-plane eccentricity, connection rotational stiffness, and bolt stagger. Two specimens were found to fail by local web buckling, and the remaining 15 specimens failed by block shear. Three typical block shear failure modes were observed at ultimate load, namely, whole block tear-out (WBT), tensile fracture (TF), and tensile fracture followed by whole block tear-out (TF–WBT). The influences of the considered test parameters on the failure mode and block shear capacity of the test specimens were thoroughly discussed. The test results were then compared with existing design rules to evaluate the consistency and accuracy of the major standards, and it was found that these standards led to inconsistent test-to-predicted ratios and tended to be conservative. Summarising all available test data, including the current tests and those previously conducted by other researchers, a reliability analysis was conducted to further examine the level of safety of the major standards. Design recommendations were finally proposed aiming to achieve reliable yet economical design approaches with consistent safety levels.