An investigation of the block shear strength of coped beams with a welded clip angle connection — Part I: Experimental study

Abstract

The ends of a coped beam are commonly connected to the web of a girder by double clip angles. The clip angles may either be bolted or welded to the web of the beam. One of the potential modes for the failure of the clip angle connection is the block shear of the beam web material. To investigate the strength and the behavior of the block shear of coped beams with welded end connections, ten full-scale coped beam tests were conducted. The test parameters included the aspect ratio of the clip angles, the web shear and tension area around the clip angles, the web thickness, beam section depth, cope length, and connection position. The test results indicated that the specimens failed, developing either tension fractures of the web near the bottom of the clip angles or local web buckling near the end of the cope. Although the final failure mode of the six specimens was local web buckling, it was observed during the tests that these specimens exhibited a significant deformation of the block shear type prior to reaching their final failure mode. No shear fracture was observed in all of the tests. A comparison between the ultimate loads in the test and the predictions using the current design equations indicates that the current design standards such as the AISC-LRFD, CSA-S16-01, Eurocode 3, BS5950-1:2000, AIJ and GB50017, are inconsistent in predicting the block shear strength of coped beams with welded end connections. The analytical study of the strength of the test specimens using the finite element method, a parametric study, and a proposed design model for designing block shears for coped beams with welded clip angles are included in a companion paper.

An investigation of the block shear strength of coped beams with a welded clip angle connection — Part II: Numerical study

“…As mentioned above and also in [1], local web buckling was also one of the failure modes for the test specimens. Although some of the test specimens failed due to the local buckling of the web, these specimens exhibited significant deformation of the block shear type prior to reaching their final failure mode.…”

“…In addition, as shown in Table 2, among the eight specimens that reached their ultimate loads, the finite element models could accurately predict the failure mode for seven of them. The discrepancy in specimen D1-457R1 might be due to the insufficient restraints provided by lateral bracing during testing, as described in the companion paper [1]. As can be seen from the test results of this specimen, severe web necking was observed in the area of tension underneath the clip angles, implying that tension fractures would probably occur as predicted.…”

“…The finite element model was calibrated by a testing program conducted by Yam et al [1]. The calibrated finite element model was then used to conduct a parametric study.…”

“…In addition, for the same connection capacity, an increase in the shear area would lead to a corresponding decrease in the tension area; hence, the connection eccentricity was reduced. As discussed in the companion paper [1], the connection eccentricity induced high compressive stress in the web between the clip angles and the cope end, initiating local web buckling of the connection. Similarly, the effect of tension area was investigated by keeping the shear area constant and varying the tension area.…”

“…Details of the results were presented in a companion paper [1]. In general, the failure mechanism in coped beams with welded end connections was different from that with bolted end connections, since there was no reduction in the web section area due to bolt holes.…”