Behaviour of channel shear connectors : push-out tests

This thesis summarizes the results of an experimental investigation involving the testing of push-out specimens with channel shear connectors. The test program involved the testing of 78 push-out specimens and was aimed at the development of new equations for channel shear connectors embedded in solid concrete slabs and slabs with wide ribbed metal deck oriented parallel to the beam. The test specimens were designed to study the effect of a number of parameters on the shear capacity of channel shear connectors. Six series of push-out specimens were tested in two phases. The primary difference between the two phases was the height of the channel connector. Other test parameters included the compressive strength of concrete, the length and the web thickness of the channel. Three different types of failure mechanisms were observed. In specimens with higher strength concrete, failure was caused by the fracture of the channel near the fillet with the channel web acting like a cantilever beam. Crushing-splitting of concrete was the observed mode of failure in specimens with solid slabs when lower strength concrete was used. In most of the specimens with metal deck slabs, a concrete shear plane type of failure was observed. In the specimens involving this type of failure, the channel connector remained intact and the concrete contained within the flute in front of channel web sheared off along the interface. The load carrying capacity of a channel connector increased almost linearly with the increase in channel length. On average, the increase was about 39% when the channel length was increased from 50 mm to 100 mm. There was a further increase of 24% when the channel length was increased from 100 mm to 150 mm. The influence of web thickness of channel connector was significant when the failure occurred due to channel web fracture but was minimal for a concrete crushing-splitting type of failure. The specimens with solid concrete slabs carried higher load compared to those with metal deck slabs. The increase in load capacity was 33% for specimens with 150 mm long channels but only 12% for those with 50 mm long channel connectors. This investigation resulted in the development of a new equation for predicting the shear strength of channel connectors embedded in solid concrete slabs. The proposed equation provides much better correlation to test results than those obtained using the current CSA equation. The results of specimens with metal deck slabs were used to develop a new equation for predicting the shear capacity of channel connectors embedded in slabs with metal deck oriented parallel to the beam. The values predicted by the proposed equation were in good agreement with the observed test values