Experimental and analytical study on grouted duct connections in precast concrete construction

Abstract

Owing to its forgiving tolerances and eliminating the need for welding, grouted dowel in-conduit connections are widely used for connecting various precast concrete elements, for instance in precast wall construction and bridge bent cap systems. Current design recommendations for such a connection treat it similar to a conventional reinforcing bar-in-concrete and do not account for the restraining effect of the duct. In the present study, a series of experimental and analytical approaches have been adopted to explore the disparity between grouted dowel connections and bar-in-concrete. The experimental program consisted of testing twenty-four pull-out specimens under monotonic loads. The main parameters investigated included the embedment length, concrete compressive strength and corrugated duct. Results from the experimental and analytical procedures showed that grouted dowel in-conduit connections behave markedly different from bars in concrete. Different failure mechanisms occurred in the grouted connections due to the confinement effect of the duct. Moreover, an increase in load carrying capacity and ductility of the connections was observed at all embedment lengths, regardless of the concrete compressive strength. Based on the experimental findings, an analytical model for predicting the embedment length of the connection was derived, calibrated and proven to be more accurate than state-of-the-art design procedures.