The assessment of reinforcing bars with inadequate anchorage

Abstract

Concrete bridge structures often fail structural assessments because they have details that do not comply with current requirements. These details often include inadequate anchorage and lap lengths. In order to provide assessment data for such situations, 96 bond tests have been performed on reinforcing bars with anchorage lengths less than those currently required, ranging from 2.5 to 30 bar diameters. The cover ranged from one to six bar diameters. The results show that the average failure load varies linearly with embedded length at constant cover. However, due to the scatter of the test data it is not possible to rely on an anchorage length of a single bar of less than about three bar diameters. Reliability increases as the number of bars anchored at a section increases. It was also found that cover has little effect on the bond performance of plain bars. Deformed bars show an increase in bond performance with increased cover thickness up to approximately four bar diameters cover. It was also found that there is a residual pull-out resistance after bond failure. This observation has significant implications for load redistribution within an overloaded structure. (A)