Bond strength of hot-dip galvanized hooked bars in high strength concrete structures

In 2001, a multi-phase research program was started at the American University of Beirut (AUB) to evaluate the effect of steel galvanizing on bond strength of reinforcement in concrete structures. This paper reports on the fourth phase of the program designed to assess the effect of steel galvanizing on bond strength of hooked bars anchored in high strength concrete structures. Twelve specimens, each simulating the rigid connection of two cantilever beams to a column, were tested. The variables included bar size and the confinement mode of the beam bars anchored in the column. Test results indicated that galvanizing caused a consistent reduction in bond strength of hooked bars ranging from 6% to 17% with an average of 13%. This is contrary to the results of the earlier phase of the AUB program which indicated strength concrete structures. Based on analysis of test results of all four phases of the AUB research program, design recommendations insignificant effect of steel galvanizing on bond strength of hooked bars anchored in normal are provided concerning the anchorage length of galvanized reinforcing bars in normal and high strength concrete structures.