Author : Rizgar Amin Agha

This paper reviews the researches on anchorages with straight end of main bars in reinforced concrete structure. The theoretical approaches by Tepfers, Cairns, Cairns and Jones and Morita and Fujii and the plastic theory by Nielsen have been studied.Also, those empirical equations for calculating the bond strength are reviewed which are from Orangun, Darwin and Btayneh. The anchorages of main reinforcement at simple supports are important in the design of reinforced concrete and the most significant characteristics of are their generally short lengths and the presence of transverse pressure from the support reactions. Published work in this area is rather limited. The only major research is that by Danish authors, working in the field of plasticity and works by Rathkjen, Jensen, Ghaghei and Regan are considered in this review.This review gives comments on types of bond failure, analyses of behaviour adjacent to a bar, analysis of the surrounds to a bar, treatments of the influences of transverse pressure and transverse reinforcements on the anchorage capacity of the main bar in structural concrete members. Two important characteristics of conditions at simple supports are that anchorage lengths are short and that the support reaction produces compressions perpendicular to the plane of the bars. Because of the first of these the treatment of bond strength must take account of the ratio of the anchorage length to the bar diameter. In relation to the second, there is ample evidence showing that transverse pressure can increase bond strength. It is concluded that the type of test specimen and the way in which loads and reactions are applied to it can materially affect the results of bond tests.

Keywords: Bond stress, bond failure, bond strength, slip, splitting of cover, concrete strength, concrete cover, anchorage length, bar diameter, rib areas ,transverse reinforcement and transverse pressure

Article published in International Journal of Current Engineering and Technology, Vol.4, No.5 (Oct-2014)