ASSESSMENT OF CONCRETE STRUCTURES AFFECTED BY COVER DELAMINATION. PART 1: EFFECT OF BOND LOSS

The behaviour of bars in concrete with corrosion-induced delamination has been investigated by testing specimens in which bars were either flush with the concrete surface or exposed to mid-barrel. The results of pull-out tests, and tests of development lengths and lap splices in beams are used to derive proposals for limiting bond stresses. The effect of cover delamination on shearcracking is investigated and a proposal is made for a reduction of the normal calculated resistance. The effects of complete loss of bond by the main steel along all or a part of a span are also studied, and methods are given for treating arching action and the effects at the ends of debonded lengths. Applications of limiting bond stresses in truss models of more complex beams are described and validated in a companion paper.