An examination of the stresses in the anchorage zone of a post-tensioned prestressed concrete beam

Abstract

Summary The work described is the result of investigations carried out in the Department of Civil Engineering of the University of Sydney in an attempt to determine the effect of high concentrations of stress in the anchorage zone of a prestressed concrete beam. The problem was idealized as that of the stress distribution due to the application ofa circular concentrated load acting at one end of a concrete cylinder, the theoretical analysis and experimental procedure being in this way simplified. A mathematical analysis of a three-dimensional case to determine the stresses throughout the anchorage zone is described and the results are compared with those of other writers. In a series of tests designed to verify the theoretical analysis, the loads required to cause failure were much greater than those predicted on the basis of current theories of failure and on the assumption of elastic behaviour. Further experimental work involving measurement by electrical resistance strain gauges of the surface strains showed good agreement with strains predicted theoretically. Attention is called to the fact that the tensile strains measured corresponded to stresses of approximately four times the ultimate tensile stress of the concrete as determined by the Brazilian method of testing.