Tests on end-zone stresses in pre-tensioned concrete I beams

Abstract

Summary A series of tests to measure the strains in the endzones of pre-tensioned prestressed concrete I beams is described. The variables were limited to the web breadth and the arrangement of prestressing wires. The maximum stress on the end face of a beam when horizontal cracking occurred was found to bear a linear relationship to the cube strength of the concrete at transfer. The strain at cracking was virtually constant. Peak tensile stresses on the end faces as predicted by various methods are compared with stresses obtained from measured strains, and suggestions are made for approximate predictions of stresses. A procedure is proposed for determining whether cracking is likely.