Title: SHEAR RESISTANCE OF CONCRETE MEMBERS WITHOUT SHEAR REINFORCEMENT UNDER SUSTAINED LOADING

Author(s): Joost Walraven, Reza Sarkhosh

Publication: Symposium Paper

Volume: 328

Issue:

Appears on pages(s): 14.1-14.18

Keywords: experiments, reinforced concrete, shear, sustained loading

DOI: 10.14359/51711158

Date: 9/12/2018

Abstract:
Concrete loaded in tension and compression is prone to the effect of sustained loading. In order to deal with that, building recommendations generally use a sustained loading factor in the range 0.7-0.8. Because the shear capacity of members without shear reinforcement is a function of the concrete strength, it may be wondered whether there is also a sustained loading effect in shear. To answer this question 42 reinforced beams without shear reinforcement have been tested. Amongst them, 28 beams were loaded to failure in about 5 minutes for getting short term reference values for the subsequent sustained loading tests. The other 14 beams were subjected to long-term sustained loading, with a ratio between the applied shear load and the short-term shear resistance between 0,86 and 0,98. In the case that no shear failure occurred during the period of sustained loading, which ranged from three months to three years, the beams where loaded to failure. It was shown that, contrary to concrete loaded in direct compression or tension, the shear capacity is not influenced by a sustained loading effect. On the basis of physical modelling of the beam behaviour it could be demonstrated that the contribution of aggregate interlock in the lower part of the curved bending-shear cracks counteracts crack propagation at the top, so that the development of the crack pattern is arrested.