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ABSTRACT: High strength concrete has, in recent years, been the focus of significant interest within the world's civil engineering community. Ever taller buildings and ever greater spans are sought in today's competitive market; as such an increase in the compressive strength of concrete is necessary. Although recent design codes provide classes of concrete up to C90/105, it is to be noted that above a characteristic compressive strength of 50MPa, the stress block is modified and, as such, the applicability of equations used for the design of concrete elements below this strength, that have been tried and tested over the years, come into question when used for compressive strengths over 50MPa. Of particular interest is the behavior of high strength concrete elements subjected to shear, because of the brittle failure that can occur, proper understanding of this behavior is necessary in order to accurately predict bearing capacity and amount of shear reinforcement needed to ensure ductile failure.
This paper presents experimental research regarding the behavior of reinforced high strength concrete beams subjected to shear. The class of concrete studied is C80/95.
The experimental research is focused on the influence that the shear span to depth ratio (a/d = 1.8 and 1.5) and the transversal reinforcement coefficient (ρ^sub sw^ = 0.00456; 0.00304; 0.0028) have on the behavior of reinforced high strength concrete beams subjected to shear forces. Experimental results are compared to design values obtained in accordance with, SR EN 1992-1-1:2004 (Eurocode 2), code provisions.
The elements behaved very well in shear, and showed an important contribution of the high strength concrete in resisting shear stresses.
KEYWORDS: High strength concrete, shear, beams, shear span to depth ratio.
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1. INTRODUCTION
Flexural failure is generally foretold by important deformation of the element, and, if necessary, appropriate measures can be taken, in order to insure structural integrity or to prevent loss of life and material damage if the situation can not be remedied. This is not the case for shear failure, which tends to be sudden and give little time for the necessary steps to be taken. For this reason a proper understanding of the shear behavior of structural elements is needed, and proper design methods applied in order to ensure safety during use...