Engineering Structures 27 (2005) 1519–1527 www.elsevier.com/locate/engstruct Experimental study on high-strength concrete beams failing in shear A. Cladera a,∗ , A.R. Marí b,1 a University of Balearic Islands, Department of Physics, Ctra. Valldemossa km 7.5, 07122 Palma de Mallorca, Spain b Technical University of Catalonia, Department of Construction Engineering, Jordi Girona 1-3, 08034 Barcelona, Spain Received 8 September 2004; received in revised form 16 March 2005; accepted 25 April 2005 Available online 24 May 2005 Abstract To better understand the response of high-strength concrete beams failing in shear with and without shear reinforcement, eighteen reinforced concrete beams were tested as a part of extensive research on shear design of reinforced high-strength concrete beams. The concrete compressive strength of the beams at the age of the tests ranged from 50 to 87 MPa. The primary design variables were the amount of shear and longitudinal reinforcement. A minimum amount of shear reinforcement related to the concrete tensile strength was also proposed. The details of the beam specimens, material properties, instrumentation and the testing procedure used are carefully described in this paper. They will be useful for researchers to compare and analyze other design approaches. The test results are presented and discussed, and the influence of each design parameter is studied separately. Furthermore, the minimum amount of web reinforcement proposed in this paper is validated using experimental data from the literature. Test results are also compared with different shear design approaches and, finally, conclusions are drawn. © 2005 Elsevier Ltd. All rights reserved. Keywords: High-strength concrete; Reinforced concrete; Beams; Tests; Shear failure; Building codes 1. Introduction The use of High-Strength Concrete (HSC) has increased considerably during the last decade, since it can be produced reliably in the field using low water–cement ratios thanks to high-quality water-reducing admixtures. Furthermore, HSC will be more and more frequently used in columns, in precast elements and in structures where durability is an important design parameter. To give a simplified explanation, HSC is obtained by improving the compactness of the concrete mix, which increases the strength of both the paste and the interface between the paste and the coarse aggregate. However, an increase in the strength of the concrete produces an increase in its brittleness and smoother shear failure surfaces (Fig. 1), leading to some concerns about the application ∗ Corresponding author. Tel.: +34 971 171378; fax: +34 971 173426. E-mail addresses: antoni.cladera@uib.es (A. Cladera), antonio.mari@upc.es (A.R. Marí). 1 Tel.: +34 93 4016508. 0141-0296/$ - see front matter © 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.engstruct.2005.04.010 Fig. 1. Crack in high-strength concrete. The crack goes through the aggregates. of high-strength concrete. Since most of the current shear procedures are based on tests carried out on beams with a concrete compressive strength lower than 40 MPa, and one of the shear transfer mechanisms is shear-friction across the cracks, the failure shear strength needs to be re-evaluated.