Local use of ECC to simultaneously enhance the shear strength and deformability of RC beams

Abstract

• A new method that can simultaneously enhance the shear strength and deformability of RC beams was proposed. • The effects of compression-zone material on the variation of V c and v s were evaluated. • Shear deflection and flexural deflection were decoupled. • The mechanisms of how compression-zone material affects the shear strength and deformability were investigated. Existing studies have substantiated that the stress (or strain) states of compression-zone concrete exert significant influence on the performance of shear-critical reinforced concrete (RC) beams. Based on this understanding, the current paper presents a tentative work by replacing the compression-zone concrete with engineered cementitious composite (ECC) to simultaneously enhance the shear strength and deformability of a RC beam. To uncover the reasons behind the enhancements due to the inclusion of ECC, the shear strength contributions from concrete ( V c ) and stirrups ( V s ) were obtained with reasonable accuracy using an innovative methodology. Shear and flexural deformations were decoupled utilizing two methods with the help of the imaging technique. The cracking process, crack width, strain fields, and principal direction evolutions were monitored by a digital image correlation (DIC) system. The test results clearly show that the inclusion of ECC in the compression zone significantly increased both the shear strength and deformability of RC beams. More specifically, the inclusion of ECC changed the crack width and pattern, the variation trends of V c and v s and the deformation proportion. Finally, existing shear deformation models were evaluated, and none of them could predict the shear deformation of beams incorporating ECC due to the high nonlinear feature.