Shear capacity of steel fibre reinforced concrete coupling beams using conventional reinforcements

The seismic performance of coupled shear wall systems is governed by the shear resistance of their coupling beams. Steel fibre reinforced concrete (SFRC) is widely applied in coupling beams for its positive contribution to their ductility. This study deals with the seismic behaviour of SFRC coupling beams using conventional reinforcements and develops a simplified model that applies the Mohr-coulomb failure criterion to predict the seismic shear strength of SFRC coupling beams. Variables studied include concrete compressive strength, fibre volume fraction and span-to-depth ratio. Results show that steel fibres improve the shear strength, deformation and energy dissipation capacity of the SFRC coupling beams. When fibre volume fraction is greater than 2.5% or span-to-depth ratio excesses 2.5, SFRC coupling beams present an excellent seismic performance and avoid effectively brittle shear failure. Using the Mohr-Coulomb failure criterion, a simplified shear model was proposed for SFRC coupling beams and presents a good accuracy and reliability. Furthermore, taking into account the negative effect of span-to-depth ratio, the proposed shear model was modified further. The comparative results demonstrated that the new shear model presents a more reasonable assessment accuracy and higher reliability.