Seismic performance of steel plate reinforced high toughness concrete coupling beams with different steel plate ratios

Embedded steel plate reinforced concrete (PRC) coupling beams are newly introduced into the family of coupling beams to improve the seismic behavior of reinforced concrete (RC) coupling beams. However, the brittle crush and spalling of concrete in these composite members noticeably reduce their deformation performance and energy-dissipating capacity which largely deteriorate the efficiency of this combination. Considering this noteworthy shortcoming, in this paper the authors propose a novel type of composite coupling beams, which is entitled steel plate reinforced high toughness concrete (PRHTC) coupling beam. This novel member replaces the conventional reinforced concrete with the high toughness concrete (HTC) which is a sort of pseudo strain-hardening cementitious composites exhibiting quasi-ductile behaviors. This study mainly investigates the seismic performance of PRHTC deep coupling beams (span-to-depth ratio, l/h = 1.5) with various steel plate reinforcement ratios. The test results indicate that the PRHTC coupling beams exhibit a ductile flexural failure mechanism with excellent energy dissipation capability. The high toughness concrete in this composite member displays multiple cracking pattern and maintains desirable integrity. All specimens attained high-level ductility factors exceeding 5.5, survived large rotations ranging from 0.064 to 0.078 rad, manifested superior stiffness retention capacity and strength retention capacity. The steel plate ratio ranging from 4.31% to 6.47% is proven to be appropriate and effective for maintaining high ductility and rotation deformability of the PRHTC coupling beams in this paper.