A STUDY ON SEISMIC PERFORMANCE OF STEEL REINFORCED ULTRA-HIGH TOUGHNESS CEMENTITIOUS COMPOSITES SHORT COLUMNS

The ultra high toughness cementitious composites (UHTCC) material, with the super crack control ability, significant energy consumption and good anti-spalling property, has been applied to steel reinforced concrete (SRC) short columns as a replacement of plain concrete matrix. In this paper, seismic cyclic loading tests were carried out on seven steel reinforced UHTCC (SUHTCC) specimens and one reference steel reinforced concrete specimen. The main experimental parameters included the stirrup ratios, the axial load ratio and the arrangement of the studs on steel flange. Results show that the bond cracks and major shear cracks occurring in SRC columns may be effectively avoided or delayed with the use of UHTCC, and thus the brittle shear-bond failure mode in SRC specimen is well translated into the shear failure mode with improved ductility, resulting in a great improvement on post-earthquake integrality. For the SUHTCC specimens, the stirrup ratio shows less effect on shear capacity; however, maximum stirrup spacing should be ensured to delay the bond failure mode. Moreover, the SUHTCC specimens with higher stirrup ratios have better post-peak hysteretic curves, higher ultimate deformation and energy consumption. The axial load ratio shows little effect on seismic failure modes and mechanical performance of SUHTCC specimens. Large deformation capacity and high energy dissipation are obtained even under high axial load ratio. Compared with these SUHTCC specimens without studs, the SUHTCC specimens with studs exhibit better pre-peak hysteretic curves and much significant effect on pre-peak seismic behavior. However, after peak load, the SUHTCC specimens with studs encounter a quick failure, resulting in the decrease of ductility. At last, based on three different design codes, the shear capacity of the SUHTCC short columns was predicted. The applicability of current JGJ 138−2016 code was preliminarily verified. Besides, the shear deformation of SUHTCC short columns was analyzed quantitatively, and the influence of different parameters was also discussed. © 2023 Tsinghua University. All rights reserved.