Experimental investigation of full-scale concrete columns confined by high-strength transverse reinforcement subjected to lateral cyclic loading

Abstract

The use of high-strength longitudinal and transverse reinforcements in confined concrete columns can improve bearing capacity and deformability. Besides, experiments on confined concrete columns with side length of 400 mm can better reflect the behaviour of confined concrete columns in engineering project. Thus, the purpose of this study is to investigate the seismic behaviour of full-scale confined concrete columns with high-strength longitudinal and transverse reinforcements. Based on 15 confined concrete columns subjected to lateral cyclic loading, the effects of axial compression ratio, shear span ratio and volumetric ratio on the seismic behaviour of confined concrete columns were studied. The results showed that the ultimate drift ratios of the 15 confined concrete columns ranged from 1/43 to 1/20, i.e. 1.2-2.5 times as much as the specified limit (1/50) of rate earthquake, indicating excellent ductility. Additionally, the high-strength transverse reinforcements could not yield at peak load but could yield at the ultimate displacement. The high-strength transverse reinforcement stresses at the peak lateral load were 430-690 MPa, approximately 56-91% of the transverse reinforcement yield strength. Finally, an empirical formula was proposed to predict the ductility factor that was then evaluated by comparing the predicted values with the experimental results of 37 confined concrete columns.

Review of studies on concrete columns confined by lateral reinforcement under axial compression and lateral cyclic loading

“…In 2020, Zheng 61 drew the similar conclusion by conducting test of 15 concrete columns confined by high‐strength lateral reinforcement subjected to lateral cyclic loading. Zheng 61 reported that the energy dissipation capacity increased with the increase in volumetric ratio.…”

“…As plotted in Figure 10, the shear bearing capacity of confined concrete column decreases with the increase in shear span ratio, while deformation capacity increases with the increase in shear span ratio. Zheng et al 61 reported that a high shear span ratio could improve the energy dissipation capacity and delay stiffness degradation. Moreover, Shi et al 80 illustrated that with shear span ratio not greater than 1, HSC columns were more prone to shear failure mode and damaged suddenly.…”

“…For confined concrete columns with high volumetric ratio, lateral reinforcement could provide strong confining pressure on core concrete, and effective confined concrete area is increased, leading to increasing effective confinement of core concrete 99 . Additionally, confined concrete columns with high volumetric ratio exhibit high energy dissipation capacity and delay stiffness degradation 49,52,61,100 …”

“…99 Additionally, confined concrete columns with high volumetric ratio exhibit high energy dissipation capacity and delay stiffness degradation. 49,52,61,100 As plotted in Figure 13, the lateral reinforcement yield strength has little effect on shear bearing capacity of confined concrete columns, but high-strength lateral reinforcement can effectively improve deformation capacity of confined concrete columns. The main reason is that high-strength lateral reinforcement may not reach its yield strength when specimens approached maximum lateral loading.…”

“…5,7,8 Similar to the studies on the concrete columns confined by lateral reinforcements under axial compression, the studies first focused on the mechanical performance of normal-strength concrete columns confined by normal-strength lateral reinforcements under lateral cyclic loading, [39][40][41][42][43][44][45][46][47][48] then subsequent research efforts transferred to the behavior of HSC columns confined by high-strength lateral reinforcements. 3,[49][50][51][52][53][54][55][56][57][58][59][60][61] The content of those studies mainly concentrated on compressionflexure calculation, 56,62,63 shear bearing capacity calculation, 41,53,58,[64][65][66] ductility and energy dissipation capacity, 3,52,60,61,[67][68][69][70] development of lateral reinforcement strain, 47,48,…”