doi:10.16186/j.cnki.1673-9787.2023070033

Received:2023-07-20

Revised:2023-10-07

Online Date:2023-11-30

Seismic performance of concrete square columns strengthened by UHPC with joints strengthened（Online）

WANG Qiang1,2, LIANG Xuhua2, LIU Xin2, ZHU Wanxu1,2, LU Chunling1,2

1.Guangxi Key Laboratory of Green Building Materials and Construction Industrialization， Guilin  541004， Guangxi， China；2.College of Civil and Architecture Engineering， Guilin University of Technology， Guilin  541004， Guangxi， China

Abstract:In order to solve the problem of debonding between ultra-high performance concrete（UHPC） and the base of reinforced concrete columns， a method of strengthening reinforced concrete square columns by UHPC with joints strengthened was proposed. To verify the effectiveness of this reinforcement method， four specimens were designed and fabricated. The seismic performance indicators such as ductility， energy dissipation and bearing capacity were analyzed for each specimen with different parameters including reinforcement and axial compression ratio. Results showed that the ductility coefficient and energy dissipation of strengthened columns increased by 15.6% and 76.4%， respectively， while the bearing capacity increased by 34.5%. The pinch effect of the reticulated curve of strengthened columns was also improved. With the increase of axial compression ratio， the bearing capacity of specimens showed an upward trend， but both ductility and energy dissipation declined. This is because the joints strengthened can increase the bonding stress between UHPC reinforcement layer and foundation base， allowing the UHPC reinforcement layer and the core concrete forced together. In addition， Cracking of concrete and buckling of longitudinal bars can be limited by the UHPC reinforcement layer. Finally， a calculation method for flexural bearing capacity of UHPC reinforced RC square columns based on plane section assumption was proposed. The calculated results are greater than 0.85 compared with the experimental results， showing high accuracy， which verifies the reasonableness of this calculation method. The research results could provide references for engineering application and design of UHPC reinforced RC square columns with joints strengthened.

Key words:joint strengthening;UHPC strengthening;RC square columns;seismic behavior;flexural bearing capacity

CLC：TU352.11;TU375.3