Distinguished punching shear behaviour of unbonded post-tensioned concrete slab – CFT column vs reinforced concrete slab – CFT column connections

  • Binh Luu-Thanh Faculty of Civil Engineering, Ho Chi Minh City University of Technology (HCMUT), 268 Ly Thuong Kiet Street, District 10, Ho Chi Minh City, Vietnam
  • Long Nguyen-Minh Faculty of Civil Engineering, Ho Chi Minh City University of Technology (HCMUT), 268 Ly Thuong Kiet Street, District 10, Ho Chi Minh City, Vietnam
  • Takayuki Namba Civil & Infrastructure Engineering Research Department, JFE Steel Corporation, Japan
  • Kei Nakagawa Planning & Marketing Department, JFE Steel Corporation, Japan
  • Koji Oki Construction Materials Engineering Department, JFE Steel Corporation, Japan
  • Cuong Ngo-Huu Faculty of Civil Engineering, Ho Chi Minh City University of Technology (HCMUT), 268 Ly Thuong Kiet Street, District 10, Ho Chi Minh City, Vietnam
Keywords: unbonded post-tensioned concrete (UPC), connection/joint, CFT column, flat slab, connection details, punching shear, experiment

Abstract

This article evaluates and compares the punching shear behaviour of unbonded prestressed concrete (UPC) slab - concrete-filled steel tube (CFT) column connections/joints with that of reinforced concrete (RC) slab connection – CFT column connections. The experimental program was carried out on five large-sized samples, including three UPC slab - CFT column samples and two RC slab - CFT column samples. Steel plate connection details were utilised to increase the bond between the concrete slab and the CFT column. The experimental results showed that the prestressing tendons significantly increased the pre and post-cracking stiffness of the slab-column connections, thereby, greatly reducing the deflection of the UPC slab - CFT column samples than that of the RC slab - CFT column samples, especially during the serviceability phase (by up to 58%). However, the use of tendons resulted in a significant decrease in the ductility and energy absorption index of the UPC slab - CFT column samples compared to that of the RC slab - CFT column samples (by up to 44% and 41%, respectively). Using prestressing tendons slightly increased the punching shear capacity, and significantly reduced the strain of the connection details such as the vertical ribs and the horizontal bearing plate. At the same time, the tendons helped greatly reduce the strain of the longitudinal rebars in the UPC slabs.

Keywords: Unbonded post-tensioned concrete (UPC); connection/joint; CFT column; flat slab; connection details; punching shear; experiment.

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Published
29-06-2022
How to Cite
Luu-Thanh, B., Nguyen-Minh, L., Namba, T., Nakagawa, K., Oki, K., & Ngo-Huu, C. (2022). Distinguished punching shear behaviour of unbonded post-tensioned concrete slab – CFT column vs reinforced concrete slab – CFT column connections. Journal of Science and Technology in Civil Engineering (STCE) - HUCE, 16(3), 29-45. https://doi.org/10.31814/stce.huce(nuce)2022-16(3)-03
Section
Research Papers