Structural Engineering and Mechanics

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Experimental study of punching shear in post-tensioned slabs with unbonded tendons

  • Choi, Seung-Ho (Department of Architectural Engineering, University of Seoul) ;
  • Hwang, Jin-Ha (Jeonnam and Jeju Branch, Korea Conformity Laboratories) ;
  • Han, Sun-Jin (Department of Architectural Engineering, University of Seoul) ;
  • Joo, Hyo-Eun (Department of Architectural Engineering, University of Seoul) ;
  • Kim, Jae-Hyun (Department of Architectural Engineering, University of Seoul) ;
  • Kim, Kang Su (Department of Architectural Engineering, University of Seoul)
  • Received : 2020.08.06
  • Accepted : 2021.07.19
  • Published : 2021.08.25
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Abstract

Post-tensioning in flat plate slabs provides the advantage of deflection and crack control under service loads, and can reduce slab thickness. However, due to the reduced slab thickness, post-tensioned flat plate slabs may be susceptible to punching shear failure under ultimate load. This study performed experimental research of the punching shear resistance of post-tensioned flat plate slabs with unbonded tendons. A total of four 3,100 mm square specimens of 150 mm thick slab were fabricated with the variables of average compressive stress in concrete, tendon layout, and aspect ratio of the column stub. Based on the test results, the load-deflection relationship, patterns of cracks, strains of flexural reinforcement, and force increments in tendons were compared. In addition, the equations for punching shear strength of unbonded post-tensioned flat plate slabs specified in the design codes (ACI 318, Eurocode 2, Model Code) were evaluated in detail.

Keywords

Acknowledgement

This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Education (No. NRF-2019R1A6A3A01091331).

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