Contribution of concrete and shear reinforcement to the punching shear resistance of column bases. (15th October 2021)

• Record Type: Journal Article
• Authors: Schmidt, Philipp; Ungermann, Jan; Hegger, Josef
• Is Part Of: Engineering structures. Volume 245(2021)
• Publication Date: 2021-10-15
• Subjects: Reinforced concrete -- Punching -- Shear reinforcement -- Activation -- Stirrup -- Column base -- Concrete contribution -- Steel contribution -- Eurocode 2 -- Model Code 2010; Structural engineering -- Periodicals; Structural analysis (Engineering) -- Periodicals; Construction, Technique de la -- Périodiques; Génie parasismique -- Périodiques; Pression du vent -- Périodiques; Earthquake engineering; Structural engineering; Wind-pressure; Periodicals; 624.105
• DOI: 10.1016/j.engstruct.2021.112901
• Languages: English
• ISSNs: 0141-0296

Abstract

Highlights: A comparison of current punching design provisions reveals major differences. Systematic punching tests are used to determine the concrete and steel contribution. In shear-reinforced column bases, a decreasing concrete contribution is observed. A high degree of activation of the shear reinforcement (~0.8∙fyw ) is identified. A 'suspension' strut-and-tie model with variable concrete contribution is suggested. The next generation of Eurocode 2 provides the most progressive design results. Abstract: The punching shear capacity of reinforced concrete flat slabs and column bases without shear reinforcement as well as with failure on the level of maximum punching strength has been analyzed extensively in the past. For shear-reinforced slabs, most punching shear models follow an additive approach assuming a combination of a contribution of concrete and a contribution of shear reinforcement (steel contribution). However, a systematic evaluation of concrete and steel contributions depending on the amount of shear reinforcement has not yet been adequately possible since only a few test series with low and medium amounts of shear reinforcement investigating the failure within the shear-reinforced zone have been available. In this paper, the development of concrete and steel contributions in shear-reinforced column bases is investigated in detail based on eleven punching tests with systematically varying shear reinforcement ratios. Significant differences between various punching design approaches regarding the interaction of concrete and steel contributions are revealed and a new method for evaluation is presented. The development of both contributions depending on the amount of shear reinforcement is discussed and compared to the design provisions according to Eurocode 2, Model Code 2010 and the draft for the next generation of Eurocode 2 which has been undergoing an optimization process in recent years.