Influence of prestressing on the punching strength of post-tensioned slabs

Previous researches on punching of post-tensioned slabs have shown a number of phenomena significantly influencing their strength and behaviour. However, no general agreement is yet found on a physical theory (either in codes of practice or in design models) suitably describing the influence of prestressing and how should it be accounted on the punching shear behaviour. In this paper, the authors present the results of tests on 15 slabs (3000 x 3000 x 250 mm) tested to failure under different loading conditions. The aim of the tests was to investigate in a separate manner the different actions induced by prestressing on the punching shear strength (in-plane forces, bending moments and bonded tendons). These results are finally investigated on the basis of the physical model of the Critical Shear Crack Theory. The fundamentals of this theory are presented and adapted to post-tensioned slabs, providing a rational explanation of the observed phenomena and measured strengths. (C) 2014 Elsevier Ltd. All rights reserved.

[1]  Ghassem Hassanzadeh.  Betongplattor på pelare : dimensioneringsmetoder för plattor med icke vidhäftande spännarmering , 1998 .

[2]  Aurelio Muttoni,et al.  The levels‐of‐approximation approach in MC 2010: application to punching shear provisions , 2012 .

[3]  Aurelio Muttoni,et al.  Background to fib Model Code 2010 shear provisions – part II: punching shear , 2013 .

[4]  Aurelio Muttoni,et al.  Punching Tests of Slabs with Low Reinforcement Ratios. Paper by Stefano Guadalini, Oliver Burdet, and , 2009 .

[5]  Aurelio Muttoni,et al.  Effect of load distribution and variable depth on shear resistance of slender beams without stirrups , 2012 .

[6]  Aurelio Muttoni,et al.  Non-axis-symmetrical punching shear around internal columns of RC slabs without transverse reinforcement , 2011 .

[7]  Aurelio Muttoni,et al.  Punching shear strength of reinforced concrete slabs without transverse reinforcement , 2008 .

[8]  Aurelio Muttoni,et al.  Post-Punching Behavior of Flat Slabs , 2013 .

[9]  Valter José da Guia Lúcio,et al.  Punching of flat slabs with in-plane forces , 2011 .

[10]  Aurelio Muttoni,et al.  Shear Strength of Members without Transverse Reinforcement as Function of Critical Shear Crack Width , 2008 .

[11]  Aurelio Muttoni,et al.  Applications of Critical Shear Crack Theory to Punching of Reinforced Concrete Slabs with Transverse Reinforcement , 2009 .

[12]  Aurelio Muttoni,et al.  Influence of Shear on Rotation Capacity of Reinforced Concrete Members Without Shear Reinforcement , 2010 .

[13]  Aurelio Muttoni,et al.  Punching shear strength of steel fibre reinforced concrete slabs , 2012 .

[14]  José Luiz Pinheiro Melges.  Análise experimental da punção em lajes de concreto armado e protendido , 2001 .

[15]  S. Kinnunen,et al.  Punching of concrete slabs without shear reinforcement , 1960 .

[16]  Aurelio Muttoni,et al.  Design for punching of prestressed concrete slabs , 2013 .

[17]  Paul E. Regan,et al.  Punching resistances of unbonded post-tensioned slabs by decompression methods , 2005 .