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RECALIBRATION AND OPTIMIZATION OF PUNCHING SHEAR FORMULAS IN CODES AND GUIDELINES
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Volume Title: ICASGE2017
DOI: ICASGE-RCS
Authors
Abstract
Reinforced concrete plates exhibit complexities – most importantly punching shear - in their structural behavior. This is due to the composite nature of the materials and factors affecting such behavior; namely concrete compressive strength fcu, flexural reinforcement ratio ρ and its yielding strength fy , effective slab depth d, and the effective perimeter bo (a function of the column geometry and slab depth). Many models have been developed – to calculate the punching shear capacity of the slab-column connection; existing in codes and guidelines as well as in earlier studies of specialized researchers; mostly empirical models. In this regards, a total of 495 punching shear sample results was collected from earlier studies. In this study, the data-set is used to compare between the already existing major formulas in international codes as well as research efforts; in terms of accuracy and using a variety of statistical inferences/indicators. The coefficients of these models are thus re-calibrated (optimized using the Matlab optimization toolbox); giving – in certain cases – a significant enhancement to the model performance. A new empirical equation is proposed, yielding excellent performance (minimum sum square error); considering the 495 samples. This paper also includes a parametric study for the punching shear input parameters and their significance as regards the output punching shear capacity of the slab-column interior connections. The compressive strength fcu showed highest significance whereas the yielding strength fy demonstrated the least significance; omitting the latter yielded a dramatic enhancement to the model of best performance.
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