Abstract
Simplified closed-form equations are commonly used in structural design to prevent punching shear failures of concrete flat slabs supported on columns in permanent and transient situations, whereas more advanced methods are generally used in verifications at accidental design situations due to the lack of suitable equivalent approaches. Following this gap in practice, the present paper shows the analytical derivation of new closed-form design expressions for dynamic punching shear for the case of notional sudden column removal. The design approach reduces the probability of propagation of damage to adjacent columns after the loss of a column and prevents accidental events to result in disproportionate consequences or even collapse of the whole structure. The new design equations are fully compatible with the punching equations in EN1992-1-1:2023 in terms of format, parameters used, modes of failure considered and partial safety factors. In addition, this formulation provides identical expressions to the code if dynamic effects and resistance reduction after column removal are ignored. The derivation is based on the analytical dynamic punching model previously developed by the authors, which adopts the widely accepted Critical Shear Crack Theory for punching shear under quasi-static loading, incorporating also energy balance principles. The closed-form expressions are validated using existing experimental data and new field data provided in this paper corresponding to the Nueva Montaña car park collapse in Spain, demonstrating the validity and applicability of the method even in cases when multiple columns are suddenly removed.