Title: Punching and post-punching response of slabs
Author(s): Denis Mitchell, William D. Cook
Publication: Symposium Paper
Appears on pages(s): 215-236
Keywords: Two-way slabs, punching shear, post-punching response, progressive collapse, structural integrity, deterioration, corrosion, delamination, codes
Factors influencing the punching shear resistance of two-way slabs are presented. Factors discussed include: construction errors; effects during construction; earthquake effects; deterioration of parking garage slabs; and design with older, deficient codes of practice. Experiments on the size effect are discussed and the provisions of the CSA Standard for the Design of Concrete Structures for the treatment of the size effect are presented. The provisions of the CSA Standard requiring structural integrity reinforcement in order to provide a secondary defense mechanism capable of preventing progressive collapse are explained. The results from experimental and analytical studies on the post-punching response of two-way slabs are described. The effects of deterioration of parking garage slabs subjected to chloride contamination and the provisions of the CSA Standard on Parking Structures to improve durability are discussed. The effects of delamination due to corrosion of the reinforcement in older parking structures are discussed and experimental studies on the effects of simulated delamination are presented. The progressive collapse in 2008 of an older parking structure in St-Laurent, Quebec, is described to illustrate some key factors influencing such a collapse.