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Title: New Insights into Punching Shear under Impact Loading

Author(s): D. Z. Yankelevsky, V. R. Fledgun, and Y. S. Karinski

Publication: Symposium Paper

Volume: 357


Appears on pages(s): 62-76

Keywords: column-slab connection, dynamic response, flat slabs, impact, progressive collapse, punching shear, reinforced concrete, shear reinforcement

DOI: 10.14359/51738760

Date: 4/1/2023


An interim report reviewing several insights that have been gained in our ongoing research on punching shear capacity of RC flat slabs subjected to impact loads is presented. A typical RC building with flat slabs that is designed according to current standards is discussed. A collapse scenario of a top slab with failed connections is considered and its impact with a slab underneath is analyzed. The suitability of standards’ design criteria to provide safe design against punching shear is evaluated.

It was found that larger span slabs undergo heavier damage, therefore we focus on shorter span slabs to examine the lower bound damage. Falling from a floor height causes complete failure of the impacted slab-column connection. The slab around the column is severely damaged and the bending and shear reinforcement is ruptured. Rebars’ yield occurs within milliseconds from impact, while the impacted slab hardly starts its downward displacement. A major part of the impacted slab moves uniformly with severe damage concentration at the slab-column connection region.

The complex impact response of the slabs is analyzed, and new insights are gained. It demonstrates that the cur-rent static-loading based design standards cannot provide resilience to flat slab connections under impact load-ing and therefore cannot prevent a progressive collapse scenario.