What type of failure occurs when a floor slab experiences excessive loads near columns?

The failure that occurs when a floor slab experiences excessive loads near columns is known as punching shear failure. This type of failure is particularly relevant in slabs supported by columns, where the area around the column is subjected to high localized stresses due to the transfer of loads.

In the case of punching shear failure, the slab tends to fail around the column in a cone or cylinder shape because the concentrated load from the column overpowers the surrounding concrete's ability to resist that load. Essentially, the slab punches downward through the supporting area around the column. This failure mode is critical to consider during design because inadequate reinforcement or insufficient slab thickness can lead to this serious and often sudden failure, especially under heavy loads or in heavily-loaded structures.

Understanding this phenomenon is vital for ensuring the safety and integrity of reinforced concrete structures, especially in high-load applications such as in parking garages or multi-story buildings where load transfer to columns is significant. Proper design measures, such as using thicker slabs or providing additional reinforcement around columns, can help mitigate the risk of punching shear failure.