What is punching shear in concrete?
Punching Shear Basics Punching shear is a phenomenon where a concentrated force on a slab causes a shear failure cone that “punches” through. Punching shear calculations require a demand value and a capacity value.
How is punching shear reinforcement calculated?
Determine whether punching shear reinforcement is required, i.e. whether vEd > vRd,c at at successive perimeters to establish uout = the length of the perimeter where vEd = vRd,c. Perimeters within 1.5 d from uout need to be reinforced.
What is punching shear reinforcement?
The weight of a slab supported on a column induces shear stresses in the slab. These stresses, if sufficient and where additional reinforcement is not provided, would result in the column ‘punching’ through the slab.
How do you resist a punching shear in a flat slab?
It can be used to develop an analytical model for the punching shear failure analysis of reinforced concrete plates. Furthermore, it has been discovered that punching shear can be prevented by increasing the depth of the concrete floor slabs, or by increasing the diameter of the columns supporting the floor.
Why punching shear is provided?
This angle of inclination is called shear. In punching and blanking operations the shear is provided respectively on punch face and die face respectively because of the cutting action will occur accordingly. Shear reduces the punch load, acts gradually and it is always less than equal to the thickness of sheet metal.
What is punching shear in a RCC footing?
The punching shear is a failure mechanism in structural members like slabs and foundation by shear under the action of concentrated loads. The action of concentrated loads is on a smaller area in the structural members. In most cases, this reaction is the one from the column acting against the slab.
What is the critical section for punching shear?
critical section for the punching shear appears at a distance “d/2” to from the junction of the column with the footing in the two directions occurs in the rectangular section formed by the points 5, 6, 7 and 8, as shown in Fig. …
What is punching shear failure in soil?
The curve shows increase in resistance after failure. Punching Shear Failure – This type of failure occurs in loose sand or soft clay with relative density less than 35 %. In this type of failure, footing penetrates into the soil without any bulging in the soil at the surface.
What is punching shear failure in footing?
Punching shear failure of foundation occurs when there is a localized force acting on the structure. It is mostly found in foundations but also common in flat slabs. In punching failure of foundations, the column breaks through the foundation mat. In flat slabs, the failure occurs at the column head.
What are the methods of controlling punching shear in concrete slabs?
To overcome the punching failure problem, there are many ways to increase the punching shear strength of concrete slabs, increasing slab thickness in the area adjacent to the column, increasing column thickness which is against the architectural desire, and finally providing slab with shear reinforcement.