Punching Shear (Shear Strength) Formula

Punching Shear (Shear Strength) and Its Calculation Formula

Introduction:

Punching shear, also known as shear strength, is a critical structural engineering parameter in reinforced concrete structures. It refers to the shear stress that occurs in the vicinity of columns or load-bearing elements where vertical loads are transferred horizontally to the slab or foundation. This article explores the concept of punching shear and presents the calculation formula used to assess it.

What is Punching Shear?

Punching shear is a phenomenon that arises when there is a concentrated load on a relatively small area of a slab or foundation. The concrete in this region is subjected to shear forces, which can lead to structural failure if not properly addressed in the design.

The Calculation Formula:

The formula used to calculate punching shear resistance is as follows:

V_u = (A_v * f_y) / s * √d * (1.0 + β₁ * √(d / x)) - (A_s * f_y)

Where:

• V_u: Punching shear resistance
• A_v: Cross-sectional area
• f_y: Yield strength of steel reinforcement
• s: Shear perimeter
• d: Effective depth or thickness of the slab or foundation
• x: Distance between the edge of the slab or foundation and the shear reinforcement
• β₁: Factor determined by design codes

Punching shear is a crucial consideration in the design of reinforced concrete structures. Proper calculation and evaluation of punching shear resistance are essential to ensure structural integrity and safety. Engineers use the provided formula along with design codes and standards to design structures that can withstand punching shear forces.