# Punching Shear Design

**What is punching Shear?**

Punching shear arises when a concentrated load is applied to a small area of a slab or, most commonly, the reaction of a column against a slab. The resulting stresses are verified along defined control perimeters around the loaded area.

Punching Shear is checked automatically in accordance with

*Codes.*

**International Design Codes**

* ACI 318-19 : *Punching Shear Design per ACI 318-19 with ideCAD

* TSC 2018 : *Punching Shear Stress at Critical Section (7.11.8) (8.3.1) TS500 Puching Shear Design Conditions

**Notation in ACI 318-19**

* A_{g }= *gross area of the concrete section, in

^{2}

**A**_{s}**area of non-prestressed longitudinal tension reinforcement, in**

_{ }=^{2}

*perimeter of critical section for two-way shear in slabs and footings.*

**b**_{o}=*effective slab width, in.*

**b**_{slab}=*dimension of the critical section*

**b**_{1 }=*measured in the direction of the span for which moments are determined.*

**b**_{o}*dimension of the critical section*

**b**_{2 }=*measured in the direction perpendicular to*

**b**_{o}*, in.*

**b**_{1}*distance from extreme compression fiber to centroid of longitudinal tension reinforcement, in.*

**d =***modulus of elasticity of concrete, psi*

**E**_{c }=*modulus of elasticity of reinforcement, psi*

**E**_{s }=

**√f**_{c}‘*square root of specified compressive strength of concrete, psi*

**=***specified compressive strength of concrete, psi*

**f**_{c}^{'}_{ }=*specified yield strength for non-prestressed reinforcement, psi*

**f**_{y }=*property of assumed critical section analogous to the polar moment of inertia*

**J**_{c }=*factored slab moment that is resisted by the column at a joint, in.-lb*

**M**_{sc}=*stress corresponding to nominal two-way shear strength provided by concrete, psi*

**v**_{c }=*factored shear stress on the slab critical section for two-way action, from the controlling load combination, without moment transfer, psi*

**v**_{uv }=*constant used to calculate*

**α**_{s }=*in slabs and footings*

**V**_{c}*strength reduction factor*

**ϕ =***= modification factor to reflect the reduced mechanical properties of lightweight concrete relative to normalweight concrete of the same compressive strength*

**λ***= factor used to modify shear strength based on the effects of member depth, commonly referred to as the size effect factor*

**λ**_{s}*net tensile strain in an extreme layer of longitudinal tension reinforcement at nominal strength, excluding strains due to effective prestress, creep, shrinkage, and temperature*

**ε**_{t }=*value of net tensile strain in the extreme layer of longitudinal tension reinforcement used to define a compression-controlled section*

**ε**_{ty }=*= factor used to determine the fraction of*

**γ**_{f}*transferred by slab flexure at slab-column connections*

**M**_{sc}*= factor used to determine the fraction of*

**γ**_{v}*transferred by the eccentricity of shear at slab-column connections*

**M**_{sc}**Download ideCAD for ACI 318-19**