Punching shear resistance of a lightweight concrete slab without shear reinforcement, v_lRd,c

The punching shear resistance of a slab should be assessed for the basic control section (see Figure 6.12). The punching shear resistance [MPa] of a lightweight concrete slab may be calculated as follows:

where:

η₁

is a coefficient for determining tensile strength of lightweight concrete

f_lck

is the characteristic compressive strength of lightweight concrete, see Table 11.3.1

k

= 1 + √200/d   ≤ 2,0
where d is the effective depth, in [mm]

ρ_l

is the reinforcement ratio for longitudinal reinforcement

σ_cp

= (σ_cy + σ_cz)/2,
where σ_cy, σ_cz are the normal concrete stresses in the critical section in y- and z- directions (in [MPa], positive if compression):
σ_cy = N_Ed,y / A_cy and σ_cy = N_Ed,z / A_cz
  N_Ed,y, N_Ed,y are the longitudinal forces across the full bay for internal columns and the longitudinal force across the control section for edge columns. The force may be from a load or prestressing action.
  A_cy, A_cz are the areas of concrete according to the definition of N_Ed,y, N_Ed,y respectively

C_lRd,c

is a Nationally Determined Parameter, see § 11.6.1 (1)

v_l,min

is a Nationally Determined Parameter, see § 11.6.1 (1), or the application for the calculation of v_l,min following the Eurocode recommendation

k₂

is a Nationally Determined Parameter, see § 11.6.4.1 (1).