Design Parameters for Vertical Bars (Concrete wall: EC2)

For some of the vertical bar parameters, additional user defined limits can be applied - where this is the case minimum and maximum values are specified in Design Settings > Concrete > Cast-in-place > Wall > Reinforcement Layout. These are considered in addition to the EC2 or NA recommendations.

Note:

In the following, the concrete area is the gross area of the general wall, or the gross area of the mid zone if one exists. For the end zone the design criteria for a reinforced concrete column element applies.

Reinforcement area for a wall

There are two NDPs which control the vertical reinforcement area¹

Limiting minimum ratio of vertical reinforcement area to gross concrete area, ρ_v,lim,min
Limiting maximum ratio of vertical reinforcement area to gross concrete area, ρ_v,lim,max

Total minimum area of vert reinforcement

A_s,min = ρ_v,lim,min * A_cg

Total maximum area of vert reinforcement

A_s,max = ρ_v,lim,max * A_cg

Where 2 layers are specified distributed equally to each face, this is a minimum of A_s,min / 2 placed at each face.

For design to the EC2 Recommendations, UK NA, Irish NA, Malaysian NA, Singapore NA and Norwegian NA the recommended values are;

ρ_v,lim,min = 0.002

ρ_v,lim,max = 0.04
For design to the Finnish NA the recommended values are;

ρ_v,lim,min = 0.002

ρ_v,lim,max = 0.06
For design to the Swedish NA the recommended values are;

ρ_v,lim,min = 0.001

ρ_v,lim,max = 0.04

You are given additional control over these values by specifying user limits for the minimum reinforcement ratio and maximum reinforcement ratio in Design Settings.

Code Requirement cl 9.6.1

For walls subjected to "predominantly out-of-plane bending", the minimum area rules for "slabs" apply if they are more critical than the above, [ cl 9.3 and reference to cl 9.2.1.1 (1) (2) and (3) ], so an additional check for any value of minor axis bending is applied.

For a wall this check is:

A_s,min = max [(2*0.26*f_ctm*l_wp*d/f_yk) , (2*0.0013*l_wp*d) , (ρ_v,min*A_cg)]

This applies for the general wall length, or the mid zone if it exists.

where

For a general wall panel length,

l_wp = l_w

Gross area of the wall, A_cg = l_w*h_w

For a mid zone panel length,

l_wp = l_mz

Gross area of the mid zone, A_cg,mz = l_mz*h_w

Effective depth of the cross section, d, is the dimension of the extreme concrete compression fibre to the centroid of reinforcement layer on the tension side, which for a wall is the line of the vertical reinforcement.

It does not apply for the end zones, since these are subject to the minimum reinforcement requirements as a column section.

Gross area of each end zone, A_cg,ez = l_ez*h_w

Length of each end zone, l_ez

Minimum Vertical Loose Bar Spacing

Clear distance between bars:²

s_cl,min ≥ max (k₁* maximum bar diameter, 20mm, d_g + k₂)

where d_g is the maximum aggregate size.

k₁ and k₂ are NDP values,

For design to EC2 Recommendations, UK NA, Irish NA, Malaysian NA, Singapore NA and Swedish NA;

k₁ = 1.0, and k₂ = 5 mm
For design to Finnish NA;

k₁ = 1.0, and k₂ = 3 mm
For design to Norwegian NA;

k₁ = 2.0, and k₂ = 5 mm

You are given additional control over the spacing by specifying a minimum clear spacing user limit in Design Settings.

Maximum Vertical Loose Bar Spacing

The limiting maximum vertical spacing, s_v,lim,max is an NDP.

For design to the EC2 Recommendations, UK NA, Irish NA, Malaysian NA, Singapore NA, Finnish NA, Norwegian NA and Swedish NA

s_v,lim,max = min (3*h_w , 400 mm)

You are given control over this value by specifying a maximum centre spacing user limit in Design Settings.

Footnotes