Precast boundary wall 200mm thick(Reinforcement mesh double layer or single?)
Precast boundary wall 200mm thick(Reinforcement mesh double layer or single?)
(OP)
Hello everyone
I have a boundary wall panel 200mm thick(6.2m L x 4.5m H) with outside elevation having 50mm recess covering 70% of panels elevation. Its subjected to wind pressure of 1.0 kN/m2 laterally(which can be from both direction) front and back. Can I use single wire mesh in the middle or have to provide two layer wire mesh for flexure due to wind. Is there any restriction on this in BS8110 or ACI 318, that upto certain wall thickness single layer to be used or double layer to be used? Thanks.
*Note that if I use single layer d = 100mm from back elevation and d = 50mm in front elevation.
I have a boundary wall panel 200mm thick(6.2m L x 4.5m H) with outside elevation having 50mm recess covering 70% of panels elevation. Its subjected to wind pressure of 1.0 kN/m2 laterally(which can be from both direction) front and back. Can I use single wire mesh in the middle or have to provide two layer wire mesh for flexure due to wind. Is there any restriction on this in BS8110 or ACI 318, that upto certain wall thickness single layer to be used or double layer to be used? Thanks.
*Note that if I use single layer d = 100mm from back elevation and d = 50mm in front elevation.






RE: Precast boundary wall 200mm thick(Reinforcement mesh double layer or single?)
RE: Precast boundary wall 200mm thick(Reinforcement mesh double layer or single?)
RE: Precast boundary wall 200mm thick(Reinforcement mesh double layer or single?)
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RE: Precast boundary wall 200mm thick(Reinforcement mesh double layer or single?)
RE: Precast boundary wall 200mm thick(Reinforcement mesh double layer or single?)
RE: Precast boundary wall 200mm thick(Reinforcement mesh double layer or single?)
According to BS 8110-1997 [23], the width of flexural cracks at a particular point on the surface of a member depends primarily on three factors:
(a)The proximity to the point considered of reinforcing bars perpendicular to the cracks; concrete cover.
(b)The proximity of the neutral axis to the point considered; h–x.
(c)The average surface strain at the point considered.
BS 8110-1997 recommends that the strain in the tension reinforcement is limited to 0.8 fy/Es (i.e. 0.8 * steel yield strain) and the design surface crack width should not exceed the appropriate value. Cracking should not lead to spoil appearance. So for members that are visible, the calculated maximum crack width should not exceed 0.30 mm. Also, cracking should not lead to steel corrosion, so for members in aggressive environment the calculated maximum crack width should not lead to a loss of the performance of the structure.
BS 8110-97 provisions are based on Beeby [12] empirical equations,
equation(10)
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where acr = distance from the point considered to the surface of the nearest longitudinal bar; εm = average strain at the level where the cracking is being considered; cmin = minimum cover to the tension steel; h = overall depth of the member; x = depth of neutral axis.
For cracked section, the value of εm is expressed as:
equation(11)
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where ε1 = strain at the level considered, calculated ignoring the stiffening effect of the concrete in the tension zone, b = width of the section at the centroid of the tension steel, a′ = distance from the compression face to the point at which the crack width is being calculated.
According to BS 8110-1997 [23], in assessing the strains, the modulus of elasticity of the concrete should be taken as half the instantaneous values.
RE: Precast boundary wall 200mm thick(Reinforcement mesh double layer or single?)
RE: Precast boundary wall 200mm thick(Reinforcement mesh double layer or single?)