Some useful tip on placing of Reinforcement

Reinforcement should be perfectly arranged and sufficiently supported prior to placing of concrete as well as safeguarded against displacement within allowable tolerances which are given below.

The tolerances, given below, should be maintained while placing reinforcement unless otherwise mentioned by the engineer:

(a) Tolerances for depth d, and minimum concrete cover in flexural members, walls and compression members should be as follow :-

Tolerances for Placing Reinforcement

Tolerance for d - Tolerance for Minimum Concrete Cover

d ≤ 200 mm ±10 mm –10 mm
d > 200 mm ±13 mm –13 mm

(b) Regardless the provision of (a) above, tolerance for the clear distance to formed soffits should be minus 6 mm and tolerance for cover should not be in excess of minus 1/3 the minimum concrete cover stated in the design drawings or specifications.

(c) Tolerance for longitudinal location of bends and ends of reinforcement should be ± 50 mm, excluding at discontinuous ends of brackets and corbels, where tolerance should be ± 13 mm and at discontinuous ends of other members, where tolerance should be ±25 mm. The tolerance for concrete cover should also be used in discontinuous ends of members.

Welded wire reinforcement (with wire size not more than MW30 or MD30) applied in slabs not over and above 3 m in span should be allowed to be curved from a point adjacent to the top of slab over the support to a point near the bottom of slab at midspan, in case such reinforcement is either continuous over, or securely anchored at support.

Welding of crossing bars should not be allowed for assembly of reinforcement unless the concerned engineer approve.

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Published By
Rajib Dey
www.constructioncost.co
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Reinforcing Of Shear Wall

The boundary elements, whether regular or hidden, are reinforced based on the rules which are assigned to columns.

For reinforcing of the wall body, there are two parallel grates (known as curtains) one at each face. They are retained collectively through an ‘S’-shaped vertical bar. The vertical and horizontal grate rebars should contain a diameter at least identical to Ø8 .The reinforcement with “S” shape must be higher or equivalent to 4Φ8/m2

To avoid cracked surfaces e.g. in pool sides, narrow spaced grates should be applied having the lower possible rebar diameter.

To avoid cracked surfaces e.g. in pool sides, narrow spaced grates should be applied having the lower possible rebar diameter.

The ‘S’- shaped reinforcement

The ‘S’-shaped bar offers anti-buckling restraint to the longitudinal reinforcement. Besides, it makes sure that the vertical and the horizontal rebars will progress work jointly regardless of a potential concrete spalling that may occur due to an strong earthquake.

The ‘S’-shaped link is developed with one closed corner at an angle similar to 180°, or 135° and the other corner bent at an angle equivalent to 90°. This is crucial for positioning it without any difficulty. Once it is applied, the second corner must be also bent at an angle at least equivalent to 135°.

It is acceptable to apply soft steel to have the ability to bent the ‘S’-shaped reinforcement manually.

If the vertical rebars are positoned in an interior layer, then the ‘S’-shaped link must detain the horizontal rebars to the region that they bisect with the vertical ones or get around both horizontal and vertical rebars simultaneously.

On the other hand, in an rectangular shear wall, the reinforcement of the boundary column and the distribution rebars of the wall’s body is carried out as two ‘Γ’ shaped parts. Folded mesh is applied to develop the ‘Γ’ shaped parts.

Ref : debug.pi.gr

Image Courtesy - debug.pi.gr

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Published By

Rajib Dey

www.constructioncost.co

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