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As per British Standards, how much minimum overlap has to be given for a 32mm rebar and 20mm rebar? Both are present in columns.

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Question ajoutée par SREEJITH KUNNATHULLY , Sr. Landscape Engineer , Arcadis
Date de publication: 2016/08/02
Imran Ahmed
par Imran Ahmed , Manager-Planning & Delay Analyst , Nesma United Industries (NUI) Saudi Arabia

 

It depends on steel bars either in tension or compression.

To avoid this complication in various codes, normal pratice is take 50 times diameter of steel bars eighter in tension or compression. Overlap for 32mm rebar will be =32*50=1600mm or 1.6m

Overlap for 20mm rebar will be =20*50=1000mm or 1.0m. Better to reduce spacing of rings(strips), if ovelap is near the support in case of column or beam.Please refer to details mentioned below by Amercan Concrete Institute(ACI) and British Code (BS)

ACI 318:08 provisions for lap length

 

Lap length in tension

 

Section 12.15.1 of the ACI 318:08 specifies the tension

 

lap lengths for class A and class B splice as 1.0ld and

 

1.3ld respectively but not less than 300 mm. Section

 

12.15.2 of CAI318:08 specifies tension lap splice

 

condition. Since in practice class B splice condition is

 

more common it was considered in this research.

 

Lap length in compression

 

Section 12.16.1 of the ACI 318:08 specifies the compression

 

lap length as 0.071fydb for fy ≤ 420MPa and 0.13fy – 24

 

for fy > 420MPa but not less than 300 mm in both cases.

 

These values are applicable for 21 < fc’≤ 70 MPa (normal

 

strength concrete). For fc’≤ 21 MPa, lap length shall be

 

increased by one-third. 48 times diameter of steel bar.

 

BS 8110:97 provisions of lap lengths

 

Lap length in tension

 

As per section 3.12.8.13 of BS 8110:97; in general, the lap

 

length in tension = 1.0 times tension anchorage length.

 

Lap length in compression

 

Section 3.12.8.15 of BS 8110:97 specifies the lap length

 

in compression = 1.25 times compression anchorage

 

length.

 

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