Reinforcements for concrete structures
In civil construction reinforcement is a backbone of any concrete structures and we often not familiar to follow accurate guidelines of use this costliest item for durable structures. Reinforcement steel named rebar enhanced concrete strength with its tensile strength characteristics. Due to similar coefficient of thermal expansion with concrete, rebar massively using in concrete structures.
Type of reinforcements
Mostly used rebars in construction are hot rolled deformed /TMT(thermo mechanically treated) bar with ribs. During manufacture no torsional force applied in TMT bars so that it can resist surface defect by cut bend better than cold rolled twisted rebars.
Technical specifications for site use and follow up
Deformed bar with grade 6o/grade 420 with carbon content 0.3%
Cover of reinforcement clear cover 40mm,50mm,75mm.
All spliced consider as tension zone UNO.
As per ACI301,318 AND SP66 lap length to be generally between 34D to 48D
Bar spliced such a way that they are capable to develop 125% specified yield strength.
Non contact spliced to be 1/5 th of lap length or 150 mm whichever is less.
Lap length for different diameter rebars chose must be larger one between development length of larger bar and splice length of smaller bar
Lap not permitted for X40 and larger diameter.
For diameter more than X40 may use coupler in staggered manner to avoid congestion. And permissible to use where area is except fatigue sensitive.
Rebar with coating like epoxy or polymer lap length to be more than normal lap length.
Mesh to lapped two square and tie @900 mm c/c.
Development length of bars not less than 200mm(in compression)300mm (in tension).But compression lap shall not less than 300mm.
Cover of reinforcement clear cover 40mm,50mm,75mm.
All spliced consider as tension zone UNO.
As per ACI301,318 AND SP66 lap length to be generally between 34D to 48D
Bar spliced such a way that they are capable to develop 125% specified yield strength.
Non contact spliced to be 1/5 th of lap length or 150 mm whichever is less.
Lap length for different diameter rebars chose must be larger one between development length of larger bar and splice length of smaller bar
Lap must be staggered and to be in cranked 1:6.
Lap in bundle to be increased 20%,33% for 3 bars and 4 bars bundle respectively.Lap not permitted for X40 and larger diameter.
For diameter more than X40 may use coupler in staggered manner to avoid congestion. And permissible to use where area is except fatigue sensitive.
Rebar with coating like epoxy or polymer lap length to be more than normal lap length.
Mesh to lapped two square and tie @900 mm c/c.
Development length of bars not less than 200mm(in compression)300mm (in tension).But compression lap shall not less than 300mm.
Things to remember:
Concrete minimum cover must not less than dia of bars and spacing shouldn’t less than two times of dia of larger rebar.
Anchorage development length in compression to be 18.5D in general.
Development length will increase with rebar diameter increase. Development length reduce with increase of concrete class.
Concrete minimum cover must not less than dia of bars and spacing shouldn’t less than two times of dia of larger rebar.
Anchorage development length in compression to be 18.5D in general.
Development length will increase with rebar diameter increase. Development length reduce with increase of concrete class.
In opening area diagonal and additional trimmer bars to be provided with (Ld+Ld)=2Ld
Reinforcement detailing at construction joints must submitted by contractor each time prior to conduct pour.
No conduit to be fix with primary reinforcement. X16 dia rebar to be provide around conduit if no rebar showing in IFC drawing.
Anchorage development length in compression to be 18.5D in general.
Development length will increase with rebar diameter increase. Development length reduce with increase of concrete class.
Concrete minimum cover must not less than dia of bars and spacing shouldn’t less than two times of dia of larger rebar.
Anchorage development length in compression to be 18.5D in general.
Development length will increase with rebar diameter increase. Development length reduce with increase of concrete class.
In opening area diagonal and additional trimmer bars to be provided with (Ld+Ld)=2Ld
Reinforcement detailing at construction joints must submitted by contractor each time prior to conduct pour.
No conduit to be fix with primary reinforcement. X16 dia rebar to be provide around conduit if no rebar showing in IFC drawing.
Check points on delivery of rebars at site:
Rebar delivery tag must included with –
1.Bar size and length
2.Unit weight with grade of rebar
3.Manufacturer name
4.Mills certificate
5.Shop drawing and BBS
6.Coating details ;Powdered epoxy resin or polymer or others.For epoxy coating (180 +-50)micron film allowable.
Note:Coating of rebar procedures to be followed after removing dust, mill scale dirt etc. and shouldn’t lapsed more than 8hours after cleaning. In no cases reinforcement accepted if diameter of rebar reduce more than 5% of it’s diameter.
1.Bar size and length
2.Unit weight with grade of rebar
3.Manufacturer name
4.Mills certificate
5.Shop drawing and BBS
6.Coating details ;Powdered epoxy resin or polymer or others.For epoxy coating (180 +-50)micron film allowable.
Note:Coating of rebar procedures to be followed after removing dust, mill scale dirt etc. and shouldn’t lapsed more than 8hours after cleaning. In no cases reinforcement accepted if diameter of rebar reduce more than 5% of it’s diameter.
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