ReinforcementSteel Do SandDonts

AN ISO 9001 COMPANY

GAMMON INDIA LIMITED Bui l ders t o t he nat natii ons

REVISION: 0

JUNE 2004

REINFORCEMENT STEEL -

DO’S AND DON’TS

PREAMBLE

In reinforced/pre-stressed concrete structures, cost of reinforcement steel constitute a sizable portion varying varying from 15% 15% to 25% of of contract value. value. Because of such such a huge share of contract value in terms terms of cost, there there is a dire need need to streamline streamline and exercis exercisee effective control on all activities related to reinforcement steel viz. planning, indenting, indenting, ordering, procurement, inventory management, storage, utilization, measurements, reconciliation etc. With a view to improve efficiency in the management of reinforcement related activities at site, the enclosed guidelines guidelines are prepared. prepared. These guidelines are presented in the form of simple Do’s and Don’ts. Some of the guidelines which are most important are highlighted in colour. The scope of these guidelines is restricted to reinforcement related activities performed at site and excludes design related issues of reinforcement.

REINFORCEMENT STEEL - DO’S AND DON’TS

1) M A N N I N G OF RE I N F O RCE M E N T A CT I V I T I E S   Ø

 Nominate one Engineer (Sr.Engineer/Asst.Engineer) as overall In-charge for manning Reinforcement related activities at site, who can be assisted by deputy(ies) as required depending upon size of the project.

2)  CONTRACT SPECIF I CATI ONS & CONDI TI ONS Ø

Ø

Ø Ø

Ø

3) Ø

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Study contract documents thoroughly as regards technical specifications of reinforcement and other relevant provisions like responsibility for preparation of Bar Bending schedule (BBS) etc. Study provisions regarding mode of measurements for payment in an item rate contract and also composite BOQ item, if any, like R.C. crash barrier payable in m inclusive of reinforcement steel. Examine payability or otherwise for laps, chairs and spacers. Arrange for latest codes referred to in the contract as regards technical specifications and mode of measurements etc. and maintain the upto date versions of the same in site library for study by all Engineers. Critically study tender drawings .

PLAN NI NG AND SCHEDUL I NG Based on BOQ (or estimated quantities in case of L.S. Contract), preliminary drawi ngs and construction programme; draw category wise and diameter wise procurement schedule (monthly/quarterly) for reinforcement steel together with corresponding accessories like binding wire, cover blocks, splices etc. If preliminary drawings not available, obtain diameterwise quantities of reinforcement steel from designer.  Normally allow for inventory of 45 days for the purpose of planning. While informing overall requirement to Corporate office, give only 90% of total requirement (and not 100%) to take care of possible variations arising due to future revisions of drawings or change in scope of work etc.

4) I NF RASTRUCTURE Ø Ø Ø Ø Ø Ø Ø

Ø Ø

Locate reinforcement yard at suitable location keeping logistics in view and in such a way that main site thoroughfare does not run through the yard. Provide one centralized reinforcement yard except when project is spread over a long stretch. Provide separate yards for raw steel, for cut and bent steel and for scrap steel. Fence all yards suitably restricting truck/trailor entry/exit at one point with lockable gate and a security guard. Yards should be spacious and well laid and well organized duly considering proper maneuverability of trucks/trailors. Provide suitable internal roads so that trucks/ trailors reach farthest unloading point in yard. Plan location of cuttings/bending machine or bench of manual bending parallel to reinforcement stack to avoid infructuous rotation of long reinforcement bars in horizontal  plane. Maintain register for Entry and Exit of vehicles duly noting registration number of vehicles and time of Entry and Exit. Within the fenced yard, install electronic weigh bridge of adequate capacity and length which should be in a position to generate untemperable computer o utputs with in-built clock.

5) ORDERI NG REI NF ORCEM ENT STEEL Ø

Ø Ø Ø Ø Ø Ø Ø Ø

Apart from giving overall phasewise requirement, submit indents for quarterly requirements to Corporate office at least 30 days in advance giving specifications, grade of reinforcement steel etc. Specify required supply length for each diameter in Purchase Order rather than accepting random lengths. Specify preference to nearly zero rolling margin. Prefer to receive reinforcement in straight length rather than with ‘U’ bends. Encourage transportation by high capacity long length trailors. Insist for manufacturer’s Test certificate with each lot. In case smaller diameter bars are continuously receive d in coils, provide decoiling machine at site Specify maximum coil weight from view point of ease in unloading with available means. Avoid excessive inventories of reinforcement steel.

Ø

Ø Ø

Ø Ø

In coastal and corrosive environment, bring reinforcement on Just-in-time basis to avoid excessive oxidation loss arising from long term storage at site or apply coat of cement wash, if long term storage is inevitable. Exercise strict diameter wise control on indenting and ordering of reinforcement. Study copy of Purchase Order issued by Corporate office, communicate to corporate office, if any amendment needed and give delivery schedule to supplier, if not specified in order. During last phase of project towards completion stage, take extra care in indenting and ordering reinforcement to avoid surplus quant ities. Order ready made cut and bent steel wherever such facilities available like in metropolitan cities.

6) RECEI VI NG REIN F ORCEMEN T STEEL Ø Ø Ø Ø Ø

Ø Ø Ø Ø Ø Ø Ø Ø Ø

 Notify receiving time slot of working hours for reinforcement as ‘bet ween sunrise and sunset’ and strictly adhere to the same. Visually carefully inspect reinforcement for excessive corrosion, scaling, pitting etc.  before acceptance. Check type and grade of reinforcement steel. Accept reinforcement steel only after weighing and don’t acknowledge weight shown in delivery challan without physically verifying weight on a weigh bridge. In case where weigh bridge is not installed, weigh at nearest ‘Dharam Kanta’ by sending a representative on receiving telephonic call from driver rather than redirecting the truck from site for weighing. After weighing do not leave truck unescorted. Weigh not only loaded truck/trailer but also verify tare weight. Guard against intentional manipulation between two weighments in loaded and unloaded conditions. File weigh bridge slips in a separate file. Insist that apart from weight, number of bars are also mentioned in delivery challan and verify the same by counting as an additional check. Take random samples and establish actual unit weights. Keep records of rolling margin supplier wise and diameter wise for each lot. Send supplier wise and diameter wise details of Rolling margin to Corporate office monthly, both for the month and on cumulative basis. Retain samples for verification by supplier till acceptance of Rolling margin values by them

Ø Ø Ø Ø Ø Ø Ø

In case reinforcement is issued by clients, take observations jointly and submit the joint records of rolling margin to the clients every month. Stock reinforcement steel separately diameter wise off the ground on suitable elevated unyielding pedestals (at least 150 mm above ground level). Plan storage of reinforcement keeping in view retrieval sequence and also in such a way that various sizes and lengths can be quickly and easily identified. Put tags of diameter, weight, batch no. etc. Unload reinforcement preferably by mechanical means like small gantry. Don’t tip tipper to unload reinforcement. Don’t handle reinforcement roughly, don’t drop from a height and don’t subject it to shock or impact and avoid accidental damage or notches causing decrease in section.

7) STORA GE Ø Ø Ø Ø Ø Ø Ø

Provide a loose protective cover like PVC sheets over the reinforcement all around including sides (Refer Appendix – K). Ensure good air circulation around the steel Provide security on 24 x 7 basis. Periodically (but at random) have surprise pre-dawn checks made to ascertain alertness of security guards and levy penalty on found sleeping while on duty. Issue steel on FIRST-IN-FIRST-OUT basis to mini mize oxidation loss. Keep record of all the steel issued from storage yard and shifted to cutting and bending yard. In case of unlikely event of theft, lodge FIR immediately and register claim with Insurance Company.

8) CEM ENT POL YM ER COM POSI TE COATI NG TREATMENT  Ø Ø Ø Ø Ø

Avoid sand blasting, if reinforcement lot is fresh. As far as possible treat reinforcement after cutting operation to avoid infructuous treatment on scrap component. Measure thickness of coating with alchometer regularly. Handle treated reinforcement with care to avoid damage to treatment. Touch up damage to treated reinforcement, if any, before concreting.

9) F USI ON BONDED EPOXY COATED REIN F ORCEME NT  Ø Ø Ø Ø Ø

If possible from logistic point of view, coat reinforcement after cutting to avoid infructuous coating on scrap component. Handle coated reinforcement with care to avoid damage to coating. Check for holidays and damage to reinforcement and touch-up the same before concreting. Touch up cut ends of coated bars. While mechanical lifting use nylon or padded slings.

10) CONSUM PTI ON F OR PERM ANE NT WORKS Ø Ø Ø Ø Ø Ø Ø

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Ø Ø Ø

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Critically study latest version of approved construction drawings and check for errors and inconsistencies. Examine fixability of reinforcement and its effect on construction sequence and consult designer, if fixability is poor. Prepare Bar Bending Schedule (BBS) preferably in A4 size sheets, if not provided in drawings and obtain consultant’s approval. Ensure BBS is simple, self-explanatory and easy to read even for fitters. Use computer for preparing BBS Plan intelligent cutting from full length bars by preparing cutting schedule rather than leaving to PRW labours. For 90 degree bends, work out bend effect at 3D for diameters upto and including 25mm and 4D for diameter above 25 mm and accordingly reduce cut length. (Refer IS: 2502 – 1963 and Appendix – ‘E’). Cut bars to exact length preferably with negative tolerance (within permissible limits) but never with positive tolerance.

Answer queries of fitters and resolve problems, if required by consulting designer. Check the bent shapes for dimensional accuracy including bend radii against a full scale template. Make available specimen bars in required cut lengths and shapes duly cut and bent in  presence of an Engineer/Foreman and use same subsequently for comparison with  production. Don’t rebend, reshape or straighten reinforcement. If bending and rebending unavoidable, ensure bending radius not less than 4 D for M.S. Bars and 6 D for deformed bars. If some bars are temporarily diverted or bent for construction requirements, ensure these are properly brought back to its original position. Use tractor trailer or hand cart etc. for internal shiftings of reinforcement steel depending upon lead involve d. Handle bundles of bars, if required using mechanical aids rather than handling one bar at a time individually. Avoid manual shifting. If unavoidable use, unskilled labour (and not fitters) for shifting. Unload cut and bent steel as near to final location as possible.

Ø Ø Ø

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Stagger laps but don’t follow stringent instructions of liberal staggering and avoid excessive laps on this count. Insist for open stirrups and links in case of complex structural members for ease in adjustments of cages. As a rule, provide minimum number of laps - more so, if nonpayable e.g. prepare cage of pile reinforcement preferably with one full ength bar or at the most with one overlap depending upon depth of pile. Wherever possible, use pre -fabricated reinforcement cages which will benefit in reducing cycle time.

Ensure pre-fabricated cage is sturdy enough to stand-up to handling and erection. Pre-fabricated cage should be liftable by available equipment at site or alternatively make available suitable equipment to handle pre-fabricated cage. Provide adequate (but not excessive) internal bracings in cage to avoid deformation of cage. Use spreader beam for lifting reinforcement cage to provide multipoint lifting and avoid deformation of cage.  Never lift reinforcement on bundle ties, even if only for a few moments to allow proper slings to be fitted. Instead excavate underneath or transfer bars to sleepers for introducing slings.

Ø

Encourage use of suitable powered cutting and bending machine rather than manual operation. (Refer Appendix – G).

Ø

Provide training to cutting and bending machine operators to improve their skill necessary to produce cut and bent products of consistent quality within the permissible deviations with desired productivity. Also use portable cutting tool for cutting reinforcement steel. Don’t cut reinforcement by gas/flame. Don’t tack weld crossing reinforcement steel but tie securely with binding wires in such a manner that bars will not slip over each other at the time of fixing and concreting.

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Cut and bend bars in multiple numbers simultaneously rather than single bar at a time. (Refer Appendix -H).

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Provide good quality accurate calibrated steel measurement tapes to all Engineers/ Supervisor/Fitters. If tape is damaged, replace rather than using undamaged portion beyond certain length. Control spacing of chairs and avoid excessive chairs. If required, arrive at optimum spacing of chairs by trials. Do not use diameter higher than 20 mm for chairs.

Ø

Use cut pieces for chairs and don’t use full length bars.

Ø

Avoid substitution of bars as far as possible. If unavoidable, avoid over consumption on this count. In case reinforcement supplied by clients, bill excess consumption to clients on account of substitution of bars. Use mechanical splices for higher diameter, if economical. Prefer mechanical splices in congested location not withstanding higher cost.

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Place reinforcement in such a way that concrete placement can be done without segregation and compaction by immersion vibrator is facilitated. Within concrete mass, avoid metal contacts of different types to ensure bimetal corrosion does not take place. Check spacings, number of bars, location etc. before concreting. Ensure good, accurate fixing with specified cover which is a prerequisite for strength, durability, structural integrity and robustness of completed reinforced structure. Determine the best fixing sequence to ensure ease and accuracy within existing and future constrains e.g. form work, starter bars, void former etc. Ensure sensible location of construction joint in case of staged construction duly consulting designer, if required. Intermittently inspect (and have inspected by consultants) reinforcement fixing while in  progress to avoid time consuming and expensive removal and refixing. Ensure bars are free to act along with concrete in the direction in which they are provided without any lateral restraint. Avoid excessive time lags between successive concrete pours to prevent deterioration of  projected exposed reinforcement. Record deviations with respect to drawings systematically to facilitate and ease  preparation of ‘As Built’ drawings.

11)  ANCI L L ARY CONSUM PTI ON Ø Ø Ø Ø Ø

Examine alternatives other than reinforcement steel for ancillary works. Do not consume reinforcement for ancillary work unless method statement is prepared and approved by Project Manager/Corporate office. As a first step, search for cut pieces for ancillary works and resort to full length bars only if cut pieces are not available. Record all consumptions of ancillary work systematically for all heads. Retrieve partially or fully ancillary reinforcement after its purpose is served.

12) COVER TO REI NF ORCEM ENT Ø Ø Ø

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Prefer light weight, non-porous and chemically inert PVC cover blocks/spacers (Refer Appendix ‘I’). Use cover blocks of same size as nominal cover. Use only one single cover block to provide necessary cover for reinforcement at any section e.g. provide 75 mm cover by one single cover block of 75 mm and not two numbers of 37 mm. Don’t use stones, brick bats, timber etc. as cover block. Check cover before concreting.

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Avoid excessive covers e.g. in beams which will reduce effective depth.

13) BI NDI NG WIRE Ø Ø Ø Ø Ø Ø Ø Ø

Don’t use binding wire thicker than 18 gauge. Use black annealed M.S. binding wire conforming to IS:280-1962 unless specifications warrant GI or other type. When three bars are to be tied together, first tie two bars followed by third bar. When four bars are to be tied, tie two pairs first. Don’t provide excessive lengths of binding wire and don’t use miltip;e binding wires. (Refer Appendix – J) Bend twisted ends of ties inwards away from concrete faces to avoid encroaching cover zone. (Refer Appendix – J) Purchase binding wire also in bulk. Check and monitor consumption of binding wire per tonne of reinforcement.

14) BUTT WELD I NG OF CUT PIE CES Ø

Butt weld cut pieces of reinforcement steel beyond economical break even length by cutting “V” grove and welding by qualified welder, especially for diameters 20 mm and above. (Refer Appendix - F) .

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Test welded joint to make sure that joint is stronger than parent bar, irrespective whether such testing is insisted by clients or not. Use Butt weld bars not more than 20% in a given cross section.

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15) BI LL I NG TO CLI ENTS Ø Ø Ø

Develop fool proof system for timely billing of all the billable steel without missing out any items. Jointly record measurements of reinforcement both payable and non-payable on day-today basis. Reconcile client’s billing with PRW billing on quarterly basis.

16) RECONCI L ATI ON OF REI NF ORCEM ENT STE  EL Ø

Reconcile reinforcement steel quarterly – the scope of reconciliation should include consolidating and verifying all receipts, checking theoretical/billable consumption, checking non-billable and ancillary consumption, verifying actual stocks and scrap by weighing, analysing the unaccountable steel and taking mid-course corrective measures etc.

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Plan reconciliation preferably just after disposal of scrap and when inventory of raw steel is minimum. Measure / weigh stock of reinforcement steel systematically duly recording measurements/weights in a separate dedicated measurement book rather than loose  papers. Measure projected reinforcement steel accurately rather than approximately averaging. Weigh scrap at the time of reconciliation .

17) SCRAP M AN AGEM ENT Ø

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Minimize scrap generation in the first place by ordering specific lengths, planning intelligent cuttings of reinforcement bars and trying optimum permutations and combinations etc. Store scrap diameter wise in different stacks lengthwise. (in 0.5 m interval). Guard scrap against theft. Periodically dispose off scrap (excluding those which could possibly be used in future) in consultation with Corporate Finance.

18) FEEDBACK Ø Ø Ø

Document experience for the benefit of others. Provide quantitative and objective feedback to Corporate office/Tendering Department. Learn from the past experiences and aim for continual improvement.

19) APPEN DI CES Appendix A - Checklist for initial scrutiny of Drawings and Bar Bending Schedules Appendix B - Pre-fixing Checklist Appendix C - Pre-concreting Checklist. Appendix D - Steel Storage and Scrap yards Appendix E - Cutting and Bending Tolerances and Bending Effect Appendix F - Butt welding of Reinforcement Bars. Appendix G - Power Bending Machine and Tools Appendix H - Cutting and Bending of Multiple Reinforcement Bars Appendix I - Common types of spacers Appendix J - Common Ties and Bad practices of Tying Reinforcement Bars Appendix K - Good & Bad practices in Transportation and Storage of Reinforcement Steel.

20) BIBILOGRAPHY 1. 2. 3. 4. 5. 6. 7.

8.

Steel Reinforcement’ Special Publication 118, Construction Industry Research & Information Association. BS 8666:2000 Specification for Scheduling, Dimensioning, Bending and Cutting of Steel Reinforcement for Concrete. IS:456-2000 Plain and Reinforced Concrete – Code of practic e. IS:2502-1963 (Reaffirmed 1990) Code of practice for Bending and Fixing of Bars for Concrete Reinforcement. SP:34 (S&T) –198 - Handbook on Concrete, Reinforcement and detailing. IS 4082-1996 Stacking and Storage of Construction Materials and Components at Site – Recommendations - (Second Revision). Mr. S.A. Reddi and Mr.S. Bhuvanesh - ‘Reinforcement Quality Assurance and Certification and Validation aspects’ published in The Indian Concrete Journal, January, 2004 Dr. N.V. Nayak - ‘ Reinforcement steel– some guidelines’.

Appendix – A

Checklist for initial scrutiny of Drawing and Bar Bending Schedules

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•

•

•

Can the reinforcement as detailed be fixed ? (if not, consult designer/detailer) Does the detailing permit sensible location of construction  joints and staged construction ? Is the reinforcement congested? What will happen at lapped cross section? Will this affect fixing or proper compaction of concrete? Would alternative detailing (e.g. staggered laps, bars reversed, two lapped bars replacing a single bar) provide greater flexibility or ease of fixing? (Consult the designer/ detailer before making changes).

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Is there scope for prefabrication? Is this desirable?

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What is the (best) fixing sequence?

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Is the reinforcement detailed to provide sufficient rigidity and stability of cages during fixing?

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Are set-up bars, bracing bars, chairs, spacers etc. required?

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Are bars of a weight that can readily be handled?

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Do schedules agree with drawings e.g. numbers, types, sizes of bars?

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Does numbers of bars allow for two faces and not just one?

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Are scheduled bending dimensions compatible with member dimensions and specified concrete cover? Does reinforcement in one member clash with that in an adjacent member? Are starter bars detailed (and scheduled) with the concrete element in which they are first cast? Starter bars are frequently the last to be fixed to ensure positional accuracy. Does the detailing permit this? If closed links (or similar) are detailed, do they cause problems by requiring threading through of main bars during fixing?

Appendix – B

Pre-fixing Check-list

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Ensure that the steel fitter possesses the latest revision of Drawings and Bar Bending Schedules.

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Determine the best fixing sequence to ensure ease and accuracy, within existing and future constraints (e.g formwork, starter bars, void formers)

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Ensure that reinforcement has not been damaged or misshapen and that it is free from surface contaminants like oil, mud etc.

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Check that the correct type and gauge of tying wire is available as well as spacers of correct size and in sufficient quantity. Check the availability of all required void formers, cast-in items, fixings etc. Ensure all starter bars from previously constructed sections are correctly located and of the correct number, type and size.(Discrepancies should be referred back to the designer). Handle reinforcement carefully without dropping from height and without subjecting to shock or impact and avoid accidental damage or notches causing decrease in section. Bear in mind that all types of reinforcement can be irrepairably damaged by poor handling, site bending, rebending, heating, welding etc.

 Appendix – C

Pre-concreting Checklist •

Check inherent rigidity of the cage or mat.

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Ensure correct numbers of bars have been fixed

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Ensure adequate provision of continuity reinforcement or connection to previous starter bars.

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Ensure that any bars temporarily respositioned have  been returned to their correct position

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Check that all laps are of the correct length and lie in the correct plane.

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Ensure that starter bars, starter boxes, void formers, fixings etc. are all present and in correct locations.

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Ensure correct use of cover blocks, reinforcement spacers etc. to prevent cage movements during concreting.

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Check for damaged reinforcement (particularly coated  bars); repair or replace as necessary.

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Check cover to reinforcement is correct at all locations

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Check that the cage is in the correct position (either line and level or relative to previously checked formwork)

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Ensure that all twisted ends of binding wire ties are bent inwards away from concrete faces to avoid encroaching cover zone.

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Ensure adeqate access for concrete compaction

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Ensure overall cleanliness of reinforcement

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Ensure overall cleanliness of form work (removal of water, tie, clippings etc.) and application of quality shuttering oil before commencing placing of reinforcement.

Appendix-D Steel Storage and Scrap Yards   m   m    5    2

4 m

  m   m    8    2

  m   m    2    3

4 m

4 m

4 m   m   m    6    1

X

13 m

  m   m    8    1

  m   m    0    2

4 m

X

13 m

4 m   m   m    8    0

  m   m    0    1

  m   m    2    1

Barbed Wire Fencing

13 m

Gate With Lock 

Aerial view of a well planned storage area

S t e e l S t o r a ge Y a r d - L a y o u t

Steel – 1 6mm dia

Steel – 18 mm d ia

Steel – 2 0m m d ia

0.5 – 1.0m

1.0 – 1 . 5m

1.5 – 2.0m

2.5 – 3 . 0m 3 2 m m 2 8 m m

1.75 m Fence

4m

2 5 m m

4 m

2 0 m m 0.15 –0.3 m

1 8 m m 1 6 m m 1 2 m m 1 0 m m 0 8 m m

Gate With Lock  Scrap Yard

Section-XX of Steel Storage Yard (Not to Scale)

Appendix-E Cutting and Bending Tolerances and Bending Effect Permissible Bending And Cutting Tolerances DIMENSION Over 

For Bent Bars

For Straight Bars

TOLERANCE

Up to and including

Plus

Minus

cm

cm

mm

mm

-

75

3

5

75

150

5

10

150

250

6

15

250

-

7

25

25

25

All Lengths

 Note : Tolerances on +ve side are less than – ve sides. Min & Max. Tolerances for (-) side are 5mm & 25mm respectively.

Appendix-E Cutting and Bending Tolerances and Bending Effect Permissible Bending And Cutting Tolerances DIMENSION Over 

For Bent Bars

For Straight Bars

TOLERANCE

Up to and including

Plus

Minus

cm

cm

mm

mm

-

75

3

5

75

150

5

10

150

250

6

15

250

-

7

25

25

25

All Lengths

 Note : Tolerances on +ve side are less than – ve sides. Min & Max. Tolerances for (-) side are 5mm & 25mm respectively.

A

R  (Radius of bend) d – D i a of b ar s

E

S t ra i gh t L en gt h L req = A + E – ½ R – d Where, L req = Required Straight Length to achieve dimensions A &E as shown in Fig. 16 d = Diameter of the rod R = Radius of bend = F o r h ig h y i e ld s t r e ng t h b a rs ( i e . , T M T & C T D b a r s o f g r a d e 415 & higher) Recommended R Values are; R = 4 d fo r d < 2 5 m m R = 6d for d > 25mm And for Mild Steel of grade Fe250 Recommended R Values are R = 3 d fo r d < 2 5 m m R = 4d for d > 25mm Thus for high yield strength bars 90 0 bend advantages are R = 3d f or d < 2 5 m m R =4d for d > 25mm

Appendix – F

Butt Welding of Reinforcement Bars I) AN EXTRACT OF SP: 34 (S&T) - 1987 CLAUSE 4.4.3 A:

IF ALL BARS USED IN A STRUCTURAL MEMBER ARE WELDED BARS

Where the strength of a welded splice or mechanical connection has been proved by test to be at least as great as that of the parent bar, the design strength of such connections shall be taken as equal to 80% of the design strength of the bar in tension splice and 100% of the strength for compression splice. B:

IF USE OF WELDED BARS RESTRICTED TO 20% OF TOTAL AREA & STAGGERED

However, 100% of the design strength may be assumed in tension when the spliced area forms not more than 20% of the total area of steel at the section and the splices are staggered at least 600mm center to center. II)

AN EXTRACT OF CLAUSE 26.2.5.2 OF IS 456:2000

26.2.5.2 STRENGTH OF WELDS

The following values may be used where the strength of the weld has been proved by tests to be at least as great as that of the parent bar. a) Splices in Compression For welded splices and mechanical connection, 100% of the design strength of joined bars. b) Splices in Tension 1. 80% of the design strength of welded bars (100% if welding is strictly supervised and if at any cross-section of the member not more than 20% of the tensile reinforcement is welded). 2. 100% of design strength of mechanical connection. III) TRADE OFF BETWEEN COST OF BUTT WELDING AND RETRIEVAL BENEFITS If cost of Butt Welding is say Rs.90/- per Weld for 28 dia & Rs.80/- per Weld for 25 dia, taking cost of Steel @ Rs.23/- per kg. and that of Scrap @ Rs.15/- per kg., following picture emerges for these two diameters for different lengths: Diameter Length of We ight of Net Cost of Cut Cost of Economical Cut Piece Cut Piece Piece Retrieved Welding Viability 28mm 3m 14.5 Kg Rs.116 Rs.90 Viable 28mm 2.75m 13.3 Kg Rs.106 Rs.90 Viable 28mm 2.25m 10.9 Kg Rs. 87 Rs.90 Not Viable 28mm 2.00m 9.7 Kg Rs. 77 Rs.90 Not Viable 25mm 3m 11.5 Kg Rs. 92 Rs.80 Viable 25mm 2.75m 10.6 Kg Rs. 85 Rs.80 Viable 25mm 2.25m 8.9 Kg Rs. 71 Rs.80 Not Viable

 Appendix-G

Power Bending Machine and Tools

Power Bender Bench

Power Bender

Power Bender Disc cutte

Rebar cutte

Appendix-H

Cutting and Bending of Multiple Reinforcement Bars

Cutting of Bars 8mm dia10Nos

Bending of Bars 8mm dia 08Nos

Cutting of Bars

Bending of Bars

Cutting of Bars 10mm dia8Nos

Cutting of Bars 16mm dia 04Nos

Bending of Bars 10mm dia 07Nos

Bending of Bars 16mm dia 04Nos

Appendix-H

Cutting and Bending of Multiple Reinforcement Bars

Cutting of Bars 8mm dia10Nos

Bending of Bars 8mm dia 08Nos

Cutting of Bars

Bending of Bars

Dia. (mm) 8 10 12 16 20 25 28 32

Cutting of Bars 10mm dia8Nos

Cutting of Bars 16mm dia 04Nos

Bending of Bars 10mm dia 07Nos

Bending of Bars 16mm dia 04Nos

Multiple Nos. while Cutting Bending 10 08 08 07 06 05 04 04 03 03 02 02 02 02 01 01

Cutting of Bars 20mm dia 03Nos

Bending of Bars 20mm dia03Nos

Cutting of Bars 25mm dia 02Nos

Cutting of Bars 28mmdia 02Nos

Bending of Bars 28mmdia 02Nos

Cutting of Bars 32mm dia 01Nos

BENDING MACHINE ICARE P36 CUTTING MACHINE ICARE C42

Bending of Bars 25mm dia 02Nos

Bending of Bars 32mm dia01Nos

Appendix-I

Common Types of Spacers

Appendix-J

Common Ties and Bad Practices of tying Reinforcement Bars

Six common ties

a)Extra length of  binding wire used

 b) Multiple excessive  binding wires used

c)Extra length of  binding wire encroaching cover zone

Bad ractices of t in Reinforcement

Appendix-K

Good and bad Practices in Transportation and Storage of Reinforcement steel

Bad practice of Transportation of Reinforcement

Bad practice of storage of Reinforcement

Bad ractice of stora e of Reinforcement

Good practice of storage of Reinforcement

Bad practice of Transportation of Reinforcement

Bad practice of storage of Reinforcement

Bad ractice of stora e of Reinforcement

Very Good practice of storage of Reinforcement. Plastic cover to reinforcement provided, should also cover side po rtions.

NOTES