Rebarworks_REV09NSCP2010

REBAR WORKS 101

Construction ManpowerDevelopment Foundation

Be familiar with pertinent code provisions/requirements

Identify grade, size and type of steel used

Prepare rebar placing/working drawings and bar bending and cutting schedule

Objectives

Material Specification PNS 49 : 1991 - Specs. For Steel Bars for

Concrete Reinforcement ASTM A 615 – Specs. For Deformed and Plain

Billet Steel Bars for Concrete Reinforcement ASTM A 616 – Specs. For Rail Steel Deformed

and Plain Bars for Concrete Reinforcement ASTM A 617 – Specs. For Axle Steel Deformed

and Plain Bars for Concrete Reinforcement ASTM A 706 – Specs. For Low Alloy Steel

Deformed Bars for Concrete Reinforcement

REINFORCING BARS SHALL BE:

• ACCURATELY PLACED

• ADEQUATELY SUPPORTED AND

• SHALL BE SECURED AGAINST DISPLACEMENT

Fundamentals

Tolerance on effective depth

(d)

Tolerance on minimum

concrete cover

d 200 mm

d > 200 mm

± 10 mm

± 12 mm

- 10 mm

- 12 mm

Placing Tolerances

Fundamentals

Cutting Reinforcing bars shall be cut cold

Bending Reinforcing bars shall be bent cold Don’t re-bend, heat or re-straighten

reinforcing bars

900 BEND 1800 BEND

E = larger of4db or 65mm

E

db = nominal diameter of main bar

Standard Hooks for Main Bars

900 BEND 1350 BEND

6db (db16mm)12db (db=20 or 25mm)

6db (db 25mm)or 75mm

E

E

Standard Hooks for Ties and Stirrups

Minimum Bend DiameterNominal Diameter

Minimum Bend Diameter

Main Bars Ties/Stirrups

6 db

4 db10

12

16

206 db

25

288 db

-32, 36

42, 58 10 db

Types of Structure Minimum Concrete Cover (mm)

Concrete cast against and permanently exposed to earth

Concrete exposed to earth or weather: 20mm through 36mm bars 16mm and smaller bars

Concrete not exposed to earth or weather or not in contact with ground: Slabs, walls, joists 32mm and smaller Beams, columns. Primary reinforcement ties, stirrups, spirals

75

5040

20

40

Concrete Cover

Sc = db, but notless than 25mm

db = bar diameter

Parallel Bars Parallel Bars in two or more layers

Sc = 25mm

Spacing Limits of RSB

Sc

Spirally reinforced or tied reinforced compression members

Sc = 1.5db but not less than 40mm

Contact Lap Splices

Sc = db, but not less than 25mm

Spacing Limits of RSB

Walls and Slabs

Sc < 3t but not greater than 450mmSc = 25 mm minimum

t = wall or slab thickness

Spacing Limits of RSB

Identifying the type, size and grade of steel used

Anong size kayaito ?

A

W

A

275

32

W

Manufacturer’sMarking

Grade

Bar Size

Weldable

PNS 49: 2002

PNS Grade Marking

Dash Metric Englishno dash

1 dash2 dash

Grade 230

Grade 415Grade 275

33 ksi

60 ksi40 ksi

275

PNS 49: 2002

lugs

Ribs

PNS 49: 2002

Quality Test Rebar (PNS 49) Classification

Regular steel bars; and Weldable

Chemical Composition Mechanical Properties

Yield strength Tensile Strength % Elongation Bend Test

Dimension and Mass Tolerance Deformation Requirements

Height of Lugs Spacing Gap distance

PNS 49: 2002Nominal Dimensions and Unit Mass Standards

Diameter, mm Perimeter, mmCross

Sectional Area, mm2

Mass, Kg/m

10 31.4 78.54 0.617

12 37.7 113.10 0.888

16 50.3 201.06 1.578

20 62.8 314.16 2.466

25 78.5 490.88 3.853

28 88.0 615.75 4.834

32 100.5 804.25 6.313

36 113.1 1017.88 7.990

40 125.7 1256.64 9.865

50 157.1 1963.50 15.413

Tolerance, height of lugs

Nominal diameter, mmMinimum height of lugs *

10 4.0

12 and 16 4.5

20 and above 5.0

*Percent of nominal diameter

Deformation Requirements

Diameter, mm

Max. average spacing of lugs, mm

Height of tolerance of lugs, mm

Max. Value summation of gaps of Lugs,

mmMin. Max.10 7.0 0.4 0.8 7.8

12 8.4 0.5 1.0 9.4

16 11.2 0.7 1.4 12.6

20 14.0 1.0 2.0 15.7

25 17.5 1.2 2.4 19.6

28 19.6 1.4 2.8 22.0

32 22.4 1.6 3.2 25.1

36 25.2 1.8 3.6 28.3

40 28.0 2.0 4.0 31.4

50 35.0 2.5 5.0 39.3

PNS 49: 2002

White - Grade 230

Yellow - Grade 275

Green - Grade 415

PNS 49: 2002

Red – Weldable Bars

Prepare Placing/working drawing

Bar cut off/bend point Splice location & length Number of bars Placing dimension Cut length Bar position/location X-dimension & clear distance

GIRDER PLACING DRAWING

Joint

COLUMN PLACING DRAWING

Perimeter beams, shall have continuous reinforcement over the span length passing thru the region bounded by the longitudinal reinforcement of the column consisting of

1. At least 1/6 of the required tension reinforcement for neg. moment but not less than 2 bars

2. At least 1/4 of the required tension reinforcement for positive moment but not less than 2 bars

And tied with closed stirrups. Closed stirrups need not be extended through any joints. Continuity with top bars spliced at midspan & bottom bars spliced at or near the support with Class B tension splices

(NSCP 2010)407.14 Requirements for Structural Integrity, Perimeter Beams

(NSCP 2010)407.14 Requirements for Structural Integrity, Interior beams

In other than perimeter beams, when closed stirrups are provided there are no additional requirement for longitudinal integrity reinforcement. Where such transverse reinforcement is not provided, at least 1/4 of the positive moment reinforcement required at midspan, but not less than 2 bars shall be continuous or shall be spliced near or over the support with a “class B” tension splice and at non- continuous supports be terminated with a standard hook

Contact Lap Splice

Splicing of Reinforcing Bars

Welded Splice

Coupled Splice

Splicing of Reinforcing Bars

GAS PRESSURE WELDING (GPW)

Splicing of Reinforcing Bars

(NSCP 2010) 412.11 Development of Flexural Reinforcement - General

.3 Reinforcement shall extend beyond the point at which it is no longer required to resist flexure for a distance equal to the effective depth of the member or 12db, whichever is greater or, except at supports of simple spans and at free end of cantilevers

Dd

412.11 Development of Flexural Reinforcement - General

L/4 d or 12db

d or 12db

TOP BAR

BOTTOM BAR

Dd

d or12db

412.11 Development of Flexural Reinforcement - General

L/3d or12 db

d or12 db

L/3

d or12db

(NSCP 2010) 412.11 Development of Flexural Reinforcement - General

.4. Continuing reinforcement shall have an embedment length not less than the development length ld beyond the point where bent or terminated tension reinforcement is no longer required to resist flexure.

412.12 Development of Positive Moment Reinforcement

.1. At least 1/3 of the positive moment reinforcement in simple members and 1/4 the positive moment reinforcement in continuous members shall extend along the same face of member into the support. In beams, such reinforcement shall extend into the support at least 150 mm

Dd

412.12 Development of Positive Moment Reinforcement

L/4

d or 12dbBOTTOM BAR

150 mm min.

1/4 x BOTTOM BAR

412.13 Development of Negative Moment Reinforcement

.1. Negative moment reinforcement in a continuous, restrained, or cantilever member or in any member of a rigid frame, shall be anchored in or through the supporting member by embedment length, hooks, or mechanical anchorage.

412.13 Development of Negative Moment Reinforcement

.3. At least 1/3 of the total tension reinforcement provided for negative moment at the support shall have an embedment length beyond the point of inflection not less than effective depth of member, 12db, or 1/16 of the clear span, whichever is greater.

Dd

412.13 Development of Negative Moment Reinforcement

L/4 d or 12db TOP BAR1/3 x TOP BAR

d or 12db or L/16

412.16, NSCP 2010, Splices of Deformed Bars & Wires in Tension

.2 Lap splices of deformed bars and deformed wires in tension shall be Class B except that Class A splices are allowed when:

a. The area of reinforcement provided is at least twice that required by analysis over the entire length of splice, and

b. 1/2 or less of the total reinforcement is spliced within the required length

CLASS A LAP SPLICE = 1.0 ld

CLASS B LAP SPLICE = 1.3 ld

412.16, NSCP 2010, Splices of Deformed Bars & Wires in Tension

Basic Development Length Formula - Tension

= db (fy Ψl Ψc )

For 20 mm dia and smaller

= db (fy Ψl Ψc )

For 25 mm dia and larger

2.1 λ √fc’

1.7 λ √fc’

Note:

Sc and cc ≥ db, stirrups and ties through out ld not less than the code min.

Or

Sc ≥ 2db and cc ≥ db

Basic Development Length Formula - Tension

= db (fy Ψl Ψc )

For 20 mm dia and smaller

= db (fy Ψl Ψc )

For 25 mm dia and larger

1.4 λ √fc’

1.1 λ √fc’

Note:

for other cases

LAP SPLICE = 0.071fydb

412.17, NSCP 2010, Splices of Deformed Bars in Compression

412.18.2, Lap Splices in Columns

.2 Where bar stress due to factored load is tensile and does not exceed 0.5Fy in tension, lap splices shall be Class B tension lap splices if more than 1/2 of the bars are spliced at any section, or Class A tension lap splices if half or fewer bars are spliced at any section and alternate lap splices are staggered by ld.

Prepare Bar Bending & Cutting Schedule

Structure Location/position of RSB Shape and dimension Bar size Cut length No. of pieces

Position/LocationStructure

Co

lum

nG

ird

er

Be

am

Main Bar

End Bar

Top Bar

Bottom Bar

Extra Top Bar

Extra Bottom Bar

Stiffener

StirrupsSpreader

Top Bar

Bottom Bar

Extra Bottom Bar

Stirrups

Shape/Dimension Bar Ø Cut Length PcsStructure Location/Position

Change in Length from Detailing Dimension to Cutting Length

Bar Φ, mm

Main Bars

Bend Correction Hook Correction

45° 90° 180° 90° 180°

8

- 0.5 db - 2.5 db + 3 db + 13.5 db

+7db + 6510

12

16

+ 11 db20

25

28

- 0.6 db - 2.9 db + 4.1 db + 14.1 db + 13.1 db32

36

Change in Length from Detailing Dimension to Cutting Length

Bar Φ, mm

Ties/Stirrups

Bend Correction

Hook Correction

90° 90° 135°

8

- 2 db

+ db + 60 + 3 db + 60

10

+ 7 db + 9 db12

16

20- 2.5 db + 13.5 db + 10.2 db

25

Structure Position/Location Shape/Dimension Bar Diameter Cut Length No. of Pieces

Cutting List (Sample Form)

Snap or Single Tie- a simple tie

wrapped once around the two crossing bar in diagonal manner.

Wrap and Snap Tie- used in tying

wall reinforcement.

Saddle or U tie- for footing bars or other mats.- for securing col. ties to vertical bars.

Wrap and Saddle Tie- used to secure heavy mats that are lifted by crane.

Figure Eight Tie- can be used instead of Wrap Snap tie.

Methods of Tying Bars

Bar Supports

Metal Concrete Plastic

Bar Supports