January, 2008 15-1

Section 15 Concrete Reinforcement

15.1 Introduction

This section is intended to aid the bridge designer and detailer in the area of concrete reinforced design and detailing. The tables in this section simplify the design and detailing of concrete reinforcement splices and required covers. Also included are suggested details intended to ease the construction process and provide seismic resistance.

15.2 Spacing

The minimum spacing shall meet NYSDOT LRFD Bridge Design Specification Section 5.10.3.1 requirements. The maximum clear spacing between parallel bars shall not be more than 450 mm. The clear space between bars shall also apply to the clear distances between the contact splices and adjacent splices of bars. Bar spacings as indicated are always between the center of the bars unless otherwise noted as a clear distance. When reinforcement in beams or girders is placed in two or more layers, the bars in the upper layers shall be placed directly above those in the bottom layer.

15.3 Cover

The following list pertains to the minimum cover for plain, epoxy and galvanized reinforcing bars. Refer to Section 5 for cover of monolithic decks.

Top of sidewalk slabs............................................................................................... 40 mm Beams and Columns................................................................................................ 50 mm Pedestal (Top).......................................................................................................... 50 mm Pedestal (Sides)....................................................................................................... 75 mm Walls and Piers above footing (Including those adjacent to water)..........................50 mm* Footings (Including unformed bottom) ..................................................................... 75 mm** Approach slab (Top)................................................................................................. 75 mm Approach slab (Bottom and Sides) .......................................................................... 75 mm Bottom of bottom slab of cast-in-place culvert ......................................................... 75 mm Bottom of top slab of cast-in-place culverts and rigid frames................................... 50 mm All other cast-in-place culvert faces ......................................................................... 50 mm Top of top slab of precast culverts (Fill <600 mm) ................................................... 50 mm Top of top slab of precast culverts (Fill ≥600 mm) ................................................... 25 mm All other precast box culvert faces ........................................................................... 25 mm Exposed faces of precast three-sided culverts ........................................................ 38 mm All other faces of precast three-sided culverts ......................................................... 50 mm Arches (Intrados and extrados)................................................................................ 50 mm Precast and cast-in-place piles ................................................................................ 50 mm

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Precast piles exposed to sea water ......................................................................... 75 mm Post-tensioned cylindrical piles (Centrifugally cast, no slump concrete exposed to sea water).............................................................................................. 40 mm All other surfaces exposed to sea water ................................................................ 100 mm

* When aesthetic treatment (formliner) is used, the maximum relief of the treatment shall be added to the minimum cover.

** May be increased to accommodate piles when necessary.

15.4 Reinforcing Bar Guidelines

Grade 420 is the standard strength reinforcing bar to be used on Department projects. Grade 520 reinforcing bar is available, though in limited quantities and at greater cost. Use of Grade 520 reinforcing bars should be limited to areas of high tensile stresses where the number of Grade 420 reinforcing bars results in insufficient spacing between the bars for concrete placement.

TABLE A

STANDARD REINFORCING BAR PROPERTIES

Size #13 #16 #19 #22 #25 #29 #32 #36

Area (mm2) 129 199 284 387 510 645 819 1006

Dia. (mm) 12.7 15.9 19.1 22.2 25.4 28.7 32.3 35.8

15.4.1 Maximum Bar Lengths

Most reinforcing bar plants in the United States produce bars in a standard length of 18.29 m (60 ft.). Therefore, plans should not include any straight bars or bent bars with a length in excess of 18.29 m. Due to handling concerns, the maximum length of a bar that requires a hook on both ends should be limited to 9 m.

15.4.1.1 Deck Slab Bars

Refer to Section 5.1.5.4 Deck Overhangs for guidance on deck slab bars.

15.4.1.2 Abutment and Pier Bars

When designing abutments and piers, it is important to envision how the contractor may build the structure and to provide details that make construction easier.

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January, 2008 15-3

Vertical bars should not extend more than 5 m out of the placement that they originate in due to handling concerns. Instead, two bars with a lap splice should be used. This is suggested as a guide, and a designer’s judgment must be used. Obviously, if a bar has a length of 5.3 m, a lap should not be introduced for the small amount of extra length required.

15.4.2 Reinforcement Splicing

15.4.2.1 General Splicing Guidelines

For #36 bars or smaller, splices can be made by lap splices with wire ties, mechanical connectors (from the Materials Bureau approved list), or by welding provided it is in accordance with the New York State Steel Construction Manual (SCM), Section 7, Part D. Tack welding is not permitted.

Splices for bars larger than #36 shall use either mechanical connectors from the Materials Bureau Approved List or welds in accordance with the proper welding procedure.

No additional payment is made for reinforcement splices. However, if the situation mandates the use of mechanical connectors or welded splices, this shall be noted on the Contract Plans.

15.4.2.2 Splicing Vertical Reinforcement in Walls

For #16, #19, and #22 bars, the splicing of the main vertical reinforcement to the reinforcement emerging from the footing may be made directly over the footing. In some cases, it may be practical to eliminate splices by extending the bars emerging from the footing to the top of the wall. Number 25 and larger bars emerging from the footing shall be extended to a distance above the footing where bars of a smaller diameter may be spliced to them. The lap length for such splices shall be based on the smaller bar.

15.5 Minimum Anchorage, Lap and Embedment

The following notes apply to the tables in this article:

1. All tables are based on formulas found in Section 5 – Concrete Structures of the NYSDOT LRFD Bridge Design Specification.

2. Lengths are based on: fy = 420 MPa and f’c = 21 MPa. 3. When an area of steel provided is more than that required to develop the ultimate

moment capacity of the section, the basic development length indicated may be reduced by the ratio: As(required) ÷ As(provided).

4. Galvanized, stainless steel clad and solid stainless steel bars are treated as uncoated bars for splice and embedment lengths.

5. Top bars are defined as horizontal reinforcement located where there is more than 300 mm of fresh concrete cast below the development length or splice.

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15-4 January, 2008

15.5.1 Basic Development Length for Bars (mm)

TABLE B

BASIC DEVELOPMENT LENGTH FOR COMPRESSION BARS

Size #13 #16 #19 #22 #25 #29 #32 #36

Ld 280 350 420 490 560 630 710 790

TABLE C

BASIC DEVELOPMENT LENGTH OF HOOKED DOWELS IN TENSION

Size #13 #16 #19 #22 #25 #29 #32 #36

Uncoated - Ldh 300

[300] 350

[300] 420

[300] 490

[340] 560

[390] 630

[440] 710

[500] 780

[550]

Epoxy-Coated Ldh

340 [300]

420 [300]

500 [350]

580 [410]

670 [470]

750 [530]

850 [600]

940 [660]

Table C Criteria (Length in Brackets requires following criteria to be met) #36 bar or smaller Side Cover ≥ 65 mm 90 Hook: cover ≥ 50 mm See Article 5.11.2.4.2 of the NYSDOT LRFD Bridge Design Specification

FIGURE 15.1

Hooked Dowel

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TABLE D

BASIC DEVELOPMENT LENGTH FOR STRAIGHT UNCOATED DOWELS & TENSION BARS (NOT TOP BARS)

Size #13 #16 #19 #22 #25 #29 #32 #36

Spacing ≥ 150 mm 300 320 420 570 750 950 1200 1480

Spacing < 150 mm 320 400 520 710 940 1180 1500 1850

TABLE E

BASIC DEVELOPMENT LENGTH FOR STRAIGHT UNCOATED DOWELS & TENSION BARS (TOP BARS)

Size #13 #16 #19 #22 #25 #29 #32 #36

Spacing ≥ 150 mm 360 450 590 800 1050 1330 1680 2070

Spacing < 150 mm 450 560 730 1000 1310 1660 2100 2580

TABLE F

DEVELOPMENT LENGTH FOR STRAIGHT EPOXY-COATED DOWELS & TENSION BARS (NOT TOP BARS)

Size #13 #16 #19 #22 #25 #29 #32 #36

Spacing ≥ 150 mm

390 (310)

480 (390)

630 (500)

850 (680)

1120 (900)

1420 (1140)

1800 (1440)

2220 (1770)

Spacing < 150 mm

480 (390)

600 (480)

780 (630)

1070 (N/A)

1400 (N/A)

1780 (N/A)

2250 (N/A)

2770 N/A)

The lengths in parentheses can only be used as described in TABLE H.

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TABLE G

DEVELOPMENT LENGTH FOR STRAIGHT EPOXY-COATED DOWELS & TENSION BARS (TOP BARS)

Size #13 #16 #19 #22 #25 #29 #32 #36

Spacing ≥ 150 mm

440 (310)

550 (540)

710 (700)

970 (960)

1270 (1260)

1610 (1590)

2040 (2020)

2510(2480)

Spacing < 150 mm

500 (540)

680 (680)

890 (880)

1210 (N/A)

1590 (N/A)

2102 (N/A)

2550 (N/A)

3140(N/A)

The lengths in parentheses can only be used as described in TABLE H.

TABLE H

THE LENGTHS IN PARENTHESES CAN ONLY BE USED IF BOTH OF THE FOLLOWING CIRCUMSTANCES ARE TRUE

Size #13 #16 #19 #22 #25 #29 #32 #36

Cover ≥ 38 48 57 67 76 86 97 107

Bar Spacing ≥ 89 111 134 155 178 201 226 251

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15.5.2 Length of Splices for Tension Bars (mm)

Modification of Basic Development Length

TABLE I

Max (%) of As Spliced within Required Lap Length

As (Provided) ÷ As (Required) 50% 75% 100%

≥ 2.0 Class A Class A Class B

< 2.0 Class B Class C Class C

The minimum lap length for a tension splice shall be as required for Class A, B, or C splice, but not less than 300 mm:

Class A Splice = 1.0 x Ld Class B Splice = 1.3 x Ld Class C Splice = 1.7 x Ld

The following Lap Splice Selection Guidelines table is only a recommendation. The designer assumes final responsibility for selecting a splice length for a given location.

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15-8 January, 2008

Superstructure Slab Splice Type Table

Longitudinal Bars (Top of Slab) Class C (Not Top Bars) P

Longitudinal Bars (Bottom of Slab) Class C (Not Top Bars) P

Transverse Bars (Top of Slab) Class B (Not Top Bars) N

Transverse Bars (Bottom of Slab) Class B (Not Top Bars) N

Longitudinal and Transverse Bars (Adj. Prestress Units) Compression Splice R

Concrete Barrier (Longitudinal) Class C (Not Top Bars) L, P

Hammerhead and Multi-Column Pier Cap Beam Splice Type

Longitudinal Bars (Top Primary Reinforcement) Class B (Top Bars) K Longitudinal Bars (Bottom Primary Reinforcement and Distribution Reinforcement) Class B (Not Top Bars) J, N

Pier Column Class C (Not Top Bars) L, P

Footing (Steel Pile Foundation) Splice Type

Longitudinal Bars (Top of Footing) Class C (Top Bars) M

Longitudinal Bars (Bottom of Footing) Class C (Top Bars) M

Footing (Concrete Piles or Spread Footing) Splice Type

Longitudinal Bars (Top of Footing) Class C (Top Bars) M

Longitudinal Bars (Bottom of Footing) Class C (Not Top Bars) L

Conventional Abutment Stem and Retaining Walls Splice Type

Rear Face of Wall (Horizontal) Class B (Not Top Bars) J, N

Rear Face of Wall (Vertical) Class C (Not Top Bars) L, P

Front Face of Wall (Horizontal) Class B (Not Top Bars) J, N

Front Face of Wall (Vertical - Conventional Abutment) Class B (Not Top Bars) J, N

Front Face of Wall (Vertical - Jointless Abutment) Class C (Not Top Bars) L, P

Bridge Seat/Top of Solid Pier (Longitudinal) Compression Splice R

LAP SPLICE SELECTION GUIDELINES

Table 15-1

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TABLE J

CLASS B SPLICE-UNCOATED (NOT TOP BARS)

Size #13 #16 #19 #22 #25 #29 #32 #36

Spacing ≥ 150 mm 340 420 540 740 970 1230 1560 1920

Spacing < 150 mm 420 520 680 920 1220 1540 1950 2400

TABLE K

CLASS B SPLICE-UNCOATED (TOP BARS)

Size #13 #16 #19 #22 #25 #29 #32 #36

Spacing ≥ 150 mm 470 590 760 1040 1360 1720 2190 2690

Spacing < 150 mm 580 730 950 1290 1700 2150 2730 3360

TABLE L

CLASS C SPLICE-UNCOATED (NOT TOP BARS)

Size #13 #16 #19 #22 #25 #29 #32 #36

Spacing ≥ 150 mm 440 550 710 970 1270 1610 2040 2510

Spacing < 150 mm 550 680 890 1210 1590 2010 2550 3140

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15-10 January, 2008

TABLE M

CLASS C SPLICE-UNCOATED (TOP BARS)

Size #13 #16 #19 #22 #25 #29 #32 #36

Spacing ≥ 150 mm 610 770 990 1350 1780 2250 2860 3510

Spacing < 150 mm 760 960 1240 1690 2230 2820 3580 4390

TABLE N

CLASS B SPLICE-EPOXY COATED (NOT TOP BARS)

Size #13 #16 #19 #22 #25 #29 #32 #36

Spacing ≥ 150 mm

500 (400)

630 (500)

810 (650)

1110 (890)

1460 (1170)

1850 (1480)

2340 (1880)

2880 (2300)

Spacing < 150 mm

630 (500)

780 (630)

`1020(810)

1390 (N/A)

1830 (N/A)

2310 (N/A)

2930 (N/A)

3600 (N/A)

The lengths in parentheses can only be used as described in TABLE H.

TABLE O

CLASS B SPLICE-EPOXY COATED (TOP BARS)

Size #13 #16 #19 #22 #25 #29 #32 #36

Spacing ≥ 150 mm

570 (560)

710 (700)

920 (910)

1260 (1240)

1660 (1640)

2090 (2070)

2660 (2630)

3260 (2330)

Spacing < 150 mm

710 (700)

890 (880)

1150 (1140)

1570 (N/A)

2070 (N/A)

2620 (N/A)

3320 (N/A)

4080 (N/A)

The lengths in parentheses can only be used as described in TABLE H.

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TABLE P

CLASS C SPLICE-EPOXY COATED (NOT TOP BARS)

Size #13 #16 #19 #22 #25 #29 #32 #36

Spacing ≥ 150 mm

660 (520)

820 (660)

1060 (850)

1450 (1160)

1910 (1530)

2410 (1930)

3070 (2450)

3760(3010)

Spacing < 150 mm

820 (660)

1020 (820)

1330 (1060)

1810 (N/A)

2390 (N/A)

3020 (N/A)

3830 (N/A)

4700(N/A)

The lengths in parentheses can only be used as described in TABLE H.

TABLE Q

CLASS C SPLICE-EPOXY COATED (TOP BARS)

Size #13 #16 #19 #22 #25 #29 #32 #36

Spacing ≥ 150 mm

740 (730)

930 (920)

1210 (1190)

1640 (1620)

2160 (2140)

2740 (2700)

3470 (3430)

4270(4220)

Spacing < 150 mm

930 (920)

1160 (1150)

1510 (1490)

2050 (N/A)

2700 (N/A)

3420 (N/A)

4340 (N/A)

5330(N/A)

The lengths in parentheses can only be used as described in TABLE H. 15.5.3 Length of Splices for Compression Bars

TABLE R

Size #13 #16 #19 #22 #25 #29 #32 #36

Beams 390 490 590 680 780 880 990 1100

Tied Columns 330 410 490 570 650 730 820 910

Spiral Columns 300 370 440 10 590 660 750 830

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15.6 Marking of Bars for Bar Lists

Bars shall be marked consecutively, beginning with the number one (1), through each structural unit. A structural unit, such as an abutment, includes all concrete subdivisions (abutment footing, abutment stem, wingwall footing, wingwall stem, etc.) which together comprise the entire unit. In the bar list, structural units are to be identified by a general heading (e.g., Beginning Abutment). Appropriate subheadings shall also precede the listing of bars in each subdivision (e.g., Wingwall 1, Beginning Abutment Stem). When a subdivision is still further divided into more than one pour, the listing of bars in each pour shall also be preceded by appropriate identification (e.g., Beginning Abutment Stem, Pour 1).

Typical bar marks shall specify the bar size, structural unit the bar originates in, whether the bar is plain, epoxy coated (E), galvanized (G), stainless steel clad (C) or solid stainless steel (S), and the bar number.

Exception: The dowels between all types of Permanent Concrete Traffic Barrier and Parapet for Structures and the structural slab or U-wingwall shall not be listed in the structural slab or wall bar list even though the bars originate in the slab or wall. These bars are to be paid for in the traffic barrier item and placed in a separate table. These bars shall not appear in the superstructure slab bar list. The reason for this policy is that the bars associated with all types of Permanent Concrete Traffic Barrier and Parapet will change if the contractor chooses the precast option for the barrier. See Notes 67 and 68 in Section 17.3.

In applying the bar marks where two or more structure units are involved, such as two or more similar abutments, piers, spans, etc., it is desirable that the same bar marks be applied to bars in similar locations in the structure unit. The fact that two bars lying in different structure units may have the same bar mark but have different lengths, or they may have the same length but have different sizes, or any combination of these factors will not be confusing to the fabricator due to the practice of providing a separate bar list, properly titled, for each structure unit.

For varying length bars, give minimum, maximum and average lengths of bars. Give number of sets of bars, even if the number of sets is one.

Any deviation from the above system of marking bars must have the approval of the D.C.E.S. See Section 15.13 for guidance on projects without bar lists.

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15.7 Footing Reinforcement

Footing reinforcement shall be designed for the applied loads, but the following minimum requirements shall be provided to maintain the integrity of the footing in the event of seismic loading:

1. Top and bottom reinforcement in footings in both the transverse and longitudinal directions shall be provided with hooks (180° or 90°) at both ends.

2. Vertical stirrups using #13 bars with alternated 135° hooks at one end and 90° hooks at the other, shall be used in all footings to connect the top and bottom reinforcement mats. Spacing shall be a maximum of 1.2 m in both directions.

3. The bottom reinforcement mat in footings with piles shall be placed 50 mm clear above the tops of the piles. In special cases, where design requirements dictate and the pile pattern permits, the bars may be located between piles. In this case, a minimum clear distance of 75 mm shall be maintained between the reinforcing bars and the piles.

4. The vertical compression reinforcement of all abutment stems and walls shall be doweled into the footing with #16 bars. These dowels should have 180° hooks on both ends. See Table C of Section 15.5.1 for required embedment length. If the vertical compression reinforcement is not lapped to dowels and is instead embedded directly into the footing, and extends up more than 1.0 m, then only the bottom of the bar requires a 180° hook. Minimum reinforcement shall be #16 bars at 450 mm.

5. The minimum top reinforcement for a continuous pier footing shall be #19 bars at 300 m in both the transverse and longitudinal directions.

6. The minimum top reinforcement for an individual pier footing shall not be less than 50% of the area of the designed bottom reinforcement or #19 bars at 300 mm in both the transverse and longitudinal directions.

15.8 Abutment Reinforcement

The top layer of bridge seat reinforcement for steel girder, prestressed concrete I-beams, and spread prestressed concrete box beams shall be #25 bars at 150 mm. For adjacent prestressed concrete box and slab unit structures, the top layer of bridge seat reinforcement shall be #25 bars at 200 mm.

Dowels on the compression side of the abutment stem shall meet the requirements of Note 4 of Section 15.7.

The minimum vertical reinforcement shall be #16 bars at 450 mm. The entire capacity of these bars shall be developed by embedment or lapping the bar.

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15.9 Column Reinforcement

All lap splices shall be located within the middle ½ of the column height. Dowels shall extend at least ¼ of the column height or 3.0 m, whichever is greater. Splices in the vertical design reinforcement shall be staggered. Vertical reinforcement shall be extended into the pier cap for the full embedment length.

Continuous ties shall surround the vertical reinforcement. Ties shall be not less than #13 bars. Spacing of lateral ties in the interior length of pier columns shall not exceed the least plan dimension of the compression member or 300 mm, whichever is less. In addition to AASHTO requirements, additional lateral ties shall be provided to make the vertical spacing between the ties 150 mm on centers at the top and bottom of the column. This occurs over either one-sixth the column height or 450 mm, whichever is greater. All stirrups and lateral ties shall be provided with 135° hooks. When spirals are provided in lieu of lateral ties, the pitch is as AASHTO specifies. Spirals should stop at the level of the footing or the capbeam and circular ties shall be used for a distance equal to ½ the greater column plan dimension, but not less than 375 mm into the footing or cap beam. In lightly reinforced footings, where there would be minimal interference between the spiral and the footing reinforcement, spirals may continue in lieu of the circular ties into the footing and the cap beam. Lateral ties in solid piers may have a 90° hook at one end with the 35° and 90° hooks alternated.

For seismic reasons, when a plinth is provided at the base of a column, the design vertical reinforcement of the columns shall extend into the footing. Additional reinforcement in the plinth may be required due to other design forces.

15.10 Pier Cap Reinforcement

The splices of top bars in the cap beam shall be staggered so no more than 50% of the bars are spliced at one location. The splices shall be located in areas of low negative moment. The splices of bottom bars in the cap beam shall be staggered so no more than 50% of the bars are spliced at any one location. The splices shall be located in areas of low positive moment.

When pier cap bars are spliced, the lap splices of the bars shall be in a vertical plane so the bars will be in the proper position for attachment to stirrups. To accommodate this type of splice, where more than one layer of reinforcement is required, it may be necessary to increase the distance between the layers of reinforcement.

Capbeams with overhangs require special attention. Two cases need to be investigated based on the geometry of the applied loads on the overhang region of the capbeam. First, AASHTO requires that shear due to concentrated loads within a distance "d" (d = capbeam depth) from the column face be included in the flexural design shear.

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For capbeam cantilever ends where the fascia beam load falls within a distance "d" from the column face, the actual behavior of the cantilever end may not be compatible with beam theory and must be checked against the requirements of AASHTO 8.15.5.8 and AASHTO 8.16.6.8, Special Provisions for Brackets and Corbels. An alternative method to analyze such cantilever ends is the strut and tie method described in the NYSDOT LRFD Bridge Design Specifications. Both the Bracket and Corbel and the Strut and Tie methods recognize that direct shear is the primary behavioral mode instead of flexure, and is resisted by tension reinforcement across the shear plane. As a result of these methods, more reinforcement may be required in the top of the overhang than would be required if a normal cantilevered beam is assumed.

15.11 Temperature and Shrinkage Reinforcement

Temperature and shrinkage reinforcement design shall be in accordance with NYSDOT LRFD Bridge Design Specifications with the following additions.

Exposed faces of abutments, walls, and solid piers shall be provided with a minimum reinforcement of #16 bars at 450 mm placed vertically and #16 bars at 300 mm placed horizontally to resist temperature and shrinkage stresses.

The rear faces of abutments and walls shall be provided with a minimum reinforcement of #16 bars at 450 mm in both directions.

15.12 Protecting Reinforcement from Corrosion

Corrosion of reinforcing steel is a major concern for an aging infrastructure. Repairing and replacing damaged concrete caused by rusting reinforcing steel requires time, money and an imposition on the traveling public. There are technologies that slow or prevent this corrosion but this protection comes at a price. A balance must be struck between the higher initial cost of these technologies and the long term benefits of enhanced performance. As such, use of these technologies should not be indiscriminately included where the costs obviously outweigh the perceived benefit. However, the designer is encouraged to investigate the applicability of these technologies and recommend their use where appropriate.

The designer has three choices available for protecting reinforcement: corrosion inhibitors, coating the reinforcement (epoxy, galvanized) and corrosion resistant metal (stainless). The decision of which protection(s) to specify is dependent on a variety of factors including location within a structural element, cost, durability, ease of placement, expected service life, and importance of the structure. See the Prestressed Concrete Construction Manual (PCCM) for details on corrosion inhibitors.

In general, uncoated (plain) steel is the most economical choice when the concrete members provide adequate cover, and the reinforcement is not exposed to chlorides or other severe environments. For most other applications, epoxy or galvanized reinforcement is the proper choice.

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Solid stainless steel and stainless steel clad reinforcement are appropriate when the added durability reduces cost, either long-term or during construction. This can occur when environmental conditions are particularly severe, when the cost of repairs is unusually high, due to heavy traffic or construction conditions, when design of concrete sections as uncracked under service load is not feasible and when cover is less than standard. In these situations solid stainless steel and stainless steel clad reinforcement will continue to be effective because it will not detrimentally corrode.

Examples of situations where other than plain, epoxy-coated or galvanized bars might be used include:

C Work on a signature structure where construction work is difficult and detracts from the image that the structure conveys about the surrounding community.

C High-volume roadways where the additional cost for more durable reinforcement is outweighed by the costs associated with traffic delays, safety of the workers and traveling public and costs to businesses served by that roadway.

C Extreme environments such as in a cap beam beneath an expansion joint or a substructure located in or near a body of salt water.

Although there are situations where use of a more durable reinforcing steel may be justified, the engineer must remember that the situations where epoxy-coated, galvanized and plain bars are the better choice are far more common. Use of solid stainless steel and stainless steel clad reinforcement is unnecessary in concrete members that have adequate cover, no exposure to chlorides, and corrosion protection methods are used such as low-permeability concrete or corrosion inhibitors.

Table 15-2 compares approximate current cost ratio estimates for reinforcing bars at the time of publication using plain reinforcing bars as a base. Please note that prices change over time and vary by geographic location. Designers should check current prices when cost is a consideration.

Bar Protection Type In-Place Cost Ratio

Solid Stainless Steel 2.0

Stainless Steel Clad 1.6

Galvanized 1.1

Epoxy Coated 1.1

Plain 1.0

Table 15-2 Approximate Reinforcement Cost Comparison

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A review of the average bid prices (in place costs) indicates that the cost to fabricate, ship, and place plain reinforcing bars is $1.23/kg over the material cost. The cost to fabricate, ship, and place epoxy-coated bars is an additional $0.30/kg ($1.53/kg over the material cost) due to the extra care required during placement and repair to the epoxy coating after placement. In the above table, it was estimated that the cost to fabricate, ship, and place solid stainless steel bars is similar to the cost for plain bars and that the cost for stainless steel clad bars falls between the costs for plain and epoxy-coated bars.

Table 15-3 illustrates the expected service life for the different types of reinforcing bars in conventional concrete with standard cover exposed to a corrosive environment:

Bar Protection Type Expected Service Life

Solid Stainless Steel 100+

Stainless Steel Clad 75

Galvanized 30

Epoxy Coated 30

Plain 10

Table 15-3 Expected Service Life

These values are approximate and are based on information obtained from industry sources, university research studies, and professional journals.

15.12.1 Epoxy-Coated Reinforcement

Epoxy-coated reinforcement is the most frequently used type of corrosion protected reinforcement. Extra care is required during placement of epoxy coated reinforcement. Repair is required of epoxy coating that is damaged before or during placement. If there is a mix of uncoated and coated reinforcements in the same structural element epoxy coated reinforcement is the preferred alternative.

15.12.2 Galvanized Reinforcement

Galvanized reinforcement may be used anywhere corrosion protected reinforcement is required as long as it is not mixed with uncoated bars in the same structural element. When uncoated bars are used in the same element with galvanized bars, the zinc on the galvanized bar sacrifices itself to protect the uncoated bar. This results in a reduced service life after the zinc is consumed and corrosion and spalling can develop.

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Galvanized bars shall not be used in prestressed beams. The current standard is to use calcium nitrite corrosion inhibitor in prestressed elements, which negates the need for other corrosion protection measures.

The standards for reinforcing bars are given in ASTM A615 and A996. These documents include the minimum dimensions for bending the various diameters and grades of bars. Unfortunately, some of these dimensions are not suitable for galvanized reinforcing bars. The bends sometimes have microcracking that is exacerbated by the galvanizing process, resulting in reinforcing that can be broken by hand.

The standard bends for galvanized reinforcing bars are given in ASTM A767. To make matters confusing for the designers, some of the bends in A767 are larger and some are smaller than the comparable bends in A615.

To avoid problems, the minimum bend diameters in both standards need to be met.

Table 15-4 gives the minimum bend diameters that should be used for detailing reinforcing when galvanized reinforcing is specified. The bar list program (Barlist.EXE) will account for these changes when the bar is coded as galvanized.

For galvanized bar sizes up to and including #19 (¾") the bend diameter for end hooks is the same. Because of this, no change will be required for most bridge deck applications of galvanized reinforcing.

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End Hook Stirrup or Tie Hooks Seismic Stirrup or Tie Hooks

180E 90E 135E 90E 135E Bar Size

Bar Diameter A or G J A or G A or G H A or G A or G H

10 9.5 125 80 150 105 65 105 115 80 13 12.7 150 105 200 130 80 130 130 80 16 15.9 175 130 250 165 95 160 165 95

19 19.1 200 155 300 205 115 305 205 115 22 22.2 275 220 380 260 140 380 260 140 25 25.4 330 250 430 295 165 430 295 165

29 28.7 375 300 475 32 32.3 425 335 550 36 35.8 475 375 600

43 43 675 550 815 57 57.3 925 725 1050

Table 15-4 HOOKS FOR GALVANIZED BARS

15.12.3 Stainless Steel Clad Reinforcement

The use of stainless steel clad reinforcement requires approval by the D.C.E.S. due to limited field experience and will be considered on a case by case basis. Bends, development length, and lap splice requirements are similar to plain bars.

The primary difference between stainless steel clad and solid stainless steel is that stainless steel clad has a plain core that must be protected after cutting, leading to increased time and effort in the field. If this operation is not performed well, there is some risk that the inner core could corrode.

Stainless steel clad reinforcement may be applicable in extreme environments such as in a cap beam beneath an expansion joint or a substructure unit located near or in a body of salt water. Stainless steel clad reinforcement is also applicable in superstructure deck slabs. When used in a superstructure deck slabs, both reinforcement mats shall be stainless steel clad reinforcement.

NYSDOT Bridge Manual

15-20 January, 2008

15.12.4 Solid Stainless Steel Reinforcement

The use of solid stainless steel reinforcement requires approval by the D.C.E.S. due to its substantial cost and will be considered on a case by case basis. Bends, development length, and lap splice requirements are similar to plain bars.

Solid stainless steel reinforcement is applicable to every situation where galvanized or stainless steel clad would be used. The extremely high cost for this added protection should be a strong consideration when contemplating using solid stainless steel reinforcement.

15.12.5 Protection of Reinforcement in Substructures

Corrosion-resistant reinforcement shall be used for the faces of substructure components that are exposed to chlorides. It is typically not necessary to use corrosion-resistant reinforcement in the rear faces of retaining walls and abutments. A substructure face is considered to be exposed to chlorides as described below.

1. Footings immersed in seawater are considered to be exposed to chlorides on all faces. All other footings are not considered to be exposed to chlorides.

2. Reinforcement extending from the footing into substructure components shall be considered exposed to chlorides if that substructure face is also considered exposed to chlorides.

3. A substructure face is considered exposed to chlorides from water containing de-icing salts if the substructure is located under:

• an open steel grating deck. • any bridge deck joint system. • a bridge deck with an open railing.

Exception: The primary longitudinal reinforcement in cap beams of piers shall not have an epoxy coating. This exception is made to improve the bond between the reinforcement and concrete for better crack control. Shear and vertical reinforcement shall follow the normal criteria.

4. A substructure is considered to be exposed to chlorides from splash or spray of water containing de-icing salts from the roadway below if the substructure is located within 9 m horizontally of the edge of the under roadway pavement. Exception: If the substructure is tall, reinforcing bars beginning with the first splice at 5 m or higher above the pavement are not considered to be exposed.

5. A substructure is considered to be exposed to chlorides from splash or spray of seawater if the substructure is located within 9 m horizontally of the edge of seawater at mean high water or, within 30 m horizontally of the edge of seawater if large waves frequently exceed the mean high water level. Exception: If the substructure is tall, reinforcing bars beginning with the first splice at 5 m or higher above mean high water are not considered to be exposed. The height shall be increased to 15 m above mean high water where large waves frequently exceed the mean high water level.

Concrete Reinforcement

January, 2008 15-21

6. All substructure components immersed in seawater are considered to be exposed to chlorides on all faces.

15.13 Reinforcing Bar Lists

Contract Plans shall include reinforcing bar lists. Contract Plans without reinforcing bar lists are no longer allowed.

15.14 Drilling and Grouting

Two specifications are currently available for use when drilling and grouting of anchor rods (bolts or reinforcing bars) is required. The specifications are 586.01 Drilling and Grouting Bolts or Reinforcing Bars and 586.20xxyy__16 Drilling and Grouting Anchor Bars in Concrete, where:

xx = 01 for fully threaded anchor bolts

xx = 02 for a reinforcing bar

yy = diameter in millimeters

Specification 586.20xxyy__16 shall be used when it is determined that proof testing of the installation will be required, and where there are not sustained tensile loads and/or overhead applications. Proof testing is defined as random pullout testing of installed anchor rods. Some examples of where proof load testing is required for this specification include the following:

1. Attaching replacement bridge railing.

2. Inserting anchor rods into an existing footing and splicing to vertical reinforcing bars for a new column.

3. Anchoring bearings that could be subjected to uplift.

4. Attaching signs to fascias of bridges.

Specification 586.20xxyy__16 is in the process of being incorporated into the Standard Specifications. Specification 586.01 shall be used when it is determined that proof load testing is not required. Some examples of where proof load testing of anchor rods is not required include:

1. Rods are in compression under all load cases.

2. Anchorage of temperature and shrinkage steel

3. Resisting shear forces only

4. Used to tie an existing wall to a new one.

NYSDOT Bridge Manual

15-22 January, 2008

A third specification is currently under development that shall be used for sustained tensile load and/or overhead applications including any vertical applications where failure would result in risk or injury to the public. This specification will eliminate the option of using §701−07 Anchoring Materials – Chemically Curing in these situations. Contact the Bridge Standards Unit for additional guidance when requiring this specification.

Several factors play a role in determining embedment depths including edge distances and bar spacing. Due to the complexity of determining these depths, it is recommended that designers consult the Bridge Standards Unit when drilling and grouting is required.