Proposed Revisions to Part 2, Sections 2.13 to Draft DEVELOPMENT AND SPLICES OF REINFORCEMENT SECTION 2.13 DEVELOPMENT REQUIREMENTS

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1 Proposed Revisions to Part 2, Sections 2.13 to 2.22 Reason for changes: To update the provisions for development and splices of reinforcement. These are to be added to the Nomenclature for Part 2. ldb = basic development length for deformed bars and deformed wire in tension, inches (mm). ldt = basic development length for headed and mechanical anchored deformed bars in tension, inches (mm) GENERAL (2017) DEVELOPMENT AND SPLICES OF REINFORCEMENT SECTION 2.13 DEVELOPMENT REQUIREMENTS a. The calculated tension or compression in the reinforcement at each section shall be developed on each side of that section by embedment length, standard hook, headed deformed bar, mechanical device, or end anchorage, or a combination thereof. For bars in compression, hooks and headed deformed bars shall not be used to develop bars. b. Tension reinforcement may be anchored by bending it across the web and making it continuous with the reinforcement on the opposite face of the member, or anchoring it there. c. Critical sections for development of reinforcement in flexural members are at points of maxim um stress and at points within the span where adjacent reinforcement terminates, or is bent. The provisions of Article c must also be satisfied. d. 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, 15 bar diameters, or 1/20 of the clear span, whichever is greater, except at supports of simple spans and at the free end of cantilevers. e. No more than 50 percent of the reinforcement shall be terminated at any section and adjacent bars shall not be terminated in the same section. This provision does not apply to base of columns. f. 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. g. Flexural reinforcement located within the width of a member used to compute the shear strength shall not be terminated in a tension zone unless one of the following conditions is satisfied. (1) Shear at the cutoff point does not exceed two-thirds of the design shear strength, ΦVn including the shear strength of furnished shear reinforcement. (2) Stirrup area in excess of that required for shear is provided along each terminated bar over a distance from the termination point equal to three-fourths the effective depth of the member. The excess stirrup area shall

2 not be less than 60bws/fy (or 0.41 bws/fy in metric). The resulting spacings shall not exceed d/(8βb), where βb is the ratio of the area of bars cut off to the total area of bars at the section. (3) For #11 (#36) and smaller bars, the continuing bars provide double the area required for flexure at the cutoff point and shear does not exceed three-fourths of the design shear strength, ΦV n POSITIVE MOMENT REINFORCEMENT (2017) a. At least one-half the positive moment reinforcement in simple members and one-fourth the positive moment reinforcement in continuous members shall extend along the same face of the member into the support. In beams, such reinforcement shall extend into the support a distance of 12 or more bar diameters (but not less than 6 inches (150mm)), or shall be extended as far as possible into the support and terminated in standard hooks or other adequate anchorage. b. When a flexural member is part of the lateral load resisting system, the positive reinforcement required to be extended into the support by Article a shall be anchored to develop the full fy in tension at the face of the support. c. At simple supports and at points of inflection, positive moment tension reinforcement shall be limited to a diameter such that ld computed for fy by Section 2.14 satisfies EQ 2-8; except EQ 2-8 need not be satisfied for reinforcement terminating beyond centerline of simple supports by a standard hook, or a mechanical anchorage at least equivalent to a standard hook. where: EQ 2-8 M = the computed moment capacity assuming all positive moment tension reinforcement at the section to be fully stressed V = the maxim um applied design shear at the section la = the embedment length beyond center of support or point of inflection la at a point of inflection shall be limited to the effective depth of the member or 12db, whichever is greater. The value of M/V in the development length limitation may be increased 30% when the ends of the reinforcement are confined by a compressive reaction NEGATIVE MOMENT REINFORCEMENT (1994) a. Tension 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. b. Negative moment reinforcement shall have an embedment length into the span as required by Article 2.13.l a and Article 2.13.l d. c. At least one-third the total reinforcement provided for negative moment at the support shall have an embedment length beyond the point of inflection not less than the effective depth of the member, 12 bar diameters, or onesixteenth of the clear span, whichever is greater SPECIAL MEMBERS (1994) Adequate end anchorage shall be provided for tension reinforcement in flexural members where reinforcement stress is not directly proportional to moment, such as: sloped, stepped, or tapered footings; brackets; deep beams; or members in which the tension reinforcement is not parallel to the compression face.

3 SECTION 2.14 DEVELOPMENT LENGTH OF DEFORMED BARS AND DEFORMED WIRE IN TENSION (2017) Development length ld, in inches (mm), of deformed bars and deformed wire in tension shall be computed as the product of the basic development length ldb of Section 2.14a and the applicable modification factor or factors of Section 2. 14b through Section 2.14f, but ld shall be not less than that specified in Section 2. 14g. a. The basic development length shall be taken as: ldb = dbfy/ f c EQ ldb = dbfy/ f c Table has been removed b. The basic development length shall be multiplied by a factor of 1.4 for top reinforcement. NOTE: EQ 2-8.1M Top reinforcement is horizontal reinforcement so placed that more than 12 inches (300 mm) of concrete is cast in the member below the bar. c. When lightweight aggregate concrete is used, the basic development length in Section 2.14a shall be multiplied by 1.3. The factors of Section 2.14b and Section 2.14d shall also be applied. d. The basic development length ldb shall be multiplied by the modification factor, λrc, which shall satisfy the following: 0.4 λrc = db/(cb+ktr) 1.0 in which, ktr = 40 Atr/(sn) where: λrc = reinforcement confinement factor cb = the smaller of the distance from center of bar or wire being developed to the nearest concrete surface and one-half the center-to-center spacing of the bars or wires being developed (in.) ktr = transverse reinforcement index Atr = total cross-sectional area of all transverse reinforcement, which is within the spacing, s, and which crosses the potential plane of splitting through the reinforcement being developed (in 2 ) s = maximum center-to-center spacing of transverse reinforcement within ld (in) n = number of bars or wires developed along plane of splitting e. Where anchorage or development for the full yield strength of reinforcement is not required, or where reinforcement in flexural members is in excess of that required by analysis, the basic development length shall be multiplied by (As required)/(as provided). f. The basic development length for bars coated with epoxy with cover less than 3 bar diameters or clear spacing between bars less than 6 bar diameters shall be multiplied by a factor of 1.5. The basic development length for all other epoxy coated bars shall be multiplied by a factor of 1.2. The product obtained when combining the factor for top reinforcement with the applicable factor for epoxy coated reinforcement need not be taken greater than 1.7.

4 g. The development length ld shall be taken as not less than 12 inches (300 mm) except in the computation of lap spl ices by Article and anchorage of shear reinforcement by Section Figure has been removed SECTION 2.15 DEVELOPMENT LENGTH OF DEFORMED BARS IN COMPRESSION (2017) The development length ld for bars in compression shall be computed as 0.02f ydb/ ( f c) (or f ydb/ 4( f c) in metric), but shall not be less than fydb or 8 inches (or 0.04 dbfy in metric or 200 mm). Where excess bar area is provided the ld length may be reduced by the ratio of required area to area provided. The development length may be reduced 25% when the reinforcement is enclosed by spirals not less than 1/4 inch (6 mm) in diameter and not more than 4-inch (100 mm) pitch. SECTION 2.16 DEVELOPMENT LENGTH OF BUNDLED BARS (2016) a. The development length of each bar of bundled bars, in tension or compression, shall be that for the individual bar, increased by 20% for a 3-bar bundle, and 33% for a 4-bar bundle. b. For determining the appropriate factors specified in Sections 2.14 and 2.15, a unit of bundled bars shall be treated as a single bar of a diameter determined from the equivalent total area and a centroid that coincides with that of the bundled bars. SECTION 2.17 DEVELOPMENT OF STANDARD HOOKS IN TENSION (2017) a. Development length ldh in inches (mm), for deformed bars in tension terminating in a standard hook (Article 2.4.1) shall be computed as the product of the basic development length lhb of Section 2. 17b and the applicable modification factor or factors of Section 2.17c but ldh shall not be less than 8db or 6 inches (150 mm), whichever is greater. b. Basic development length lhb for a hooked bar shall be 1200dbfy/(60,000 f c) (or 100dbfy/(420 f c) in metric). c. Basic development length lhb shall be multiplied by applicable modification factor or factors for: ( 1 ) Epoxy-coated reinforcement. 1.2 (2) Concrete cover For #11 (#36) bar and smaller, side cover (normal to plane of hook) not less than 2-1/2 inches (60 mm), and for 90-degree hook, cover on bar extension beyond hook not less than 2 inches (50 mm) 0.8 (3) Ties or stirrups i. For 90-degree hooks of #11 (#36) and smaller bars that are either enclosed within ties or stirrups perpendicular to the bar being developed, spaced not greater than 3db along the development length, ldh of the hook; or enclosed within ties or stirrups parallel to the bar being developed spaced not greater than 3db along the length of the tail extension of the hook plus bend, and in both cases the first tie or stirrup enclosing the bent portion of the hook within 2db of the outside of the bend (Figure 8-2-3). 0.8 ii. For 180-degree hooks of #11 (#36) and smaller bars that are enclosed within ties or stirrups perpendicular to the bar being developed, spaced not greater than 3db along the development length, ldh, of the hook, and the first tie

5 or stirrup enclosing the bent portion of the hook is within 2db of the outside of the bend (4) Excess reinforcement Where anchorage or development for fy is not specifically required, or where (As required) reinforcement is provided in excess of that required by analysis (As provided) (5) Lightweight aggregate concrete d. For bars being developed by a standard hook at discontinuous ends of members with both side cover and top (or bottom) cover over hook less than 2-1/2 inches (60 mm), hooked bar shall be enclosed within ties or stirrups spaced along full development length /dh not greater than 3db, where db is diameter of hooked bar (Figure 8-2-3). For this case, factor of Section 2. 17c(3) shall not apply. e. Hooks shall not be considered effective in developing bars in compression.

6 Information deleted in 1990 revision. Figure Standard Hook Bars and Tie Requirements SECTION 2.18 COMBINATION DEVELOPMENT LENGTH SECTION 2.19 DEVELOPMENT OF WELDED WIRE REINFORCEMENT IN TENSION DEFORMED WIRE REINFORCEMENT (2017) a. Development length ld, in inches (mm), of welded deformed wire reinforcement measured from point of critical section to end of wire shall be computed as the product of the basic development length of Article l b or Article lc and applicable modification factor or factors of Section 2. 14b, Section 2. 14c and Section 2. 14d; but ld shall not be less than 8 inches (200 mm) except in computation of lap splices by Article and development of shear reinforcement by Section b. Basic development length of welded deformed wire reinforcement, with at least one cross wire within the development length not less than 2 inches (50 mm) from point of critical section, shall be 0.03db(f y - 20,000)/ f c NOTE: The 20,000 has units of psi. EQ db(f y - 140)/ f c NOTE: The 140 has units of MPa. EQ 2-9M but not less than (0.20Aw/sw)(fy/ f c) EQ 2-10 (2.4Aw/sw)(fy/ f c) EQ 2-10M c. Basic development length of welded deformed wire reinforcement, with no cross wires within the development length, shall be determined as for deformed wire in accordance with Article 2.14a PLAIN WIRE REINFORCEMENT (2017)

7 Yield strength of welded plain wire reinforcement shall be considered developed by embedment of two cross wires with the closer cross wire not less than 2 inches (50 mm) from point of critical section. However, development length ld measured from point of critical section to outermost cross wire shall not be less than (0.27Aw/sw)(fy/ f c) EQ 2-11 (3.24Aw/sw)(fy/ f c) EQ 2-11M modified by a factor of Section 2.14c for lightweight aggregate concrete and a factor of Section 2.14e for excess reinforcement, but ld shall not be less than 6 inches (150 mm), except in computation of lap splices by Article SECTION 2.20 DEVELOPMENT OF HEADED AND MECHANICALLY ANCHORED DEFORMED BARS IN TENSION (2017) a. Development length for headed deformed bars in tension, ld shall be determined from (b). Use of heads to develop deformed bars and tension shall be limited to conditions satisfying (1) through (6): (1) Bar fy shall not exceed 60,000 psi (420 MPa); (2) Bar size shall not exceed #11 (#36); (3) Concrete shall be normal weight; (4) Net bearing area of head Abrg shall not be less than 4Ab; (5) Clear cover for bar shall not be less than 2db; and (6) Clear spacing between bars shall not be less than 4db. b. For headed deformed bars satisfying ASTM A970 including Appendix A, Requirements for Class HA Headed Dimensions, development length in tension ldt shall be (0.016Ψefy/( f 'c))db (or (0.19Ψefy/( f 'c))db in metric), where the value of f 'c used to calculate ldt shall not exceed 6000 psi (40 MPa) and the factor Ψe shall be taken as 1.2 for epoxycoated reinforcement and 1.0 for other cases. Length ldt shall not be less than the larger of 8db or 6 in. (150mm). c. Heads shall not be considered effective in developing bars in compression. d. Any mechanical attachment or device capable of developing fy of deformed bars is allowed, provided that test results showing the adequacy of such attachment or device is approved by the Engineer. e. Development of deformed bars shall be permitted to consist of a combination of mechanical anchorage plus additional embedment length of deformed bars between the critical section and the mechanical attachment or device. f. If mechanical anchorages are to be used, complete details shall be shown in the contract documents. SECTION 2.21 ANCHORAGE OF SHEAR REINFORCEMENT (2017) a. Shear reinforcement shall extend to a distance d from the extreme compression fiber and shall be carried as close to the compression and tension surfaces of the member as cover requirements and the proximity of other reinforcement permit. Shear reinforcement shall be anchored at both ends for its design yield strength. b. The ends of single leg, single U-stirrup, or multiple U-stirrups, shall be anchored by one of the following means: ( 1 ) For #5 (#16) bar and D31 wire, and smaller, and for #6, #7, and #8 (#19, #22, and #25) bars with fy of 40,000 psi (280 MPa) or less, a standard hook around longitudinal reinforcement. (2) See Figure For #6, #7, and #8 (#19, #22, and #25) stirrups with fy greater than 40,000 psi (280 MPa), a standard hook around a longitudinal bar plus an embedment between mid-height of the member and the outside end of the hook equal to or greater than 0.014dbfy / f c(or 0. 17dbfy / f c in metric). (3) For each leg of welded plain wire reinforcement forming a single U-stirrup, either: (a) Two longitudinal wires spaced at 2-inch (50 mm) spacing along the beam at the top of the U-stirrup. (b) One longitudinal wire located not more than d/4 from the compression face and a second wire closer to the compression face and spaced at least 2 inches (50 mm) from the first wire. The second wire may be located

8 beyond a bend or on a bend which has an inside diameter of at least 8 wire diameters. (4) For each end of a single leg stirrup of welded plain or deformed wire reinforcement, two longitudinal wires at a minimal spacing of 2 inches (50mm) and with the inner wire at not less than d/4 or 2 inches (50mm) from mid-depth of the member shall be provided. The outer longitudinal wire at the tension face shall not be farther from the face than the portion of the primary flexural reinforcement closest to the face. c. Pairs of U-stirrups or ties so placed as to form a closed unit shall be considered properly spliced when the laps are 1.3 l d. In members at least 18 inches (460 mm) deep, such splices with Abf y not more than 9,000 lbs/leg (40kN/leg) shall be considered adequate if stirrup legs extend the full depth of the member. d. Between the anchored ends, each bend in the continuous portion of a transverse single U-stirrup or multiple U-stirrups shall enclose a longitudinal bar. f. Longitudinal bars bent to act as shear reinforcement shall, in a region of tension, be continuous with the longitudinal reinforcement and in a compression zone shall be anchored, above or below the mid-depth d/2 as specified for development length in Section 2.14 for that part of the stress in the reinforcement needed to satisfy EQ Figure #6, #7, or #8 Stirrups (f y > 40,000 psi) (#19, #22, or #25 Stirrups (fy > 280 MPa))

9 SECTION 2.22 SPLICES OF REINFORCEMENT Splices of reinforcement shall be made only as shown on design drawings, or as specified, or as authorized by the Engineer LAP SPLICES (2016) a. Lap splices shall not be used for bars larger than # 1 1 (#36), for reinforcement in tension. b. Lap splices within a bundle, shall be as specified in Article Individual bar splices within a bundle shall not overlap. Entire bundles shall not be lap spliced. c. Bars spliced by noncontact lap splices in flexural members shall not be spaced center to center of bars transversely farther apart than the lesser of 1/5 the required lap splice length, nor 6 inches (150 mm) WELDED SPLICES AND MECHANICAL CONNECTIONS (2005) a. Welded splices and other mechanical connections may be used. Except as provided herein, all welding shall conform to "Structural Welding Code-Reinforcing Steel" (AWS D 1.4). b. A full welded splice shall have bars butted and welded to develop in tension at least 125% of specified yield strength fy of the bar. c. A full mechanical connection shall develop in tension or compression, as required, at least 125% of specified yield strength fy of the bar. d. Welded splices and mechanical connections not meeting requirements of Article b or Article c may be used in accordance with Article d SPLICES OF DEFORMED BARS AND DEFORMED WIRE IN TENSION (2017) The provisions herein shall be used for #11 (#36) bars or smaller in normal weight concrete. a. Minimum length of lap for tension lap splices shall be as required for Class A or Class B lap splices, but not less than 12 inches (300 mm), where: where: Class A lap splice = 1.0ld Class B lap splice = 1.3ld ld = the tensile development length for the specified yield strength fy in accordance with Section b. Except as specified herein, lap splices of deformed bars and deformed wire in tension, shall be Class B lap splices. Class A lap splices may be used where: (1) The area of reinforcement provided is at least twice that required by analysis over the entire length of the lap splice, and (2) One-half or less of the total reinforcement is spliced within the required lap splice length. c. Welded splices or mechanical connections used where area of reinforcement provided is less than twice that required by analysis shall meet requirements of Article b or Article c. d. Welded splices or mechanical connections not meeting the requirements of Article b or Article c shall be permitted for #5 (#16) bars or smaller if the following requirements are met: Table has been removed

10 (1) Splices shall be staggered at least 24 inches (600 mm) and in such manner as to develop at every section at least twice the calculated tensile force at that section but not less than 20,000 psi (140 MPa) for total area of reinforcement provided. (2) In computing tensile force developed at each section, spliced reinforcement may be rated at the specified splice strength, but not greater than fy. Unspliced reinforcement shall be rated at that fraction of fy defined by the ratio of the shorter actual development length to ld required to develop the specified yield strength fy. The stress in the unspliced reinforcement shall be taken as fy times the ratio of the shortest length embedded beyond the section to ld, but not greater than fy. e. Splices in "tension tie members" shall be made with a full welded splice or full mechanical connection in accordance with Articles b or c, and splices in adjacent bars shall be staggered at least 30 inches (750 mm) SPLICES OF DEFORMED BARS IN COMPRESSION (2017) a. Minimum length of lap for compression lap splices shall be fydb, in inches (or 0.07fydb in millimeters), but not less than 12 inches (300 mm). For f 'c less than 3000 psi (20 MPa), length of lap shall be increased by 1/3. b. When bars of different size are lap spliced in compression, splice length shall be the larger of the compression development length of the larger bar or compression lap splice length of the smaller bar. Lap splices of #14 (#43) and #18 (#57) to #11 (#36) and smaller bars shall be permitted. c. Welded splices or mechanical connections used in compression shall meet requirements of Article b or Article c END BEARING SPLICES (2017) a. In bars required for compression only, compressive stress may be transmitted by bearing of square cut ends held in concentric contact by a suitable device. b. Bar ends shall terminate in flat surfaces within 1-1/2 degrees of a right angle to the axis of the bars and shall be fitted within 3 degrees of full bearing after assembly. c. End bearing splices shall be used only in members containing closed ties, closed stirrups, or spirals SPLICE REQUIREMENTS FOR COLUMNS (2017) a. Lap splices, mechanical splices, butt-welded splices, and end-bearing splices shall be used with the limitations of Article b. A splice shall satisfy requirements for all load combinations for the column. b. Lap splices for columns: (1) Where the bar stress due to the factored loads is compressive, lap splices shall conform to Articles a, b, and where applicable, Article b(4) or Article b(5). (2) Where the bar stress due to factored loads is tensile and does not exceed 0.5 fy in tension, lap splices shall be Class B tension lap splices if more than one-half of the bars are spliced at any section, or Class A tension lap splice if half or fewer of the bars are spliced at any section and alternate lap splices are staggered by ld. (3) Where the bar stress due to factored loads is greater than 0.5fy in tension, lap splices shall be Class B tension lap splices. (4) In tied reinforced compression members, where ties throughout the lap splice length have an effective area not less than hs in both directions, lap splice length shall be multiplied by 0.83, but lap length shall not be less than 12 inches (300mm). Tie legs perpendicular to dimension h shall be used in determining effective area. (5) In spirally reinforced compression members, lap splice length of bars within a spiral may be multiplied by 0.75, but lap length shall not be less than 12 inches (300mm). (6) At footings, it shall be permitted to lap splice #14 (#36) and #18 (#43) longitudinal bars in compression only with dowels. Such dowels shall not be larger than #11 (#36) bars and shall extend into the supported member a distance not less than the larger of ld of the #14 (#43) and #18 (#57) bars or the compression lap splice length of the dowels. Such dowels shall extend into the footing a distance not less than ld of the dowels. c. Mechanical or welded splices in columns shall meet the requirements of Article b or Article c.

11 d. End-bearing splices in columns complying with Article , shall be permitted to be used for column bars stressed in compression provided the splices are staggered or additional bars are provided at spliced locations. The continuing bars in each face of the column shall have a tensile strength, based on fy not less than 0.25fy times the area of the vertical reinforcement in that face SPLICES OF WELDED DEFORMED WIRE REINFORCEMENT IN TENSION (2017) a. Minimum length of lap for lap splices of welded deformed wire reinforcement measured between the end of each reinforcement sheet shall not be less than 1.7ld nor 8 inches (200 mm), and the overlap measured between outermost cross wires of each reinforcement sheet shall not be less than 2 inches (50 mm). ld shall be the development length for the specified yield strength f y in accordance with Article b. Lap splices of welded deformed wire reinforcement, with no cross wires within the lap splice length, shall be determined as for deformed wire reinforcement. c. Where any plain wire reinforcement or deformed wire larger than D 31 is present in welded deformed wire reinforcement in the direction of the lap splice, or where welded deformed wire reinforcement is lap spliced to welded plain wire reinforcement, the reinforcement shall be lap spliced in accordance with Article SPLICES OF WELDED PLAIN WIRE REINFORCEMENT IN TENSION (2017) Minimum length of lap for lap splices of welded plain wire reinforcement shall be in accordance with the following: a. When area of reinforcement provided is less than twice that required by analysis at splice location, length of overlap measured between outermost cross wires of each reinforcement sheet shall not be less than one spacing of cross wire plus 2 inches (50 mm), nor less than 1.5ld nor 6 inches (150 mm). ld shall be the development length for the specified yield strength fy in accordance with Article b. When area of reinforcement provided is at least twice that required by analysis at splice location, length of overlap measured between outermost cross wires of each reinforcement sheet shall not be less than 1.5ld nor 2 inches (50 mm). ld shall be the development length for the specified yield strength fy in accordance with Article