Section 5 Reinforced Concrete 5.1 Basics of Reinforced Concrete 1 PCA Video, VC114 ’88 Mod ‘07: Fundamentals 3 of Reinforcing and Prestressed Concrete Structural Engineering Concepts 4 Reinforcement Inspection 10 CRSI Video, Mod ‘08: Field Inspection of 11 Reinforcing Bars WCI Video: Jobsite Handling of Epoxy Coated 21 Rebar CRSI: MSP Chp. 8, Placing Reinforcing Bars 22 Bar Supports 24 Bar Ties 27 Clearances 29 Splices 37 Reinforced Concrete Section 5.1 Concrete Cracks Basics of Reinforced Concrete • Concrete is strong in compression and weak in tension. Compression Tension • Tensile capacity is approximately 10% of the compressive strength of concrete. January, 2020 1 Reinforced Concrete Section 5.1 Beam Exercise Basics of Reinforced Concrete Cont’d: • Steel reinforcement is strong in tension. • Reinforcement is added to carry tensile loads in concrete members. • Temperature reinforcement is added to carry tensile loads due to thermal expansion of concrete members. January, 2020 2 Reinforced Concrete Section 5.1 Why Use Rebar? Simply supported beam example Applied Load View PCA Video Fundamentals of Reinforcing and Prestressed Concrete (PCA VC114 ’88 Mod ‘07) January, 2020 3 Reinforced Concrete Section 5.1 Structural Engineering Concepts Shear & Moment Diagram Uniformly Loaded Simple Beam January, 2020 4 Reinforced Concrete Section 5.1 Maximum Shear Load at Bridge Ends and Piers Larger Stirrup Spacing @ Midspan Tighter Stirrup Spacing Near Abutments Tighter Stirrup Spacing at Beam Ends January, 2020 5 Reinforced Concrete Section 5.1 Shear & Moment Diagram Uniformly Loaded Continuous 3 Span Uniformly Loaded Continuous Beam 3 Spans Maximum negative moment in deck over piers. Additional longitudinal reinforcement added in top mat. January, 2020 6 Reinforced Concrete Section 5.1 Beam Capacity Strength of the Beam Beam Cross-section Beam Side View M = Astfy(d-1/2a) = 0.85fc′ab(d-1/2a) January, 2020 7 Reinforced Concrete Section 5.1 Case Study I-25: Walnut Street Denver, CO January, 2020 8 Reinforced Concrete Section 5.1 Thoughts? Deck To Be Placed Later Construction Joint I-25: Walnut Street Pier Collapse January, 2020 9 Reinforced Concrete Section 5.1 Pier Collapse I-25: Walnut Street, Denver, CO Oct. 4, 1985 Fatalities: 1 Injuries: 4 Reinforcement Inspection January, 2020 10 Reinforced Concrete Section 5.1 View CRSI Video CRSI Field Insp Reinf Bars Mod 08 Type of Reinforcement • Source • Certifications • Grade • Epoxy coated or uncoated or stainless January, 2020 11 Reinforced Concrete Section 5.1 Documentation Bills of material – what was delivered Certifications Rebar (steel) mill certificate January, 2020 12 Reinforced Concrete Section 5.1 January, 2020 13 Reinforced Concrete Section 5.1 English Rebar Numbers • #3 - #8; Diameter in 1/8″ units #8/8 = 1″ dia. • #9 - #18; Based on area of square bars formerly used with sides of 1″, 1-1/8″, 1-1/4″, 1-1/2″ & 2″ and then rounded to closest 1/8″ unit diameter. Metric to English Bar Conversion • (Bar # - 1) divided by 3 then round to nearest english bar # • #25 metric = (25-1)/3 = #8 english January, 2020 14 Reinforced Concrete Section 5.1 QPL Appendix A http://www.oregon.gov/ODOT/HWY/CONSTRUCTION/QPL/Docs/QPL.pdf Rebar Exercise Mill: Size: Dia: Type: Grade: January, 2020 15 Oregon DOT – QPL (July 2019) Attachment “A” Approved Rebar Producers (English Units) Page A 1 Appendix A—Approved Reinforcing Steel Producers The ASTM specifications for billet-steel and low-alloy reinforcing bars (A615 and A706, respectively) require identification marks to be rolled into the surface of one side of the bar to denote the producer’s mill designation, bar size, type of steel and minimum yield designation. Grade 420 bars show these marks in the following order: 1st ---Producing Mill (usually a letter) 2nd --- Bar Size Number (# 4 through # 18) 3rd --- Type of Steel: S Billet (A 615) W for Low Alloy ( A 706) 4th ---Minimum Yield Designation The minimum yield designation for Grade 420 bars is either one (1) single, longitudinal line (grade line) or the number 4 (grade mark). A grade line is smaller and is located between the two main ribs, which are on opposite sides of all bars made in the United States. A grade line must be continued through at least 5 deformation spaces, and it may be placed on the side of the bar opposite the bar marks. A grade mark is the fourth mark on the bar. VARIATIONS: Bar identification marks may also be oriented to read horizontally (90° to those illustrated). Grade numbers may be placed within consecutive deformation spaces to read vertically or horizontally. The Identification marks for the Approved Producers are shown in the following figures. Rebar grades shown on these pages are for reference only. Check the specs for the appropriate requirements. Oregon DOT – QPL (July 2019) Oregon DOT – QPL (July 2019) Attachment “A” Approved Rebar Producers (English Units) Page A 2 ArcelorMittal Vinton, Inc. El Paso Texas ODOT # 1841 Nucor Steel Utah ODOT # 1112 Oregon DOT – QPL (July 2019) Oregon DOT – QPL (July 2019) Attachment “A” Approved Rebar Producers (English Units) Page A 3 CMC Steel Mesa Arizona ODOT #4118 Oregon DOT – QPL (July 2019) Oregon DOT – QPL (July 2019) Attachment “A” Approved Rebar Producers (English Units) Page A 4 Nucor Steel Seattle Washington ODOT # 2935 Oregon DOT – QPL (July 2019) Oregon DOT – QPL (July 2019) Attachment “A” Approved Rebar Producers (English Units) Page A 5 Optimus Beaumont Texas ODOT #4838 Oregon DOT – QPL (July 2019) Oregon DOT – QPL (July 2019) Attachment “A” Approved Rebar Producers (English Units) Page A 6 CMC Steel California ODOT #1842 Was Gerdau @ Rancho Cucamonga California Oregon DOT – QPL (July 2019) Oregon DOT – QPL (July 2019) Attachment “A” Approved Rebar Producers (English Units) Page A 7 CMC Steel California ODOT #1842 Was Gerdau @ Rancho Cucamonga California Oregon DOT – QPL (July 2019) Oregon DOT – QPL (July 2019) Attachment “A” Approved Rebar Producers (English Units) Page A 8 Gerdau St. Paul Minnesota ODOT # 1623 Oregon DOT – QPL (July 2019) Oregon DOT – QPL (July 2019) Attachment “A” Approved Rebar Producers (English Units) Page A 9 Cascade Steel Mc- Minnville Oregon ODOT # 1111 Oregon DOT – QPL (July 2019) Oregon DOT – QPL (July 2019) Attachment “A” Approved Rebar Producers (English Units) Page A 10 A706/A615 GRADE 60 REBARS MARKINGS Rebar sizes: #3 thru #6 NUCOR STEEL – KINGMAN, AZ ODOT #4356 Current SI Marking New IN-LBS Oregon DOT – QPL (July 2019) Oregon DOT – QPL (July 2019) Attachment “A” Approved Rebar Producers (English Units) Page A 11 EVRAZ INC, NA PUEBLO, COLORADO ODOT #1621 (COILED REBAR #3-#6) Oregon DOT – QPL (July 2019) Oregon DOT – QPL (July 2019) Attachment “A” Approved Rebar Producers (English Units) Page A 12 NUCOR-BAURBONNAIS (KANKAKEE) ODOT #4943 (BAR SIZE #3-#11) Oregon DOT – QPL (July 2019) Oregon DOT – QPL (July 2019) Attachment “A” Approved Rebar Producers (English Units) Page A 13 CMC STEEL-DURANT OKLAHOMA #4-#11 STRAIGHT #3-#6 COILED ODOT #5138 Oregon DOT – QPL (July 2019) Oregon DOT – QPL (July 2019) Attachment “A” Approved Rebar Producers (English Units) Page A 14 ASTM A1035 CS (AAHSTO M334) ChrǀmX 9100 SIZE #3-#8 PRODUCED BY: CASCADE STEEL ROLLING MILLS, INC. ODOT #3517 Oregon DOT – QPL (July 2019) Reinforced Concrete Section 5.1 Rebar Exercise Mill: Size: Dia: Type: Grade: Size & Shape • Bar size • Bar length • Bar shape (correct radius) • Agrees with shop drawings January, 2020 16 Reinforced Concrete Section 5.1 REBAR MATERIAL TAG AB A. Quantity B. Size C C. Bend diagram D. Project D E. Bar ID or mark → Verify E Doubled Up Horizontal Bars in Abutment? January, 2020 17 Reinforced Concrete Section 5.1 Hooked Bar in Middle of Deck by Itself? Rebar Condition January, 2020 18 Reinforced Concrete Section 5.1 Condition • Look for any loose scale or rust, grease, oil, paint, or other foreign material that could harm the bond with the concrete. • Properly stored off the ground to avoid water and mud which can cause corrosion. • Do not use cracked or split bars (look at bends). • Look for epoxy damage. Field Bent Bars? January, 2020 19 Reinforced Concrete Section 5.1 Epoxy Damage Rebar Jobsite Storage Total exposure time of epoxy-coated bar in storage or in place is not to exceed 2 months without covering. (530.40) Epoxy breaks down under prolonged UV exposure – it gets chalky January, 2020 20 Reinforced Concrete Section 5.1 Faded Epoxy & Bare Ties? View WCI Video Jobsite Handling Epoxy Coated Rebar January, 2020 21 Reinforced Concrete Section 5.1 Layout • Number • Spacing • Alignment Placement Tolerances according to “Manual of Standard Practice” 530.41 January, 2020 22 Reinforced Concrete Section 5.1 Effective Depth “d” Distance from the compression face of the beam to the centroid of the reinforcement Transverse Bar Alignment Shift? January, 2020 23 Reinforced Concrete Section 5.1 Longitudinal Bar Alignment Shift? Bar Supports January, 2020 24 Reinforced Concrete Section 5.1 Rail Stirrup Height Uneven? Transverse Deck Bars Drop at Corner? January, 2020 25 Reinforced Concrete Section 5.1 Bar Supports 00530.41(b) & (c) 2′ Centers (plans) Concrete blocks (Dobies) or other approved devices No rocks, broken brick, or wood Bar Supports Plans, General Notes Support the bottom mat reinforcing steel from the forms with precast mortar blocks at 24” max. centers each way. Support the top mat reinforcing steel from the bottom mat reinforcing steel with wire bar supports as shown in Chapter 3 of the CRSI Manual of Standard Practice (SBU, BBU or CHCU). Place wire bar supports at 24” max. centers. January, 2020 26 14871 Contract Plans 195/468 Reinforced Concrete Section 5.1 Large Support Spacing Caused Epoxy Ties to Unzip Ties January, 2020 27 Reinforced Concrete Section 5.1 Top mat of Ties footings & 00530.41(b) decks: Tie 100% Epoxy coated ties for epoxy rebar If spacing < 6″ Tie 50% Other locations: Tie 100% If spacing < 1′ Tie 50% No Ties for Up to 10 Feet? January, 2020 28 Reinforced Concrete Section 5.1 Missing Ties Clearances January, 2020 29 Reinforced Concrete Section 5.1 Concrete Cover Affects Rebar Corrosion Concrete cover Clearances • Within tolerances recommended in CRSI’s Manual of Standard Practice, Chapter 8 unless otherwise specified.