Reinforcement 2 Purpose of Reinforcement Concrete properties Strong

Reinforcement

2 Purpose of Reinforcement • Concrete properties § Strong in compression § Weak in tension • Reinforcement supplies strength to withstand tensile and shear forces experienced by concrete

3 Compressive Forces on Concrete can withstand compression

4 Concrete Under Compression This 2” X 2” cube of concrete withstands a 4000 psi compressive force

5 Tensile Forces on Concrete Without reinforcement, concrete will fail in tension

6 Concrete in Tension The same 2” X 2” cube of concrete fails under a 400 psi tensile force

7 Non-reinforced Concrete Behavior

8 Flexural Forces on Concrete Without reinforcement, the bottom side will fail in tension

9 Reinforced Concrete Behavior

10 Concrete Behavior Under Shear • Vertical Shear

11 Concrete Behavior Under Shear • Horizontal shear, shear reinforcement

12 www. concrete-pipe. org

13 Steel Nomenclature • • As 1 = Sidewall outside face As 2 = Top slab inside face As 3 = Bottom slab inside face As 4 = Sidewall inside face As 5 = Top slab inside distribution steel As 6 = Top slab outside distribution steel As 7 = Top slab outside face As 8 = Bottom slab outside face

C 1577 14

15 Effectiveness of Placement

Effectiveness of Placement 1” cover vs. 1 -1/4” cover for various fill heights 16

Reinforcement Type and Identification

18 Reinforcement Types • Reinforcing bars • Reinforcing wire • Bar mats and welded wire fabric • Zinc or epoxy coated reinforcement • Prestressing and post tensioning v. All types must meet “Buy America” Requirements for federally funded projects.

19 Reinforcing Bars • Conform to specifications § § ASTM A 615 ASTM A 616 ASTM A 617 ASTM A 706 (New Billet) (Rail) (Axle) (Weldable) • Other bars may be used if permitted by design. • Mill certificates required for each shipment.

20 Grade 40 & 50 Rebar 6

21 Grade 60 & A 706 Rebar Type and Identification 4 4 4

Steel Area Using Different Combinations of Bar Sizes and Spacing 22

23 Reinforcing Wire • Conform to (except prestressing wire) § ASTM A 1064 • Other wire may be used if permitted by design. • Mill certificates for each shipment.

24 Bar Mats and Welded Wire Fabric • Conform to § ASTM A 184 § ASTM A 1064 • Mill certificates for each shipment. • Applications of rolled vs. straight

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Welded Wire Fabric

Welded Wire Fabric

Cage Basics Spacing between pipe longitudinals Area of one circumferential wire (. 025 sq. in. ) Length of roll 3 x 8 W 2. 5 x. W 2. 0 93”x 600’ 1/2 x 1/2 Overhangs Area of one longitud. Spacing between pipe inal wire (. 02 sq. in. ) Width of mesh – from top circumferentials to bottom circumferential W = Plain/Smooth, D = Deformed

29 Wire Sizes • No. = Cross sectional Area in Hundredths of Sq. In. • Thus § W 5 = 0. 05 Sq. In. § W 5. 5 = 0. 055 Sq. In. § D 10 = 0. 10 Sq. In.

Cage Basics • Given 3 x 8 W 2. 5 x. W 2. 0 • What is the steel area per foot of pipe? A = 0. 025 x 12 3 = 0. 10 in 2/ft

31 Structural integrity depends on • Grade of the reinforcing steel • Size of the reinforcing steel • Spacing of the reinforcing steel • Positioning of the reinforcing steel

Welding

33 ACI 318 - Materials • Precast plant-fabricated § Deformed reinforcement § Plain reinforcement

34 Welding Requirements Welding of reinforcement § Maintain product integrity § Two weldability limits • Max. Carbon content (0. 30%) [AWS D 1. 4] • Carbon equivalent (CE) § ACI 318 And AWS D 1. 4, CE are: • For #6 And smaller - 0. 55% • For #7 And larger - 0. 45% § The lower The CE, The better The weldability § For larger CE values, The rebar must be preheated

35 ASTM A 615 Reinforcement ASTM A 615 rebar § Must be used with extreme caution § Generally not acceptable § Check CE = %C + %Mn / 6

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ASTM A 706 Reinforcement ASTM A 706 rebar § Is a low-alloy weldable grade § Check CE = %C + %Mn/6 + %Cu/40 + %Ni/20 + %Cr/10 - %Mo/50 - %V/10

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Arc Welding See end of Chapter 2 for full size table AWS D 1. 4

Pre-Heating Guidelines

41 QUESTIONS?