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Concrete Structures. Units of Measure. Concrete: Cubic Yard Steel: Lb or tons Formwork: Square feet per contact area. Types of Concrete construction. 1. Foundations 2. Columns 3. Slabs and beams. Shallow Foundation. Isolated Footing. Combined Footing. Continuous Wall Footing.
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Concrete Structures Prof Awad S. Hanna
Units of Measure Concrete: Cubic Yard Steel: Lb or tons Formwork: Square feet per contact area Prof Awad S. Hanna
Types of Concrete construction 1. Foundations 2. Columns 3. Slabs and beams Prof Awad S. Hanna
Shallow Foundation Isolated Footing Combined Footing Continuous Wall Footing Strap Footing Raft Foundation Prof Awad S. Hanna
Deep Foundation Caissons Piles Prof Awad S. Hanna
Columns • Shapes • Square - Rectangle - Circular • Others • Reinforcement • Ordinary - Spiral Prof Awad S. Hanna
Slabs and Beams: One-Way slabs One-Way Slab, Beam, and Girder One-Way Slab, Supported by Beams or Walls One-Way Joist Slab Prof Awad S. Hanna
Slabs and Beams: Two-Way Slabs Flat Plate Waffle Slab Flat Slab Two-Way Slab Supported by Beams Prof Awad S. Hanna
Estimating Issues 1. Formwork is the largest cost item that represent 40% to 60% of concrete structure cost. Distribution of costs for cast-in-place concrete slab wall: Prof Awad S. Hanna
2.Waste allowance from 2% to 10% should be added for concrete and concrete formwork. Prof Awad S. Hanna
1. Center Line Method Building size: 30’ x 40’ Calculations: 1. Length = 30’10” - 1’6” = 29’4” 2. Width = 40’10” - 1’6” = 39’4” 3. Perimeter = 29’4” + 29’4” + 39’4” +39’4” = 137”4” 4. Volume of concrete = 137.33’ x 1’ x 1.5’ = 206 ft3 30’10” 30’ 40’0” 40’10” Prof Awad S. Hanna
2. Sectional Method Calculations: 1.Length = 10.833’+40.833’ = 81.67’ 2.Width = 27.833’+27.833’ = 55.67’ 3.Perimeter = 81.67’+55.67’ = 137.34 Total Linear ft 4.Volume = 137.34’x1’x1.5’ = 206 Cubic feet 5.volume in CY = 206/27 = 7.6 Cubic Yards 30’10” 27’10” 40’10” Prof Awad S. Hanna
COST OF OTHER COMPONENTS OF CONCRETE WORK 1. Reinforcement Steel 2. Forms 3. Concrete Mix 4. Finishing 5. Curing Prof Awad S. Hanna
Table 1.DIMENSIONS & WEIGHT OF WELDED WIRE FABRIC Prof Awad S. Hanna
Table 2SIZES & WEIGHTS OF REINFORCING BAR Prof Awad S. Hanna
EXAMPLE: How many pounds of rebar are required for the concrete floor area below? 60’ 20’ 6” Concrete slab with #4 rebar 15” on center each way 40’ 30’ Prof Awad S. Hanna
Step #1: Calculate the total SF of area involved. 20'0" X 30'0" = 600 SF 30'0" X 40'0" = 1 200 SF Total = 1,800 SF floor area Step #2: Calculate the pounds of rebar per SF of floor based on the unit spacing of the rebar at any point of intersection. Unit area: 15" X 15" = 1.25' X 1.25' = 1.56 SF Unit rebar length: 1.25' + 1.25' = 2.5 LF Lbs. of rebar/unit:= 2.5 LF X .668 lbs/ LF = 1.67 lbs • It is now known that there are 1. 67 lbs of rebar per 1.56 SQ FT of floor area. 1.67 / 1.56 = 1.07 lbs/SF of floor area. SO: 1.07 lbs/ SF X 1,800 SF = 1,926 lbs of #4 rebar required. Prof Awad S. Hanna