Question

4'0" (1200 mm) #4 REBAR 12" OC. BOTH WAYS #5 DOWELS @ 12" O.C. ALTERNATING DIRECTIONS #4 REBAR 12" OC 5 EACH #4 CONT. REBAR

Based on Examples 1 and 3 in the lecture note, the amount of concrete poured, rebar, and form used in continuous footings and foundation wall can be estimated. Show all your calculations by sending Excel file or hand calculation via Folio email.

Determine the amount of rebar needed for the continuous footing shown in Figure above. Allow for two inches of cover. Add 10 percent for lap and waste to the continuous bars.

#5 Dowel bar (                ) pounds

#4 Rebar @ 12” O.C (                ) pounds

#4 Continuous rebar (               ) pounds (apply waste factor for lap)

Total pounds (                          )          

Tons (                     )

Question 18 options:

	Total pounds ( 3465 )           Tons ( 1.73 )
	Total pounds ( 1498 )           Tons ( 0.75 )
	Total pounds ( 1898 )           Tons ( 0.949 )
	Total pounds ( 3465 )           Tons ( 3.45 )

Answer 1

Hi,

Solution as follows:

1. Center line length

Data Given,

• Length from outer to outer of footing = 40 feet
• Width from outer to outer of footing = 26 feet
• Width of footing = 3 feet

Center line length method is a quick and accurate method to work out quantities of uniform size continuous footings, walls etc.

Center line length = 2 x 40 + 2 x 26 – 4 x 3 = 120 ft

2. Concrete Quantity for footing and walls

Data Given,

• Center line length [calculated above] = 120 ft
• Width of footing = 3 ft
• Depth of footing = 1’3” = 1.25 ft
• Thickness of wall = 1 feet
• Height of wall = 12 feet

Concrete quantity in footing = 120 x 3 x 1.25 = 450 ft³

Concrete quantity in wall = 120 x 1 x 12 = 1440 ft³

Total = 450 + 1440 = 1890 ft³

3. Forms Quantity for footing and walls

Data Given,

• Center line length [calculated above] = 120 ft
• Width of footing = 3 ft
• Depth of footing = 1’3” = 1.25 ft
• Thickness of wall = 1 feet
• Height of wall = 12 feet

Forms will be required at both faces of walls and footings.

Forms quantity in footing = 2 x 120 x 1.25 = 300 ft²

Concrete quantity in wall =2 x 120 x 12 = 2880 ft²

Total = 300 + 2880 = 3180 ft²

4. Rebar Quantity for footing

Rebar Quantity calculated below:

TABLE 1 : REBAR SCHEDULE
Sl. No.	Particulars	Bar No.	Total Nos.	Total Length (ft)	Unit Wt (lbs per ft.)	Total Weight (lbs)	Waste	Total Weight i.c. waste (lbs)	Total Weight (ton)
	Total Length of Footing = 120 feet
1	Dowel Bars (1'+2'4") - #5@12" O.C. alternate	#5	242	3.33	1.043	841		841	0.421
2	Footing Short rebar (#4@12" O.C.)	#4	121	2.67	0.668	216		216	0.108
3	Footing Long rebar	#4	5	120.00	0.668	401	10%	441	0.221
	Total (lbs)					1,457		1,498	0.75