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5. ACI 318 Verification # 1

ACI 318 Verification # 1

Figure 1: Book 1 (left), Book 2 (center) and Book 3 (right)

Information presented on this page is intended to demonstrate the section design convergence of ACI 318-2014 provisions for isolated foundations that can be achieved with SkyCiv. All examples are taken from the following references:

Book 1: Jack O.McCormac, Russell H.Brown. Reinforced Concrete Design (Tenth Edition), 2015.
Book 2: American Concrete Institute. ACI SP-17(14) The Reinforced Concrete Design Handbook, 2016.
Book 3: M. Nadim Hassoun, Akthem Al-Manaseer. Structural Concrete Theory and Design (Sixth Edition), 2015.

Example # 1 Design of axially loaded Isolated Footing.

reference: Book 2, pp.425.

DESCRIPTION
An Isolated foundation is subjected to three (3) static load cases  (Dead, Live and Earthquake load). The resulting shear, moment, load transfer and development length are compared with manual calculations. The foundation model lies in the X-Z plane.

GEOMETRY AND MATERIAL PROPERTIES

Figure 2: Footing model and material properties of example #1

Three static loads cases are considered:

$$\text{DL} = 541.00 \text{ kips}$$
$$\text{LL} = 194.00 \text{ kips}$$
$$\text{ E} = 18.00 \text{ kips}$$

The results of service and factor load combination are in computed in reference of ASCE/SEI 7-10.

ANALYSIS

The analysis is done using the rigid conventional method. See the Isolated Footing User Manual for more explanation on using SkyCiv Foundation.

RESULT COMPARISON

The most significant results are compared in the table below:

Results
Parameter Manual SkyCiv
One way shear
Actual Shear 231 229.9
ΦVc 348 348.36
Two way shear
Bo 198 200
(a) 22.6.5.2 253.00 252.98
(b) 22.6.5.2 379.50 379.47
(c) 22.6.5.2 442.09 440.90
ΦVc 958.00 1005.06
Flexure
Actual Moment 1005 999.58
ΦBn 2546 2545.92
ldc = fy*Ψ/50*λ*√fc*db 14.30 14.23
ldc = 0.0003*fy*Ψ*db 13.5 13.5
Development Length
confinement term 2.5 2.5
ld 28.5 28.5
Note: discrepancy are due to the “d” effective depth measurement, SkyCiv calculates actual measurement for both directions

Example #2 Design of axially loaded Isolated Footing.

reference: Book 1, pp.357.

DESCRIPTION
An Isolated foundation is subjected to two (2) static load cases  (Dead and Live). The resulting shear , moment, load transfer and development length are compared with manual calculations. The foundation model lies in the X-Z plane.

GEOMETRY AND MATERIAL PROPERTIES

Figure 3: Footing model and material properties of Example #2

Two static loads cases are considered:

$$\text{DL} = 200.00 \text{ kips}$$
$$\text{LL} = 160.00 \text{ kips}$$

The results of service and factor load combination are in computed in reference of ASCE/SEI 7-10.

ANALYSIS

The analysis is done using the rigid conventional method. See the Isolated Footing User Manual for more explanation on using SkyCiv Foundation.

RESULT COMPARISON

The most significant results are compared in the table below:

Results
Parameter Manual SkyCiv
Soil Pressure 6.12 6.12
One way shear
Actual Shear 121.62 121.70
Two way shear
Bo 142 140
ΦVc 442.09 440.9
Flexure
Actual Moment 404 404.91
Development Length
confinement term 2.5 2.5
ld 32.3 32.862
Note: discrepancy are due to the “d” effective depth measurement, SkyCiv calculates actual measurement for both directions.

Example # 3 Design of axially loaded Isolated Footing.

reference: Book 1, pp.365.

DESCRIPTION
An Isolated foundation is subjected to two (2) static load cases  (Dead and Live). The resulting shear, moment, load transfer and development length are compared with manual calculations. The foundation model lies in the X-Z plane.

GEOMETRY AND MATERIAL PROPERTIES

Figure 4: Footing model and material properties of example # 3

Two static loads cases are considered:

$$\text{DL} = 185.00 \text{ kips}$$
$$\text{LL} = 150 \text{ kips}$$

The results of service and factor load combination are in computed in reference of ASCE/SEI 7-10.

ANALYSIS

The analysis is done using the rigid conventional method. See the Isolated Footing User Manual for more explanation on using SkyCiv Foundation.

RESULT COMPARISON

The most significant results are compared in the table below:

Results
Parameter Manual SkyCiv
Soil Pressure 4.17 4.17
One way shear
Actual Shear 152.49 149.02
Two way shear
Bo 142 144
ΦVc 415.58 413.16
Flexure
Actual Moment 643.9 644.53
Note: discrepancy are due to the “d” effective depth measurement, SkyCiv calculates actual measurement for both directions.

Example # 4 Design of axially loaded Isolated Footing.

reference: Book 3, pp.461.

DESCRIPTION
A Isolated foundation is subjected to two (2) static load cases (Dead and Live). The resulting shear, moment, load transfer and development length are compared with manual calculations. The foundation model lies in the X-Z plane.

GEOMETRY AND MATERIAL PROPERTIES

Figure 5: Footing model and material properties of example # 4

Two static loads cases are considered:

$$\text{DL} = 245.00 \text{ kips}$$
$$\text{LL} = 200.00 \text{ kips}$$

The results of service and factor load combination are in computed in reference of ASCE/SEI 7-10.

ANALYSIS

The analysis is done using the rigid conventional method. See the Isolated Footing User Manual for more explanation on using SkyCiv Foundation.

RESULT COMPARISON

The most significant results are compared in the table below:

Results
Parameter Manual SkyCiv
Soil Pressure 6.14 6.14
One way shear
Actual Shear 161.2 161.17
Two way shear
Bo 150 152
ΦVc 554 552.44
Flexure
Actual Moment 554.5 554.52
Note: discrepancy are due to the “d” effective depth measurement, SkyCiv calculates actual measurement for both directions.

Albert Pamonag
Structural Engineer, Product Development
B.S. Civil Engineering