Concept explainers
Three columns, A, B, and C, are collinear, 500 mm in diameter, and 2.0 m on-center. They have unfactored vertical downward loads of 1,000,550, and 700 kN, respectively, and are to be supported on a single, 1.0 m deep rectangular combined footing. The soil beneath this proposed footing has the following properties:
- using ASD, determine the minimum footing length, L, and the placement of the columns on the footing that will place the resultant load at the centroid of the footing. The footing must extend at least 500 mm beyond the edges of columns A and C.
- Using the results from part (a), determine the minimum footing width, B, that will maintain a factor of safety of 2.5 against a bearing capacity failure. Show the final design in a sketch.
Hint: Assume a value for B, compute the allowable bearing capacity, then solve for B. Repeat this process until the computed B is approximately equal to the assumed B.
Want to see the full answer?
Check out a sample textbook solutionChapter 7 Solutions
Foundation Design: Principles and Practices (3rd Edition)
Additional Engineering Textbook Solutions
Elementary Surveying (14th Edition)
Materials for Civil and Construction Engineers (4th Edition)
Elementary Surveying: An Introduction To Geomatics (15th Edition)
Structural Steel Design (6th Edition)
Structural Analysis (10th Edition)
Machine Tool Practices (10th Edition)
- Redo Problem 16.1 with the following: = 115 lb/ft3, c = 1100 lb/ft2, =35, Df = 3.5 ft, B = 5 ft, and factor of safety = 4. 16.1 A continuous footing is shown in Figure 16.17. Using Terzaghis bearing capacity factors, determine the gross allowable load per unit area (qall) that the footing can carry. Assume general shear failure. Given: = 19 kN/m3, c = 31kN/m2, =28, Df = 1.5 m, B = 2 m, and factor of safety = 3.5. Figure 16.17arrow_forwardDetermine the maximum column load that can be applied on a 1.5 m × 1.5 m square foundation placed at a depth of 1.0 m within a soil, where γ = 19.0 kN/m3, c′ = 10 kN/m2, and ф′ = 24°. Allow a factor of safety of 3.0.arrow_forwardA column is to be supported by a square footing, 2.00 m on a side, on a founding depth of 1.00 m into a cohesionless soil deposit. The unit weight of the soil is 16 kN/m³ and the angle of internal friction of 25 deg. Nq= 12.7 Ny= 8.34 Evaluate the contribution of the depth of embedment to the ultimate bearing capacity of the soil, in kPa. 2 Evaluate the contrbution of the footing dimension to the ultimate bearing capacity of the soil, in kPa. 3 Evaluate the concentric load, in kN, that the footing can safely support, using a factor of safety of 3.0 against bearing capacity failure.arrow_forward
- Proportion a rectangular combined footing for two columns 5 m apart. The exterior column of size 0.3 m x 0.3 m carries a load of 600 kN and interior column of size 0.4 m x 0.4 m carries a load of 900 kN. The allowable soil pressure is 100 kN/m2arrow_forwardA square footing 2.5 m X 2.5 m is built on a homogeneous bed of sand of density 19 kN/m3 having an angle of shearing resistance of 36o . The depth of foundation is 1.5 m below the ground surface. Calculate the safe load that can be applied on the footing with a factor of safety of 3.arrow_forwardA circular footing having a diameter of 1.2 m. has its bottom at a depth of 2.6 m. from the ground surface. The water table is located at a depth of 1.2 m. below the ground. The soil has the following properties: γd = 18.26 kN/m3, γsat = 19.10 kN/m3, c = 15.18 kPa, Nc = 35.06, Nq = 22.03, Nγ = 19.01. Determine the allowable load, in kN, that the footing can carry using factor of safety of 2.7arrow_forward
- A square foundation is 1.5 m x 1.5 m in plan. The soil supporting the foundation has a friction angle of f = 20° and c = 15.2 kN/m 2. The unit weight of soil, , is 17.8 kN/m 3. Determine the allowable gross load on thefoundation with a factor of safety (FS) of 4. Assume that the depth of thefoundation (Df) is 1 m and that general shear failure occurs in the soil.arrow_forwardA square footing which carries an axial load of 13000 kg has its bottom resting on a ground water table at a depth of 2.5 m from the ground surface. Nc = 35, Nq = 22, Nγ = 19. Take PDRY = 1910 kg/m3 and PSAT = 1600 kg/m3, c = 1800 kg/m2. Compute the net soil pressure.arrow_forwardThe four columns shown below have the following loads and dimensions (in the directions shown): Columns 1 and 2: DL=150 kN; LL=150 kN; 40 cm x 30 cm Columns 3 and 4: DL=300 kN; LL=250 kN; 50 cm x 40 cm Estimate the design safety factor for bearing capacity failure if the footing is placed at a depth of 2 m below the surface of a sandly-silty soil with c = 25 kPa, φ = 15° and γ = 17 kN/m3. Given the allowable bearing capacity of the soil qa = 125 kPa. Calculate the minimum concrete thickness, d', of the footing based on punching shear under column 4 (only). Use fc’ = 24 MPa, fy = 345 MParrow_forward
- A circular footing having a diameter of 1.1 m. has its bottom at a depth of 2.9 m. from the ground surface. The water table is located at a depth of 1.4 m. below the ground. The soil has the following properties: γd = 18.07 kN/m3, γsat = 19.45 kN/m3, c = 15.19 kPa, Nc = 35.04, Nq = 22.05, Nγ = 19.04. Determine the allowable load, in kN, that the footing can carry using factor of safety of 2.5. Round off to two decimal places.arrow_forwardA square footing 2.5 m X 2.5 m is built on a homogeneous bed of sand of density 19 kN/m3having an angle of shearing resistance of 36o. The depth of foundation is 1.5 m below the ground surface. Calculate the safe load that can be applied on the footing with a factor of safety of 3. Take bearing capacity factors as Nc= 27, Nq = 30, Nγ = 35arrow_forwardQ/ for the circular footing 5m diameter . find the thickness of footing if (factor of safety = 3) . salty sand . Ƴsaturated = 19 kN/m3 C = 10 kN/m2 ƴd = 15 kN/m3arrow_forward
- Principles of Geotechnical Engineering (MindTap C...Civil EngineeringISBN:9781305970939Author:Braja M. Das, Khaled SobhanPublisher:Cengage LearningPrinciples of Foundation Engineering (MindTap Cou...Civil EngineeringISBN:9781337705028Author:Braja M. Das, Nagaratnam SivakuganPublisher:Cengage LearningFundamentals of Geotechnical Engineering (MindTap...Civil EngineeringISBN:9781305635180Author:Braja M. Das, Nagaratnam SivakuganPublisher:Cengage Learning