Question

USING UNITED STATES IBC CHAPTER 8:

1. Define the following:
   a. Shallow Foundation:
   
   b. Expansive Soil:

c. Foundation Drain:

2. Describe the situations when a sub-surface investigation for Ground-Water table is required and when it can be waived.

3. In the absence of a load-bearing test for foundation to be built on a crystalline bedrock, a vertical foundation pressure up to _______ may be used in design.
   
   A. 3000 psf                                 B. 4000 psf                          C. 6000 psf                          D. 12000 psf

4. For concrete used in foundation, the specified minimum compressive strength should be _________.  
   
   A. 3000 psi                                  B. 3500 psi                          C. 4000 psi                          D. 5000 psi
   
5. For precast pre-stressed deep foundations elements, the concrete cover must be at least _____ inches.

A. 1.5 inches                              B. 2.0 inches                       C. 2.5 inches                       D. 3.0 inches     

       

6. The minimum depth of a footing placed below undisturbed ground surface shall be _____ inches.

A. 12 inches                                B. 15 inches                        C. 18 inches                        D. 24 inches

7. Code waives the frost protection requirement of foundation for a free-standing building with maximum area of ______.

A. 400 sq. ft.                               B. 600 sq. ft.                       C. 800 sq. ft.                       D. 1000 sq. ft.

8. In the absence of design, the width of concrete footing supporting a 2-story light-frame construction shall be accepted to be _______.

A. 12 inches                                B. 15 inches                        C. 18 inches                        D. 24 inches

9. The edge thickness of plain concrete footings supporting walls other than light-frame construction shall not      
      be less than _______.

A. 6 inches                                  B. 8 inches                          C. 10 inches                        D. 12 inches

           10.   For Type ____ buildings, timber footings are allowed by the code.

     A. Type II                                        B. Type III                            C. Type IV                            D. Type V

Answer 1

Answer 1)

A shallow foundation is a foundation which transfers the load of the superstructure very near to its surface. It is also called as open foundation or mat foundation or spread foundation. Its depth to width ratio is less than or equal to 1. They are used when the soil is sufficiently strong or stiff to sustain the imposed load.

Answer 2)

The soil which has a tendency to increase the volume when water is available in it and decrease the volume when water is not available is called expansive soil. These type of soild are subjected to huge amount of uplift pressure due to swelling. Such type of soils can damage the structure because of its cohesive property.

Answer 3)

Foundation drain is an exterior drainage system installed on the outer face of the foundation wall and near the wall footing, covered with a layer of gravel, serving the purpose of draining out excess water seeping into the foundation. It captures the excess water and drains it either towards the storm sewer or a catch basin or soak-pit at some distance from the superstructure.

Answer 4)

The subsurface investigations are done to gain information about physical properties and characteristics of the subsoil material as well as details of other geological features of the site area.

The investigations must be done when-

• the safe bearing capacity of the soil is to be fixed.
• the likely settlement of the selected foundation is to be calculated.
• the depth of foundation is to be fixed.
• When the superstructure has heavy imposed loads
• To know the underground water level of the soil

Subsurface investigations take alot of time for a large area to be covered and hampers the speed of construction. Hence, in situations where speed is the concern, one can waive off the subsurface investigations and go with other options like Geophysical methods which gives quicker and faster results.