Chapter 12 Flashcards
What is a foundation?
foundation is the element of a structure which connects the structure to the ground, and transfers loads from the structure to the ground.
What are the jobs of the foundation?
1. Distribute the load to a large bearing area. 2. To load the bearing area with a uniform load. 3. To prevent lateral movement and support the super structure.
What are the parts of a foundation? Describe each
1. Superstructure: Habitable section of a building above grade. 2. Sub Structure: Habitable below grade section of a building. Foundation: Part of the building that transfers loads from the building to the ground.
What are dead loads?
Dead Loads are static or constant loads
applied to the structure from walls,
floors, etc..
What are live loads?
Live Loads are loads that change. This
includes movable objects, people, and
weather like rain and snow.
These two types of loads are considered
to be dynamic loads. They are often
considered live, but in some cases
require special consideration.
Wind and seismic loads
What is Bearing Capacity?
The weight that different soils or
substrata can support
Upward forces cause what?
Heaving
Downforces cause what?
Subsidence
What is Uniformly settling?
Uniform settling: building settles uniformly, but may cause disruption in services like entrances or other site features (water, sewage, or other services may be impacted).
What is differential settling?
•Differential Settling: Building settles at different rates and can cause damage to finishes, cladding and potentially the structural integrity.
What is the difference between differential and uniform settling?
Uniform settling is where the whole structure settles by the same amount; whereas, differential settling refers to stresses being placed on a structure that it was not meant to bear, and that could lead to contortion of the structure’s frame.
What is heaving vs. differential settling?
differential settling refers to stresses being placed on a structure that it was not meant to bear, and that could lead to contortion of the structure’s frame; whereas, heaving is just upward forces pushing on a structure.
How deep should foundations in our be to resist heaving?
36”-48” (3 feet - 4 feet)
What is shallow foundation?
A type of foundation that extends a relatively short distance below the ground and beat directly on the upper soil stratum.
If the total width of a building is
20’ and you decide to use a Wall Footing
at 4’ then you would be using what type of foundation?
Shallow foundation
What are two types of shallow foundations?
Foundation systems consisting of footings
Monolithic concrete foundation under the building’s entire footprint.
What is the footing?
The widened base of a column or wall is called the footing
What is the primary purpose of the footing?
to distribute the superimposed load on a large area of the soil so that the pressure on the soil is less than or equal to the soil’s strength (Bearing Capacity).
What are 4 types of footings?
Wall Footing
•Isolated Column Footing
•Combined Footing
•Cantilever (Strap) Footing
What is wall footing?
Footing runs continuously along the wall
above and transmits the load to the
ground.
What are 3 pros and cons of wall footings?
Pros Cons
1. Created below grade and 1. High concrete use and
often habitable sub structure. thus increasing cost
Thus increasing the total 2.Can be prone to heaving
square footage of the building. 3.If not properly checked
2. Easy space to run services. can become areas of
3. Can act as passive cooling. mold of infestation
What is column footing?
A shallow footing that distributes the
loads from the column to the pad below.
What is used to support individual columns on a
concrete pad?
Column footing
Column footings are made up of ?
Constructed primarily of reinforced
concrete
Column footings are connected via a ?
Columns are connected via a strap beam
What are four PROS of column footings?
PROS: •Allows structure to be raised off of ground. •Is more economical than a deep wall foundation or basement foundation. •In warmer climates the space below can provide passive cooling. •Often used in areas with a high water level.
What are three CONS of column footings?
CONS: •Space below building can be prone to moisture damage. Especially if you are using wood joists. •Space below floor has to be insulated during cold weather. •If not properly maintained can become areas of mold or infestation.
What is combined footings?
An economical column pad system when
columns are tightly spaced or pad may
extend beyond the property line.