Foundation Engineering PDF Flashcards
A footing carrying single column
Spread footing
Its function is to “spread” the column load laterally to the soil so that the stress intensity is reduced to a value that the soil can safely carry.
Spread footing
Can be classified as wall and column footing.
Spread footing
Simply a strip of reinforced concrete, wider that the wall, that distributes its pressure.
Wall footing
Usually square, sometimes rectangular, and represents the simplest and most economical type.
Single column footing
Design Procedures:
A. Proportioning of footing
B. Structural design of footing
Concrete cover minimum for foundation
75mm
Concrete cover minimum for beams
40mm
Nilalagay para lumutang yung mga bakal sa footing
Spacer block
Surcharge
q
Allowable soil pressure or allowable bearing capacity
qa
Depth of soil
Ds
Depth of footing
Df
Thickness of concrete
Dc
It is obtained by using the services of geotechnical engineer. Will determine safe values from the principles of soil mechanics based on test borings, load tests, and other experimental investigations.
Allowable soil pressure, qa
Where allowable stress or allowable strength design is used.
Basic load combinations
When using these, a one third increase shall be permitted in allowable stresses for all combinations, including W or E
Alternate Basic Load Combinations
Load due to fluids with well - defined pressures and maximum heights
F
Load due to lateral pressure of soil and water in soil
H
Roof live load, including any permitted live load reduction
Lr
Rain load on the undeflected roof
R
Self - straining force and effects arising from contraction or expansion resulting from temperature change, shrinkage, moisture change, creep in component materials, movement due to differential settlement, or combination thereof
T
Load due to wind pressure
W
Ratio of long side to short side of concentrated load or reaction area
B
Perimeter of critical section
bo
Critical area
Ao
Nominal shear strength
Vn
Effective depth
d
The total effective depth of bottom reinforcement is at least ____.
150mm
Reinforcement shall be distributed uniformly across the entire width of footings
One way footings
In square, reinforcement shall be distributed uniformly across entire width of footing in both directions.
Two way footings
Minimum area of flexural reinforcement
As min
Shall be provided at every section where tension reinforcement is required by analysis
As min
Minimum steel ratio
P min
Clear spacing
Sc
For parallel non prestressed reinforcement in a horizontal layer, _______ shall be at least the greatest of 25mm, db and 4/3 MSA
Clear spacing
Shall not be spaced farther apart than three times the wall or slab thickness, 3Dc, nor farther than 450mm
Primary flexural reinforcement
If ld min > ld available
Provide standard hooks
All forces acting at the base of a column shall be transferred into the footing by ____________ and by _________, ___________, and _________.
Bearing on concrete
Reinforcement, dowels, and mechanical connectors
Bearing strength of concrete
fc
Column area or the loaded area
A1
Supporting area
A2
Development length
Ldc
