What is the factor of safety against uplift?
Factor of Safety Against Uplift Pressure Generally, the factor of safety against uplift is in the range of 1.2 – 1.5. Usually, it is kept at 1.2.
How do you calculate uplift force?
The uplift force on each outer post is (1/2 the span projection + the outer overhang) * (1/2 the span width + the side overhang) = (25% of the roof area) * the net uplift (all the uplift minus the self-weight or ‘dead load’).
What is uplift pressure in foundation?
An uplift pressure is any pressure exerted beneath a structure (e.g. A retaining wall) that has the potential to raise the structure higher relative to its surroundings.
What is uplift force?
An uplift force is any upward pressure applied to a structure that has the potential to raise it relative to its surroundings. Uplift forces can be a consequence of pressure from the ground below, wind, surface water, and so on. This can cause damage to the roof if the difference in pressure becomes too great.
How can uplift pressure be reduced?
Direct reduction of uplift pressures can be accomplished by the incorporation of a drain curtain, also known as drainage or relief wells.
What is uplift resistance?
Uplift Resistance is Easy to Achieve with Cleats Instead of Concrete. Uplift is a term used to describe the force that works to pull a post out of the ground. This is typically associated with wind forces acting on the underside of a structure, such as a pole barn roof or the surface of a deck.
How do you control uplift pressure?
How can you prevent uplift pressure?
The piling method is the most effective method to resist Uplift pressure. Various types of piles are available to be used for countering uplift pressure based on soil condition and their necessity on site. For instance, end bearing pile, friction pile, un-reamed pile, sheet pile, tension pile, and compaction pile.
How can you prevent uplift pressure in a dam?
Because uplift pressures can greatly impact the stability of concrete gravity dams, they must be analyzed and accounted for during design and evaluation of such structures. Direct reduction of uplift pressures can be accomplished by the incorporation of a drain curtain, also known as drainage or relief wells.
What should the factor of safety against uplift be?
Generally, the factor of safety against uplift is in the range of 1.2 – 1.5. Usually, it is kept at 1.2. The following procedure could be used to check the uplift.
When to reduce FS to 1.5 for uplift?
For uplift conditions Fs = 2.5 F s could be reduced to 2, if the capacity of pile could be established by a pull-out test. F s could be further reduced to 1.5 if the weight of the pile itself is 0.75 times the uplift force or greater.
What should be the factor of safety of a pile?
With negative stress friction acting, factor of safety as above should be obtained. With negative friction, the factor of safety should not be less than 2. 2. For uplift conditions Fs = 2.5 F s could be reduced to 2, if the capacity of pile could be established by a pull-out test.
How to calculate uplift pressure of a base slab?
How to Calculate Uplift Force. The pressure at a depth “h”; p. P = hρg. Further, this question can be written as. P = ϒ w h. Area of the base slab = A. Uplift Force = ϒ w h A. Factor of Safety Against Uplift Pressure. Generally, the factor of safety against uplift is in the range of 1.2 – 1.5. Usually, it is kept at 1.2.