How do you calculate uplift load?
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 does uplift mean in construction?
A third category is uplift, which also relates to the first two. Gravity loads include the dead load of the lumber and other material that is part of the building; live loads include occupants, snow, furniture, or other temporary loads.
What is uplift capacity?
A measure of the resistance of a pile to being pulled out of the ground.
What is uplift soil?
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. Permitting flow through a permeable stratum will reduce the hydrostatic pressure in the water due to energy losses.
What is uplift resistance?
The uplift resistance of soils is normally associated with the design of foundations for structures such as transmission line towers where an adequate margin of safety is required against failure. This represents the design for safety case.
What force is creating the uplift?
Uplift forces can be a consequence of pressure from the ground below, wind, surface water, and so on. Water pressure can exert an uplift force on a structure due to high rainfall, for example by causing clay soils to expand.
What is net uplift?
An Asset Owner’s TCR Net Uplift Annual Amount is equal the difference between (i) the sum of that Asset Owner’s charges calculated under Section 8.5. An Asset Owner’s ARR Net Uplift Annual Amount is equal the difference between (i) the sum of that Asset Owner’s charges calculated under Section 8.7.
What is Mac Arthur pile?
Mac-arthur piles are the heavy steel casing with a core is driven into ground. When the desired depth is reached, the core is withdrawn and a corrugated steel shell is placed in the casing. The last operation consists in filling and gradually compacting the concrete and withdrawing the casing.
What is pier foundation?
A pier foundation is a collection of large diameter cylindrical columns to support the superstructure and transfer large super-imposed loads to the firm strata below. It stood several feet above the ground. It is also known as “post foundation”.
What are the two types of piles?
Depending on their function, piles are classified as bearing piles, friction piles, friction-cum-bearing piles, batter piles, guide piles, and sheet piles. Based on the composition of materials, piles are classified as timber piles, concrete piles, sand piles, or steel piles.
How is uplift pressure used in building design?
The structure must be designed properly to provide greater resistance against uplift forces in order to prevent risks due to water pressure. So, the uplift pressure must be taken into consideration during design stage since rehabilitation and maintenance of foundation cannot be carried out easily in the future.
Which is greater downward load or uplift pressure?
The weight of the substructure should be greater than uplift pressure in order to meet the requirements of applicable codes, i.e. summation of downward load per given area should be larger than that of the vertical load per given area. The downward load should at least greater than 25% compared to the upward load due to hydrostatic load.
How is a pile related to an uplift load?
The uplift capacity theories of piles have been mostly extended from the analysis of horizontal plate anchors under uplift load and development of failure surfaces starting from the edges of the anchor. Pile is considered as a cylindrical shaft and the failure surfaces may be similar to those developed for the anchors.
How much uplift can you put on a roof?
As we head up the exterior walls, though, there is less building material to resist the wind. At the lower edge of the roof, for example, the rafters can experience 240 pounds of uplift, minus the dead load of the roof framing and cladding, which is no more than 10 lb. per sq. ft., or a maximum of 120 pounds at each rafter seat cut.
https://www.youtube.com/watch?v=wBTdsDFbH5c