What is Load Bearing Capacity
In the designing of the Reinforced Cement Concrete structure, Calculation of the design load is the primary step.
Bearing capacity of a foundation is the maximum load that can be applied on a foundation, before failure or uncontrolled deformations occur.
Imposed loads varies from approximately 1.5 kN/m2 (153 kg/m2) in domestic buildings to approximately 10 kN/m2 (1053 kg/m2) in heavy industrial areas. 500 kg/m2 is typical for office, storage space and similar.
The Load-bearing Capacity calculation involves measuring the concrete's member's existing dimensions and estimating the reinforcement area and concrete strength. Additionally, the load acting on the structural area needs to be calculated.
The next following step is to calculate the beams' capacity using the equation of strength design method.
Finally, the designer can evaluate the beams load carrying capacity
h2>Types Of Loads on Structures
The different types of Loads acting on Structures for buildings and other structures can be broadly classified as
- Vertical loads,
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- Horizontal loads,
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- Longitudinal Loads,
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The Vertical Loads are again subdivided into
- Dead Load
- Live Load
- Impact Load
The Horizontal Loads are divided into
- Wind Load
- Earthquake Load
Longitudinal Loads
The Longitudinal Loads comprises of tractive or braking effort.
Calculation of Load Bearing Capacity In Reinforced Cement Concrete Structure
Assumptions:
- Slab is supported on all edges e.g. with the help of beams.
- Slab can carry any kind of loading like point load, UDL, etc.
- We know the drawing details of slab-like no. Of steel bars and type of concrete.
- We just want to know the theoretical capacity of the slab not actually otherwise we may need to do the plate load test which is destructive in nature.
Let's calculate the capacity of Slab
Step 1 - Find out the no. Of bars and their dimensions in one meter span of slab in shorter direction.
Step 2 - find out the grade of concrete.
Step 3 - using the IS 456 page 90 formula, calculate the area of steel present in tension and the thickness of slab and thereafter find the moment of resistance of slab.
fck = Grade of Concrete
Fy = Grade of Steel
B = width of Beam
D = Effective Depth Of Beam
xu= Depth of Neutral Axis from top of Beam Section
xu,lim=limiting depth of neutral axis (NA) from top of beam section for balanced section
Ast=area of steel
Compressive force , C=0.36fckBxu
Tensile force, T = 0.87fyAst
Lever arm, LA=d-0.42xu
Moment of Resistance, MOR=C LA=T LA
MOR=0.36fckBxu(d-0.42xu)
MOR=0.87fyAst(d-0.42xu)
The Above general formulae for MOR
For under-reinforced section, xu<xu,lim
xu,lim depends on fy & d only.
Step 4 - After knowing the Moment of resistance you can find out the load on the beam as you know the span of the beam because
Moment = force perpendicular distance
Conclusion:
This article summarizes different types of Loads on structures and an easy step by step Methods to calculate the Load Bearing Capacity of Reinforced Cement Concrete structures.
FAQs
Bearing capacity of a foundation is the maximum load that can be applied on a foundation, before failure or uncontrolled deformations occur. Imposed loads varies from approximately 1.5 kN/m2 (153 kg/m2) in domestic buildings to approximately 10 kN/m2 (1053 kg/m2) in heavy industrial areas.
How to calculate load bearing capacity of reinforced concrete slab? ›
Step 1 - Find out the no. Of bars and their dimensions in one meter span of slab in shorter direction. Step 2 - find out the grade of concrete. Step 3 - using the IS 456 page 90 formula, calculate the area of steel present in temaion and the thickness of slab and thereafter find the moment of resistance of slab.
How do you calculate the bearing strength of concrete? ›
The bearing strength of concrete is simply the compressive strength of the concrete and the ratio of the total surface area to the load bearing area (known as bearing ratio).
What is the formula for load bearing capacity? ›
It represents the load under which the bearing can operate for one million revolutions without experiencing failure. Use the formula C0 = (P0 / F0) x C to calculate the static load carrying capacity, C0, of the bearing.
What is the bearing strength of concrete as per ACI 318? ›
Inputs
Parameter | Value |
---|
Concrete strength | f c ′ f'_c fc′ = 3,500 psi |
Allowable bearing pressure | q a q_a qa = 4,000 psf |
Depth of soil over footing | h s o i l h_{soil} hsoil = 1 ft * |
Soil unit weight | γs = 235 pcf * |
5 more rows
How do you calculate allowable bearing capacity? ›
Allowable bearing capacity is the maximum pressure that can be applied to the soil, considering factors such as safety against shear failure and excessive settlement. It is calculated by dividing the ultimate bearing capacity by a factor of safety.
What is the formula for calculating bearing? ›
Another example is calculating the bearing between two points with given latitude and longitude. The formula for this is: β = atan2(X,Y), where X and Y are two quantities that can be calculated based on the given latitude and longitude.
What is the formula for maximum bearing capacity? ›
Net ultimate bearing capacity qαστ or qult: is the net stress that causes shear failure in the foundation soil. Net allowable pressure qεπ: is the net ultimate bearing capacity divided by a factor of safety F, qεπ = qαστ/F = (q'αστ - γDf)/F.
How do you calculate bearing load? ›
Bearing calculation
The Computation of Bearing Loads is simplified as follows: R= Radial load – loads that are perpendicular to the shaft. T= Thrust load – loads that are parallel to the axis of the bearing. C= Combined load is a result of calculating both Radial and Thrust loads using the combined load calculations.
How do you calculate load capacity? ›
Take the total load, and divide by the overall recommended load to get the percentage. For example, if the total load is up to 800 watts and this is a 20 amp circuit, then the load usage is 800 watts divided by 1920 watts equal to 0.416 or 42%.
A bearing's ability to withstand a load is determined by how close the Hertzian contact pressure is to the stress limit of the bearing. The closer it is to the bearing's stress limit, the less time it will take for the bearing to experience plastic deformation.
What is the formula of bearing capacity ratio? ›
Net ultimate bearing capacity (qₙᵤ): the net pressure increase at the foundation base that will result in shear failure of the soil. It is calculated by subtracting the weight of the soil (𝝲) multiplied by the foundation depth (D) from the ultimate bearing capacity (qᵤ).
What is allowable bearing capacity concrete? ›
The allowable bearing capacity (qa) is the maximum bearing stress that can be applied to the foundation such that it is safe against instability due to shear failure and the maximum tolerable settlement is not exceeded.
How much can reinforced concrete hold? ›
To summarize: A 4-inch concrete driveway can support weights up to approximately 6,000 pounds. A 5-inch concrete driveway can support weights up to approximately 10,000 pounds. A 6-inch concrete driveway can support weights exceeding 12,000 pounds, depending on the specific design and construction.
What is the bearing strength of a concrete slab? ›
With natural strength, even a standard concrete with minimal thickness has impressive load bearing capabilities. 3000 psi is the standard of compressive strength on a concrete slab.
What is the maximum bearing pressure of concrete? ›
The maximum bearing pressure should not exceed the bearing strength equal to 0.6 fck, where fck is the smaller characteristic cube strength of concrete or bedding material.