The two criteria for the determination of allowable bearing capacity of a foundation are (2024)

FAQs

The two criteria for the determination of allowable bearing capacity of a foundation are? ›

The two criteria for the determination of allowable bearing capacity of a foundation are. Tensile failure and compression failure.

Detailed Solution

For satisfactory performance, the foundation must satisfy the shear and settlement criteria. These two criteria are independent to each other and must be satisfied separately. Shear Criteria: A foundation must be safe against shear failure or soil rupture.

Allowable bearing capacity: The maximum pressure that can be applied to the soil from the foundation so that the two requirements are satisfied: Acceptable safety factor against shear failure below the foundation. Acceptable total and differential settelement.

In case the soil does not provide sufficient bearing capacity, Safe bearing pressure can be improved using the following methods: Increasing the depth of the foundation. Draining the soil. Compacting the soil.

Bearing Capacity Testing: Testing methods include Plate Bearing Test, Standard Penetration Test (SPT), Cone Penetration Test (CPT), and the Pressuremeter Test, which provide data for determining soil's bearing capacity.

The foundation type needs to be chosen based on soil conditions, structural load, and regional climate.

Tests performed on a site to determine soil bearing capacity include Standard Penetration Test (SPT), Plate Load Test, Dynamic Cone Penetration Test, and Borehole Test.

The basic allowable bearing pressure shall be determined from the resistance to penetration of the standard sampling spoon. The basic allowable bearing pressure in tons per square foot shall equal 0.10 times N but not greater than six tons per square foot, nor less than three tons per square foot.

The allowable bearing pressure depends on the size of the footing (and hence the influence depth) and the settlement tolerances.

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 load bearing capacity of a building? ›

Detailed Solution

When factor of safety is applied on the net ultimate bearing capacity, then it is called net safe bearing capacity (q_ns). While designing the foundation, safe bearing capacity is considered, because it is less than the true bearing capacity of soil and we are on safer side.

Ultimate bearing capacity is the theoretical maximum pressure which can be supported without failure; allowable bearing capacity is the ultimate bearing capacity divided by a factor of safety.

The factors that affect the bearing capacity of soil include the SPT value, depth of footing, width and length of foundation, cohesion, unit weight, angle of inclination, types of footing, and depth of water table.

Estimating soil bearing capacity can be done through field tests that measure the soil's reaction to applied loads. Standard penetration test (SPT) involves driving a steel rod into the soil at a constant rate and recording the number of blows required to penetrate a certain depth.

Bearing capacity, in a nutshell, is the ability of soil to support loads applied to the ground above. It is primarily determined by the type of soil, its shear strength, and its density. It is also affected by the depth of the load's embedment; the deeper it is found, the greater the bearing capacity.

The type of foundation used in a structure depends on several factors, including the size and weight of the structure, the soil conditions at the construction site, and the local building codes and regulations.

The bearing capacities of shallow foundations in rocks are governed by the non-persistency, the number of discontinuous joint tips, dip, dip direction and spacing of discontinuity, shear strength characteristics of discontinuity material and intact rock strength.