IS 6403: Code of practice for determination of bearing capacity of shallow foundations : Bureau of Indian Standards : Free Download, Borrow, and Streaming : Internet Archive (2024)

FAQs

Is code is 6403 1981 recommends a bearing capacity equation which is similar to __________? ›

Explanation: IS code (IS : 6403-1981) recommends a bearing capacity equation which is similar in nature to those given by Meyerhof and Brinch Hasen.

IS: 6403 – 1981 code of practice is used for the determination of bearing capacity of the shallow foundation. In this code a modification was done on ultimate bearing capacity formula which was first given by Brinch Hansen and known as Brinch Hansen's method.

IS 6403: Code of practice for determination of bearing capacity of shallow foundations.

From the monotonicity analysis, the ultimate bearing capacity increases with the increase of internal friction angle ( ), soil unit weight ( ), foundation width (B) and foundation depth (D), whereas it decreases with the increase of the length to width ratio of foundation (L/B).

Tensile failure and compression failure.

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.

How can one calculate bearing capacity? The bearing capacity of soil is calculated using the formula: qf = c'Nc + γDNγ + 0.5γBNγ. Here, qf is the ultimate bearing capacity, c' is the cohesion of soil, Nc, Nq, and Nγ are bearing capacity factors, D is the depth of footing, and γ is the unit weight of soil.

The safe bearing capacity of soil is defined as the maximum load per unit area that the soil can bear without any displacement or settlement. This is measured in terms of kilograms per square centimeter. If the load exceeds this mark, the soil will start to displace or break.

No footing or foundation shall be placed on soil with a bearing capacity of less than 2,000 pounds per square foot unless the footing or foundation has been designed through structural analysis. The soil—bearing values of common soils may be determined through soil identification.

What is ideal soil bearing capacity? ›

The safe bearing capacity is determined by subtracting a safety factor from the final bearing capacity, typically between 3 to 5, to ensure the soil can sustain the maximum force without giving way. This value is used in foundation-planning spreadsheet calculations.

Shallow foundations consist of foundations such as strip footings, spread footings, and mat foundations, whereas deep foundations consist of foundations such as piles and drilled shafts.

The bearing capacity of a shallow foundation can be defined as the maximum value of the load applied, for which no point of the subsoil reaches failure point (Frolich method) or else for which failure extends to a considerable volume of soil (Prandtl method and successive).

The factor of safety for shallow foundation against overturning shall be not less than 1.5 when a dead load, live load, and earth pressures are considered together with wind load or seismic forces. When dead load, live load, and earth pressures only are considered, the factor of safety shall be not less than 2.

The bearing capacity of soil is calculated using the formula: qf = c'Nc + γDNγ + 0.5γBNγ. Here, qf is the ultimate bearing capacity, c' is the cohesion of soil, Nc, Nq, and Nγ are bearing capacity factors, D is the depth of footing, and γ is the unit weight of soil.

Safe bearing capacity (qsafe): - It is the working pressure that would ensure a margin of safety against the collapse of the structure from shear failure. The safe bearing capacity is usually a fraction of the ultimate net bearing capacity.

The safe bearing capacity is determined by subtracting a safety factor from the final bearing capacity, typically between 3 to 5, to ensure the soil can sustain the maximum force without giving way. This value is used in foundation-planning spreadsheet calculations.

Herein bearing capacity of subsoil namely unconfined compressive strength and undrained shear strength are important parameters. Bearing capacity of subsoil can be expressed by using undrained shear strength. Value of undrained shear strength without confining pressure is equal to unconfined compressive strength.