Challenge

Week 4 Challenge

AIM:

To design the abutment foundation as per IRC 6 loads and to optimize design as per IRC 112.
To Detail the steel in the shallow foundation for the abutment.
To calculate the reaction on the bearings from the superstructure considering the given sections.
To explain how a shallow foundation differs from flyovers and in river bridges in terms of stability, design, construction.

PROCEDURE:

This project is about the design of the abutment. The Superstructure consists of an RCC beam of 14.4 m span supported on the elastomeric bearing.
The substructure consists of an abutment on the open foundation.
open foundation design involves the steps Design data, load calculations, load combination, design of foundation, dimensions of the slab and reinforcement detailing.

Design data:

The design data will have the following details carriageway details, span, superstructure details, material grade, geotechnical data.
This design data gives details about dimensions like width, c/c distance, thickness, spacing, wall level, the density of soil and others.
And also we assume heel slab thickness, toe slab thickness and footing dimensions.

Load calculation:

The load data involves the calculation of dead load, live load, superimposed loads, earth pressure loads, and weight of abutment, footing and soil.
In these calculations, we calculate total weight, longitudinal moment, transverse moment, reactions, braking forces and others.

Load combination:

In this, we have two checks base pressure check and stability check, in the stability check we check for overturning stability and sliding stability.

Design of foundation:

The design of the foundation is can be done using the SLS method and ULS method.
The ultimate limit state method checks for a moment of resistance flexural capacity and shear check, uls for verification of Equilibrium and verification of structural strength.
The serviceability limits state checks for stress check and crack width check, allowable stress and allowable crack width.
Rare Combination for checking stress limits, Quasi-permanent Combination For checking crack width in RCC structures.

Shallow foundation:

The foundation which is placed near the surface of the earth or transfers the loads at a shallow depth is called the shallow foundation.
Shallow foundations are commonly used as they are the most economical foundation type and they are easy to construct.
A shallow foundation is constructed in a place where the good load-bearing soil is at a relatively low depth.
Shallow foundations normally are constructed in a shorter time. Settling both the foundation and ground underneath is quicker as there is less land that is required to cover.
They are placed at shallow depths where a depth less than their width, D < B.
stability of the structure should be ensured. Failure will occur due to inadequate bearing capacity or overturning or sliding.

Shallow foundation design requirements:

There must be an adequate factor of safety. The applied bearing pressure must not exceed the safe bearing capacity, qs'
which is the ultimate bearing capacity divided by an appropriate factor of safety F, assumed that the foundation and the structure supported will not fail due to the above conditions.
settlements should not exceed the tolerable limits of the structure supported by the foundation,The applied bearing pressure must not exceed the allowable bearing pressure, q

quit = ultimate bearing capacity.
q, = safe bearing capacity.
F = factor of safety .

quit/f

Types of shallow foundation

Shallow foundation construction:

Foundation placement, which involves the location and depth of the foundation, requires a careful investigation of the site and detailed information about the sub-surface stratum.
The foundation placement should be such that any future influence should not affect it.
Safety against bearing capacity involves with suitable proportioning of the footing to avoid a catastrophic collapse of the soil beneath the foundation.
This occurs if the shear strength of soil is inadequate to support the applied load.
A footing may have to carry a load-bearing wall or a single column or more than one column to support the structure.
Columns generally carry different loads depending on the location and based on the type of structure,Each column has to carry a different type of load, and the major areas are dead and live loads.

Calculate the loads acting on the footing.
2.Obtain a soil profile or soil profiles showing the soil stratification at the site.
Establish the maximum water level.
Obtain the field and laboratory measurements and test results.
Determine the depth and location of the footing.
Determine the bearing capacity of the supporting stratum.
Proportion of the footing sizes.
Check the footing contact pressure.
Check the stability of the footing against sliding, overturning, and uplift pressures.
Estimate the total and differential settlements.
Design the footing structure

RESULT:

Abutment foundation design as per IRC 6 loads and optimized design as per IRC 112 have been done.
Detailing of the steel in the shallow foundation for the abutment has been shown.
The reaction on the bearings from the superstructure was calculated
The shallow foundation which differs from flyovers and river bridges in terms of stability, design, construction has been explained.

Ship work like this
in your own course.