Task:

Height of the retaining wall H=2120 mm,

Elastic Modulus of Concrete =20,000 MPa

Elastic Modulus of Steel = 200,000 GPa

Static General Analysis is going to be exacuted.

Retaining wall is fixed at the bottom.

Load will be applied as uniform pressure along the retaining wall.

Pressure, p=k ρ g H

where k is a constant varies between 0.2-0.5. Also known as lateral earth pressure coefficient.

Analysis steps:

Run the model with considering lateral soil pressure only.

Afterwards, additional pressure caused by vehicles on the road will be applied as additional pressure.

Any assumptions taken have been stated in the report below.

## Executive Summary

This report includes modeling and analysis of the model due to specific circumstance given.

Due to preliminary design of retaining wall, rebar diameters chosen and analysed.

During this entire process, modeling and analysis of model tasks handled on Abaqus

Software.

At the first heading: problem definition touch upon the variables, needs and loads while

second heading touch upon assumed variables, formulas and calculations. Third heading

reported as results and discussion about the results by asking the question: ‘What could

have been miscalculated?’

## Problem Definition

Retaining walls has a great variety of usage area but there is only one purpose to construct

retaining wall and that is carrying the horizontal stress exerted by soil. Soil creates vertical

and horizontal stresses and to simplify, horizontal stress generated by soil is derived from

vertical stress. Such as, multiplication of vertical stress with the coefficient ‘k’ gives us the

horizontal stress at exact point.

Objective of this project is to observe the importance of live loads on retaining walls.

In this project, retaining wall carries the soil at the side of a road. Roads transmits the loads

on them to soil below them thus soil generates additional stress on reinforced concrete

retaining wall.

In Step-1, only horizontal soil pressure applied on wall and analyzed. In Step-2, model

analyzed for worst case scenario and that is trucks on the roads. So, in second step, there

are two stress generators, they are; soil itself, additional live load on wall generated by

trucks.

## Analysis Description

Methodology of analysis of this 1040mm x 200mm x 2120mm retaining wall is;

• Model creation with properly chosen parameters. (Radius of rebars are 5mm, Steel

is used for rebars, earth pressure coefficient ‘k’ taken 0.3, density of soil selected

2700kg/m3.)

Pressure on the retaining wall due to horizontal stress generated by soil is calculated by

formula;

While assigning the pressure onto wall, pressure converted to net force as F = A * p

Therefore;

p = 0.3 * 2700kg/m^{3} * 9.81m/s^{2} * 2.12m = 16.845 kN

F= A * p = 2.12m * 1.04m * 16.845 = 37.14

For step-2, mass of a single truck assumed 40 tonnes. To apply this load on model, following

calculations have done to translate the loading to net force;

pt = 0.3 * 80t * 9.81m/s^{2} = 235.44 kN

## Results and Discussion

First, lateral load generated by soil’s weight have to be applied incrementally rather than uniformly over the

depth of retaining wall and live loads effect on stress has to be decreased over the depth of

retaining wall. But in this model, we applied maximum soil pressure and live load on

retaining wall uniformly which is an overdesign but there is nothing wrong with being ‘safe’

in design since soil is unpredictable.

Relationship between steel and concrete in this modeling is assigned ‘perfectly’ which is not

attainable in real world. In real life, ribbed steel bars invented to increase the surface area

between steel and concrete and this helps steel to hold concrete and consumes the tension

forces with its ductility. But there is not a perfect connection between them even with ribbed bars.

To summarize, even tough it is an overdesign as stated above, effect of trucks can’t be

ignored. This is an important point to stop and think about when analyzing

loads appropriately with the knowledge of soil behavour will make whole process cheaper,

safer but will make application of load’s harder.