CHAPTER ONE
1.0          Introduction

In the design and analysis of reinforced concrete member is based on the assumption that concrete and steel reinforcement combine to create new composite material.

Generally the concrete is design to carry the compressive load while the reinforcing bar is design to carry tensile loads.

The mechanics of members consisting of two materials:

To compound this problem, one of the material concrete behaves differently if it is not neglected entirely.

Although we will encounter some peculiar aspects of behavior of concrete members we will usually be close to a solution for most problems if we can apply the following three basic ideals.

Geometry of deformation of section will be consistent under given types of loading i.e. moment will always cause strain to carry linearly with distance from neutral axis etc.

Mechanics of materials will allow us to relate stresses to strains.

Section will be equilibrium: external moment will be resisted by internal moment.

External axial load will be equal to the sum of internal axial forces.

Many new engineers overly impressed speed and apparent accuracy of modern structural analysis computational procedures think less about equilibrium and details.

We will use some or all of these ideas in solving most of the analysis problems we will have in the course of the project work.

Design of members and structures of reinforced concrete is a problem distinct from but closely related to analysis.

Strictly speaking, it is almost impossible to exactly analyze a concrete structure and to design exactly is no less difficult.

Fortunately, we can make a few fundamental assumptions which make the design of reinforced concrete quite simple if not easy.

A unique problem to the design of reinforced concrete structures is the need to detail each member throughout.

In general steel structure only requires the detailed design of connection.

For concrete structures, we must determine not only the area of longitudinal and lateral performance this procedure can be made reasonably simple.

Purpose of this project work is to establish a firm understanding of behaviour of reinforced concrete structure, then to develop method used in current practice and to achieve familiarity with codes and specification governing practical design.

In this project work we will learn to understand the basic performance of concrete and steel as structural materials. And the behaviour of reinforced concrete members and structures.

If we understand the basic concept behind code provision for design, we will be able to:

1. Approach the design in a more knowledgeable fashion not like following a black box.
2. Understand and adapt the changes in code provisions better and faster.
3. The overall goal is to be able to design reinforced concrete structure that are

Safe

Economical

Efficient.

Reinforced concrete is one of the principle building materials used in engineered structure because.

1. Low cost
2. Weathering and fire resistance
3. Good compressive strength
4. Formability.

All these criteria make concrete an attractive material for wide range of structural applications such as building, dams, reservoir tank etc.

1.1          Background of Study

Reinforced concrete structure is one of the most popular structure systems.

The importance of building in relation to development and civilization cannot be over emphasized as history testified that the provision of building is necessary to draw an environment out of the state of underdevelopment.

The land use plan can be used with high-rise structure so as to accommodate more people on a small piece of land

This gesture therefore calls for the design of waffle slab.

The ultimate goal of this program is that user can analyze their own design and also determine structural proportion of their design idea.

Waffle slabs have economical and constructional benefit. They are used for heavy loads and large span structures as they exhibit higher stiffness and smaller deflection. As a result, waffle slabs has been widely used for office buildings, hotels, auditoriums, vestibules, theatre halls, show rooms of shops where columns free space is often the main requiremen.

1.2          Objectives of Study

The main objective of this project work is to come up with a design of  waffle slab

1. To come up with a relatively high compressive strength of concrete design.
2. To implement a better resistance to fire than steel of concrete design.
3. To come up with a cast to take the shape required so as to make it widely used in precast structural components.

The structure will be design for safety to meet it design purpose throughout its life span and also economical.

These will illustrate the step load analysis and design procedure of a typical requirements.

1. To withstand the environmental condition over time
2. To be very aesthetic in appearance
3. To be structurally safe.

1.3 Problem of Study

This research is motivated by the failure of building in modern day.

Some of the benefit of waffle slab are as follows.

1. The load carrying capacity of waffle slab is greater than other types of slab.
2. waffle slab are used for large span slabs or floors and used when there is limited requirement for number of columns.

iii.            waffle slab are lightweight and requires less amount of concrete, hence it’s economical

1. They provide good structural stability along with aesthetic appearance. Hence, it is constructed for airports, hospitals, temples, churches et.

1.4 Research Question

The following question will guide this research work:

1. Is speed and time a major constrain to the designer?

1.5 Scope of Study

The project work cover only the design analysis and determination of loads and stresses acting on the waffle slab.

The design shall be in accordance with BS 8110 code of practice.

The natural external forces as to be experience during its life span shall be considered such as temperature, wind forces, and soil resistance.

It shall be design specifically to suit it intended purpose.

The design of the waffle slab shall be considered to avoid repetition and also save time. It is also design structurally to meets it’s serviceability over the intended life span such as serviceability over the intended life span such as fire resistance, cracking and defection etc.

1.6   Significance of Study

The structural stability of any reinforced concrete structure depends on the designer and it is of a great importance to know some of the significance of using manual design. The conventional approach towards drafting was not only time taking but also called for lot of inconveniences furthermore; the designs thus created were far from being accurate.

1.7 Limitation of Study

This project work occur with time constrain when academic demand is high.

Financial constrain, this project work occur when there is higher demand for the payment of our fees.

Research material. it was not easy for us to get material needed to carry out the project work.

1.8 Definition of Terms

1. Structure: something built or constructed as a building bridges, or dams.
2. Design: to prepare the preliminary sketch or the plan for (a work to be executed). Is also the creation of a plan or convention for the construction of structure.
3. BS 8110:Bs 8110 is a code of practice for the structural use of concrete.
4. Slab:

A slab is a part of a reinforced concrete structure which is more often than not is subjected to bending (tensile or compressive).

1. Waffle Slab:

Waffle slab is a structural component which is plain on its top and contain grid like system on its bottom surface. The top slab is normally thin and the bottom grid line are generally ribs which are laid perpendicular to each other with equal depth