CHAPTER ONE

INTRODUCTION

1.1 BACKGROUND OF THE STUDY

Reinforced concrete structures are one of the most popular structure systems. Many architecture students are using reinforced concrete structure systems for their designs. But there are many cases where they design structurally questionable buildings because they are trying to express their design ideas with limited knowledge about R.C. Design. Frequently the structural member design would not be their primary focus. Although there is the possibility that excessive structural considerations may disturbing their search for unique designs, basic structural calculation is important for design. Structurally sound solutions can make their design concepts closer to reality.

Unfortunately most architecture schools concentrate their curriculum on visual design education rather than a balanced education of design and structure. The balanced education does not mean equal class time for structural and design classes. But it is essential that students can at least discriminate that their design has a reasonable structure. Many students use the commonly available books on architectural graphic standards as a reference. But they are not applicable to many different conditions. Furthermore, reinforced concrete structures need a lot of calculations and different condition inputs because it is a composite material of concrete and steel.

The Reinforced Concrete Structure Design program (RCSD), which has been developed for this thesis, can help architecture students and users to analyze their designs and understand structural fundamentals. Although there are many reinforced concrete structure programs, most programs are targeting advanced level users who have a background in structural engineering.

The RCSD program is for beginner level users such as architecture undergraduate and graduate students with limited knowledge about structures. For this, it provides a graphical input method and a step-by-step calculation procedure to help users. With this program, it is possible for the user to design basic structural parts such as slab, beam, column and footing. Also the program is based on the American Concrete Institute Code. The ultimate goal of this program is that users can analyse their own designs using this program and determine structural proportions of their design idea.

Portland cement concrete containing higher-strength, solid materials to improve its structural properties. Generally, steel wires or bars are used for such reinforcement, but for some purposes glass fibers or chopped wires have provided desired results.

Unreinforced concrete cracks under relatively small loads or temperature changes because of low tensile strength. The cracks are unsightly and can cause structural failures. To prevent cracking or to control the size of crack openings, reinforcement is incorporated in the concrete. Reinforcement may also be used to help resist compressive forces or to improve dynamic properties.

Steel usually is used in concrete. It is elastic, yet has considerable reserve strength beyond its elastic limit. Under a specific axial load, it changes in length only about one-tenth as much as concrete. In compression, steel is more than 10 times stronger than concrete, and in tension, more than 100 times stronger.

During construction, the bars are placed in a form and then concrete from a mixer is cast to embed them. After the concrete has hardened, deformation is resisted and stresses are transferred from concrete to reinforcement by friction and adhesion along the surface of the reinforcement. Individual wires or bars resist stretching and tensile stress in the concrete only in the direction in which such reinforcement extends. Tensile stresses and deformations, however, may occur simultaneously in other directions. Therefore reinforcement must usually be placed in more than one direction. For this purpose, reinforcement sometimes is assembled as a rectangular grid. Bars, grids, and fabric have the disadvantage that the principal effect of reinforcement occurs primarily in the plane of the layer in which they are placed. Consequently, the reinforcement often must be set in several layers or formed into cages. Under some conditions, fiber-reinforced concrete is an alternative to such arrangements. See Composite beam, Concrete, Concrete beam, Concrete column, Concrete slab, Prestressed concrete

1.2STATEMENT OF RESEARCH PROBLEM 

The researcher come to notice that most of the building that get collapsed are structures erected during the late 1980s, and these structures where not built using reinforced concretes, unlike those that are designed and built even as early as of 1900s have not even shown weakness and loss of strength. Going by that analysis, the researcher seeks to create and analysis the importance of using reinforced concrete in today’s modern building so as to erect structures that can last the test of time and withstand every bit of effects against it. 

1.3 OBJECTIVES OF THE STUDY

The researcher seeks to establish the essence of using a reinforced concrete in today’s modern building, also, to make a comparative analysis of reinforced concrete and concrete, the strength, loads and durability. With the use of reinforced concrete on building, the following seems to be a characteristic of such buildings which the researcher seeks to highlights its importance too.  

1.High relative strength

2.High toleration of tensile strain

3.Good bond to the concrete, irrespective of pH, moisture, and similar factors

4.Thermal compatibility, not causing unacceptable stresses in response to changing temperatures.

5.Durability in the concrete environment, irrespective of corrosion or sustained stress.

1.4DEFINITION OF TERMS

Reinforced concrete: Reinforced concrete (RC) is a composite material in which concrete's relatively low tensile strength and ductility are counteracted by the inclusion of reinforcement having higher tensile strength and/or ductility. The reinforcement is usually, though not necessarily, steel reinforcing bars (rebar) and is usually embedded passively in the concrete before the concrete sets.

Concrete: Concrete is a composite material composed of aggregate bonded together with a fluid cement which hardens over time. Most use of the term "concrete" refers to Portland cement concrete or to concretes made with other hydraulic cements, such as ciment fondu. However, road surfaces are also a type of concrete, "asphaltic concrete", where the cement material is bitumen.

PH: pH is a measure of how acidic/basic water is. The range goes from 0 - 14, with 7 being neutral. pHs of less than 7 indicate acidity, whereas a pH of greater than 7 indicates a base. pH is really a measure of the relative amount of free hydrogen and hydroxyl ions in the water

RCSD: Reinforced Concrete Structure Design program 

Toleration: Toleration in this study is the amount of time a reinforced concrete can withstand the test of time and moisture 

REFERENCE

Spiegel, Leonard. Reinforced Concrete Design, 4th ed., Prentice-Hall, Inc., 1998.

Stephens, Lod. Visual Basic Code Library, John Wiley & Sons, Inc., 1999.

U.S. News, Best Graduate School - Architecture Ranked in 1997 [online], Available

from: http://www.usnews.com/usnews/edu/beyond/gradrank/gbarch.htm [Accessed 3/13/2002]

Williams, Alan. Design of Reinforced Concrete Structures, 2nd ed., Engineering

press, 2000.

Rice, Paul F., and Hoffman, Edward S. Structural Design Guide to the ACI Building

Code, 3rd ed., Van Nostrand Reinhold Company, Inc., 1985.

Ray, S. S. Reinforced Concrete: analysis and design, Blackwell Science Ltd., 1994.

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