## Theory of structure (TOS)

Theory of structure (TOS) :In a broad sense, the design of a structure consists of two parts: the first part deals with the determination of forces at any point or member of the given structure and the second part deals with the selection and design of suitable sections to resist these forces so that the stresses and deformations developed in the structure due to these forces are within permissible limits. The first part can be termed as “structural analysis” and the second part as “proportioning” or “dimensioning” of members .

Before we can start the analysis, we shall require the entire details of the structure, loading and sectional properties. To proportion a structure, we must first know how it will behave under loading. Therefore, the process of analysis and design forms an integral part of any design. There is a definite advantage in combining design and analysis, and were it not for the fact that such a textbook would be enormous, it would have been ideal to include both in one volume. In practice, the properties of members are so chosen as to obtain a specified structure, and then the analysis is carried out. Often the designer may have to readjust his initial dimensions in order to get the desired response from the structure. Therefore, the intended purpose of any analysis is to know how the structure responds to a given loading and thereby evaluate the stresses and deformations.

The ultimate aim in learning the methods of analysis is, to help design efficient, elegant and economical structures. Analysis helps the designer to chose the right type of sections consistent with economy and safety of the structure. The purpose of structural analysis is to determine the reactions, internal forces, such as axial, shear, bending and torsional, and deformations at any point of a given structure caused by the applied loads and forces.

Truss A truss is an articulated structure composed of straight members arranged and connected in such a way that they transmit primarily axial force. If all the members lie in one plane it is called a plane truss. A three-dimensional truss is called a space truss. PLANE TRUSS The basic form of a truss is a triangle formed by three members joined together at their common ends forming three joints. Such a triangle is clearly rigid. Another two members connected to two of the joints with their far ends connected to form another joint forms a stable system of two triangles. If the whole structure is built up in this way it must be internally rigid. Such a truss if supported suitably will be stable. For example, The truss has to be supported in general by three reaction components, all of which are neither parallel nor concurrent. Such a truss…

Continue Reading
Plane Truss and Geometric stability and static determinacy of trusses
ANALYSIS AND DESIGN In a broad sense, the analysis and design of a structure consists of two parts: The first part deals with the determination of forces at any point or member of the given structure. The second part deals with the selection analysis and design of a structure suitable sections to resist these forces so that the stresses and deformations developed in the structure due to these forces are within permissible limits. The first part can be termed as "structural analysis" and the second part as "proportioning" or "dimensioning" of members . Before we can start the analysis, we shall require the entire details of the structure, loading and sectional properties. To proportion a structure, we must first know how it will behave under loading. Therefore, the process of analysis and design of a structure forms an integral part of any design. In practice, the properties of members are…

Continue Reading
ANALYSIS AND DESIGN OF A STRUCTURE
FORMS OF STRUCTURES Any civil engineering structure is conceived keeping in mind its intended use, the materials available, cost and aesthetic considerations. The structural analyst encounters a great variety of structures and these are briefly reviewed here. One of the simplest structures is a, simply supported beam, supported on a pin at one end' and a roller at the other (Fig. 1.1a). Such a beam, it may be recalled from the fundamentals of strength of materials, is quite stable and statically determinate and transmits the external loads to the supports mainly through shear and moment. The other types of beams which are more complicated from the point of view of analysis are those with fixed ends and those that are continuous over supports (Figs. 1.1 b and c). As we shall see later, such beams are statically indeterminate and cannot be solved using equations of static equilibrium alone. For longer…

Continue Reading
Forms of structure(beam,trusses arch and frames) in structure analysis
SI Units for Structural Engineers The international system of units SI (System Internationale units) Units for Structural Engineers, commonly called SI, is being adopted allover the world as a uniform measurement system. While the complete transition from customary units to the SI system may take years, the use of SI (System Internationale units) Units for Structural Engineers units in the fields of engineering and science is proceeding rather rapidly, and it will soon be come necessary for the modern civil engineer to gain experience in using the SI system. Fortunately, the cl1~ngeover from the now common MKS units to SI units is quite simple, unlike the changeover from FPS to MKS units. In this book, SI units have been used throughout, with only mi.nor modifications, to suit the requirements of the engineering world. The basic and derived units for various categories of measurement are discussed in the following sections. TYPICAL BASIC…

Continue Reading
SI Units for Structural Engineers