# Esforços dinâmicos

Páginas: 14 (3309 palavras) Publicado: 18 de outubro de 2011
Module 1
Energy Methods in Structural Analysis
Version 2 CE IIT, Kharagpur

Lesson 1
General Introduction
Version 2 CE IIT, Kharagpur

Instructional Objectives
After reading this chapter the student will be able to 1. Differentiate between various structural forms such as beams, plane truss, space truss, plane frame, space frame, arches, cables, plates and shells. 2. State and useconditions of static equilibrium. 3. Calculate the degree of static and kinematic indeterminacy of a given structure such as beams, truss and frames. 4. Differentiate between stable and unstable structure. 5. Define flexibility and stiffness coefficients. 6. Write force-displacement relations for simple structure.

1.1 Introduction

1.2 Classification of Structures
All structural forms used for load transfer from one point to another are 3dimensional in nature. In principle one could model them as 3-dimensional elastic structure and obtainsolutions (response of structures to loads) by solving the associated partial differential equations. In due course of time, you will appreciate the difficulty associated with the 3-dimensional analysis. Also, in many of the structures, one or two dimensions are smaller than other dimensions. This geometrical feature can be exploited from the analysis point of view. The dimensional reduction will greatlyreduce the complexity of associated governing equations from 3 to 2 or even to one dimension. This is indeed at a cost. This reduction is achieved by making certain assumptions (like Bernoulli-Euler’ kinematic assumption in the case of beam theory) based on its observed behaviour under loads. Structures may be classified as 3-, 2- and 1-dimensional (see Fig. 1.1(a) and (b)). This simplification...

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