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Unformatted text preview: CONTENTS 1. OBJECTIVE 1 2. INTRODUCTION 1 3. THEORY 3 4. APPARATUS 4 5. EXPERIMENTAL PROCEDURES 6 6. EXPERIMENTAL RESULTS, CALCULATIONS AND GRAPHS 7 7. DISCUSSION 8 8. FURTHER DISCUSSION 12 9. CONCLUSION 15 10. REFERENCES 15 OBJECTIVES In this experiment, the load-deflection behaviour of statically determinate and statically indeterminate truss models are studied and compared with the theoretical behaviour. INTRODUCTION Trusses are the major types of engineering structure. They are designed to support loads and are usually stationary fully constrained structures, such as bridges, buildings, etc. The truss provides a practical and an economical solution to many engineering situations. Trusses consist exclusively of straight members connected at joints located at the ends of each member by means of rivets or welding. These members are slender and can only support little lateral load, therefore, all loads must be applied to various joints and not to rhe members themselves (refer to <+">Fig 2(a)<-">). Each member of the truss is acted upon by two equal and opposite forces directed along the members which mean that this only causes axial tension or compression to the members (refer to Fig 2(b) & 2(c). The amount of deflection of members due to applied loads is essential in the determination of the strength, stability and safety of the entire structure. The knowledge of the amount of deflection for certian materials can contribute to the quality of the st ructure. THEORY In this experiment, we are going to study two different types of truss models: (a) Statically determinate plane truss model. (b) Statically indeterminate plane truss model. A truss is statically determinate if the forces in all the members of the truss can be calculated by considering equilibrium at joints. A truss is statically inderterminate if the number of unknown forces are more than the number of equilibrium equations. To calculate these forces in a indeterminate truss, equations expressing the following conditions are required. (a) Equilibrium at each joint. (b) Restrictions on displacements (compatibility). (c) Force-displacement relation of each member. In the truss analysis that follow, the truss members are assumed to be linearly elastic. APPARATUS (1) Statically determinate truss model set-up (as shown in Fig. 5(a)). (2) Statically indeterminate truss model set-up (as shown in Fig. 5(b)). (3) Strain monitoring equipment. (4) Weights (5) Vernier calipers. (6) ruler. EXPERIMENTAL PROCEDURES 5.1 sTATICALLY DETERMINATE TRUSS MODEL (1) The structure was set up as shown in Fig. 5(a)....
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This note was uploaded on 10/18/2009 for the course ECONS 111 taught by Professor Yo during the Spring '09 term at Nassau CC.
- Spring '09