Fundamental questions in Structural Analysis
- 1. Structural Analysis – Fundamentals-I Dr. Nitin S. Naik Department of Structural Engineering Sanjivani College of Engineering, Kopargaon
- 2. Q.No.1- What is the exact difference between moment and bending moment? • Moment: It is the product of force and displacement. Moment is calculated about a point or about an axis. Moment of number of forces about a point is equal to algebraic sum of moment of all forces about a point. • Bending Moment: It is the unbalanced moment calculated either to the right of a section or to the left of a section. • Moment produces rotatory effect, while bending moment causes bending of a member.
- 3. Q.No.2- Figure shows a cross section and L section of a beam. A, B, C, D etc. are the connectors used to connect the web section and the flange section. State for which type of force these connectors should be designed. When a beam is carrying loading, it bends as well as it is subjected to shear stresses. When the above beam bends , the flange section will slide along the length on the web section at the interface developing shear stress. To maintain proper connection between the flange and web, the connectors should be designed for shear. The failure of these connectors will take place in shear, hence such connectors are called as shear connectors.
- 4. Q.No.3- What is a difference between a truss and a frame? 2m 2m 2m 10 kN 10 kN 10 kN 10 kN 10 kN/m 10 kN Truss carries a load at joints only, while frame can carry load any where. The members of a truss are subjected to axial forces only, while the members of a frame are subjected to shear force and bending moments.
- 5. Q.No.4- A member is simply supported at the near end and fixed at the far end, what is the stiffness of the beam in this case? In the above case the moment required to produce unit rotation of end A is equal to 4EI/L and this is the stiffness of the beam. While for a beam whose both ends are simply supported , the stiffness is equal to 3EL/L
- 6. Q.No. 5- Select the correct statement 1.Moment causes rotation of a joint 2.Force causes displacement of a joint 3.Torque causes rotation of a joint 4.All of these • Options: 1. Only a is correct 2. Only b is correct 3. Both a and b are correct 4. Both b and c are correct 5. d is correct The cause-effect relationship is Force-Displacement Moment-Rotation Torque-Torsion, Hence the correct option is 3
- 7. Influence lines are used while designing beams and trusses used in bridges, crane rails, conveyor belts, floor girders, and other structures which are subjected to moving load along their span. The influence lines show where a load will create the maximum effect for any of the functions such as reaction, shear force, bending moment. Q.No.6- What is the use of an influence line diagram? 1
- 8. • The determinate structures can be analyzed by using conditions of equilibrium alone, but in case of indeterminate structures we must use additional condition to perform analyse of the structure, such condition is called as compatibility condition. In the given beam we can not calculate the support reactions using equilibrium conditions alone. We must use compatibility condition of displacement here and that condition is deflection at support B is equal to zero. Q.No.7- In case of analysis of propped cantilever beams (indeterminate structures), in addition to equilibrium conditions an additional equation is required. For the beam shown in figure which additional equation you can use.
- 9. • Castigliano's theorem- It states that the partial derivative of the total strain energy stored in a beam with respect to the redundant force is equal to zero. • It is also called as a theorem of minimum work and can be stated as- • Redundant reaction forces in a statically indeterminate structure will be such that it makes the strain energy to its minimum value. Q.No.8- State Castigliano’s theorem used for the analysis of indeterminate structure. 0 Displacementatand corresponding the redunt nt 0 a L M M dx EI W VB=W
- 10. • Change in temperature causes stresses in indeterminate structures ( Thermal Stresses). In case of indeterminate structures the degree of freedom is restricted by the redundant reactions/ support conditions. Q.No.9- Change in temperature causes stresses in which type of structure, Determinate or Indeterminate ? Explain why?
- 11. Q.No.10- Match the pairs
- 12. Thank you………….