I.II Equation of motion i- Characteristics of a SDOF Why SDOF? 1- Simple starting point 2- Many multi-degree of freedom structures can be approximated by a SDOF system i- Characteristics of a SDOF 1- Rigid girder of mass m () 2- Weightless columns of stiffness k 3- Weightless a damper with a damping coefficient c
ii- Newton’s second law FI = rate of change of momentum of any mass is equal to the force acting on it (for constant m) iii- D’Alembert principle (dynamic equilibrium)
Where
Example 1[Ref 1 ] Weight = w lb Length = 10’ E = 29,000 ksi and The weight contribution !!
Example 1 (cont’d)
Example 2 [Ref 1 ]