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Unformatted text preview: 2 2 2 2 1 1 o n n n o n Q / k Force due to the free part = k sin t / Q / k Force due to the forced part = k sin t / ϖ - - - Problem #2. Consider the figure below that describes a vibrating system with damping. The foundation weighs 800 kN, where the foundation and the soil mass are idealized as a mass-spring-dashpot system. Assume that the spring constant is 200,000 kN/m, and the dashpot coefficient is 2,340 kN-s/m. The foundation is subject to a vertical earthquake force Q = Q o sinωt where Q o = 25 kN and ω = 100 radians/second. a) Redo the figure in AutoCAD with pastel colors. b) Determine the critical damping coefficient c c . c) Determine the damping ratio. d) Determine the logarithmic decrement. e) The damped natural frequency. f) Determine the amplitude of the vertical vibration. g) Determine the maximum dynamic force transmitted to the subgrade....
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- Fall '09
- Damping ratio, Logarithmic decrement, dynamic force