Structural Dynamics Lecture 3 Outline of Lecture 3（结构动力学讲座3的轮廓讲座3）.pdf

Structural Dynamics Lecture 3 Outline of Lecture 3 Single-Degree-of-Freedom Systems (cont.) Forced Vibrations due to Arbitrary Excitation. D’Alembert’s Principle. Vibrations due to Movable Su ort. Earthquake Excitations.Earthquake Excitations. Vibrations due to Indirectly Acting Dynamic Loads. 1 Structural Dynamics Lecture 3 Single-Degreee-of-Freedom Systems (cont.) Forced Vibrations due to Arbitrary Excitation Equations of motion of a linear viscous damped system: 2 Structural Dynamics Lecture 3 Box 1 : Equation of momentum : Impulse (momentum) of external and internal forces, [kg s]. Equation of momentum: The increase of momentum of the particle during a time interval is equal to the impulse, i.e. the time integral over the same interval of all external and internal forces. 3 Structural Dynamics Lecture 3 The load is constant for and zero out-side this interval. The load is a lied at the time , where the displacement is and the velocity is . The impulse of is equal to for arbitrary . Assume that is small compared to the undamped eigenperiod of the oscillator. Then, w