Answer Happy

Question 2: A free vibration test has been conducted on the one-storey shear frame shown below. Masses of the frame are assumed to be lumped at the floor level and the floor is considered rigid. The frame was subjected to a lateral static load P= 200 kN on the floor level that produced an initial lateral displacement yo = 0.5 cm. The frame began to vibrate when P was suddenly removed. The undamped natural period (approximately same as damped natural period) of the frame was measured to be 1 sec, and the lateral displacement became 0.4 cm after one vibration cycle. Determine (a) the mass M lumped at the floor level; and (b) damping ratio of the system. Assume small damping (g=9.8 m/sec?). M P