Page 1 İNŞ498-Fall-13 Problem Set #3 …../…. . Surname , Name ...

İNŞ498-Fall-13Problem Set #3Number: __ __ __ __ __ __ __ __ __ __ __Surname , Name : __ __ __ __ __ __ __ __ __ __ __ __ ____ __ / __ __ / 2012…../…..

İNŞ498-Fall-13Problem Set #3Number: __ __ __ __ __ __ __ __ __ __ __Surname , Name : __ __ __ __ __ __ __ __ __ __ __ __ __ANADOLU UNIVERSITY Department of Civil Engineering__ __ / __ __ / 2012(Due date, time & place: 21.11.2012 at 09:00, in homework box for İNŞ498 at room İNŞ125.[Mr. Onur TUNABOYU])1-) (50 Point) A machine is supported on four steel springs for which damping can be neglected. The natural frequencyof vertical vibration of the machine-spring system is 200 cycles per minute. The machine generates a vertical forcep(t)=p 0 sin ωt. The amplitude of the resulting steady-state vertical displacement of the machine is u 0 = 0.2 in. when themachine is running at 20 revolutions per minute (rpm), 1.042 in. at 180 rpm, and 0.0248 in. at 600 rpm. Calculate theamplitude of vertical motion of the machine if the steel springs are replaced by four rubber isolators which provide thesame stiffness, but introduce damping equivalent to ζ = 25% for the system. Comment on the effectiveness of theisolators at various machine speeds.Q1Q2Σ…../…..

İNŞ498-Fall-13Number : __ __ __ __ __ __ __ __ __ __ ____ __ / __ __ / 2012Problem Set #3 Surname , Name : __ __ __ __ __ __ __ __ __ __ __ __ __2-) (50 Point) An air-conditioning unit weighing 1200 lb is bolted at the middle of two parallel simply supported steelbeams as seen in the figure below. The clear span of the beams is 8 ft. The second moment of cross-sectional area ofeach beam is 10 in 4 . The motor in the unit runs at 300 rpm and produces an unbalanced force of 60 lb at this speed.Neglect the weight of the beams and assume 1 % viscous damping in the system; for steel E = 30,000 ksi. Determinethe amplitudes of steady-state deflection and steady-state acceleration (in g’s) of the beams at their midpoints whichresult from the unbalanced force.…../…..