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Unformatted text preview: CE 573: Structural Dynamics HW#5 Supplemental Problem Given : Another common model used for buildings is the portal frame model, which tries to account for flexibility of both horizontal and vertical members by allowing for rotations at connections. In this problem, we seek to obtain the dynamic properties of the simple portal frame shown above. Assume that it has the three degrees of freedom shown (notice that 1 x is the same at both connections), a uniform weight per unit length kip ft 1.2 w = for the horizontal member (including dead load), negligible weight for the vertical members, a length parameter ft, 18 L = 29000 E = ksi, and . 4 430 in I = Assumptions : a) Mass matrix: for translational degrees of freedom, the mass is simply the total mass of the member that is translating. If there is more than one translational degree of freedom for a given member, the total mass is split among all DOF according to their tributary lengths. For rotational degrees of freedom, the “mass” is actually the mass moment of inertia for the member...
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This note was uploaded on 05/09/2008 for the course CE 573 taught by Professor Whalen during the Fall '05 term at Purdue.
 Fall '05
 Whalen

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