June 23, 2013
June 23, 2013
June 26, 2013
23.628.1 - 23.628.10
Full-scale Mechanical Vibrations LaboratoryA unique full-scale experimental laboratory was recently developed to improve students’physical understanding of the complex principles presented in mechanical vibrations courses.Rather than creating the typical small scale model with lumped masses to illustrate importantmechanical vibrations concepts, a full-scale structure was used to improve the relevance of theexperiments so that students can connect the results with the real world. The Bridge House, aone-story building constructed by undergraduate students, is apply named since it spans a smallseasonal creek in the student outdoor experimental construction laboratory. This structure isideal for vibration experimentation since it is simple enough for the students to quickly model byhand calculations and with computational models, yet complex enough so that the results can bereadily applied to an actual structure. Forced vibration testing (FVT) was employed to excite thebuilding. The goal of the FVT was to experimentally determine the building’s naturalfrequencies, mode shapes, and damping so that the students could compare their predictions ofthe dynamic response of the building.Two experiments were conducted by the students, a vertical floor FVT where the shaker isplaced vertically at the midpoint and at a quarterpoint along the Bridge House floor, and a lateralroof FVT where the shaker is mounted to the underside of the central roof beam. The verticalfloor vibration experiment allowed students to physically feel the difference between modeshapes by walking along the floor and experiencing maximum vertical excitation at the peaks aswell as minimal vertical excitation at the nodes. The lateral roof vibration experiment provided abasis for the students to compare their hand calculations and computational model predictions ofthe dynamic response of the structure. Prior to conducting the lateral roof vibration experimentsthe students’ computational model predictions of the Bridge House response varied widely. Bycomparing their predictions to the FVT, the computational models improved, dramaticallynarrowing the range of fundamental frequencies reported by the students; consequently, ahealthy skepticism for the computational results was forged in the students’ minds. Bothformative and summative evaluations were used to assess improvement in student learning andto enhance the laboratory experience for future students. Additional laboratory modules that canbe explored by the students include the study of soil-structure-interaction, rigid versus flexiblediaphragm response, the influence of different brace sizes on the modal parameters as well asthermal effects on vibration response of the structure.
McDaniel, C. C., & Archer, G. C. (2013, June), Full-scale Mechanical Vibrations Laboratory Paper presented at 2013 ASEE Annual Conference & Exposition, Atlanta, Georgia. https://peer.asee.org/19642
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