June 23, 2013
June 23, 2013
June 26, 2013
23.1168.1 - 23.1168.10
The Bridge House: A Living Dynamics LaboratoryIn 1965, a class of undergraduate students launched a project to utilize the rough terrainsurrounding their local campus. Their solution was to span a ravine with a bridge-like structuresimilar to that of Mies Van Der Rohe’s Glass House. Over the years, the building has mostlybeen forgotten and has fallen into a state of disrepair. Fortunately, in 2011 another team ofstudents took on the task of revitalizing the building and have created a living structuraldynamics laboratory. The relatively small building has a clearly visible structural system thatlends itself to rapid analysis by undergraduate students. By positioning small (< 100 lb) shakingdevices at various locations on the floor and at two predetermined ceiling mounts, the studentscan explore the actual dynamic behavior of the structure through standard accelerometers,common data acquisition hardware and some custom software. Comparison of the student’spredictions using hand calculations and increasingly advanced computational modeling with theactual structural response has been found to have several benefits. Students not only sharpentheir modeling skills, they can explore the accuracy of their modeling assumptions and learn ahealthy skepticism for computational results.While simple, the structure possesses several interesting structural features, the first of which areremovable braces (supplementing moment-resisting frames). This permits the exploration ofsystem identification and damage detection exercises. Furthermore, the removable braces aretuned such that in some configurations, the natural frequencies of two modes collide. With this,the students can explore mode coupling and the beating phenomenon. Students can also exploreboth rigid and flexible diaphragms using the roof diaphragm alone. With the braces one or twoparallel walls removed, the bare steel roof deck exhibits distortions in some modes yet remainsrigid in others. In addition to these features, students can explore the attachment of thediaphragms to the steel beams, the flexibility of the foundations, the presence of physicallydiscernible vertical vibrations, and a shift in modal frequencies due to thermal effects.This paper presents both the layout and configuration of the physical structure including theremovable braces, flexible foundations, diaphragm attachment, and the associated structuraldynamic behavior. It also details the use of the shaking devices employed to excite the buildingstructure and the software and hardware necessary to obtain the building response. Mostimportantly the concepts and execution of the learning modules for the student exploration ofstructural dynamics are presented. The learning modules, hardware, and software have beencustomized for the Bridge House structure, but are equally adaptable to any small structure (up toand including 3-story lecture halls) on campuses nationwide.
Archer, G. C., & McDaniel, C. C., & Ramos, P. D. (2013, June), The Bridge House: A Living Dynamics Laboratory Paper presented at 2013 ASEE Annual Conference & Exposition, Atlanta, Georgia. https://peer.asee.org/22553
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