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Refinement of the Inverted T-Beam Bridge System for VirginiaArif Edwin, Ezra Bin 01 August 2017 (has links)
The inverted T-beam bridge system is a bridge construction technique that follows accelerated bridge construction processes. The system was discovered in France and first adopted in the U.S. by the Minnesota Department of Transportation. In 2012 the system was modified and adopted by Virginia, with research being carried out at Virginia Polytechnic Institute and State University (Virginia Tech). The research focused on multiple items involving the system, but the most relevant one is that regarding the transverse bending behavior of the system for different geometries, and joint types between adjacent precast beam members. The study found that using a joint system without any mechanical connection between adjacent beams was most efficient, and gave adequate performance under monotonic loading. The study recommended cyclic load testing be carried out on this joint type, as well as a welded joint similar to those found in decked bulb-T systems.
The research contained herein presents the setup and results of this testing. From the work it was found that the no-connection joint behaves adequately under cyclic loading at service loads, however surface roughening between precast and cast-in-place concrete must be adequate. The welded connection behaves well, granted the surfaces to be welded are properly prepared. From these results it is recommended to evaluate different surface roughening techniques, and repeat the cyclic testing using the best. The surface roughening technique chosen should be used to provide guidance on this aspect of construction with inverted T-beams. / Master of Science / The inverted T-beam bridge system is a new type of bridge system intended for use in short to medium length bridges. The system was discovered in France in 2004, where a similar type was being used. It was first modified slightly, and adopted in the in Minnesota. In 2012, the system was again modified to increase its strength and its construction speed, and was then adopted in Virginia. The modifications to the system in Virginia focused on the connections between the individual units making up the bridge, and the geometry of each of these units.
The focus of this research was to quantify the long-term performance of two of the connection types currently used on bridges in Virginia. This was achieved by subjecting a test specimen to repeated loads in the laboratory at Virginia Tech. The loading used in the laboratory represented the conditions that a real bridge of this type would be subjected to.
The research showed that the two connection types performed well under the repeated loading conditions. However, it was concluded that the concrete surfaces which are in contact with one another must be properly roughened, so that the system maintains its strength.
The importance of this research is due to the fact that the large costs associated with maintaining the nation’s bridge infrastructure can be substantially reduced due to this system’s quick and simple construction. In addition to this, road users experience less disruption because of the shortened construction times.
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