Recent Experimental Devices to Obtain the Dynamic Parameters of Bridges,
NEW MEXICO STATE UNIV LAS CRUCES
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Full scale testing of structures continues to be the best means of obtaining the dynamic parameters necessary for design. For bridge structures, through, barriers exist that restrict field testing with difficulties that include possible structural damage, inadequate test control, cost, and limitations in accessibility. These difficulties contribute to a current lack of understanding of the dynamic behavior of bridges. To alleviate this problem, New Mexico State University NMSU has devised two test instruments, the tricoil sensor and a portable vibration machine. The tricoil sensor was designed to clearly measure movement in three orthogonal directions and succeeds in being superior to its counterpart, the accelerometer. The vibration machine complements the tricoil sensor with its operator control and operational flexibility. A thorough discussion of both instruments detail their composition, how they work, and their functional capacities. A small bridge was constructed at NMSU to test the two instruments. Of particular concern was the vibration machines ability to produce a measurable response in a non-destructive manner. Three tests were initiated to define the fundamental frequencies and damping coefficients of the test bridge and to produce frequency response curves. An outline of the test procedures with corresponding results confirm the effectiveness of the two instruments.