Balancing of Movable Bridges by the Strain Gauge Technique

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@Computerized Data Acquisition and Ana1jsis SystemThe test method described in this paper involves the recording ofan analog signal for playback during analysis. A computerized dataacquisition and analysis system has been developed to provide onsiteresults. The strain gage and inclinometer signals (whereapplicable) are entered directly to the system and converted to adigital form. At the end of each test, the system can provide thepresent balance state, predict the load curves for proposed weightchanges, and recommend weight changes based on available weightlocations.The system has the advantage of producing instant results. Thismeans results are available soon after changes in the weights havebeen made. These can be used to verify the effects of the weightchanges and if needed recommend further fine tuning of the weightplacement.The system is more compact and lighter than the current system andwith some training, a non-engineer can run the test.
Case Study No. 1The Route 52 Ocean City. New Jersey Bascule SpanUpon analysis, the span was found to have an extreme verticalimbalance moment. This would require placement of weight above thetrunnion to a degree not possible with the available weightlocations. Subsequent investigation found that the original woodand asphalt concrete deck was removed. A lighter steel grid deckis presently in place (See Figure 4). To correct this imbalance,major reconstruction of the span would be required. To minimizethe effect until corrections are made, operating the span at fullopening position can be avoided unless waterway traffic requiresit.Case Study No. 2Route 52 Somerset. New Jersey Bascule SDanIncorrect wiring of one of the wheatstone bridges produced a gageconfiguration sensitive to direct shear in one plane. The resultwas an output cosine wave in phase with the pinion shaft rotation.The mistake was identified, corrected by re-wiring of thewheatstone bridge and the test was performed.
Page 1 and 2: At4ERICM CONSULTING ENGINEERS COUNC
Page 3 and 4: IntroductionSeveral moveable bridge
Page 5: Test MethodThis test method for bal
Page 9 and 10: Data ReductionTo analyze the balanc
Page 11 and 12: For bascule spans, leaf moment is d
Page 13 and 14: 3. Calculate the vertical and horiz
Page 15: The Balance StateNo set standard of
Page 19: Case Study No. 3EBThe Eastern Boule
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Balancing of Movable Bridges by the Strain Gauge Technique

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