Strain Gauge Balancing of the Lea Joyner

Transcription

1 Strain Gauge Balancing of the Lea Joyner Double Leaf Bascule Span Bridge Louisville Ave. Across the Ouachita River Monroe, Louisiana By Stewart P. Hingle, P.E. Louisiana Department of Transportation and Development Bridge Design Section

2 What is Strain Gauge Balancing?

3 What is Strain Gauge Balancing? A method of determining the balance of a movable bridge by using strain gauges to measure the torque in the span drive pinion shaft.

4 When Can This Method Be Used?

5 When Can This Method Be Used? Can only be used on spans where the imbalance of the span is resisted by the span drive pinion shaft.

6 When Can This Method Be Used? Can only be used on spans where the imbalance of the span is resisted by the span drive pinion shaft. Such As

7 When Can This Method Be Used? Can only be used on spans where the imbalance of the span is resisted by the span drive pinion shaft. Such As Rack and Pinion Bascule Spans

8 When Can This Method Be Used? Can only be used on spans where the imbalance of the span is resisted by the span drive pinion shaft. Such As Rack and Pinion Bascule Spans Rack and Pinion Vertical Lift Spans

9 When Can t This Method Be Used?

10 When Can t This Method Be Used? Spans that do not have a rack and pinion drive system

11 When Can t This Method Be Used? Spans that do not have a rack and pinion drive system Such As

12 When Can t This Method Be Used? Spans that do not have a rack and pinion drive system. Such As Spans driven by hydraulic cylinders

13 When Can t This Method Be Used? Spans that have a rack and pinion drive system, but the imbalance of the span is not resisted by the rack and pinion

14 When Can t This Method Be Used? Spans that have a rack and pinion drive system, but the imbalance of the span is not resisted by the rack and pinion Such As

15 When Can t This Method Be Used? Spans that have a rack and pinion drive system, but the imbalance of the span is not resisted by the rack and pinion. Such As Rack and pinion swing spans

16 Lea Joyner Bridge Monroe, Louisiana

17 Lea Joyner Bridge

18 Bridge Information

19 Bridge Information Double leaf bascule

20 Bridge Information Double leaf bascule Four lanes

21 Bridge Information Double leaf bascule Four lanes No shoulders

22 Bridge Information Double leaf bascule Four lanes No shoulders Pedestrian sidewalks on both sides

23 Bridge Information Double leaf bascule Four lanes No shoulders Pedestrian sidewalks on both sides 39,000 ADT

24 Bridge Information Double leaf bascule Four lanes No shoulders Pedestrian sidewalks on both sides 39,000 ADT About six openings a week

25 Bridge Information

26 Bridge History

27 Bridge History Built in 1936

28 Bridge History Built in 1936 Originally had a timber deck with asphalt planks

29 Bridge History Built in 1936 Originally had a timber deck with asphalt planks 1950, timber deck replaced by lighter grid deck

30 Bridge History Built in 1936 Originally had a timber deck with asphalt planks 1950, timber deck replaced by lighter grid deck Plans instructed Contractor to adjust concrete fill in grid deck to balance span

31 Bridge History Counterweight compartments added to the span

32 Bridge History Counterweight compartments added to the span 2007, rehabilitation project

33 Bridge History Counterweight compartments added to the span 2007, rehabilitation project Span was determined to be very span light

34 Bridge History Counterweight compartments added to the span 2007, rehabilitation project Span was determined to be very span light Repairs added heavier structural members and additional counterweight to the span

35 Bridge History After repairs were completed

36 Bridge History After repairs were completed Contractor used motor amperage to determine the span balance

37 Bridge History After repairs were completed Contractor used motor amperage to determine the span balance Estimated that the spans were between 500 and 1,000 pounds span heavy at the tip of the span

38 Bridge History Had another rehabilitation project coming up to replace the grid deck

39 Bridge History Had another rehabilitation project coming up to replace the grid deck Decided we needed a more accurate measurement of the imbalance

40 Bridge History Had another rehabilitation project coming up to replace the grid deck Decided we needed a more accurate measurement of the imbalance Brought in a Consultant to perform this strain gauge balancing

41 Modjeski & Masters

42 Modjeski & Masters David Barrett, P.E. & Geoffrey Forest, P.E.

43 Drive System

44 Strain Gauge Process

45 Strain Gauge Process

46 Strain Gauge Process

47 Strain Gauge Process

48 Strain Gauge Process

49 Strain Gauge Process

50 Strain Gauge Results

51 Strain Gauge Results

52 Thank You!