Construction Perspective

Transcription

1 Construction Perspective MAH

2 MAH : MAH : Spans: 5 (963 ) Girders: Skew = 0 Frames: Slotted L4 x4 x½ 3 piece and 4 piece Expected Deflection during Pour = Frame Spacing: 24 2

3 MAH : Overhang from 4 to 4-3 3

4 Cross Frame Cross Frame Cross Frames 4

5 MAH : Remedy: Structure was milled ¾ to 1 ¼ FAI Structure was given a 2-3 microsilica overlay Extra tall overhang brackets were used to dissipate web loading on the adjacent sister structure. 5

6 FAI : FAI : Spans: 3 (184 ) Beams: 45 Type III Prestressed Concrete Skew = 23 Frames: Slotted MC 18x47.2 Expected Deflection during Pour = 1 5 / 16 Frame Spacing:

7 Overhang = 4-2 ½ 7

8 8

9 FAI : The beam rotation also caused the deck to be thin and the resteel cover to be less than specified. 9

10 FAI : Corrections Performed: Fascia bearings at piers were replaced and beveled shim plates were added to address translational rotation. Topics: Typical Deck Forming Typical Overhang Forming Bridge Paving Machine Use of Screed Elevations 10

11 Deck Forming: Deck Forming: Hanger Generic Interior Cross Section Strut Falsework Between the Beams 11

12 Deck Forming: Stay-in in-place forms (SIP): Edge Forms Corrugated, galvanized metal Assume 18 psf for additional concrete Soffit Hanger Haunch 12

13 Stay-in in-place forms (SIP): Stay-in in-place forms (SIP): Clip angle 13

14 Stay-in in-place forms (SIP): Haunch Styrofoam Topics: Typical Deck Forming Typical Overhang Forming Bridge Paving Machine Use of Screed Elevations 14

15 Spacing is typically 2-3 Typically no haunch No SIP forms Vertical leg length is currently determined by capacity of bracket only. 15

16 Overhang brackets can cause localized buckling and rotation of deep girders Inspection Rail 16

17 Topics: Std. Max = 50 Deep Max = 70 Typical Deck Forming Typical Overhang Forming Bridge Paving Machine Use of Screed Elevations 17

18 Rail Augers Vibrating Rollers Rotating Rollers 18

19 Bid-Well 3600 Bid-Well Wheel Base = 3 Max. Paving Width = 96 Basic Machine = 5990 lbs. Additional = 53 lbs. / ft. 19

20 Bid-Well 4800 Bid-Well Wheel Base = 4 Max. Paving Width = 120 Basic Machine = 7600 lbs. Additional = 75 lbs. / ft. 20

21 Bid-Well 4800 w/ 66 Deep Truss Deck Placement: Contractor Typical Method of Placement Max. Paving Width = 160 Specialty Item Do Not Use without Consulting OCA 21

22 Deck Placement: Design Assumes Loading Along the Skew -OR - Deck Placement: Magical Simultaneous Loading 22

23 Deck Placement Going Forward: Load and finish along skew (±5 ) up to 50. Above 50, finish at 50 and load at actual skew (±5 ), but limit leading edge of concrete to 20 ahead of bridge paving machine. Calculating Bid-Well Machine Length: Skew Width + Extra x w 1.06 x w 1.10 x w 1.15 x w 1.22 x w 1.31 x w 1.41 x w 1.56 x w Machine Length = Width + Extra Length 23

24 Bid-Well Limitations: Connections 24

25 Bid-Well Limitations: Bid-Well Limitations: Break Break Crown Must be an even truss dimension Crown Must be an even truss dimension Break Break 25

26 Bid-Well Limitations: Bid-Well Limitations: Break Varies Varies Varies Varies 7 Varies Crown Variable Break 26

27 Deck Placement: Deck Placement: 27

28 Topics: Typical Deck Forming Typical Overhang Forming Bridge Paving Machine Use of Screed Elevations Setting Grade: Contractor receives a table of screed elevations at quarter points of each span. Deviations in the camber of the beams is normally corrected by varying the haunch height Haunch 28

29 Setting Grade: The haunch height is determined by subtracting the elevation of the top of the beams from the theoretical bottom of the deck The theoretical bottom of the deck is determined by subtracting the thickness of the deck from the given screed rail elevations Screed Elevation Theoretical Deck Thickness Bottom of Deck } Setting Grade: Example of a haunch height or fill table Beam Rear Row Elev. Abut 1/4 Pt 1/2 Pt 3/4 Pt Pier 1 Screed A Deck Bot Beam Top Haunch Ht Top of Beam 29

30 Setting Grade: Grade must be set by instrument Rails Cups or Saddles Dry Run Check deck thickness and concrete cover over reinforcing steel ** Make sure bridge paving rails are secure with no deflection Make sure bridge paving machine is functioning properly 30

31 Dry Run Contractor can only make adjustments for deflections due to the finishing machine weight (not the concrete dead load) Contractor assumes deflections due to concrete dead loads have been addressed in the screed elevations provided Questions?? Questions to: 31