Retrofit Measures for Superstructures, Bearings, and Seats

Transcription

1 Retrofit Measures for Superstructures, Bearings, and Seats Presented by Richard V Nutt Elements to be Retrofitted Bridge Decks and Girders Bearings, Anchorages and Pedestals Expansion Joints 1

2 Elements to be Retrofitted Bridge Decks and Girders Bearings, Anchorages and Pedestals Expansion Joints Retrofit of Bridge Decks and Girders Lateral Load Path Enhancement Deck to Girder Connection Diaphragm Strenthening or Stiffening Ductile End Diaphragms Girder Strengthening Provide Longitudinal Continuity Web and Flange Plates Superstructure Joint Strengthening Reduction of Dead Load Strengthening of Continuous Superstructures 2

3 Retrofit of Bridge Decks and Girders Lateral Load Path Enhancement Deck to Girder Connection Diaphragm Strenthening or Stiffening Ductile End Diaphragms Girder Strengthening Provide Longitudinal Continuity Web and Flange Plates Superstructure Joint Strengthening Reduction of Dead Load Strengthening of Continuous Superstructures Lateral Load Path Enhancement Deck to Girder Connection Diaphragm Strenthening or Stiffening Ductile End Diaphragms Girder Strengthening 3

4 Deck to Girder Connection CL Girder Existing Concrete Deck Two rows of threaded rods at a specified pitch for entire length of the girders Drill and bond (epoxy cartridge) into existing concrete deck Stagger as shown below LC Girder Lateral Load Path Enhancement Deck to Girder Connection Diaphragm Strenthening or Stiffening Ductile End Diaphragms Girder Strengthening 4

5 Diaphragm Strengthening Symmetrical about centerline of bridge Existing top chord Existing angle brace B Steel tube A A Existing bottom chord B Steel tube Diaphragm Elevation Diaphragm Strengthening Details C L Existing bottom chord C L New steel tube Steel tube Existing angle Centerline of welded studs Existing angles Oversize holes in tube Steel tube Oversize holes in tube Section A-A Studs - welded to existing angles - staggered with nut and washer Oversize holes on outside face of tube Section B-B 5

6 Lateral Load Path Enhancement Deck to Girder Connection Diaphragm Strenthening or Stiffening Ductile End Diaphragms Girder Strengthening EBF Diaphragm Retrofit 6

7 SPS Diaphragm Retrofit TADAS Diaphragm Retrofit 7

8 Lateral Load Path Enhancement Deck to Girder Connection Diaphragm Strenthening or Stiffening Ductile End Diaphragms Girder Strengthening Girder Bracing Retrofit Existing Diaphragm Girder with Bearing Stiffeners New Brace New Structural T Gusset New Gusset 8

9 Bearing Stiffener Retrofit Existing Diaphragm Girder with Bearing Stiffener New Stiffener Knee Brace - Bolt to Bearing Stiffener and Diaphragm Retrofit of Bridge Decks and Girders Lateral Load Path Enhancement Deck to Girder Connection Diaphragm Strenthening or Stiffening Ductile End Diaphragms Girder Strengthening Provide Longitudinal Continuity Web and Flange Plates Superstructure Joint Strengthening Reduction of Dead Load Strengthening of Continuous Superstructures 9

10 Provide Longitudinal Continuity Web and Flange Plates Superstructure Joint Strengthening Web Splice Retrofit Splice plate - place bolts through holes drilled in girders - use slotted holes to accomodate thermal movement A1 A2 A1 A2 Elevation of Girders 10

11 Web Splice Details Splice plate Large offset of girder webs Girders C LBent Section A2 - A2 End bracing C Bent L Small offset of girder webs Section A1 - A1 Methods for accomodating girder misalignment Shim Provide Longitudinal Continuity Web and Flange Plates Superstructure Joint Strengthening 11

12 Provide Superstructure Continuity Remove and Replace Existing RC Deck Bearing Stiffeners Steel Girder A Weld New Steel Splice Plate to Top Flange Steel Girder B Double Angle to Splice Bottom Flange Bearings (Fixed) Retrofit of Bridge Decks and Girders Lateral Load Path Enhancement Deck to Girder Connection Diaphragm Strenthening or Stiffening Ductile End Diaphragms Girder Strengthening Provide Longitudinal Continuity Web and Flange Plates Superstructure Joint Strengthening Reduction of Dead Load Strengthening of Continuous Superstructures 12

13 Retrofit of Bridge Decks and Girders Lateral Load Path Enhancement Deck to Girder Connection Diaphragm Strenthening or Stiffening Ductile End Diaphragms Girder Strengthening Provide Longitudinal Continuity Web and Flange Plates Superstructure Joint Strengthening Reduction of Dead Load Strengthening of Continuous Superstructures Strengthen Superstructure C L Expansion Joint C Bent L C Openings L C Openings L C Openings L Core hole for rebar A A Soffit slab overlay Existing box girder superstructure PLAN Soffit slab overlay Drill and bond into existing girder stem Drill and bond into existing soffit SECTION A - A 13

14 Elements to be Retrofitted Bridge Decks and Girders Bearings, Anchorages and Pedestals Expansion Joints Retrofit of Bearings, Anchorages and Pedestals Strengthening of Existing Bearings Bearing Replacement Strengthening Superstructure to Substructure Connections 14

15 Retrofit of Bearings, Anchorages and Pedestals Strengthening of Existing Bearings Bearing Replacement Strengthening Superstructure to Substructure Connections Strengthening of Existing Bearings Fixed Bearings Sole Plate to Girder Bearing to Masonry Plate Masonry Plate to Substructure Expansion Bearings Sole Plate to Girder Masonry Plate to Substructure 15

16 Bearing Sole Plate Connection Bottom Flange Bearing Stiffener Bolts to Replace Existing Rivets New Plates Existing Bearing (Fixed) Vulnerable Tall Bearing (Exp) Existing Rocker Bearing Before 16

17 17 Expansion Bearing Retrofit Expansion Bearing Retrofit Steel Wedge After New high strength bolts Flange of plate girder Existing bearing Extension of anchor plate Reinforcing steel mat Drill and bond extra anchor bolts Anchor Plate Retrofit Anchor Plate Retrofit

18 Masonry Plate Retrofit Vulnerable Tall Bearing (Fixed) 18

19 Bearing Encasement Retrofit Bearing Encasement Retrofit 19

20 Bearing Encasement Retrofit Retrofit of Bearings, Anchorages and Pedestals Strengthening of Existing Bearings Bearing Replacement Strengthening Superstructure to Substructure Connections 20

21 Bearing Replacement Conventional Bearings Seismic Isolation Bearings Bearing Replacement Conventional Bearings Seismic Isolation Bearings 21

22 22 Bearing Replacement (Before) Bearing Replacement (Before) Existing Bearing Before Bearing Replacement (After) Bearing Replacement (After) New Bolt - Drilled and Grouted Into Existing Concrete Elastomeric Bearing Pad New Concrete Pedestal Existing Bolts to Remain After

23 Bearing Replacement Conventional Bearings Seismic Isolation Bearings Lead Rubber Bearing 23

24 Friction Pendulum Bearing Eradiquake Isolation Bearing 24

25 Characteristics of Typical Isolation Bearings Knock-off off Device Expansion Joint Backwall Sacrificial Knock-Off Element Friction or Settlement Slab Bearing Abutment Superstructure 25

26 Retrofit of Bearings, Anchorages and Pedestals Strengthening of Existing Bearings Bearing Replacement Strengthening Superstructure to Substructure Connections Pipe Shear Key Cast-in-place Deck and Diaphragm Patch Core Hole after Placing Pipe Core Vertical Hole into Pier Concrete (Between Girders) Insert Concrete Filled Steel Pipe A A Precast Girders Pipe XX-strong Polystyrene Section A-A Pre-molded Expansion Joint Filler 26

27 Elements to be Retrofitted Bridge Decks and Girders Bearings, Anchorages and Pedestals Expansion Joints Retrofit of Expansion Joints Bearing Seat Extensions Seat Extensions and Catcher Blocks Pipe Extenders Restrainers Longitudinal Joint Restrainers Transverse Restrainers Vertical Motion Restrainers Energy Dissipation Devices Shock Transmission Units 27

28 Bearing Seat Extensions Seat Extensions and Catcher Blocks Pipe Extenders Abutment Seat Extender 28

29 Bearing Seat Extensions Seat Extensions and Catcher Blocks Pipe Extenders Pipe Seat Extender 29

30 Restrainers Longitudinal Joint Restrainers Transverse Restrainers Vertical Motion Restrainers Caltrans Cable Restrainer Swaged fitting & stud Cable yield indicator Disc springs 25 mm Dia stud threaded 19 mm cable Washer, nut & thread locking system, each end Thick steel washer Bearing plate Face of concrete Steel spherical washer 30

31 Cable Restrainer Hardware END VIEW PLAN Wall thickness Front of disc Reduced section SECTION B-B 45 bevel Disc gap SECTION A-A CABLE YIELD INDICATOR AS INSTALLED ON STUD DISC SPRINGS Multi-cable Restrainer Assembly 31

32 Bumper Block End Diaphragm Anchorage 32

33 Precast Girder Anchorage Deck Anchorage 33

34 Restrainer Orientation (Rigid Supports) Restrainer Orientation (Flexible Supports) 34

35 Restrainer at Pier Restrainer Cable Restrainers Longitudinal Joint Restrainers Transverse Restrainers Vertical Motion Restrainers 35

36 Transverse Shear Keys Steel plate with welded anchor studs gap* * Provide clearance at closest point between shear key and existing bearing assembly Bottom flange of existing girder Existing keeper plate Roughen existing surface to 1/4" Horizontal stirrups in both directions Drill and bond dowels Existing girder and bearing assembly Bearing Keeper Brackets Leave small gap Centerline Keeper bracket - weld to plate extension New high strength bolts Existing steel bearing Bearing plate extension - weld to existing plate Reinforcing mat - center of pad 36

37 Steel Pipe Restrainers Restrainers Longitudinal Joint Restrainers Transverse Restrainers Vertical Motion Restrainers 37

38 Vertical Hold Down Retrofit Retrofit of Expansion Joints Bearing Seat Extensions Seat Extensions and Catcher Blocks Pipe Extenders Restrainers Longitudinal Joint Restrainers Transverse Restrainers Vertical Motion Restrainers Energy Dissipation Devices Shock Transmission Units 38

39 Retrofit of Expansion Joints Bearing Seat Extensions Seat Extensions and Catcher Blocks Pipe Extenders Restrainers Longitudinal Joint Restrainers Transverse Restrainers Vertical Motion Restrainers Energy Dissipation Devices Shock Transmission Units 39