Bearing with Bridges – Bearings and Expansion Joints on...

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TRANSPORTATION RESEARCH BOARD

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Bearing with Bridges –Bearings and Expansion

Joints on Highway BridgesJune 18, 2020

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Learning Objective

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1. Identify current practices that may mitigate damages to bridge bearing and expansion joints

Domestic Scan 17-03Experiences in the Performance of Bridge Bearings and

Expansion Joints used for Highway BridgesFindings, Conclusions and Recommendations

Bijan Khaleghi, PhD, PE, SEState Bridge Design engineerWashington State DOT Bridge & Structures Office

NCHRP 20-68A “US Domestic Scan Program”

Dissemination Plan

Richard Zeldenrust, PE, SEWashington State Bridge and

Structures OfficeOlympia, Washington

Webinar Outline† NCHRP 20-68A “US Domestic Scan Program”† General Guidance to the Scan Team† Major Findings

Bearings: • Design, Construction, • Inspection and Maintenance

Expansion Joints: • Design, Construction• Inspection and Maintenance

† Over-arching Issues† Recommendations† Overall Conclusions 2

NCHRP 20-68A “US Domestic Scan Program”

The program was requested by the AASHTO Subcommittee on Construction (SOC), with funding provided through NCHRP.

The purpose of Project 20-68A is to accelerate innovation by:

1. Facilitating information sharing and technology exchange among states and other transportation agencies;

2. Identifying actionable items of common interest

3. Discussing design, construction, maintenance and operation of transportation agencies that have experienced good performance of bridge joints and/or bearings.

4. Examine details for various bridge types, materials, span arrangements, geometry, and sizes

Domestic Scan Scan 17-03 Team MembersMr. Harry Capers – Scan Manager

Bijan Khaleghi - AASHTO Chair State Bridge Design Engineer Washington State DOTBridge & Structures Office

Zhengzheng “Jenny” Fu, P.E. Assistant Bridge Design AdministratorLADOTD Room 603A

Ed KestoryDistrict Structures Maintenance Engineer, District 5 Bridge InspectionFlorida DOT

Ahmed N. Mongi, P.E. QA/QC Unit Leader, Design SectionDivision of Highways, Engineering Division, West Virginia DOT

Rebecca Nix Bridge Management EngineerUtah Department of Transportation

Rich Zeldenrust, PE, SEDesign Unit ManagerWashington State DOTBridge & Structures Office

Linh Warren, P.E.Structural EngineerFHWA Office of Bridges and Structures

John F. Stanton, PhD, PE -- SMEProfessor, Civil and Environmental Engineering University of Washington

Jill Walsh, PhD, PE –Tech. ConsultantAssistant Professor Saint Martin’s University 4

General Guidance to the Scan Team

Based on an initial review of bearing and joint performance it is suggested that the following state DOT’s be studied:

1. States with severe climate challenges (cold and freezing conditions) - Illinois, New York and Massachusetts

2. States with considerable precipitation and cold climates -Washington State and Oregon.

3. States with very high ADT’s on bridges - California, Texas, & New York

4. Coastal states with large size bridges such as Florida, Virginia, and Louisiana

5. States with success details (Minnesota) and lessons learned to offer (Pennsylvania).

Scan Team Members and Host States

MS AL GA

VA MDDC(FHWA)

Team Member Home State

Participating State Agencies

Manufacturers • DS Brown • Mageba• Scougal• RJ Watson • Watson Bowman

Company Speaker Bearings JointsDS Brown Mark KaczinskiMageba Amit KutumbaleScougal Rob AndersonRJ Watson Zachary SearerWatson Bowman Gary Moore

Pre-scan Meeting 10/01/17Scan conducted 3/19-3/23/2018Summary report 04/24/18Formal report - draft 06/22/18Formal report - final 08/21/18

Domestic Scan Schedule: States and Manufacturers Presentations

Topics Considered by the Scan Team

• Design, details, construction specifications and maintenance procedures for durable bearings and expansion joints with good performance history.

• Visual inspection and testing of joint and bearing details;

• Specialized technology used in monitoring, inspecting, and repair of joint and bearings.

• Relative costs for design, construction, maintenance, and inspection of various joint and bearings.

• Lessons learned and suggestions for improvement.”

Anticipated Scan Outcomes• This scan would be of specific interest to:

– AASHTO COBS Committee T-2 “Bearings and Expansion Devices”

– AASHTO Subcommittees on Materials and on Maintenance.

• The scan report will provide current information on successful expansion joints and bearings to:

o Bridge owners including State DOTs and Local transportation agencies

o AASHTO for developing work plans and research needs.

o FHWA and other Federal offices,

o Bearing and joint manufacturers,

o University researchers,

o Bridge Consultants and Contractors, Others 9

Suggestions for Amplifying Questions (Sent to DOTs)

1) Questions focusing on the Performance a. Successful Strategies b. Advances in Practice & Emerging Technologies

2) QA/QC a. Training and Mentoring b. Quality Control /Assurance Plan / Certifications

3) Performance Measures a. Metrics, Evaluations of performance b. Corrective Action Procedures

4) Sustainability a. Succession planning and training b. Modernization and upgrading of equipment

Bearings: Design, Construction, Inspection

and Maintenance

Joint failure resulted in Bearing and Pier cap Failure

Bearings: Types, Design, Construction, Inspection

Elastomeric Bearing

Bearings – Design - 1• Uplift and horizontal forces.

– Design system to avoid uplift forces. – Design system to resist horizontal forces.

• Provision for replacement.– Make provision at design time for jacking /replacement

• Type selection.– Steel-reinforced elastomeric for short-medium span. – HLMR (pot, disk, spherical) for high loads. – No new rocker steel bearings.

• HLMR type selection – no agreement– Some states ban pots (elastomer leakage) moving from pots to disks bearings– Some states mostly spherical bearings 13

Bearings – Design - 2• Steel-reinforced elastomeric bearings.

– Most states use Method B. (More logical).

– Walking out of place: Some states require minimum compressive stress. Some use a recess. Others recommend bonded external plates.

• Sliding surfaces. AASHTO specifies only PTFE. More durable materials are now available.

• Lack of AASHTO Disk bearing design specifications.

• Performance-based specifications. (incentive for innovation)

– Manufacturers would prefer PBS for bearings.

– PBS is commonly used in Europe and elsewhere.

– How to implement and transition to PBS?14

Bearings – Inspection and Maintenance

• Instantaneous movements (CR, SH, T, ES, etc.).– How to accommodate? Design for full horizontal

capacity/lift and reset.

• Storage and Handling.– Do not open (HLMR) bearings or seismic isolation

bearings on site (contamination).

• Steel prices fluctuation.• Steel rocker and roller bearings.

– Need to clean to prevent freezing. or replace.

• Bearing replacement.– Adjust the height if old bearing is replaced by an Steel-

reinforced elastomeric bearings SREB.15

Expansion Joints: Design, Construction, Inspection and Maintenance

Joints – Design - 1• Joint type selection – guidelines:

0” < D < 2” : plug or filler type.2” < D < 4” : gland type (e.g. strip seal). <5” (WA)4” < D : finger joint, modular joint, etc.

• Skew bridges.• Extra stress in gland types. • Finger joints bind up.

• More taxing for modular joints.• Major problems.

– Indirect damage: Leaking onto bearings and girder ends.

– Direct damage: Snowplow hits, raised fingers in finger joints 18

Integral or semi-integral Jointless Bridges & Link Slab

Joints – Design 2• Compression seals.

– Less widely used today.

• Strip seals vs pre-formed silicone.– Strip seal gland secured by a groove formed in steel end dam. Sometimes

use adhesive in groove.– Pre-formed silicone, secured by adhesive.– Need test program to determine best approach.

Durability and ease of replacement).

• Modular joints.– Early versions showed fatigue problems.– Now mostly resolved – Requiring fatigue test– Large opening needed in deck to accommodate support beams and boxes.– Not used in large pier skews

Joints – Construction - 1• Construction/installation is where most problems occur.

– Pre-submit installation procedures.– Pre-construction meeting.– Manufacturer’s rep on site (especially for large joints).

• Installation temperature.– Opening must be consistent with plans for that temperature.

• Lane closures and stage construction.– Some lane closures are unavoidable.– Need to connect sections. Welds are best. Bolts eventually corrode.

• Modular joints.– Large ones are heavy, may need a crane for installation.– Concrete must be consolidated around support beams. – Allow for (thermal) change of opening during installation.

Modular Joints

Modular Joint with Noise Panels

California Plate Joint Seal Assembly

Expansion Joint Noise Mitigation Study

AASHTO fatigue testing of modular expansion joints

Joints – Construction - 2• Concrete for joint construction - pour-backs.

– May need high early strength concrete (Closure time).

– Consolidation important. Shall consider SCC.

– UHPC is an option. Very hard in case of replacement.

– Make sure that chemical admixtures for the concrete are compatible with adhesive used for preformed silicone seals.

• Plug type joints.– Need good bond between plug material and concrete.

– Polymeric concrete may be slippery. Add grit to surface

• Continuation of joint into barrier.– Set joint back from face of barrier.

– Wide joints need plate to protect from snowplow.23

Joints – Inspection and Maintenance

• Active maintenance program is essential to:– Prolong joint life.– Protect bearings/piers by preventing leaks.– Document important modifications/repairs– Keep as-built drawings up to date for all repairs.– Document hardware types for replacement parts.– Document repairs made by maintenance staff

Some states use State personnel for Joints Inspection and Maintenance, others contract out.

Joints – Inspection and Maintenance Levels of Maintenance Work

Level I: clean joints. Frequency varies by state.

Level II: Minor repairs when cleaning. e.g. gland patching.

Level III: Partial replacement (e.g. gland in strip seal or preformed silicone).

Level IV: Total replacement, including steel end dam.

An Owners Perspective; Performance of Bearings and Expansion Joints For Highway Bridges in Washington State

June 18, 2020

Ralph Dornsife/Richard ZeldenrustWashington State Bridge and

Structures OfficeOlympia, Washington

Expansion Joint Functions

•Accommodate movements•Minimize induced stresses•Minimize water/salt infiltration•Provide smooth riding surface

Erosion and Undermining of Foundation Elements

Bridge Movement Sources

• Thermal variations• Live loading

• Source• Direction

• Concrete shrinkage• Concrete post-tensioning shortening & creep• Wind and seismic loadings• Structure settlement

Thermal and Shrinkage Movements

• Concrete Structures : 0°F to 100°F• Steel Structures

• Western WA: 0°F to 120°F• Eastern WA: -30°F to 120°F

• .0002 Ultimate Shrinkage Strain

Expansion Joint Classifications

I. Small Movement Range JointsTotal Movement Range < 1.75"

II. Medium Movement Range Joints1.75" < Total Movement Range < 5"

III. Large Movement Range JointsTotal Movement Range > 5"

Small Movement Range

•Compression seal•Poured flexible sealant•Glued pre-formed seal•Asphaltic plug

Compression Seal

Shown With Steel Armoring Shown Without Steel Armoring

Steel AngleWelded Steel Studsspaced alternately

Elastomeric Compression Seal

Compression SealInstallation Criteria

• Working range• 45% max. compression• 85% min. compression

• Uniform width opening• Formed gap consistent w/

temperature at pour• Sawcut gap consistent w/

temperature at sawcutting• Installation depth

Poured Sealant

Backer Rod

Poured-in-Place Silicone Sealant

Polyester Concrete Header (Typ.)

Primer

Glued Pre-formed Seal (EMSEAL BEJS)

Asphaltic Plug Joint

fied Asphalt

Polymer Modi-Steel Plate

Backer Rod

Locating Spike

Shown with Asphalt Overlay Shown without Asphalt Overlay

Asphalt Overlay

Medium Movement Range

•Sliding steel plates•Bolt-down elastomeric panel•Armored elastomeric strip seal•Unarmored silicone strip seal

Sliding Steel Plates

Sliding Steel PlateSteel Angle (Typ.)

Steel Angle Anchorage (Typ.)

Anchor Bolt (Typ.)

I-5 Seattle (Holgate) Steel Sliding Plate Failure

May 2014

Bolt-Down Elastomeric Panel

Adhesive or ExpansionAnchor (Typ.)

Steel Plate Reinforcement (Typ.)

Block Out Limits (Typ.)

Expansion Gap

Armored Strip Seal Joint

Heavy Duty Anchorage Shown Standard Anchorage Shown

Elastomeric Strip Seal

Extruded Steel Shape (Typ.)

Welded Steel Studs spaced alternately

Steel Plate - welded to extruded steel shape at specified spacing

Bent Steel Reinforcement Bar welded to steel plate

Opening "G" vs. Temperature

Unarmored Strip Seal (RJW Silicoflex / WBA SPS)

Large Movement Range

•Finger-type joint•Bridge modular expansion joint (BMEJ)

Steel Finger-Type Joint

Plan View

Section A-A

Steel Finger Joints

Bridge Modular Expansion Joint(BMEJ)

Center Beam (Typ.)

Elastomeric Strip Seal Gland (Typ.)

Elastomeric Box-Type Seal (Typ.)

Center Beam-to-Support Bar Welded Connection(Multiple Support Bar System Shown)

Box-Type Seals Shown Gland-Type Seals ShownSection through Support Box ShownSection between Support Boxes Shown

Compression Spring with BondedPTFE Surface

Stainless Steel Sliding Surface

Edge Beam (Typ.)

Support Bar (3 Total - Center One Shown)Control Springs between Adjacent Support Bars

Support Bearing with PTFE Surface

End Control Spring

Support Box (Typ.)

Welded Steel Studsfor Anchorage (Typ.)

Bridge Modular Expansion Joint

Appropriate Joint Typesfor Overlay / Rehab Projects

Less Preferred• Asphaltic plugs• Bolt-down panels• Steel sliding plates• Steel finger joints

More Preferred• Poured silicone sealants• Compression seals• Armored strip seals• Modular exp. joints• Experimental

– Glued pre-formed seals– Unarmored strip seals

Case StudiesExpansion Joint Failures

• Armored Strip Seal Anchorage• Modular Expansion Joint Installation

Armored Strip Seal Anchorage Failure

Broken stud welds Cracked frame rail and torn seal

Armored Strip SealAnchorage Failure

Armored Strip Seal Anchorage Failure

Modular Expansion Joint Installation Deficiencies

Watson Bowman Acme 9-inch Modular Expansion Joints:

•Extensive deck cracking adjacent to joint•Loud banging noises coming from joint under traffic loads

• No reinforcement bars atop support boxes

• Poor concrete consolidation under support boxes

• Role of qualified installation technician

• Benefit of pre-pour conference

Bearing Functions

•Effectively transfer service loads from superstructure to substructure

•Accommodate anticipated movements•Restrain undesired movements•In some instances, provide seismic isolation

Types of Bearings

•Elastomeric pads•Plain•Steel reinforced•Fabric pad sliding bearings

•Steel pin, roller, rocker•Pot•Disk •Spherical•Seismic Isolation

Design Load in Tons

•Steel Reinforced Elastomeric < 400•Fabric pad (PTFE/SS) < 300•Steel pin > 300 •Spherical or disk > 400•Seismic Isolation < 400

Elastomeric Bearing Pads

•Plain elastomeric pads (PEP)•Layered fiberglass reinforced (FGP)•Steel reinforced elastomeric pads•Cotton duck reinforced pads (CDP)

•64 plies per inch•Stiff in compression•Limited rotational capacity•Often used with PTFE / SS sliding surfaces

Shape Factor (SF)

SF = Plan Area of BearingArea of Perimeter Free to Bulge

Steel Reinforced Elastomeric Bearing Shown

Fabric Pad Bearing Shown

Area free to bulge

Area free to bulge ??

Steel Reinforced Bearing Pad Design Criteria

•Fatigue (limit LL stress)•Stability (limit plan and height dimensions)•Delamination (limit DL+LL stress)•Steel shim yield and rupture•Excessive shear deformation (minimum height)•Rotational flexibility (minimum height)

Strain-Based Method B

AxialShear Strain ShearShear Strain

RotationShear Strain

Deformations of Typical Elastomeric Layer

Steel Reinf. Elastomeric Brg. Pad

Grout Pad

Centerline of Girder

Elastomeric Bearing Pad 21-1/2" X 21-1/2" X 6"

1" Gap (Typ.)

10 – ½" steel shims 9 – ½" thick internal elastomeric layers 2 – ¼" thick external elastomeric layers

Fabric Pad Sliding Bearing(Cotton Duck Reinforced)

Sole Plate

Masonry Plate

Fabric PadTeflon

Stainless Steel Sheet Recessed Backing Plate

Anchor Bolt (Typ.)

Pin Bearing

Upper Block

Lower Block

Steel Pin

Keeper Ring

Nut and Washer

Sole Plate

Base PlateAnchor Bolt (Typ.)

Fixed and Rocker Bearing

Rocker BearingFixed Bearing

Roller Bearings

Pintles may provide transverse force restraint

Stop bars

Pot Bearing

Confined ElastomerPiston

Circular Sealing RingFlat Sealing Rings

Cylinder Wall Base Plate

Anchor Bolt (Typ.)

Disk Bearing

Plan View Cross Section

Urethane Disk

Shear-resisting Ring

Shear-resisting Pin

Note: Base Plate and Anchor Bolts not shown

Spherical Bearing

Stainless Steel SurfacePTFE Surface

Base PlateAnchor Bolt (Typ.)

Seismic Isolation Bearings

•Elastomeric with Lead Core•High Damping Rubber•Friction Pendulum•Many other hybrid variations

IsolationEnergy Dissipation

Design Objectives

•High quality at reasonable cost•Simple to install•Long-term durability•Maintenance-free•Accessible for inspection•Removable and replaceable

Questions ?

• Richard Zeldenrust• WA State Dept. of Transportation

Bridge & Structures Office• 360-705-7196 (Voice)• 360-705-6814 (Fax)• e-mail: zeldenr@wsdot.wa.gov

Findings, Conclusions and Recommendations

Domestic Scan 17-03Experiences in the Performance of Bridge Bearings and

Expansion Joints used for Highway BridgesNCHRP 20-68A “US Domestic Scan Program”

üOver-arching Issues (Joints and Bearings)

üRecommendations

üOverall Conclusions

Over-arching Issues (Joints and Bearings)• Funding Challenges:

– Lack of funding for preservation projects - Gas taxes not increased bridge s.– New bridges attract funding more than preservation and maintenance.

• Attraction and retention of staff.– Design-build reduces interesting work for DOTs. – Staff retiring/transferring to private sector.

• Training and knowledge transfer.– Need: experienced engineering staff, challenging projects and training program

• Design challenges and incentives for innovation.– AASHTO requirements are prescriptive - Consider performance based design – Difficult for manufacturers to understand states pre-approved requirement

(different practices among states) 2

Recommendations

• Training tools. Develop training tools to help transfer knowledge from experienced to newer employees.

• Selection guides. Develop guides for selecting joints and bearings, based on the information assembled in this scan and elsewhere.

• Gathering field information. Develop web-based methods for gathering and organizing field information on joints and bearings.

• Elastomeric Bearings – Resolve the inconsistencies between the LRFD design spec and M251 Standard Specification for Elastomeric Bearings.

• Disk Bearings – Develop NCHRP topic for writing a design specification for disk bearings.

Overall Conclusions -1 Wide variation in practices among states.

• Variations depend partly on climate, traffic.• Sharing of best practices likely to prove real benefits.

Considerations for Life-cycle costs.§ Cost of failed joints and bearings high in proportion to initial cost.§ Maintenance is essential to prevent problems to other bridge components.

Preservation and Maintenance Funding Availability.o Almost all states reported limited funding, need to allocate funds

strategically (e.g. policy for maintenance vs. replacement.)

Continuity of operations.• Staff retention and training.• Transfer of knowledge to less experienced staff.

Overall Conclusions - 2Bearings – Common types for new construction

o Large loads: HLMR bearings (Pot, Disk, Spherical), vary among states.o Small to moderate loads: Elastomeric bearings are very widely used.

Older bearing types (steel rocker, roller)o Replace as the opportunity arises.

Jointless bridges. The best joint is no joint”. o Elimination of joints provides benefits and protects bearings.o Link slabs at interior piers.o Integral or semi-integral abutments at bridge ends.o Integral pier diaphragm makes system continuous for LL and EQ resilienceo Joint elimination of exiting short span bridges - (Limited longitudinal CR,

SH, T, and other movements).

Rich Zeldenrust,ZeldenR@wsdot.wa.gov

Ralph Dornsife, DornsiR@wsdot.wa.gov

Bijan Khaleghi, Bijan.Khaleghi@wsdot.wa.gov

Thank You

Today’s Presenters• Bijan Khaleghi, State bridge engineer,

Washington State DOT, KhalegB@wsdot.wa.gov

• Richard Zeldenrust, Design supervisor, Washington State DOT, ZeldenR@wsdot.wa.gov

Upcoming related TRB webinars

• Pavement Deflections – Past, Present, and Future – June 24

• Seismic Design Basics – July 16

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