2015 ODOT Bridge Design Conference May 12, DeJong Rd Bridge High- Seismic Zone Case Study: Bridge Rehab vs. Replacement.

Transcription

1 2015 ODOT Bridge Design Conference May 12, 2014 DeJong Rd Bridge High- Seismic Zone Case Study: Bridge Rehab vs. Replacement Mary Ann Triska 2015 HDR, all rights reserved.

2 Presentation Outline Project Overview Existing Conditions Alternatives Analysis Selection & Conclusions

3 Presentation Outline Project Overview Existing Conditions Alternatives Analysis Selection & Conclusions

4 What is this project unique? Rural lifeline Scenic location Multi-type, long structure Low ADT Low sufficiency rating Requires frequent maintenance Seismically vulnerable Replace or Rehab?

5 Bridge Facts To OR 18 DeJong Bridge To Ballard & Polk County

6 Bridge Facts Built o 1960 Sufficiency Rating o 47.5 ADT o 558 (harvest season) o 20% trucks Detour o 7.6 miles 1942: Original DeJong Rd Bridge.

7 Geometry Overall Geometry o Length 740' o Width 24' roadway RCDG RCBG Structure Type o RCDG on two column bents 3 spans; (36', 48', 36 ) o RCBG on single column piers 3 spans; (80', 100', 80 ) o Precast RC beams on timber pile bents 12 30' spans Precast RC

8 Geometry RCDG Spans 1-3

9 Geometry RCBG Spans 4-6

10 Geometry Precast RC Beams on Timber Piles Spans 7-18

11 Client Goals Serve local, Yamhill County, and Polk County citizens that depend on the bridge Safe o Functional deficiencies o History or damage during flood events Reliable o Load posted structure Cost Effective o Reduce County maintenance efforts and cost o Make a sound financial decision

12 Project Objectives and Scope Phase 1: Alternatives Analysis (this project) Phase 2: Final Design Phase 3: Construction

13 Project Objectives and Scope Phase 1: Alternatives Analysis o Define deficiencies o Develop rehabilitation & replacement alternatives Scope of work Costs Impacts, benefits, & risks o Desired Outcomes: Informed decision: rehabilitate or replace TS&L Report Cost & Scope for funding

14 Presentation Outline Project Overview Existing Conditions Alternatives Analysis Selection & Conclusions

15 Investigations Scope of Field Work Survey Geotechnical Environmental o Wetlands & Waters o Historic/Arch/Cult Roadway Right-of-way Utilities Structural Inspections

16 Investigations Analysis Roadway o New concept alignment Structural o Structural evaluation o Seismic modeling o Load rating update

17 Investigations Seismic Vulnerabilities Spread footings Bent & pier columns Sub / superstructure connections Seat width Tall end diaphragms Bearings Spans 7-18

18 Seismic Analysis Modeling SAP2000 Spline model Modeled Spans 1-6 only Accounted for mass of Spans 7-18 RSA o Lower Level M9.0 CSZ, serviceability o Upper Level 1000 yr, life safety Tension and compression models

19 Findings Deficiencies Lack of seismic resiliency o All spread footings deficient structural capacity & overturning o Bents 2 & 3 columns deficient displacement & shear capacity o Bents 2 & 3 crossbeams deficient flexural capacity o Piers 2 & 3 columns deficient shear capacity o Pier 4 column deficient flexural capacity o Pier 1 & 4 diaphragms/girder support deficient flexural capacity o Piers 1 & 4 steel rocker bearings

20 Findings Deficiencies Deteriorated & damaged timber o Piles 15 piles in Condition State 2» Checking, decay, and section loss 4 piles in Condition State 4» Decay and section loss 11 replaced with steel piles o Timber Caps 51' in Condition State 2» Decay, section loss, and splitting 28' in Condition State 3» Decay and section loss 6' in Condition State 4» Decay and section loss

21 Findings Deficiencies Hydraulic debris collection o Piles and cross-bracing catch debris Lack of scour protection o Erosion holes around Pier 4 (max 3 ft depth) o Pier 2 footing exposed Vehicular safety deficiencies o Substandard bridge rail, transitions, approach rail and rail ends o 1 foot shoulder width on bridge Element condition deficiencies o Joint seals o Steel rocker bearing

22 Findings Deficiencies Load rating structural deficiencies o Bent 2 & 3 Crossbeams All Vehicles in shear o Bent 2 & 3 Crossbeams Permit Vehicles in flexure o Span 1 & 3 Girders HS20 & Permit Vehicles in shear o Span 7-18 Girders Permit 6 Vehicle in flexure o Additional deficiencies anticipated due to Tier 2 LRFR update

23 Presentation Outline Project Overview Existing Conditions Alternatives Analysis Selection & Conclusions

24 Alternatives Rehabilitation 1A: o Replace Spans 7-18 o Rehabilitate Spans 1-6 1B: o Replace substructure Spans 7-18 o Rehabilitate Spans 7-18 superstructure o Rehabilitate Spans 1-6 1C: o Rehabilitate Spans 1-18 Alternatives Replacement 2A: o Replace -- prestressed girder & slab bridge 2B: o Replace steel girder & prestresed slab bridge

25 Design Considerations Limit Impacts o Environments o No Raise o Adjacent Properties o Historic Structures Full Traffic Closures Acceptable

26 Rehab - Alternative 1A Replace Spans 7-18 with 5 precast slab spans Rehab Spans 1-6 o RCDG girder and crossbeam strengthening o Type F rail retrofit o Replace 2 joints o Phase 1 & 2 seismic retrofit Bent 1 Seismic Retrofit Replacement Typical Section

27 Rehab - Alternative 1B Replace substructure Spans 7-18 Rehab Spans 7-18 superstructure o FRP flexural strengthening of beams o Thrie-beam rail retrofit o Replace 2 joints o Phase 1 seismic retrofit Rehab Spans 1-6 o RCDG girder and crossbeam strengthening o Thrie-beam rail retrofit o Replace 2 joints o Phase 1 & 2 seismic retrofit Typical Substructure Replacement

28 Rehab - Alternative 1C Rehab substructure Spans 7-18 o Replace timber piles with steel h-piles Rehab Spans 7-18 superstructure o FRP flexural strengthening of beams o Thrie-beam rail retrofit o Replace 2 joints o Phase 1 seismic retrofit Rehab Spans 1-6 o RCDG girder and crossbeam strengthening o Thrie-beam rail retrofit o Replace 2 joints o Phase 1 seismic retrofit Bent 2 & 3 Retrofit

29 Common Rehabilitations Bearing Replacement Drainage Rehabilitation o Pipe existing drains to new stormwater facility Scour Protection o Riprap at Bents 2-3 & Piers 1-4 Guardrail and Transitions o New transitions, guardrail & terminals Pavement o Rehab 200' for approach Roadway Design Exceptions o 1 foot shoulder o NW guardrail length

30 Alternative 2A Concrete Girders 7 Spans 1in-water Pier Alternative 2B Steel Girders 6 Spans No In-Water Piers

31 Alternatives Analysis Cost Alt. 1A Rehab Alt. 1B Rehab Alt. 1C Rehab Alt. 2A Replace Alt. 2B Replace Phase 1 Retrofit $0.1M $0.1M $0.1M - - Phase 2 Retrofit $1M $1M $1M - - Other Costs $5.3M $4.6M $3.4M $9.5M $10.6M Total Cost $6.4M $5.7M $4.5M $9.5M $10.6M Total Project Cost includes: o Permanent construction o Temporary items (access, traffic control, etc.) o Mobilization (10% of all other construction items) o Contingencies (35% of construction items) o CE (20% of construction items) o PE (15% of construction Items + Contingencies)

32 Alternatives Analysis - Cost Alt. 1A 1% 16% Construction Phase 1 Seismic Retrofit Phase 2 Seismic Retrofit 83% Alt. 1B 3% Alt. 1C 2% 17% 81% 97%

33 Presentation Outline Project Overview Existing Conditions Alternatives Analysis Selection & Conclusions

34 Client Goals Serve local, Yamhill County, and Polk County citizens that depend on the bridge Safety o Functional deficiencies o History or damage during flood events Reliable o Load posted structure Cost Effective o Reduce County maintenance efforts and cost o Make a sound financial decision Debris $3.5 Million

35 Alternatives Rehabilitation Alternatives Replacement 1A: 2A: o Replace Spans 7-18 o Rehabilitate Spans 1-6 1B: o Replace substructure Spans 7-18 o Rehabilitate Spans 7-18 superstructure o Rehabilitate Spans C: o Rehabilitate Spans 1-18 PREFERRED o Replace -- prestressed girder & slab bridge 2B: o Replace steel girder & prestresed slab bridge Most likely to be funded

36 THANK YOU 2015 HDR, all rights reserved.