Engineers Club Of Memphis V2

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Lunch time seminar describing a case study that documents the cost benefits of a steel truss bridge compared to other bridge alternates.

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  • So basically, what we’re trying to answer is …
  • Here’s a photo of the general topography and profile of the roadway at the bridge site.
  • A couple of things we immediately notice from a site photo are:…Involve audience, interactive ???
  • Also we note:… obviously we’re in a detour condition, … chance to upgrade the approach railings, do we have a narrow bridge, and / or wonder about …Involve audience, interactive ???
  • You’d be worried about flooding, overtopping, channel cleanout Looking upstream, we note:…Involve audience, interactive ???
  • Lesson: Truss Vehicular Product Design WorksheetTopic: Bridge Geometry & DescriptionPage Name: Vehicle Style Options
  • Engineers Club Of Memphis V2

    1. 1. Structure Type Studies forLocal Infrastructure Managers Engineers Club of Memphis 8.22.2011
    2. 2. U.S. Bridge History Working Together Engineering Case Study Project Profiles Engineers Club of Memphis - 8.22.2011
    3. 3. U.S. BridgeU.S. Bridge has been Bridging America for 75 years. Since 1936 we have been manufacturing bridges in the United States with the highest regard for our customers needs and quality of our work. As the largest manufacturer pre-fabricated steel truss bridges in the United States, we remain the trusted leader in the industry. Engineers Club of Memphis - 8.22.2011
    4. 4. History  Founded as American Culvert in 1936 by brothers Herman & Ted Rogovin Engineers Club of Memphis - 8.22.2011
    5. 5. History Designing & Building Truss Bridges for over 60 years Engineers Club of Memphis - 8.22.2011
    6. 6. Location  Cambridge, Ohio  Juncture of I-70 & I77  21 shops covering 250,000 sq ft. in 11 buildings Engineers Club of Memphis - 8.22.2011
    7. 7. How we work with you Feasibility Assessments Programming Costs Specifications & Schematic Details Preliminary Engineering Modeling & Rendering Engineers Club of Memphis - 8.22.2011
    8. 8. How we work with you … Hard Bid Quotes & Information Engineering Design & Plan Submittals Construction Submittals Engineers Club of Memphis - 8.22.2011
    9. 9. How we work with you … On-Site Installation Assistance Engineers Club of Memphis - 8.22.2011
    10. 10. Structure Type Study Reference Paper Engineers Club of Memphis - 8.22.2011
    11. 11. Purpose of the Paper To give local infrastructure managers a guide and reference to use when scoping and evaluating a site for a bridge project. Ensures all costs and factors are considered, including life cycle costs. Real world sites and examples. First of a 3 Part Series. Eventually 2 more sites will be investigated. Engineers Club of Memphis - 8.22.2011
    12. 12. Engineers Club of Memphis - 8.22.2011
    13. 13. Why was THIS bridge built here? Engineers Club of Memphis - 8.22.2011
    14. 14. Existing Site, Bridge & Conditions Situated in a low-land area Rural character (narrow 10 ft. lanes, no shoulders) Low Volume ~ 350 vehicles per day (vpd) Loosely consolidated sandy-silt, silt and clay Bedrock not encountered in the soil borings Existing 3-span beam bridge (simple spans) Steel floor with asphalt fill and wearing surface Frame-bent piers from steel caps on piles Built as a temporary structure 30 years prior Bridge in poor condition and closed Engineers Club of Memphis - 8.22.2011
    15. 15. Hydraulic Conditions Channel was wooded & unmaintained Woody debris on the piers a maintenance problem Flooding of approach roadways Flood level at, or nearly at low-steel elevation Channel was constricting, as velocities through channel were 5x greater than up- or downstream Engineers Club of Memphis - 8.22.2011
    16. 16. Existing bridge Engineers Club of Memphis - 8.22.2011
    17. 17. Utilities Surrounding low land Rural roadway & character Farm drive Engineers Club of Memphis - 8.22.2011
    18. 18. DETOURED! Subsurface Conditions Engineers Club of Memphis - 8.22.2011
    19. 19. Wooded area Entrenched stream Woody debris Engineers Club of Memphis - 8.22.2011
    20. 20. What goes into Scoping a project What’s important to consider?  Funding strings? or no funding strings?  What are the goals of the project?  How easy is it going to be to build?  Maintenance - What am I going to be stuck with?  How long will this bridge be here?  What else is important? Engineers Club of Memphis - 8.22.2011
    21. 21. Goals for the Project Provide adequate bridge width for facility Provide adequate span to allow hydraulic clearance Minimized impacts to profile grade Minimized in-stream work Minimize impacted R/W & construction footprints Minimize detour (closure duration) Minimize adjacent road damage Minimize construction risk Minimize construction costs Engineers Club of Memphis - 8.22.2011
    22. 22. Scope of Proposed Work Projected Traffic: 500 vpd. Bridge Width: 11ft lanes plus 4 ft shoulders = 30 ft rail/rail Approach slabs, guardrail, embankment & pavement Design Year Flood: 10-year, Low steel = EL 1028.0 ft Ordinary High Water (OHW) = EL 1024.0 ft. Increase hyd. opening using 2:1 slopes & spill-thru abutments Deep foundations using friction resistance CIP/steel pipe piles Over-the-side drainage with splash guards 120 ft. (+/- ) span range New rock channel protection along end slopes & aprons Taper improvements into existing Engineers Club of Memphis - 8.22.2011
    23. 23. What’s left? Alternates of span configurations? Alternates of structure types? Engineers Club of Memphis - 8.22.2011
    24. 24. Remaining Variables Structure Depth Profile Grade Impacted Footprint Proposed Span ~ 120 ft Exist Span = 90 ft (+/-) STRUCTURE DEPTH 100-year EL = 1029.6 OHW EL = 1024.0 10-year EL = 1028.0 Normal EL = 1020.0 Engineers Club of Memphis - 8.22.2011
    25. 25. Case Study No. 1 Structure Type Study Narrative (21 Pages) Alternate Descriptions Life Cycle Cost Analysis Evaluation Matrix Evaluation of Alternatives Evaluation of NPV of Alternatives Conclusion & Summary 6 Appendices with drawings, cost estimates, etc. Engineers Club of Memphis - 8.22.2011
    26. 26. Alternatives Alt. 1 – 3-Span, Cast-in-Place Slab Alt. 2 – Single Span, P/S AASHTO Girders Alt. 3 – Single Span, Steel Low (Pony) Truss Alt. 4 – 3-Span, Composite P/S Concrete Box Beams Engineers Club of Memphis - 8.22.2011
    27. 27. Basis for Comparisons Initial Construction  Engineering costs (15% of construction)  Roadway pay items (Appendices A & B)  Bridge pay items (Appendices A & B)  Right-of-way costs Engineers Club of Memphis - 8.22.2011
    28. 28. Basis for Comparisons Life Cycle Costs  Initial cost to construct  Annual maintenance and inspections  Annual work activities  Minor rehabilitation projects (20 years)  Major rehabilitation projects (50 years)  Residual Values  Net Present Value (NPV) Engineers Club of Memphis - 8.22.2011
    29. 29. Annual Work Activities Debris Removal Bridge Inspection Engineers Club of Memphis - 8.22.2011
    30. 30. 10 Year Work Activities Silane Sealer Light Patching Engineers Club of Memphis - 8.22.2011
    31. 31. 50 Year Work Activities Deck slab replacement Deck edge replacement Superstructure replacement or reconditioning Engineers Club of Memphis - 8.22.2011
    32. 32. … and also qualitative measures Temporary construction Environmental permitting Ease of delivery Construction equipment Engineers Club of Memphis - 8.22.2011
    33. 33. Life Cycle Costs: Net Present Values  Cost basis = 2002 State Bid Tabulations  Design Life Term = 75 years  Interval timeline = 10 years; 20 years; 50 years  Inflation (2002 – 2010) = 135%  Discount rate = 2.7% per year n NPV = Σ RCFt / (1+i)t t=0to calculate NPV: where: RCFt = Real Cash Flow i = Annual Discount Rate n = term Engineers Club of Memphis - 8.22.2011
    34. 34. #1 3-Span Concrete Slab Bridge 36 ft - 45 ft - 36 ft spans c/c of bearings Bridge Limits = 118.3 ft Project Limits = 450 ft Structure depth = 2.07 ft (Slab thickness = 22 in.) Profile grade impacts: similar to existing Engineering = $113,000 Construction = $753,000 Maintenance: 7 projects in 75 yrs @ $1,332,800 Life Cycle Costs (NPV) = $1,124,115 Engineers Club of Memphis - 8.22.2011
    35. 35. #1 3-Span Concrete Slab Bridge Engineers Club of Memphis - 8.22.2011
    36. 36. #1 – Three Span Concrete Slab Bridge Engineers Club of Memphis - 8.22.2011
    37. 37. Engineers Club of Memphis - 8.22.2011
    38. 38. #2 Single Span Prestressed I-Beam Bridge 114 ft span c/c of bearings Bridge Limits = 117.2 ft Project Limits = 1,350 ft Structure depth = 7.07 ft (AASHTO Type IV = 72 in.) Profile grade impacts: +3.3 ft Engineering = $145,800 Construction = $972,00 Maintenance: 7 projects in 75 yrs @ $2,155,400 Life Cycle Costs (NPV) = $1,432,261 Engineers Club of Memphis - 8.22.2011
    39. 39. #2 Single Span Prestressed I-Beam Bridge Engineers Club of Memphis - 8.22.2011
    40. 40. #2 Single Span Prestressed I-Beam Bridge Engineers Club of Memphis - 8.22.2011
    41. 41. Engineers Club of Memphis - 8.22.2011
    42. 42. #3 Single Span Steel Half-Through Truss 116 ft span c/c of bearings Bridge Limits = 120.0 ft Project Limits = 450 ft Structure depth = 3.56 ft (W30 FB + 10 ½” Slab) Profile grade impacts: similar to existing Engineering = $104,400 Construction = $835,000 Maintenance: 7 projects in 75 yrs @ $1,886,600 Life Cycle Costs (NPV) = $1,212,231 Engineers Club of Memphis - 8.22.2011
    43. 43. #3 Single Span Steel Half-Through Truss Engineers Club of Memphis - 8.22.2011
    44. 44. #3 Single Span Steel Half-Through Truss Engineers Club of Memphis - 8.22.2011
    45. 45. Engineers Club of Memphis - 8.22.2011
    46. 46. #4 3-Span Composite Box Beam Bridge 36 ft - 45 ft - 36 ft spans c/c of bearings Bridge Limits = 118.5 ft Project Limits = 450 ft Structure depth = 2.16 ft (CB17 + 6” Topping) Profile grade impacts: similar to existing Engineering = $109,400 Construction = $729,000 Maintenance: 7 projects in 75 yrs @ $1,763,200 Life Cycle Costs (NPV) = $1,188,875 Engineers Club of Memphis - 8.22.2011
    47. 47. #4 3-Span Composite Box Beam Bridge Engineers Club of Memphis - 8.22.2011
    48. 48. #4 3-Span Composite Box Beam Bridge Engineers Club of Memphis - 8.22.2011
    49. 49. Engineers Club of Memphis - 8.22.2011
    50. 50. Comparison MatrixComparisons Alternate 1 Alternate 2 Alternate 3 Alternate 4 (3-Span (1-Span (1-Span Steel Half (3-Span Comp. CIP Slab) P/S Girder) Truss, DOT) Box Beam)Construction $876,000 $1,143,000 $949,400 $848,400Cost (3.2%) (34.7%) (11.9%) (0.0%)(+/- % Min.)Life Cycle Cost $1,124,000 $1,432,000 $1,212,000 $1,189,000(+/- % Min.) (0.0%) (27.4%) (7.8%) (5.8%)Total Cost/ $247/sf $325 /sf $264 /sf $239 /sfSF of BridgeSpans: 3 spans 1 span 1 span 3 spansBridge Limits: 118.32 ft 117.16 ft 120.0 ft 118.50 ftWork Limits: 450 ft 1,350 ft 450 ft 450 ftEmbankment 0.07 ft 3.35 ft -0.09 ft 0.07 ftRise Engineers Club of Memphis - 8.22.2011
    51. 51. Comparison Matrix, cont’dComparisons Alternate 1 Alternate 2 Alternate 3 Alternate 4 (3-Span (1-Span (1-Span Steel Half (3-Span Box CIP Slab) P/S Girder) Truss, DOT) Beam)HydraulicClearance 1.9 ft 0.3 ft 0.3 ft 1.8 ft(10 yr flood)Substructure 4 2 2 4UnitsDeep 4,680 ft 5,760 ft 3,960 ft 4,770 ftFoundations Driven Driven Driven DrivenEnvironmental ACOE 404 Permit ACOE 404 temp. ACOE 404 Permit No work in streamImpacts for pier const. work area for pier const. Strip take on 2R/W Strip take on 1 side Strip take on 1 side Strip take on 1 side sides (embank &Impacts (ditch) (ditch) (ditch) ditch) Engineers Club of Memphis - 8.22.2011
    52. 52. Comparison Matrix, cont’dConstruction Alternate 1 Alternate 2 Alternate 3 Alternate 4Comparisons (3-Span (1-Span (1-Span Steel Half (3-Span Box CIP Slab) P/S Girder) Truss, DOT) Beam) Work area for liftingTemporary Causeway Causeway to beams noneWorks or Areas & form shoring construct piers (60T ea.)Flood Risk High Medium Low Mediumduring Const.Utilities n/a n/a n/a n/aEquipment 500T Crane; 250T Crane; 250T Crane; Concrete pumpNeeded Concrete pump Concrete pump Concrete pump In-stream piers are In-stream piers are Delivery of long Smaller crane lifts;Other susceptible to susceptible to beams; road crane lifts fromFactors debris; smaller debris damage roadway crane lifts Engineers Club of Memphis - 8.22.2011
    53. 53. Conclusions Based on the owner preference for a clear-span bridge, the lowest cost one-span bridge is the steel low-truss bridge. This is, in fact, what the owner selected, and the structure was constructed in 2002. The premium to do the selected alternative over least cost alternative is $101,000 (initial costs) which is reduced over time to a Net Present Value premium of only $23,000 (75 years). Engineers Club of Memphis - 8.22.2011
    54. 54. PROJECT PROFILEOwner: Shelby County, TNRoute: Bass Rd.Contract Docs: ShelbyCounty, TNContractor: Shelby CountyRoads & BridgesBridge Contractor:U.S. BridgeStyle: Hybrid Cambridge /SenecaFloor Framing: RaisedConnections: WeldedSpan: 70 ft.Width: 32 ft.Finish: PaintedFloor/Deck: ConcreteRailing: W-BeamBass Rd. Shelby County, TN
    55. 55. PROJECT PROFILE Owner: Shelby County, TN Route: Kenville-Rosemark Rd. Contract Docs: Shelby County, TN Contractor: Shelby County Roads & Bridges Bridge Contractor:U.S. Bridge Style: Hybrid Cambridge / Seneca Floor Framing: Raised Connections: Welded Span: 60 ft. Width: 40 ft. Finish: Painted Floor/Deck: Concrete Railing: W-BeamKenville-Rosemark Rd., Shelby County, TN
    56. 56. PROJECT PROFILE Owner: Shelby County, TN Route: Sycamore Rd. Contract Docs: Shelby County, TN Contractor: Shelby County Roads & Bridges Bridge Contractor:U.S. Bridge Style: Hybrid Cambridge / Seneca Floor Framing: Raised Connections: Welded Span: 55 ft. Width: 30 ft. Finish: Painted Floor/Deck: Concrete Railing: W-BeamSycamore Rd., Shelby County, TN
    57. 57. Lunch and Learn Presentations Available: Prefabricated Steel Truss Bridges Historical Bridge Rehabilitation Steel Truss Bridge Rehabilitation Engineers Club of Memphis - 8.22.2011
    58. 58. Geometry & Description – Bridge Styles Cortez Beam Bridge 1 Cambridge Flat 1 Cambridge 2 Viking 4 Cost Scale __________________________________ 5 Seneca 1 3 4 Thru-Truss 3 Least Expensive Most Expensive
    59. 59. Geometry and Description - Finishes Weathering Painted Weathering Galvanized Galvanized & Painted Galvanized Weathering Painted Galvanized
    60. 60. Accessories - Railing Systems Guard Rail Systems Type Independent Rail System Independent Rail Attached to Stringer W Beam with Bracket Attached to Truss W Beam Attached Directly to Truss Truss Mounted Rail System
    61. 61. Accessories – Approach Railing Approach Rails Yes or No W Beam to Thrie Beam to Tubular Railing Thrie Beam Transition to Tubular Rail Thrie Beam Transition Thrie Beam Transition to Tubular Rail to Tubular Rail W Beam Flared End
    62. 62. Thank you for your time. Engineers Club of Memphis 8.22.2011

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