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1. BRIDGE FOUNDATION DESIGN
2. ODOT FOUNDATION DESIGN
14. Construct Subsurface Profile Stratigraphy & Geologic Model Groundwater Conditions Engineering Design Parameters Foundation TypeSeismic Analysis
15. Subsurface Geologic Profile
16. Seismic Analysis (Earthquake Design)Two Level DesignSeismic design is evaluated in terms of the overall bridge performance using the 500 yr. & 1000 yr. mean return period earthquakes. Bridge performance must meet Serviceability criteria for 500 year event and Life Safety criteria (no collapse) for 1000 yr event.
17. Seismic Analysis (cont.) Ground Acceleration (PGA) 2002 USGS Maps Site Specific Analysis (optional) Liquefaction Analysis Lateral Spread, Slope Instability Approach Fill Settlement Bridge Damage Potential Mitigation Measures
19. Foundation type depends on combinations of: Foundation Materials & Conditions Structure Type & Loads Performance Criteria Site Conditions/Construction Constraints Extreme Event Effects Seismic Loads (Liquefaction Potential) Scour Depths Costs & Construction Time
20. Other Project Considerations: In-Water Work Periods Environmental Restrictions Noise or Vibration Constraints Construction Access/Traffic Control
21. Shallow Foundations Spread Footings (on engineered fill) MSE Abutment Wall w/ Spread FootingDeep Foundations Driven Piles Drilled Shafts Micropiles
22. Spread Footing Design Settlement Bearing Resistance Sliding Resistance Overturning (eccentricity) Overall Stability (slope stability)
23. Pile Design Most Common Steel Pipe Piles (open or closed end) H-Piles Less Common Prestressed Concrete Timber
24. Pile Design Bearing Resistance (compression and tension) Lateral Resistance Settlement and Downdrag Analysis Corrosion Potential/Protection Tip Protection Pile Drivability (construction) Group Settlement, Group Effects
25. Drilled Shafts High bearing resistance High lateral resistance Cost-effective in river environments Can be socketed into bedrock Potential construction issues Hole stability (caving, groundwater) Difficulty with drilling obstructions Need very good subsurface data Need good experienced contractors
27. Micropiles Small diameter, drilled-in-place piles Rarely used Relatively expensive Applicable for: low overhead clearance boulders in foundation soils underpinning projects
28. Project description (scope & purpose) Office research & summary of pertinent records relating to foundation design and construction. Description of the geologic setting Summary of hydraulics information affecting foundation recommendations Subsurface explorations and conditions Boring logs Groundwater conditions Special field testing Laboratory test results
29. Seismic Analysis & Recommendations 500 yr. and 1000 yr. event analysis Peak Ground Acceleration (PGA), Sa & S1 AASHTO soil site class and response spectra Liquefaction Assessment Extent of Liquefaction & Potential Impacts Lateral Spread Potential Reduced Foundation Capacities Settlement, Downdrag Potential Liquefied Soil Parameters for Bridge Analysis Mitigation Recommendations Site Specific Analysis & Response Spectra (optional)
30. Foundation Recommendations Spread Footings (on engineered fill) Piles Drilled Shafts Micropiles
31. Spread Footings Recommended Footing Elevation(s) Nominal Bearing Resistance Factored Bearing Resistance (Allowable Bearing Capacity) Nominal bearing resistance for service limit state (settlement) Description and properties of the anticipated foundation material
32. Pile Foundations Type (Pipe Pile, H-pile, Concrete or Timber) Size or Dimensions (O.D., wall thickness, etc.) Material Specification (e.g., ASTM spec & grade of steel), Tip Treatment (PP open or closed-end, reinforcement) Nominal Bearing Resistances, estimated tip elevation for bearing estimated cutoff elevation, estimated or order lengths Minimum Required Tip Elevation (reason for reqd. tip elev.) Resistance Factors (f factor) and Factored Resistances Nominal (Ultimate) Uplift Capacities Soil Parameters for Lateral Load Analysis Pile Group Settlement
33. Pile Foundations (continued) Downdrag Effects (reduced capacities or mitigation) Liquefaction Effects: reduced pile capacities (axial, uplift, lateral, etc) Pile Drivability Analysis Wave Equation Parameters (for special provisions/contractors)
34. Pile Driving Stress Problems
35. Drilled Shafts Shaft Type (i.e., end-bearing, friction or both) Nominal Resistance for various diameters and lengths Estimated Shaft Settlement vs. Shaft Diameter and Load Factored Resistance and Resistance Factors Soil Parameters for Lateral Load Analysis Liquefaction Effects: reduced shaft capacities (axial, uplift, lateral, etc) Load Test recommendations (if appropriate)
36. Construction & Specification Recommendations Pile Foundations Pile Driving Criteria Wave Equation Input Criteria (if applicable) Number of Pile Splices Is Set Period (freeze) acceptable? Is Preboring or Jetting acceptable? Effects of driving on adjacent structures Potential Driving Obstructions (e.g., boulders, existing piles, utilities) been identified?
37. Construction & Specification Recommendations Drilled Shafts End bearing or friction shaft designation Temporary or Permanent casing recommendations Groundwater conditions Boulders and/or obstructions expected to be encountered Cross Hole Sonic Logging (CSL) Quality Control
39. Construction & Specification Recommendations Other Foundation Recommendations Detour Bridge Recommendations Falsework Support Falsework foundation type recommendations Foundation Excavations Groundwater conditions & possible mitigation Shoring and Bracing Cofferdams Unique Special Provisions Specific Geotechnical/Geologic information
40. Foundation Data Sheet (part of bridge plans) Locations all explorations (borings, test pits, hand augers, etc.) Explorations plotted in elevation view Subsurface conditions depicted with soil and rock unit descriptions SPT (N values), Undisturbed Samples Highest measured groundwater levels and the date measured Percent rock core recovery and rock hardness.
42. Distributed To: Structural Designer(s) Specification Writer Project Managers Office (inspector) Project Team Leader Region Geo-Office HQ Bridge Engineering Office FHWA (for large projects)
43. Plans Review Pile type, size and grade Drilled Shaft size, tip elevations, min. rock socket depth Nominal Resistances Resistance Factors Pile Driving Criteria Required Pile Tip Elevation Pile Tip treatment Splicing Detail Footings: Nominal Resistance Maximum Footing Elevation
44. Specifications Piling (Section 520) Estimated Pile Lengths (steel piles) Number of Pile Splices Tip Treatment (open or closed end, reinforcement) Driving Criteria Wave Equation Input (if applicable) Pile freeze, preboring or jetting allowed
45. Specifications Shafts (Section 512) Designated Friction or End Bearing Permanent Casing Requirements Crosshole Sonic Log (CSL) testing required
46. Pile Hammer & Equipment Review & Approval Pile Driving Criteria (inspectors graph) Pile Driving Problem Solving Pile Record Books Drilled Shaft Installation Plan Drilled Shaft Construction Forms Review of CSL test results Materials Substitutions Foundation Inspection Assistance Claims Resolution