490 likes | 700 Views
Schematic Design of an Accelerated Bridge Construction Project. Michael P. Culmo, P.E. Vice President of Transportation and Structures CME Associates, Inc., East Hartford, CT. Reference Manual. Use the Connections Details Manual Type study concept Select details from various states.
E N D
Schematic Design of an Accelerated Bridge Construction Project Michael P. Culmo, P.E. Vice President of Transportation and Structures CME Associates, Inc., East Hartford, CT
Reference Manual Use the Connections Details Manual Type study concept Select details from various states
4 lane bridge over an expressway Existing bridge has deteriorated beyond repair Heavy traffic on both roadways There is a short but undesirable detour Case Scenario
Public hearing held Businesses do not want a long construction process with stage construction Businesses are not keen about a detour They will accept a short term closure with the detour As opposed to a long term staged project Public Involvement
Build a temporary bridge to speed up construction of the new bridge $$$$ Not that fast Use multi-stage construction Very long construction Will require long term lane closures Establish the detour and accelerate the bridge construction to less than 30 days Design Approach Options
Deck Joints Low Clearance Existing bridge issues
After a formal type study, the owner opted with the following structure criteria Use NEXT Beams to accelerate construction Design as simple span for Dead Load and continuous spans for Live Load Increase clearance by raising approach grades (3’) Use integral abutments (no deck joints) Composite concrete deck Membrane waterproofing and Bituminous wearing surface Use Precast Rail System (Vermont/NH system) Proposed Bridge Type
Push abutments back to top of slope Minimize wingwall requirements Use integral abutments with flying wings Eliminate spray attack on abutments Place abutments in a different footprint than the existing facilitates construction Use open frame pier bent on spread footings Substructures
Proposed Bridge Move abutment away from roadway No Deck joints Increase vertical clearance
Preliminary Beam Sizing Use PCI NEXT Beam Standards Beam Design
LLDF Beam Design
AASHTO LL Distribution Factor – Type K Beam Design Moment Shear
AASHTO LLDF Type H Beam Design Shear Moment
FHWA manual “Connection details for prefabricated bridge elements and systems” Review Chapter 1 Investigate connection types, materials, tolerances 2. Search applicable sections of other chapters for details How to select details
After reviewing chapter 1, the owner chose the following connection types Grouted reinforcing splice couplers Quick, proven system Can develop full bar strength Simplifies the design process (similar to CIP) Grouted Voids Easy for simple connections Concrete Closure pours between precast elements Use for a limited number of connections (slower) Section 1.4 Typical Connection Types
Emulates a reinforcing steel lap splice Multiple companies – non-proprietary Used in precast parking garages and stadiums and bridges Grouted Reinforcing Splice Connectors
Emulates a reinforcing steel lap splice Multiple companies – non-proprietary Used in precast parking garages and stadiums and bridges Time Lapse Video on YoutubeTM Search “Georgia Pier Construction” Grouted Reinforcing Splice Connectors • Installation Video on YoutubeTM • Search “Georgia Pier Construction” • Installation video
Completed Pier Column to cap connection Column to footing connection Footing to subgrade connection
Integral Abutment to precast piles Section 3.2.3.1 Precast Integral Abutment to Piles Detail developed by Maine DOT Used on three different bridges Abutment Details
Completed Abutment Approach slab connection Flying Wingwall connection Abutment cap connection Pile to cap connection
Design as a conventional cast in place deck Use max stem spacing for design (5.0 feet) Design overhang from outside stem (2.53 feet) Deck Design with Next Beam
Superstructure to Integral Abutment Connection Use a similar detail at the pier
Completed Bridge Composite Deck Membrane waterproofing with bit. Wearing surface Precast Parapet Precast Pier Precast Integral Abutment
Typical New Bridge (Cost=$200/sf) = $1,920,000 Premium for ABC (assume 20%) = $384,000 Temporary Bridge (Cost=$60/sf) = ($576,000) Net Savings = $192,000 Note: These prices will vary by region Costs
Ways to reduce bid prices with ABC Standardization Programmatic (not one of a kind) Reduced project site costs (trailers, etc.) Reduced Maintenance of Traffic Costs Inflation Other Non- Bid Savings with ABC Fewer Police Details Reduced Resident Engineering time User Costs Plus: $$ Can be significant Minus: $$ Not in the budget Other Cost Savings
Florida has had very good success with precast piers in very harsh environments Precast concrete beams require no maintenance Integral abutments eliminate deck joints Quality
Rapid Construction High Quality Low Cost Old Adage You can only have any two By elimination of temporary bridges or costly stage construction schemes, you CAN have all three
It is possible to build a complete bridge in 30 days (or less) The FHWA manual provides a starting point for a complete bridge prefabrication project You do not need to sacrifice quality to get rapid construction You can save money on an accelerated bridge project by: Reducing construction time Eliminate temporary bridges or staging Conclusions
culmo@cmeengineering.com Questions