Designing Bridgesfor
Constructability
Kevin H. Miller, PEBergmann Associates
What is Constructability ?Construction Industry
Institute
“the optimum use of construction knowledge and experience in planning, design, procurement and field operations to achieve the overall project objectives”
Using construction knowledge to design bridges that can be constructed efficiently with
minimal change orders
What are the advantages of constructability ?
•More competitive bids•Fewer change orders•Reduced construction costs•Reduced time of construction•Save lives ??
How can constructable designs be achieved ?
• Early and continuous involvement of construction personnel
• Tap the knowledgeContractorsInspectorsFabricatorsOwners
• Build a data base of change orders & RFIs
• Use lessons learned checklist• Establish a constructability program
Why don’t we do it ?• Adds time to design schedule • Initial cost• Availability of qualified staff• Reluctance to reach out to
contractors
• Right-of-Way• Utilities• Data Collection• Mobilization• Clearing & Grubbing• Demolition• Excavation• Cofferdams• Deep Foundations
• Substructures• Bank Protection• Bearings• Steel Fabrication, Erection
and Framing• Precast Concrete
Fabrication and Installation• Decks & Approach Slabs• Bridge Rail• Highway Approach
Do you have sufficient Right-of-Way?
• Staging area• Limits of excavation layback• Access for demolition, construction
and maintenance• On-site detour
• Right-of-Way• Utilities• Data Collection• Mobilization• Clearing & Grubbing• Demolition• Excavation• Cofferdams• Deep Foundations
• Substructures• Bank Protection• Bearings• Steel Fabrication, Erection
and Framing• Precast Concrete
Fabrication and Installation• Decks & Approach Slabs• Bridge Rail• Highway Approach
Consider more soil borings
• Right-of-Way• Utilities• Data Collection• Mobilization• Clearing & Grubbing• Demolition• Excavation• Cofferdams• Deep Foundations
• Substructures• Bank Protection• Bearings• Steel Fabrication, Erection
and Framing• Precast Concrete
Fabrication and Installation• Decks & Approach Slabs• Bridge Rail• Highway Approach
• Right-of-Way• Utilities• Data Collection• Mobilization• Clearing & Grubbing• Demolition• Excavation• Cofferdams• Deep Foundations
• Substructures• Bank Protection• Bearings• Steel Fabrication, Erection
and Framing• Precast Concrete
Fabrication and Installation• Decks & Approach Slabs• Bridge Rail• Highway Approach
Is it necessary to remove the entire substructure?
• Temporary cofferdams• Scour protection
• Right-of-Way• Utilities• Data Collection• Mobilization• Clearing & Grubbing• Demolition• Excavation• Cofferdams• Deep Foundations
• Substructures• Bank Protection• Bearings• Steel Fabrication, Erection
and Framing• Precast Concrete
Fabrication and Installation• Decks & Approach Slabs• Bridge Rail• Highway Approach
Cofferdams
• Can cofferdam be built without interfering with battered piles?
• To tremie seal or not to tremie seal?• Consider in-the-wet construction
“In-the-wet" drilled shaft installation using the existing
bridge as falsework
• Right-of-Way• Utilities• Data Collection• Mobilization• Clearing & Grubbing• Demolition• Excavation• Cofferdams• Deep Foundations
• Substructures• Bank Protection• Bearings• Steel Fabrication, Erection
and Framing• Precast Concrete
Fabrication and Installation• Decks & Approach Slabs• Bridge Rail• Highway Approach
Drilled Shafts
• Minimize footprint of foundation
• Right-of-Way• Utilities• Data Collection• Mobilization• Clearing & Grubbing• Demolition• Excavation• Cofferdams• Deep Foundations
• Substructures• Bank Protection• Bearings• Steel Fabrication, Erection
and Framing• Precast Concrete
Fabrication and Installation• Decks & Approach Slabs• Bridge Rail• Highway Approach
Reinforcing
– Bundle bars– Larger bars at greater spacing
• Avoid threading bars through hoops• Simplify, line up front and back mats
• Avoid rebar congestion
• Consolidate several small repair areas• Provide sufficient depth for repair• Over estimate repair area
Substructure Concrete Repairs
• Right-of-Way• Utilities• Data Collection• Mobilization• Clearing & Grubbing• Demolition• Excavation• Cofferdams• Deep Foundations
• Substructures• Bank Protection• Bearings• Steel Fabrication, Erection
and Framing• Precast Concrete
Fabrication and Installation• Decks & Approach Slabs• Bridge Rail• Highway Approach
• Right-of-Way• Utilities• Data Collection• Mobilization• Clearing & Grubbing• Demolition• Excavation• Cofferdams• Deep Foundations
• Substructures• Bank Protection• Bearings• Steel Fabrication,
Erection and Framing• Precast Concrete
Fabrication and Installation• Decks & Approach Slabs• Bridge Rail• Highway Approach
Steel Fabrication• Girder economy• Avoid flange width transitions• Avoid sizing in increments of 1/8”
thickness• Use a minimum web thickness of ½”• Consider how steel delivered to site• Consider lead time on steel• Consider how erect steel – any DEC
permits needed?
• Right-of-Way• Utilities• Data Collection• Mobilization• Clearing & Grubbing• Demolition• Excavation• Cofferdams• Deep Foundations
• Substructures• Bank Protection• Bearings• Steel Fabrication, Erection
and Framing• Precast Concrete
Fabrication and Installation
• Decks & Approach Slabs• Bridge Rail• Highway Approach
Can you use precast?
Tolerances with Precast
6”
• Right-of-Way• Utilities• Data Collection• Mobilization• Clearing & Grubbing• Demolition• Excavation• Cofferdams• Deep Foundations
• Substructures• Bank Protection• Bearings• Steel Fabrication, Erection
and Framing• Precast Concrete
Fabrication and Installation• Decks &
Approach Slabs• Bridge Rail• Highway Approach
Avoid Complex Geometry
• Heavy skews• Horizontal curves• Spirals• Superelevation transitions• Can it be built with SIP forms?
Horizontal Curves on Bridges
• Avoid curved girders if possible• Straight girders with curved deck• Varying width shoulders with straight
deck and girders
A Few General Tips
• Leave the methods and means to the builders
• Think about allowable tolerances• Repetition is a good thing• Avoid skews, at least heavy skews• “Keep it simple”• “If in doubt, rip it out”
As Designed As Built
Constructability and Safety
Questions?