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?