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Erection of Cable-Stayed Bridges Having Composite Decks with Precast Concrete Slabs :

Erection of Cable-Stayed Bridges Having Composite Decks with Precast Concrete Slabs Presented by: Adam Berg & David Jacobson CEE 949 03-26-03

Erection of Cable-Stayed Bridges:

Erection of Cable-Stayed Bridges Overview of cable-stayed bridges Types of cable-stayed bridge decks Erection methods and analysis Conclusion

Cable-Stayed Bridges:

Cable-Stayed Bridges The known use of cable “stays” dates back to ancient Egyptian times

Cable-Stayed Bridges:

Cable-Stayed Bridges Modern use of cable-stayed bridges evolved in 1950’s (Germany)

Advantages of Cable-Stayed Bridges:

Advantages of Cable-Stayed Bridges Economical choice for spans between 200 and 1000 meters Self-anchoring during construction React to live loads with only small deformations Easily constructed by cantilever method

Concrete Bridge Decks:

Concrete Bridge Decks Used for spans up to 350 m Axial forces induced into the deck by cable stays serve as a cost-free prestress

Composite Bridge Decks:

Composite Bridge Decks Advantageous for spans from about 350 m to 700 m Axial forces induced into the deck by cable stays serve as a cost-free prestress

Steel Girder w/ Orthotropic Decks:

Steel Girder w/ Orthotropic Decks Advantageous for spans greater than 700 m

Erection of Cable-Stayed Bridges:

Erection of Cable-Stayed Bridges Cantilever style construction Goal is to prevent locked in curvature and bending moments in bridge deck

Pure Concrete Deck Cable Tensioning:

Pure Concrete Deck Cable Tensioning Proper one-step tensioning will yield this dead load configuration Dead Load Configuration: Full deck loads, w, and deck moments, M

Pure Concrete Deck Cable Tensioning:

Pure Concrete Deck Cable Tensioning 3 2 4 1

Pure Concrete Deck Cable Tensioning:

Pure Concrete Deck Cable Tensioning

Erection of Cable-Stayed Bridges..:

Erection of Cable-Stayed Bridges.. Methods of erecting cable-stayed bridges having concrete or orthotropic decks are fairly well established. However, erection methods/analysis of composite decks with precast concrete slabs are not well published.

Composite Deck Cable Tensioning:

Composite Deck Cable Tensioning One-step tensioning processes lock in initial deck curvature and moments

Construction Stages for Two-Step Composite Deck Cable Tensioning:

Construction Stages for Two-Step Composite Deck Cable Tensioning Steel stage Erection of pre-fabricated steel grid

Construction Stages for Two-Step Composite Deck Cable Tensioning:

Construction Stages for Two-Step Composite Deck Cable Tensioning Panel stage Placement of precast concrete slabs on steel grid Cables are tensioned as the first step of tensioning

Construction Stages for Two-Step Composite Deck Cable Tensioning:

Construction Stages for Two-Step Composite Deck Cable Tensioning Freeze stage Survey is conducted to check precision of grid geometry and cable forces Joints between precast concrete slabs are cast; resulting deck acts continuously and compositely

Construction Stages for Two-Step Composite Deck Cable Tensioning:

Construction Stages for Two-Step Composite Deck Cable Tensioning Final stage After sufficient deck strength is realized, cables are stressed to their final lengths (second step of tensioning)