Reconstruction of the Eads Bridge Highway Deck
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Reconstruction of the Eads Bridge Highway Deck Michael J. Cronin, PE, SE Eads Bridge History y Opened to traffic July 4, 1874 y Designed and planned by James Buchanan Eads − Underwater salvage expert − Shipbuilder − No formal education − Hired by the St. Louis and Illinois Bridge Company as engineer-in-chief for this project Eads Bridge History y Design and construction innovations − deep pressurized caisson construction Eads Bridge History y Design and construction innovations − deep pressurized caisson construction − high strength cast steel Eads Bridge History y Design and construction innovations − deep pressurized caisson construction − high strength cast steel − design of components to permit ease of replacement Eads Bridge History y Design and construction innovations − deep pressurized caisson construction − high strength cast steel − design of components to permit ease of replacement − cantilever construction of main arch spans Eads Bridge History y Design and construction innovations − Deep pressurized caisson construction − high strength cast steel − design of components to permit ease of replacement − cantilever construction of main arch spans − 500 ft spans were 200 ft longer than any built previously Bridge Ownership History y Illinois and St Louis Bridge Company y Missouri Pacific Railroad Company y Terminal Railroad Association y City of St. Louis / Bi-State Development Agency Rehabilitation Challenges y Preserve historically important aesthetic elements y Use existing substructure to support new highway deck y Maintain light rail traffic during construction New Cross Section y Four 11 ft lanes designed for HS-20 loading y 1 ft offset between outside lanes and the Jersey barriers y 5 ft sidewalk on south side of roadway Bridge Sections y West Approach y West Arcade y Main Spans y East Arcade y East Approach West Approach & East Arcade y Substructure: 3 longitudinal walls − Outside walls of stone or brick masonry, original construction − Center wall of minimally reinforce concrete, constructed in the 1920’s y Substructure repairs − Tuckpointing − Crack repair − Reinforced concrete pads West Approach & East Arcade y Longitudinal concrete beams over First and Second Streets − Spalled and cracked − Some section loss in reinforcing − Capacity found to be marginally acceptable y Repairs − fiber composite wrap − total replacement West Approach & East Arcade y Existing superstructure: transverse concrete floorbeams with distinctive sloped ends y Replaced with prestressed concrete I girders with special ends − designed as 2 span continuous to maintain distribution to supporting walls y Precast SIP form panels utilized West Arcade y Substructure: 2 longitudinal walls y East portion - stone masonry arches in fairly good condition − concrete infill used to strengthen arches y West portion - reinforced concrete open arches in poor condition − total replacement with new reinforced concrete arches West Arcade y Existing superstructure − non-composite rolled beams at 4 ft spacing − deck replaced in early 1980’s − design called for cleaning & painting beams, scarifying & overlaying deck y Change order proposed by contractor − total replacement of superstructure with composite rolled beams at 8.5 ft spacing Main Spans y Existing substructure - 2 piers and 2 abutments founded on bedrock − Good condition − Top surfaces of piers and abutments required crack repair and resurfacing Main Spans y Arch truss superstructure − no retrofit required if dead load from new floor system and deck is held < 116 psf Main Span Floor System y Existing floor system: half-filled grid deck on floorbeams at 6 ft spacing y New floor system eliminated floorbeams between columns - 12 ft spacing y Exodermic™ Deck specified to span the 12 ft between floorbeams − 74 psf using standard weight aggregate Main Span Floor System y The Exodermic™ deck, or an “unfilled steel grid deck composite with a ±4.5” reinforced concrete slab” provides: − Light weight − Structural efficiency − Protection of Light Rail operating below ExodermicTM Bridge Deck Special Main Span Features y Overlook areas at piers and abutments y Bridge can be closed to traffic for special weekend events y Electrical outlets built into north barrier East Approach y 10 spans of new steel superstructure on new concrete substructure - 1000 ft y Highway deck starts above MetroLink track and end below y Highway deck had to be built around MetroLink bridge and elevated station as well as abandoned foundations East Approach y Drilled shaft construction − one shaft per pier − up to 7 ft in diameter − utilized to minimize footprint and to avoid vibrating adjacent MetroLink foundation East Approach y Steel straddle bents − transverse beams − support the highway deck over the MetroLink tracks and elevated station platform where traditional supports cannot be used Connection to MetroLink y Handicap accessible ramp built to connect sidewalk to East Riverfront Station Reopening - July 4, 2003 THANK YOU.