Q-Bridge Transverse Analysis Daniel Mariscal, P.E. AECOM - Tampa, Florida Project Location United States of America Project Location State of Connecticut Project Location City of New Haven Project Location Interchange: • Interstate I-95 • Interstate I-91 • CT Route 34 • Pearl Harbor Memorial Bridge, Over the Quinnipiac River (Q-Bridge) Existing Bridge: Steel Girder • Bridge Owner: Connecticut Department of Transportation Existing Bridge: Steel Girder • Plate Steel Girder, Opened in January 1958 • Main Span 118m, Once the Longest Plate Girder in Western Hemisphere • Functionally Obsolete, Carried Three Lanes in Each Direction Replacement Bridge: Extradosed Bridge • Several Alternatives Studied • Concrete Extradosed Bridge Selected (First Extradosed Built in the USA) • New Bridge Carries Five Lanes in Each Direction. Economical Bridge Types Sources: Podolny, Stroh Steel Box 200 600 Q-Bridge = 515 ft. Segmental 200 600 Extradosed 400 800 Truss 500 1,200 Arch 500 1,200 Cable Stayed 600 1,800 2,800 1,500 Suspension 0 1,000 2,000 3,000 4,000 Span in Feet Girder Bridge POSTENSIONING TENDONS Girder Depth: 1:16 to 1:18 Cable-Stayed Bridge Girder Depth: STAY CABLES 5 to 6 ft. Tower Height: V 0.25 Span H Extradosed Bridge STAY CABLES Girder Depth: 1:30 to 1:35 Tower Height: 1:10 to 1:15 What is an Extradosed Bridge? • Hybrid Bridge Type: – Cable-Stayed Bridge – Post-Tensioned Girder Bridge • Tower Height is Shorter than Cable Stayed Bridges • Girder Depth is Shallower than Girder Bridges, but Deeper than Cable- Stayed Bridges • Stay Cable Planes are Flatter than Cable-Stayed Bridges, and cover a Shorter Portion of the Span • Alternate Load Paths – Relatively Stiff Girder – Stay Cables – Primarily for Dead Loads • Stay Cables are Sized to Contribute to the Deck Prestressing • Low Fatigue Range for Stay Cables • Uniform Stress Range for Stay Cables Why an Extradosed Bridge? • Falls Within Span Length Range – Longer Main Span Avoids Old Bridge Foundation • Under Clearance: Coast Guard – Shallower Girder – Lower Profile • Over Clearance: FAA – Shorter Towers – Airport Flight Path : Tweed New Haven Airport • Superior Aesthetics Project Description FAA Clearance (2 Miles from Tweed Airport) Coast Guard Clearance Project Description • Northbound Bridge, Dedicated June, 2012 • Northbound Bridge Carried Both Northbound and Southbound Traffic • Southbound Bridge, Dedicated September, 2015 • Total Project Cost $2.0 Billion (approx.) • Main Span Cost $600 Million (approx.) Project Staging Quinnipiac River •• StageStage 3:2: DemolishBuild1: Existing NB Structure,Existing Bridge: Structure, NorthboundMove NB Build& SB(NB) SBTraffic & Structure Southbound (SB) Traffic Main Span Erection Sequence Cast-in-Place, Balance Cantilever Erection •• StageStage 7634251 -- FinishingClosureBalancedContinuationAssemblyConstruction atat Works Cantilever ofMainSide Travelingof- Cantilever SpanSubstructuresSpan Construction Forms Construction and and Pier Cable Tables Installation Project Design - Longitudinal • Design Started in 2001 • Bentley’s RM Bridge (formerly TDV’s RM 2000) • Single Spine Model: Beam Elements Project Design - Longitudinal • Stage Construction • Dead Loads • Post-Tensioning • Creep & Shrinkage • Thermal Loads • Live Loads Project Design - Longitudinal Longitudinal Model, Erection Sequence Project Design - Longitudinal Longitudinal Model, Erection Sequence Project Design - Longitudinal Longitudinal Model, Erection Sequence Project Design - Longitudinal Longitudinal Model, Erection Sequence Project Design - Longitudinal Longitudinal Model, Erection Sequence Project Design - Longitudinal Longitudinal Model, Erection Sequence Project Design - Longitudinal Longitudinal Model, Erection Sequence Project Design - Longitudinal Longitudinal Model, Erection Sequence Project Design - Longitudinal Longitudinal Model, Erection Sequence Project Design - Longitudinal Longitudinal Model, Erection Sequence Project Design - Longitudinal Longitudinal Model, Erection Sequence Project Design - Longitudinal Longitudinal Model, Erection Sequence Project Design - Longitudinal Longitudinal Model, Erection Sequence Project Design - Longitudinal Longitudinal Model, Stresses Summary Project Design - Longitudinal Longitudinal Model, Stresses Summary Project Design - Longitudinal Longitudinal Model, Stresses Summary Project Design - Longitudinal Longitudinal Model, Stresses Summary Project Design - Transverse • Intergraph’s GT STRUDL • 3-Dimensional Plate Element Model: – Dead Loads – Live Loads – Web Shear Distribution – Dishing Deformation at Cable Stay Locations • 2-Dimensional Frame Beam Element Model: – Interior Transverse Top Slab Post-Tensioning – Exterior Transverse Draped Post-Tensioning • Excel Spreadsheets Project Design - Transverse 3-Dimensional Plate Element Model Stay Cables As Springs Project Design - Transverse 2-Dimensional Frame Beam Element Model External PT Loading Project Design – Transverse Review • New Software Available: Midas FEA • Increased Computing Power • As-Built Model • 3-Dimensional Model Using Solid Elements: 8-Node Hexahedron & 6-Node Wedge for the Superstructure • Linear Elastic Model • Creep & Shrinkage Not Implicitly Modeled • Construction Sequence • Superstructure & Substructure • Stay Cables, Longitudinal & Transverse Post-Tensioning Model Development – Cross Sections • Multi-Cell Concrete Box • Variable Deck Width Along Length of Bridge • Variable Girder Depth At Towers • Variable Bottom Slab Thickness At Towers • Variable Botom Slab Thickenes Model Development – Cross Sections Variable Deck Width Along the Length of Bridge BEGIN OF BRIDGE END OF BRIDGE Model Development – Cross Sections Variable Girder Depth At Towers Model Development – Cross Sections Variable Bottom Slab Thickness At Towers Model Development – Cross Sections Full Bridge Model: 57,094 Solid Elements, 2,688 Plate Elements, 14,639 Line Elements Model Development – Cross Sections Close-Up At Bridge End Model Development – Cross Sections • Cross Sections Drawn in Microstation • 40 Different Cross Sections Representing Entire Bridge Length Cross Section Variable Geometry • Cross Sections Exported to DXF • DXF Cross Sections Imported into Midas FEA Model Development – Cross Sections Cross Sections Drawn in Microstation Model Development – Cross Sections Cross Sections Imported to Midas FEA Model Development – Cross Sections Cross Sections Imported to Midas FEA Model Development – Cross Sections Cross Sections with “Mesh Control” Model Development – Cross Sections Two Cross Sections Create Solid by “Lofting” Model Development – Cross Sections Auto-Mesh Solid Model Development – Cross Sections Solid Elements Created Model Development – Cross Sections Close-Up At Tower Variable Girder Depth and Bottom Slab Thickness Model Development - PT • Variable Cross Section Variable PT Geometry • 140 Different Top Transverse PT Geometries • 39 Different Transverse External PT Geometries • PT Geometry Developed In Excel, Points • PT Geometry Imported Into AutoCAD, Polylines • PT Geometry Exported To DXF • DXF Geometry Imported Into Midas FEA Model Development - PT Variable PT Geometry Created Using Excel Model Development - PT Geometry Imported Into AutoCAD Using Scripts Model Development - PT Geometry Exported From AutoCAD to DXF Model Development - PT DXF PT Geometry Lines Imported Into FEA Model Development - PT Transverse Top Slab PT: “Bar In Solid” T1 Tendons: 4 x 15.2mm Strands T2 Tendons: 2 x 15.2 mm Strands Model Development - PT Transverse External PT Geometry Lines Model Development - PT Transverse External PT: “Line Element” T3 Tendons: 19 x 15.2mm Strands T4 Tendons: 7 x 15.2 mm Strands Model Development - PT Top Cantilever PT Geometry Lines Model Development - PT Longitudinal Cantilever PT: “Bar In Solid” C1 Tendons: 27 x 15.2mm Strands C2 Tendons: 23 x 15.2 mm Strands C3 Tendons: 19 x 15.2mm Strands Model Development - PT Bottom Continuity PT Geometry Lines Model Development - PT Longitudinal Bottom Slab PT: “Bar In Solid” B1 & B3 Tendons: 9 x 15.2mm Strands B2 Tendons: 12 x 15.2 mm Strands Model Development - PT All Geometry Line, Including for Stay Cables Model Development - PT Typical Stay Cable Segment With Diaphragm Solid Elements Plate Elements Model Development - PT Typical Stay Cable Segment With Diaphragm Transverse Post-Tensioning Top Slab PT External PT Model Development - PT Longitudinal Cantilever Post-Tensioning Model Development - Loads Traveler Loads: Pressure Loads Model Development - Staging Construction Sequence: Total 142 Steps, 2.1 Hours Model Development - Staging Construction Sequence Model Development - Staging Construction Sequence Model Development - Staging Construction Sequence Model Development - Staging Construction Sequence Model Development - Staging Construction Sequence Model Development - Staging Construction Sequence Model Development - Staging Construction Sequence Model Development – Live Loads Live Loads: Arbitrary Load/Vehicle Truck Load Model Development – Live Loads Live Loads: 25 Positions Across Deck Model Development – Live Loads Transverse Live Loads: 7 Locations Along Main Span Model Verification • Model Verification Against RM Bridge Single Spine Model • Uniform 10kN/m2 Pressure Load Applied on Entire Deck Area Model Verification: Reactions 10kN/m2 Uniform Pressure Over Deck Location RM Result FEA Result RM/FEA Anchor Pier 1 3805 3941 0.97 Tower 2 12022 9935 1.21 21111 25300 0.83 11863 9797 1.21 Tower 3 11484 9475 1.21 19790 23800 0.83 11582 9585 1.21 Anchor Pier 4 4050 9816 1.06 TOTAL 95707 95649 1.00 Model Verification: