Widening Existing Transversely Stressed Concrete Bridges on Logan Enhancement Project Muhammad Shariq Senior Structural Engineer - GHD Palisa Huoth Senior Structural Engineer - GHD Presentation Overview Background Case Study Design Image place holder Construction Recommendations Background Supply Demand • Increased Demand • Need of more improved and efficient systems • Brownfield Infrastructure upgrades • Maximising the utilisation of existing assets Enhanced Safety • BRIDGE WIDENINGS Reduced Congestion • Provisions for Future widening Efficient Motorway Enhanced network Connectivity Project | Logan Enhancement Project (LEP) - QLD • Transurban Queensland $512 million project • Widening sections of the Logan and Gateway motorways. Brisbane Team and key stakeholders CLIENT ROAD AUTHORITY CONTRACTOR INDEPENDENT VERIFIER DESIGN JOINT VENTURE Logan Enhancement Project (LEP) - QLD Highlights: • Improving key congestion hot spots: • Logan Motorway • Mt Lindesay Highway • Beaudesert Road interchange and the Wembley Road • Logan Motorway interchange BR03 Widening • Constructing new south-facing on and off-ramps on the Gateway Motorway at Compton Road Key Objectives: • Sustainability & Optimisation, • Future proofing • Minimising Construction Impact • Safety Logan Enhancement Project (LEP) - QLD Workflow • Tender Design Tender • Detail Design Design Detail Design based on and further Construction • Further Investigation reference investigations design • Construction Detail Design Delivery Developed Substantial Final Detail Issued for Concept Design Detail Design Design Construction 25% Design 65% Design 85% Design 100% Design Case Study – Scrubby Creek Bridge (BR03) • Dual Carriageway • 8 Spans • Prestressed DUs • Transversely post- tensioned • Total Length170m • 8 Driven Piles • Built 1996 Previous Conditional Assessments • TMR Level 2 Inspection report 2008 and 2012 • TMR Level 1 Inspection report 2015 • Rehabilitation of Deck Surfacing and Pier 4 Expansion Joint 2015 Southbound• Non Level-destructive 2 Inspection- Water Integrity leaks, Vegetation Testing at Headstock, Partial Replacement of Expansion Joints Northbound Level 2 Inspection- Crack on Surfacing and Vegetation at Headstocks Design | Scrubby Creek Bridges (Plan) NORTH EXISTING BRIDGE ORIGINAL WIDENING WIDENING PROVISION LOGAN BRISBANE Image place holder EXISTING BRIDGE WIDENING BR03 SCRUBBY CREEK PLAN Design | Scrubby Creek Bridges (Cross-section) Original Widening provision in the middle Image place holder Detailed Design (Connecting Superstructure) General arrangement of stressing bar through deck units • Interface Deck Unit • Coupling of PT bars • Accessible for Maintenance Detailed Design (Connecting Substructure) • Rigid connection • Post Installed Dowels • Composite Connection Design Challenges and considerations For 2 no.s PT bars on Scrubby Creek Bridges that were identified as condition state of 3 in previous NDT report as per • Available Information and gaps SWTC. Undertake design check • Connection of the existing and new structure and core out, remove bars for visual assessment, unless other bars identified as more representative • Design for each of the construction stages Are the bars in No further rectification work satisfactory condition required for the remaining PT based on visual bars • Bridge Loadings inspection Yes No Identify the location and assess the nature of the • Integrity of transverse PT bars observed defects. Assess overall bar condition and Level 2 inspection assessment, apply engineering judgement to determine appropriate actions Provide a desktop analysis Bridge capacity Yes advising client of future adequate without maintenance requirements for Category 3 bars? PT bar monitoring and replacements No Core out, remove and replace the worst Condition State 3 PT bar Yes The actual condition No Any additional of the PT bar and Category 3 PT bars grout satisfactory? identified? Yes No No further rectification work required for the remaining PT bars Further Investigations and Construction Condition of Existing Structure • Non Destructive Testing • Categorise Condition • Confirmation of Condition • Undertaken by specialist Contractor • Piles not driven to set • Cast in place piles required for design Construction | Key Challenges and Solutions Staging Solution • Staged construction • Alignment Image place holder • Consideration of sight distance (effects of anti- gawk screens) • Limited access- worked within construction program Construction | Key Challenges and Solutions Proximity Solution • Mitigated risks of damage to existing pile Image place holder • Worked with Contractor to devise solution • Removed pile for increased tolerance Construction | Key Challenges and Solutions Tie-in Existing Solution • Adjustable mortar pad heights Figure 1: Typical Cross section Image place holder • Oversized voids • Alignment adjusted • Worked with Construction to modify dowel design Figure 2: Abutment Dowelling Recommendations • Not as ‘simple’ as it appears • Clients - Provide as much record information as possible • Designers - Ongoing and early engagement between Asset Owner, Authorities, Image place holder Contractor, Reviewers and Designers • Communicate design sensitivity • Authorities - Plan for future Construction | Current status • Commenced in June 2017 • Enhanced Safety • Expected Completed Mid 2019 • Enhanced Connectivity Image place holder www.ghd.com.