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

• $512 million project • Widening sections of the Logan and Gateway motorways.

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 and the Wembley Road • Logan Motorway interchange BR03 Widening

• Constructing new south-facing on and off-ramps on the 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