interspan_greenland

Post-Tensioning Bar for Greenland Centre, Sydney

The Greenland Centre Sydney is one of the city’s most ambitious adaptive reuse projects — transforming a 1960s 29-storey commercial tower into a 70-level residential high-rise. The redevelopment involved the selective demolition of the upper portion of the existing structure, while 26 levels were retained and integrated into the new tower. A complex outrigger system was designed to effectively transfer loads between the new and existing structural elements, ensuring performance, safety, and durability.

Interspan’s Post-Tensioning System for this Adaptive Reuse Tower

Interspan was engaged to design and deliver a high-capacity post-tensioning bar system for the critical outrigger connection between Levels 26 and 28.
Our scope included the supply, installation, stressing, and grouting of 1,200 metres of 75mm diameter post-tensioning bars, linking the outrigger beam to the building’s core.

Through careful coordination and precision installation within a confined, high-rise environment, Interspan delivered a solution that met the project’s stringent structural, safety, and quality assurance standards — contributing to the successful completion of one of Australia’s tallest residential conversions.

Project Details

General contractor: Probuild

Customer/Owner: Greenland Australia

Designer: Arup

Work Period:  2019

Solution: Post-tensioning Bar

GLOBAL LEADER IN SPECIALISED CONSTRUCTION SERVICES

Interspan delivers efficient, durable and sustainable solutions across bridges, tanks, buildings, ports and energy infrastructure — helping clients optimise structural performance, reduce costs, and lower embodied carbon in construction.

Our expertise spans post-tensioning, structural strengthening and specialised concrete technologies, applied across both new and existing structures.

By integrating engineering design, construction methodology and material efficiency, we deliver technically robust outcomes that enhance safety, service life and overall project value.

EXISTING STRUCTURES

External post-tensioning is a proven active strengthening method for upgrading existing structures, including bridges, buildings and tanks. It involves installing prestressing cables or bars outside the structural section, guided by deviators along the most effective load path.

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Replacing bearings and expansion joints is essential to restore performance and extend the service life of ageing bridges and civil structures. Upgrading these components restores the structure’s ability to accommodate movement, rotation, and stress, improving durability and long-term serviceability.

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Jacking and structural monitoring are both critical parts of any safe load transfer process and require expert engineering guidance.

Interspan designs custom solutions for diverse projects where precision loading/unloading and monitoring of structural elements are required.

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Forensic services are often utilised to assess potential compliance issues between the approved structural documentation and
the built structure. We utilise both non-destructive and destructive testing methods to understand the composition of existing structures.

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Over the last decade, Interspan has developed proven epoxy-based, retrofitted Tendon Truncation procedures that ensure post-tensioned tendon forces can be safely transferred into the remaining structure.

Our teams have decades of experience with post-tensioned structures, and we know how and where to use truncations as well as how to install them safely.

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We have significant experience with structural grouting, and our pumps can mix and place proprietary grouts with or without cementitious or epoxy-based aggregate.

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Corrosion is one of the most common and expensive durability issues stakeholders encounter in both building and civil structures.

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We understand structures. We know why they crack and how to fix them. Our experienced teams design custom solutions to address any kind of crack that emerges. Typically, a crack is the symptom of a problem, not the cause.

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We promote innovative, proven solutions utilising various CFRP-based strengthening techniques depending on the nature of strengthening required for your project. Our knowledge and experience in this area are second to none, and we’re extremely proud of the work our teams do every day.

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We provide solutions for all types of concrete repair. Whether it is due to deterioration, carbonation, damage, or defective concrete, we put forward a remediation solution to ensure the section’s durability and strength are fully reinstated.

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NEW STRUCTURES

Innovative construction methodologies enable works to be completed outside the critical path in a safe and controlled environment. This approach reduces project costs and schedules, improves safety, and minimises disruption.

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Interspan has extensive experience in the supply and installation of post-tensioning works in bridges, using state-of-the-art equipment to apply uniform stress to the separate strands of the tendon simultaneously.

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Lifting and jacking operations are essential when prefabricated elements or existing structures need to be moved, raised, or installed with precision.

These techniques reduce reliance on heavy craneage, minimise risks, and enable construction in challenging environments or tight timeframes.

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Stress bar post-tensioning systems provide a cost-effective solution for applying post-tensioning forces to short, straight tendons without requiring any profiles.

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Through effective design, post-tensioned slabs enable material and embodied carbon reductions versus a conventionally reinforced slab, while maintaining the inherent benefits of concrete construction.

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