Pouring concrete for a high-rise hospital presents unique challenges that go well beyond what standard building projects demand. Tight urban sites, soaring structural requirements, and the need to keep floors rising on an aggressive schedule all push contractors toward specialized formwork solutions. One of the most effective tools for this kind of work is a self-climbing formwork system that can carry not only the forms but also heavy concrete placing equipment. How Climbing Formwork Makes Concrete Construction Easy explains the basic principles behind this technology and why it has become a go-to approach for core construction in tall buildings.
A striking real-world example comes from Montreal, where the Centre hospitalier de l’Université de Montréal (CHUM) project demanded a formwork system capable of lifting a concrete placing boom alongside the forming equipment through 28 floors. The Doka Super Climber system met this challenge by combining climbing capacity, load-bearing strength, and workspace integration into a single automated setup. This article examines the engineering behind that solution and the lessons it holds for any contractor tackling tall concrete cores.
The Demands of High-Rise Hospital Concrete Construction
Hospital buildings are among the most structurally demanding projects in commercial construction. They require deep foundations, thick shear walls, large floor-to-floor heights for mechanical systems, and continuous vertical circulation cores for elevators, stairwells, and services. When a hospital rises to 28 stories and 411 feet, as CHUM does, every concrete pour must be carefully sequenced to maintain structural integrity while hitting tight milestone dates.
Core Wall Complexity
The CHUM project required two reductions in core wall thickness as the building rose. This is common in high-rise design because lateral loads decrease at higher elevations, allowing engineers to slim down the walls and save material. However, for the concrete contractor, thickness changes mean the formwork system must adapt without slowing down the pour cycle. Traditional jump form systems often require dismantling and reconfiguring panels when wall dimensions shift. A self-climbing system with adjustable panels can accommodate these changes more efficiently.
Carrying a Concrete Placing Boom
One of the most unusual requirements on the CHUM project was mounting a Putzmeister concrete placing boom directly onto the formwork system. Placing booms are heavy pieces of equipment that distribute concrete horizontally across a floor plate as it is being poured. Normally, they sit on the completed slab or on a separate tower. By integrating the boom with the climbing formwork, the contractor eliminated the need for a second support structure and freed up crane time for other tasks. This demanded a formwork system with exceptional load-bearing capacity across every stage of the climb cycle.
Tight Urban Site Constraints
Downtown Montreal does not offer generous laydown areas or wide access routes. The CHUM site is hemmed in by existing buildings and city streets. Every square foot of workspace matters. A self-climbing system that consolidates formwork, working platforms, and the placing boom into one package reduces the site footprint and keeps the surrounding area free for material delivery and crane operations.
How the Doka Super Climber System Works
The Doka Super Climber is a self-climbing formwork system designed for building cores and other vertical structures that rise floor by floor. Unlike crane-lifted jump forms, which require a tower crane to move the assembly upward, the Super Climber climbs under its own power using hydraulic cylinders. This independence from the tower crane is a significant advantage on congested sites where crane time is the most constrained resource.
Single-Stroke Hydraulic Climbing
The core of the system is a single-stroke cylinder that raises the entire assembly in one smooth motion. This includes:
- The formwork panels themselves
- The concrete placing boom
- Multiple levels of working platforms
- Stored materials and equipment for the next pour
Climbing everything as a single unit eliminates the need for partial lifts, reconfigurations between floors, or separate crane picks for the boom and the forms. Each upward movement takes the entire system to the next casting position in one step, reducing the cycle time between pours significantly.
Load Capacity for Heavy Equipment
The Super Climber is engineered to handle the loads generated by the largest placing booms on the market. No extra bracing or temporary support structures are needed at the climbing level. This was critical for the CHUM project, where the Putzmeister boom had to remain operational during the climb sequence to maintain the pour schedule. The system’s structural frame distributes boom forces directly into the already-cast concrete walls through the climbing shoes, keeping the load path short and predictable.
Flex Corners for Quick Stripping
Doka’s special Flex Corner elements allow the formwork to strip away from the concrete walls in a single quick movement. On a conventional corner form, stripping requires multiple operations as panels are unbolted and pulled free from each face. The Flex Corner hinges inward, releasing both adjacent wall faces at once. This speeds up the strip-and-climb cycle and reduces the physical effort crews must expend on each floor. Over 28 stories, those minutes saved per cycle add up to days of schedule compression.
| Feature | Benefit |
|---|---|
| Single-stroke hydraulic climb | Moves forms, boom, and platforms in one step |
| Integrated placing boom mount | Eliminates separate boom tower or crane dependency |
| Flex Corner hinge panels | One-movement stripping reduces cycle time per floor |
| Self-climbing operation | No crane required for vertical movement |
| Multi-level working platforms | Provides safe access at pour, strip, and finishing levels |
Adapting Climbing Formwork to Complex Core Designs
No two high-rise cores are identical, and the CHUM project presented several design features that demanded formwork flexibility. Beyond the thickness reductions in the core walls, the building stairwells required a different climbing approach because of space restrictions and the presence of tower crane masts.
The SKE100 Solution for Confined Stair Shafts
The contractor placed four tower cranes inside four separate stairwells. One of those stairwells needed a climbing formwork system that could operate in extremely tight quarters because the crane mast occupied most of the interior space. Doka’s SKE100 was selected for this location because it could be mounted on the exterior of the core wall rather than requiring interior space for climbing components.
The SKE100 is a self-climbing system that attaches to the outside face of the wall and still has the structural capacity to raise a gantry system above. This exterior mounting approach left the cramped stairwell interior free for the crane mast while still providing the full climbing function needed to keep pace with the rest of the core. A total of six SKE100 climbers were used on this single stair core, demonstrating the system’s scalability for confined conditions.
Engineering Support and Field Service
Doka provided more than just hardware on the CHUM project. The company supplied formwork design calculations, detailed engineering drawings, and on-site field service personnel. For a complex core with multiple thickness transitions and an integrated placing boom, the design calculations must account for every load case during pouring, climbing, and stripping. On-site field service ensured that the installation followed the design intent and that any site-specific adjustments could be made quickly. This level of technical support is especially valuable when the formwork system is integrated with other site equipment such as tower cranes and concrete pumps.
Coordination Across Multiple Contractors
Major hospital projects involve a web of contractors and subcontractors. On CHUM, the concrete contractor Coffrage Alliance Ltee worked in partnership with Nadeau Specialites de Construction under the project umbrella of Laing O’Rourke and OHL Canada Montreal. Coordinating the formwork climbing sequence with the tower crane schedule, rebar installation, MEP rough-ins, and concrete deliveries required daily communication. The self-climbing nature of the Super Climber simplified this coordination because the vertical movement did not depend on crane availability. As Frank Trimboli, sales manager at Doka Toronto, noted: safety on a restricted site was a primary concern, and the Super Climber’s ability to roll forms back and climb everything in one step was the deciding factor.
Safety and Efficiency Benefits on Urban Hospital Sites
Working on a downtown hospital site means that safety and efficiency are not competing priorities they reinforce each other. A clean, well-organized work area reduces accidents. A system that minimizes manual handling reduces fatigue-related errors. The Super Climber delivered on both fronts.
Enclosed Working Platforms at Every Level
The system provides multiple levels of protected working platforms that rise with the forms. Crews access the pour level, the stripping level, and the finishing level without needing to erect or relocate separate scaffolding. This built-in access eliminates one of the most common fall hazards on high-rise formwork operations. The platforms also serve as catch decks, containing dropped tools and materials within the system envelope rather than letting them fall to lower levels.
Reduced Crane Dependency
Because the Super Climber moves itself, the tower cranes on the CHUM project could focus on material deliveries rather than formwork repositioning. On a typical floor cycle, a crane-dependent jump form requires multiple lifts to move panels, platforms, and the placing boom. The self-climbing approach reduces those lifts to near zero for the core cycle, freeing crane capacity for rebar bundles, embeds, and other critical supplies. This crane-time savings directly translates to a faster floor cycle and lower overall project cost.
Schedule Performance
The first phase of the CHUM project was scheduled for completion in spring 2016. Achieving that target on a 28-story core with thickness transitions, an integrated placing boom, and tight urban logistics required a formwork system that could maintain a consistent climbing rhythm. Self-climbing systems typically achieve cycle times of three to five days per floor on complex cores, compared with five to eight days for crane-dependent jump forms. Over 28 floors, that difference can amount to several months of schedule savings.
- Core walls are poured with the placing boom mounted on the climbing formwork assembly
- Once concrete reaches sufficient strength, Flex Corners release the panels from the wall faces
- The single-stroke hydraulic cylinder lifts the entire assembly one floor height
- Climbing shoes engage the next set of anchor points in the already-cured wall
- Form panels are advanced and locked into position for the next pour
This repeating cycle continues floor after floor with no crane involvement, no partial disassembly, and no separate boom relocation. For contractors managing high-rise core construction, the lessons from the CHUM project are clear: investing in a self-climbing formwork system that integrates placing equipment, adjusts to wall thickness changes, and operates independently of tower cranes pays back in schedule reliability, site safety, and crew productivity. Concrete Formwork Systems Types Design and Best Practices covers the broader range of formwork options available for projects of all scales, while Masonry Design and Formwork Engineering Reinforced Masonry Walls explores the structural engineering principles behind formwork design. For teams looking specifically at scaffold access and safety integration with formwork systems, Scaffolding and Formwork Scaffold Design Concrete Formwork Systems provides practical guidance on combining access, formwork, and fall protection into a unified jobsite plan.