by Jacques van der Walt
Innovative Formwork Design for a Complex Structure
Designing formwork for a structure situated within an existing dome-shaped building is a rare and challenging project. The complexity is amplified by the unique requirements and constraints posed by the project. Before embarking on the design, we engaged in numerous detailed discussions with our customer, covering critical aspects such as access and egress, crane limitations, concrete placement and mix designs, and curing processes.
Structural Specifications and Challenges
The structure predominantly consists of walls with varying thicknesses from 1000mm to 1200mm, with heights reaching up to 5.4 meters. The reinforcement specifications for these walls were unprecedented in my 16 years of experience. The density of the reinforcement necessitated careful planning to minimize interference from our standard wall form tie rods. To address this, we proactively provided our tie rod set-out plans to the customer, allowing them to mark positions before installing the reinforcement.
Due to the high density of reinforcement, the customer opted to use self-compacting concrete, as traditional vibration methods were impractical. This decision introduced another layer of complexity.
We employed our standard Startec Panels, a 60kPa wall form system, which needed to withstand the pressure exerted by the self-compacting concrete. Extensive research and the combined expertise of our engineering department enabled us to meet this requirement successfully. The customer completed the wall pours without any deficiencies.
Slab Construction and Shoring Systems
The structure features a slab spanning most of its area, with thicknesses ranging from 1000mm to 1400mm. For this, we selected our heavy shoring system, Rapidshor, to ensure safe and robust slab design. This slab is crucial as it must support the installation of mechanical machines. Since the structure is enclosed within a dome, there is no top access for crane operations, necessitating the installation of these machines as the structure is being constructed.
Following the installation of the mechanical machines, we face the challenge of forming the next level of walls around the existing equipment. This task demands precise coordination and innovative solutions to manage the space and complex geometry.
Unique Architectural Form and Roofing Challenges
The structure resembles an old Orthodox church, comprising four sub-structures topped with pitched roofs set at approximately 60 degrees. Forming these roof slabs presents significant challenges due to the need to work around existing mechanical installations and the necessity of manually removing formwork internally. Some roof sections reach heights of up to 9.46 meters, with slab thicknesses up to 800mm. We have considered various methods for the formwork design of these roofs, and while we face numerous challenges, we believe we have a promising solution in development.
This project exemplifies the intricate and innovative work required in modern construction, particularly when dealing with unique and demanding structural designs. Through meticulous planning, collaboration, and engineering expertise, we aim to overcome these challenges and deliver a successful outcome.