A retractable roof structure is a type of structure in which a part or the entire portion of the roof can be moved or retracted to use the facility in its open or closed state.
This unique roof system is also known as operable roofs or operable skylights, or retractable skylights. It is considered a kinematic system that protects architectural spaces from extreme weather conditions and also adds aesthetic and functional values to the building.
Retractable roof structures are commonly used in stadiums, restaurants, swim centers, and facilities that wish to provide an outdoor experience.
This article briefs the important features and typology of retractable roof structures.
Features of Retractable Roofs
Retractable roof structures can close in a compact form and be transformed to their full load capacity configuration. The word “retractable” means something that can be pulled backward or inward.
A common retractable roof stadium consists of a roof panel that is adjusted over carriers that are mainly steel trusses. These carriers powered by DC motors roll over the steel rails that facilitate the desired retracting movement of the movable roof structures.Â
The roof is designed to retract either through sliding, lifting, rotating, or folding. It can also adopt an expandable system or a combined system.
The complete system possesses its support design, traction, and control systems for the safe and reliable folding, retracting, or sliding of roofs.
Design of Retractable Roof Systems
Retractable roofs come in different designs based on the application. Each type must adopt a smart design so that the system can move hundreds of thousands of kilograms of steel, glass, cladding, ceiling materials, and the related mechanical and electrical services within a short period.
One of the important factors governing the design of any retractable roof system is the frequency of opening and closing the roof structure. This is decided during the design of the building. The anticipated frequency of opening and closing of the roof structure determines the:
- Design of retractable roof system
- Type of movement of retractable roof system
- Size of moving elements
- Type of moving system
Typology of Retractable Roof StructuresÂ
The retractable roof structures adopted for stadiums and sports halls can have different structural designs of movable and fixed elements. The materials for movable structures for the roof are selected based on the size, weight, frequency of opening and closing, duration and type of movement, and additional loads.
Based on the structural design of movable and fixed elements, retractable roofs can be classified into three types:
- Retractable roof structures composed of rigid elements
- Retractable roof structures composed of membranes
- Retractable roof structures as a combination of different elements (rigid elements and membranes)
 1. Retractable Roof Structures Composed of Rigid Elements
In this type, the entire roof or small individual parts of the retractable roof are composed of rigid elements that move in various ways. For example, the Wembley Football Stadium in London, UK (2007) is a structure of rigid elements that undergo sliding movement.
2. Retractable Roof Structures Composed of Membranes
This type of roof structure has the roof and small individual parts made out of membranes that can retract. For example, Tennis Stadium Rothenbaum, Hamburg, Germany (1997) has a roof structure made of membranes that undergo folding movement.
3. Retractable Roof Structures as Combination of Different Elements
In this type, the entire roof or small individual parts of the retractable roof are composed of different retractable structural elements (rigid and membrane elements). For example, the Big “O” Olympic Stadium, Montreal, Canada (1976) is a structure with fixed and movable roof elements made of rigid and membrane types. They are designed for folding movement.
Benefits of Retractable Roofs
The benefits of retractable roofs are:
- Retractable roof stadiums allow for playing outdoor sports in more favorable conditions and for the comfort of the spectators during extreme heat or cold weather conditions.
- Retractable roofs permit the growth of natural grass playing fields in environments with extreme weather conditions.
- Retractable roofs help control the amount of sunlight falling within the space without interrupting the view.
- Retractable roofs for building facilities add value to the property.
- Retractable roofs are aesthetically pleasing and come in various design options irrespective of their application.Â
FAQs
A retractable roof structure is a type of structure in which a part or the entire portion of the roof can be moved or retracted to use the facility in its open or closed state.
Retractable roof structures are commonly used in stadiums, restaurants, swim centers, and facilities that wish to provide an outdoor experience.
A retractable roof is designed to retract either through sliding, lifting, rotating, or folding. It can also adopt an expandable system or a combined system.
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