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Portal frames are made in a variety of shapes and sizes. They are usually made from steel, but can also be made from concrete or timber. The portal structure is designed in such a way that it has no intermediate columns, as a result large open areas can easily be created within the structure. Porta
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1. Portal Framed Construction
2. Portal frames are made in a variety of shapes and sizes. They are usually made from steel, but can also be made from concrete or timber. The portal structure is designed in such a way that it has no intermediate columns, as a result large open areas can easily be created within the structure.
Portal Frames are generally used for single storey construction which require a large unobstructed floor space ie
Factories
Shopping Centres
Warehouses
3. Internal view of a portal framed warehouse
4. Advantages and disadvantages of steel Portal Frames Advantages
Speed and ease of erection
Building can be quickly closed in and made water tight.
Framework prefabricated in a workshop and not affected by weather.
Site works such as drainage, roads etc can be carried out until framework is ready for erection.
No weather hold up during erecting the framework.
Connected together in factories by welding and site connections should be bolted.
Disadvantages
Although steel is incombustible it has a poor resistance to fire as it bends easily when hot.
Subject to corrosion
5. Portal Frame
6. Base joint for Portal Frame
7. Ridge joint for Portal Frame
8. Knee joint for Portal Frame
9. Diagonal bracing for Portal Frame With all types of frameworks we must think on stability ie movement. To help strengthen the framework and prevent movement diagonal bracing will be used.
10. Cladding rails for Portal Frame This slide shows the cladding rails for attaching the external metal cladding panels to.
These rails can be fixed horizontal or vertical depending on the way the cladding panels are fixed.
11. Tie cables for Portal Frame
These wire and tubular ties are used to prevent sagging of the cladding rails which can add considerable force unto the joints of the external cladding.
12. External wall detail Here we see the finish of the external cladding panels with the lower level facing brickwork.
The blockwork behind creates a protective wall or firewall.