| Portal frame is a common structural system in steel structure buildings. The portal frame is generally dominated by H-beams, and the main structure is made of jibs. The units are composed of columns and beams as portals, and there are also columns without columns or continuous spans. The portal frames are connected by supports and purlins. The portal frame appeared in the 1930s and became popular because of its simple force bearing, clear force transmission path, quick component production, easy factory processing, and short construction period. Portal frames are often used in the construction of wide-span structural projects, such as agricultural buildings, steel structure warehouses, garages, hangars, indoor stadiums, steel structure workshops, etc. |
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Portal frames were used because their structural efficiency allowed large spaces to be built with very little material and at low cost. Today, a large portion of construction steel is used in the construction of portal frames. |
| In simple terms, a portal frame is a structural frame that takes a very simple form and features beams or rafters supported by columns at both ends. However, since the connection between the beam and the column is rigid, the moment in the beam is transferred to the column. This allows the beam to reduce the section size and to span large distances. Typically, the connection between the beam and the column is rigid and requires the addition of a hip, bracket. When a pitch is required, the portal frame can have a single pitch or a double pitch with a rigid connection at the apex. Other forms include bundled portal frames, braced door frames, and multi-span portal frames, which can cover very large areas. In general, when the portal frame includes spacing, the wider the span of the portal frame, the higher the point. If in order to reduce the overall height, then it can take the form of curved rafters or folding. This also helps reduce water runoff and water load, which is important on large steel roofs. A curved, or folded form can increase the slope of the item towards the eaves. |
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| The portal frame is arranged according to the overall length and width of the building, and the interval between the portal frame is generally 6-8 meters apart. A good portal frame structure will usually be covered with prefabricated composite metal panels with insulation. Masonry cladding can be set lower for greater resilience and safety. The portal frame structure needs to pay attention to the design of the connection parts to ensure sufficient supporting force to prevent structural deformation. The support also needs to ensure the lateral stability of the parallel frame, usually pay more attention to the design of the end or middle part between the frames. It is because the portal frame can be a simple and fast structural form to erect, and can achieve long-span durability, low cost, and use of less material. Moreover, the portal frame is relatively lightweight and can be installed directly at the construction site. |
| There are many types of portal frames to accommodate different space constraints or different building size requirements. There are mainly the following types of portal frames. 1. Pitched roof symmetric portal frame 2. Portal frame with internal mezzanine floor 3. Crane portal frame with column brackets 4. Tied portal frame 5. Mono-pitch portal frame 6. Propped portal frame 7. Mansard portal frame 8. Curved rafter portal frame 9. Cellular beam portal frame |
