Multi-storey steel frame structure consist of beams and columns from welded H-shaped steel, hot-rolled H-shaped steel. In this frames, the beam and column system takes the gravity load such as dead and live loads. Now steel frame structure is mostly used for residential, commercial, institutional buildings all over the world.
The advantages of using steel frame in the construction of multi-storey buildings are listed below:
- Steel, by virtue of its high strength to weight ratio enables large spans and light weight construction.
- Steel frames can have a variety of structural forms like braced frames and moment resistant frames suitable to meet the specific requirements.
- Steel frames are faster to erect compared with reinforced concrete frames resulting in economy.
- The elements of framework are usually prefabricated in the factory under effective quality control thus enabling a better product.
- Subsequent alterations or strengthening of floors are relatively easy in steel frames compared with concrete frames.
- The steel frame construction is more suitable to withstand lateral loads caused by wind or earthquake.
What is a Multi Storey Building?
A multi storey building, just like what its name suggests is a building consisting of multiple storeys or multiple floors. It comes with stairs or lifts. Some buildings also incorporate ramps. Unlike a single storey building, there are more considerations when it comes to building a multi storey building including its points of access and air circulation. Contractors or builders also need to take fire safety, light, maintenance, evacuation, and cleaning into consideration.
There are different kinds of multi storey buildings. First is the low-rise building. From its name, it’s a kind of multi-storey building consisting only of a few floors, usually 4 or less. A mid-rise building is one that comes with 5-10 storeys and comes with a lift. A high-rise building is one that has 7-10 storey. There are also skyscrapers consisting of 40 or more storeys, supertall buildings that go over 300m and megatall buildings going as high as 600m.
How Do You Make a Multi Storey Building?
There are different steps to follow when it comes to making a multi storey building and here are the ones use by builders:
This process usually involves the use of software or programs to ensure the safety and feasibility of the design. It starts with creating the formwork. Licensed professionals will have to design the formwork. The staircase design is also a part of the design process since this is going to be a major part of the multi storey building. Additionally, it will also include designs for the slabs and the deep beams.
Laying out the foundation is a crucial part of the process since it will handle most of the lateral weight of the building. First, excavation should be done. It involves digging trenches and holes as well as leveling the ground. Some contractors already have excavation equipment while others might have to outsource it to other companies that will charge on an hourly basis.
Once the excavation is done, the surface will be “dressed” or leveled. PCC will then be poured over the dressed surface and then foundations and columns will be laid out.
Casting the Columns
Laying out the columns involves the use of link bars and column ties. This depends on the size of the structure. There are specific requirements for each size of the building. An L Bar is used to displace the main bars included. Contractors will need to check the height of the cast. It should be accurate. They also need to check that the formwork plumb is good.
After this comes the laying out of the beam bottom and the checking of the slabs.
How Do Multi-Level Steel Buildings Work?
The building process starts with the design. Even when the original plan is only for a single-storey building, it should be considered as if you are building a multi-level steel building to ensure flexibility and stability.
Multi-level steel building process depends greatly on the ground circumstances. If there is higher wind loading, the price for structural frame increases per floor area.
But steel is the most suitable material for providing stability to a multi-level building. It prevents frame sway thanks to the beams and columns as well as the spatial continuity between them. Steel braced frames can also be used to provide resistance to torsional load as well as lateral load.
What are the Advantages of Multi Storeyed Buildings?
Why go for multi storeyed buildings? The vertical structure of multi storeyed buildings offers a lot of advantages, primarily, additional space without taking up more square footage. There is more storage space for warehouses and it makes it easier to move materials, thanks to lifts.
In the case of service facilities, multi storeyed buildings are also good because of their enhanced efficiency. With multi storey designs suitable for service facilities, the costs of heating can be reduced. There are extra measures done to prevent heat loss in a multi storey building, thereby reducing the electrical costs.
It also creates a nice place to work in. Multi storey buildings enjoy an aerial view, which can help boost morale in the workplace.
There is also better productivity. Multi storey buildings are designed properly with ventilation, lighting heating, and access in mind. That means it creates a space that is more conducive to productivity.
How Many Tons of Steel Are in a Multi Storey Building?
Most commercial buildings will require 20-30 pieces of steel every day for the duration of the building process. That equates to about 10-12 tons of steel. But this will also depend on a lot of things including the design. There is no specific amount of steel for each type of building because it will depend on design and size.
If the structure is load bearing, something that is common when said structure is installed in a rural area, the building can require structural steel amounting to up to 1.5 metric tons for every 1000 square feet of space. This will also include parts such as roof slab, lintels, beams, and shades. The minimum requirement is 1.2 metric tons.
Components & Accessories
A multi storey steel building can be composed of the following parts and accessories:
The main or primary frame is made up of two types of members: hot rolled and built-up. Built-up members usually make up the 90% of the overall weight of the frame while hot rolled members make up the rest.
Purlins and eave struts are some of the secondary members included in prefab buildings. They are generally used in building warehouses, sheds, and even canopies. That is because of their lightweight and economical properties. Eave struts, particularly, provide additional support for the frame and the roof.
Roofing is an indispensable element to multi storey steel buildings. They bring lightweight features to the table Because of their excellent weight ratio and weather proof functionality, they can be relied on not to succumb tt corrosion easily.
They can be used alongside roofing sheets that are also durable. Three types of roofing sheets commonly used for multi storey steel building purposes are tiled, corrugated, and troughed. They are all long-lasting and offer excellent fire-resistant properties. Their lightweight features make them easier to install.
Eave gutter and trim, gable trim, downspouts, flashing, and curved eave panels make up a multi store building as well. They are usually made from steel, albeit coated with Aluzinc. They can also be made from aluminum sheets. These are pliable enough to be shaped in any form using folding machines and presses. These trims and flashings help make the building more resistant to harsh weather conditions and they also contribute to the neat appearance of a building.
Some of the accessories that are used in multi storey buildings included doors, insulation, windows, ventilators, and louvers. These can be sourced from third party providers or can be manufactured in-house.
The accessories and trims used in a building will depend on the design, so each building will require different kinds of trims and accessories.