1. What is a pre-engineered steel building?
A pre-engineered steel building (PEB) is a type of building made from steel components, fabricated and installed according to pre-specified architectural and technical drawings.
A pre-engineered steel building product is executed in 3 main stages: Design, component fabrication, and on-site erection.
2. History of the formation and development of pre-engineered steel buildings
Along with the development of technology and techniques in construction, the pre-engineered steel building solution was introduced to Vietnam in the early 20th century, a period when the country was a French colony. Most of the structures during this period were built by the French, such as the Opera House, cinemas, railway factories, shipyards, textile mills, coal plants, etc.
The 1950s – 1960s
During the period when Northern Vietnam was independent, with the support and assistance of socialist countries, several large pre-engineered steel building projects were constructed, such as the Lam Thao phosphate plant, Thai Nguyen iron and steel plant, Hanoi mechanical plant, etc.
The 1954 – 1975 period
During this period, structures were built on a small scale, with fast assembly and disassembly to suit evacuation and wartime requirements, such as warehouses, truss-based factory buildings, etc.
The 1975 – 1990 period
After the country's reunification in 1975, projects were mainly focused on restoration, reconstruction, and utilizing structures built by foreign entities to serve production.
From 1990 to present
This is a period of strong growth and development in construction. With the robust development of the economy and construction, large projects in Vietnam during this period were mainly built using steel structures, such as the Nam Dinh Sports Palace, Tuan Chau Dolphin Show Pavilion, Hanoi Museum, Marriott Hotel, etc.
3. Basic structure of a pre-engineered steel building
- Foundation structure system
Similar to reinforced concrete buildings, the foundation system of a pre-engineered steel building is constructed of reinforced concrete. The system serves to transfer the load from above to the hard soil layer below. Depending on the geology and load of the project, the foundation can be a single footing, strip footing, raft foundation, etc.
Before pouring foundation concrete, foundation bolts (or anchor bolts) are linked accurately and firmly to the foundation steel system. The foundation bolt installation step is an important step and requires high precision to ensure that the installation of column and beam structural members is easy and accurate. Foundation bolts often used are M22, M24, M30 bolts... with strength grades 6.6, 8.8, 10.9... depending on the calculations of the projects.
- Factory floor
Factory floors are typically poured with concrete over a base layer of compacted sand. The thickness of the concrete floor depends on the load of machinery and vehicles moving within the factory. The surface is usually polished or coated with epoxy to ensure a clean and glossy finish during use.
Depending on the soil conditions and the load-bearing requirements of the floor, appropriate foundation reinforcement is selected (reinforced concrete floor, non-reinforced concrete floor, or even a floor reinforced with concrete piles).
- The main structural frame system consists of columns, beams, and steel trusses
Steel columns and trusses are the main components of a pre-engineered steel building, designed to have sufficient load-bearing capacity and to span large distances, which can reach up to 100m depending on the requirements of each factory.
Columns and trusses are often designed as tapered H-shaped steel sections or truss structures. The connection between columns and trusses is usually made with gusset plates and high-strength bolts.
- Roof monitors and canopy roofs
Roof monitors are usually placed on the top of the factory to provide natural light and ventilation, helping to keep the factory airy during production.
A canopy roof is a porch roof system used for sun and rain protection, featuring a steel structure clad with aluminum, corrugated metal, or glass.
- Purlins and bracing systems
Galvanized steel purlins are typically C, Z, or U-shaped, with various heights and thicknesses based on the column spacing and load. The purlin spacing ranges from 1m to 1.4m. They are connected to the trusses by bolts through pre-welded gusset plates, primarily serving to support the corrugated metal roof system above.
The gable bracing, roof bracing, and purlin bracing systems increase the connectivity between frames, ensuring the stability of the structural frame during erection and throughout its service life.
- Corrugated metal roofs, cladding panels
Corrugated metal or panel roofs for factories are diverse, but the most common are corrugated metal and panels equipped with an additional insulation layer made of air bubbles or glass wool to help with heat and noise insulation for the factory.
4. Basic materials for constructing pre-engineered steel buildings
There are 3 basic materials for constructing pre-engineered steel buildings: steel frames, roof sheeting, and cladding panels.
- Steel frame
The steel frame can be said to be one of the main, indispensable materials for pre-engineered steel buildings. Depending on the purpose of each project, investors can choose steel frames of different sizes.
The entire steel structure can be mass-produced and delivered to the site for assembly. As a result, construction time is shortened. In addition, steel is lighter than concrete, reducing the load pressure in all aspects.
- Roof sheeting
Besides the steel frame, corrugated metal is used to shield and roof almost all industrial projects such as factories, warehouses, garages, etc. Because corrugated metal is lightweight and comes in a variety of colors, it is becoming increasingly popular. There are many types of corrugated metal, and the appropriate choice is made depending on each project.
Currently, there are 3 popular types of corrugated metal: 3-layer insulated metal, standard single-layer metal, and translucent metal. However, corrugated metal does not have soundproofing capabilities, so noise reduction is limited.
- Cladding and profiled panels
After the main frame and roof are in place, wall cladding is an indispensable part of a pre-engineered building. To ensure durability, people previously chose bricks to build walls and partitions for projects. However, bricks need to be extracted from nature and undergo a firing process, which affects environmental protection and natural resources. Furthermore, traditional bricks are heavy, and the construction process is time-consuming. Therefore, today, people often use cladding panels made of metal, panels, or other prefabricated materials to replace these traditional fired bricks. This type of material is lighter than others, helping to reduce load pressure in all aspects on the project.
5. Advantages and disadvantages of pre-engineered steel buildings
Advantages of pre-engineered steel buildings compared to reinforced concrete buildings
| Feature | Pre-engineered steel building | Reinforced concrete building |
|---|---|---|
| Construction cost | Thanks to the systematic implementation method, design, production, and assembly costs have been significantly reduced. The overall price per square meter can be up to 30% lower than the construction cost of reinforced concrete buildings | More expensive |
| Load-bearing capacity | Easy to calculate and design for loads. All components are pre-manufactured at the factory under controlled conditions with modern technology, ensuring quality | Easy to calculate and design for loads, however, because construction takes place on-site, it is difficult to ensure product quality without strict supervision measures at every step of the construction process. |
| Construction time | Manufacturing, assembly, and construction time is up to 50% faster than reinforced concrete construction. A pre-engineered steel building can be completed in just a few weeks, or even a few days with intensive labor. | Slow and time-consuming |
| Construction quality | Components are fabricated in the factory through strict processes, standards, and quality control before being installed on-site. | On-site construction is difficult to ensure the same quality as factory fabrication without strict inspection and supervision measures. It is difficult to repair and costly to fix defective products during construction. |
| Upgrading, maintenance, and repair work | Easy to upgrade, low maintenance costs. Flexible in expanding space by adding additional steel frames. | Difficult to repair; modifications are time-consuming, requiring demolition and chipping, and are costly. |
| Architecture | Components are produced in the factory according to pre-approved drawings, making it difficult to create shapes like curves or moldings. | Flexible in design, easy to create smooth, soft, and curved shapes. |
| Project lifespan | Most pre-engineered steel building frames have a lifespan of 100 years or more, for example: San Sebastian Church completed in 1891, Brooklyn Bridge completed in 1883, etc. | Depending on the investment level and project quality, the structure has a lifespan of 40 – 100 years. |
| Environmental hygiene | Pre-engineered steel building components are produced in the factory, so all auxiliary materials are utilized and recycled, significantly reducing construction waste. | Materials are often wasted. On-site pollution, dust, and dirt cause water source contamination. |
Disadvantages of pre-engineered steel buildings
Besides the outstanding advantages, pre-engineered steel buildings also have some disadvantages as follows:
| No. | Disadvantage | Solution |
|---|---|---|
| 1 | Steel frames have lower heat resistance compared to reinforced concrete. | Fire-resistant paint, which can withstand temperatures up to 1000 degrees Celsius. Encasing with concrete, ceramic, or fire-resistant materials, etc. Additionally, the project must comply with fire prevention and fighting equipment requirements. |
| 2 | Susceptible to corrosion or oxidation in hot and humid conditions. | Anti-rust paint, which ensures the steel does not oxidize or rust while enhancing the aesthetics of the project. |
6. Applications of pre-engineered steel buildings in modern life
Pre-engineered steel buildings are increasingly demonstrating their advantages; therefore, building with pre-engineered steel is one of the optimal solutions for projects in industrial and civil construction such as: Factories, Warehouses, Workshops, Offices, Gas stations, Showrooms, Subway stations, Parking sheds, Schools, Indoor stadium roofs, Bridges, Station waiting halls, Outdoor stadiums, etc.
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