Large-span steel structures are increasingly popular in projects such as industrial factories, exhibition centers, and aircraft hangars due to their ability to create spacious interiors without the need for intermediate support columns. However, constructing large-span components presents many complex technical safety challenges. This article will delve into the techniques of erecting large-span steel structures and effective deflection control procedures.
1. Technical challenges in constructing large spans.
Constructing large-span steel structures presents unique challenges compared to conventional construction. The first challenge stems from the enormous size and weight of the components, requiring a sufficiently large construction space for machinery movement and cranes with extremely high lifting capacities.
Furthermore, large-span beams and trusses are highly susceptible to deformation, sagging, or twisting during lifting and installation due to their own weight. Weather conditions also play a significant role; temperature fluctuations throughout the day can cause thermal expansion of the structure, leading to misalignment of bolt holes and making assembly difficult. Additionally, when working at high altitudes, structures that are not yet fully connected are highly sensitive to wind, requiring temporary bracing measures to ensure the absolute safety of workers and the structure.
See also: Steel structures in harsh environments
2. Lifting and specialized equipment diagrams
To move heavy steel components into the correct position, the contractor needs to develop a detailed lifting plan. For large construction sites, a common solution is to use self-propelled cranes with high lifting capacity, or combine multiple cranes simultaneously (synchronous lifting). During lifting, workers must stand at least 5 meters from the landing point and use additional handles at both ends of the steel frame to safely adjust its position.
In situations where space is limited in urban areas or the weight of steel structures exceeds the capacity of conventional cranes (e.g., weighing thousands of tons), a hydraulic strand jack system is an optimal solution. This system operates like a linear winch, using bundles of steel cables and hydraulic cylinders to lift components synchronously and safely, incorporating an automatic locking mechanism in case of pressure loss.
3. High-strength bolt tightening procedure
High-strength bolted connections (such as grades 8.8, 10.9, or 12.9) are a crucial component determining the load-bearing capacity and stability of large-span structures. If the tightening torque is not correct, the joint can slip immediately, endangering the entire system.
The bolt tightening process is strictly controlled through torque values, calculated based on the nominal bolt diameter and the friction coefficient between the threads and the contact surface. In practical construction, installers often use torque wrenches or technical torque measuring devices to tighten bolts to the design value. After assembly, all tightening forces at critical connection points are thoroughly checked to ensure safe power transmission throughout the entire service life.
4. Structural deformation control and safety
A major technical problem with large-span beams or trusses is sagging due to their own weight and additional loads (such as purlins, roofing sheets, and insulation). To eliminate this, contractors often apply pre-cambering techniques during the factory fabrication phase. By calculating and designing a slight camber at the lower chord (usually 10-20 cm), the component will naturally sag during lifting and under actual load, achieving the standard straightness and preventing the roof from sagging, which can be aesthetically unpleasing and cause water accumulation.
During construction, temporary bracing systems are immediately installed to keep the steel frame stable. The installation must strictly adhere to a sequence: starting from the section already rigidly braced (columns and roof), then extending to adjacent frames. After completion, specialized measuring equipment such as total stations and laser levels are used to recheck the vertical alignment of the columns and the deflection of the bending elements. The actual deflection must be within the permissible limits of the design standards (e.g., L/200, L/150 for metal roofs) for safe acceptance and handover of the project.
HAI LONG CONSTRUCTION IS A REPUTABLE STEEL STRUCTURE MANUFACTURER
Choosing the right steel structure processing partner is the decisive factor for the success of each construction project. In the context of the market increasingly demanding high quality, progress and safety, Hai Long Steel Structure Proud to be the leading brand trusted by many large domestic and foreign investors:
- Team experienced engineers, architects and experts, knowledgeable about the design and construction of warehouse factories according to international standards.
- Diverse construction capacity, meeting all project sizes and requirements, from simple to complex factories.
- We own a steel structure factory with a modern system of machinery and equipment., ensuring fast, accurate and safe construction.
- Professional construction process, is strictly managed.
You are looking for one Prestigious and professional steel structure manufacturing and erection unit? Please contact Hai Long Construction for free consultation and quote:
- HAI LONG CONSTRUCTION JOINT STOCK COMPANY
- Address: Taiyo Building, 97 Bach Dang, Hong Bang Ward, Hai Phong City, Vietnam.
- Hotline: 084 6625 888
- Email: info@hailongjsc.vn
