The foundation system is a critical component that ensures the stability and longevity of any steel structure building. For industrial warehouses and plants, selecting the right foundation and ensuring the precise installation of anchor bolts are paramount to the structural integrity.
Compared to traditional concrete structures, steel buildings are significantly lighter. However, steel columns transfer concentrated forces—modest axial loads alongside substantial shear and moment forces—to their foundations. The choice of foundation is adapted to the site's soil conditions:
- Isolated Spread Footings: These are the most common and economical solution for sites with good soil bearing capacity.
- Strip Footings: Used when soil conditions are less favorable, distributing the load over a longer area.
- Pile Foundations (e.g., Bored Piles, Rotary Drilled Piles): Employed in cases of very poor soil conditions, transferring the loads to deeper, stable strata.
The connection between the foundation and the steel column is fundamentally different from reinforced concrete construction. Instead of using reinforcing bars, Anchor Bolts (or embedment bolts) are cast into the concrete foundation to secure the steel column base plates. A leveling course of high-strength grout is typically applied on the foundation surface to ensure a uniform and reliable bearing connection. For buried column bases, shear studs are often welded to the embedded portion of the steel column to enhance composite action with the concrete.
- Definition: Anchor bolts are pre-positioned steel connectors embedded in the concrete foundation before pouring. They are the critical link that fixes the steel superstructure to the base.
- Classification:
- By Shape: L-shaped Bolts (for diameters smaller than M39) and Bolts with Anchor Plates (for diameters larger than M39).
- By Installation Method: Direct Embedment and Sleeve Method.
In our steel fabrication workshop, anchor bolts are manufactured with precision. Threads are typically machined on horizontal lathes, and hooks are formed as required. After processing, they are bundled, packaged, and shipped to the construction site alongside their corresponding nuts and washers.
Protecting the bolt threads is crucial. Before concrete pouring, the threaded portions must be coated with grease and carefully wrapped with plastic film or protective sleeves. This prevents contamination by concrete, rust, and damage, ensuring the nuts can be screwed on easily after construction.
The Direct Embedment Method is most frequently used. This process involves:
- Layout and Positioning: Precise marking on the foundation formwork.
- Fixing with a Template: A sturdy steel template or jig is used to hold all bolts for a single column base in the exact position, maintaining correct spacing and elevation.
- Integration with Rebar: The bolt assembly is tied to the reinforcement cage to form a single, rigid unit.
Concrete Pouring: Concrete is poured in a single stage, permanently fixing the bolts in place. Any adjustment after the concrete sets is extremely difficult, highlighting the importance of initial accuracy.
The selection of a foundation for a steel structure building is a direct function of soil investigation and load analysis. Furthermore, the installation accuracy of the anchor bolts is non-negotiable, as it directly governs the stability and safety of the entire structure. Our construction protocols strictly adhere to international standards, guaranteeing the highest quality in foundation and bolt work. This rigorous approach provides a dependable and durable foundation for the long-term service of your industrial facility.
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