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Products Description
Embedded Bolts: The Pre-embedded Fastening Core for Structures and Equipment
In fields such as construction engineering, large-scale equipment installation, and bridge construction, forming a permanent or semi-permanent connection between components or equipment and concrete foundations is crucial to ensuring structural stability and safe operation of equipment. Embedded bolts, as fasteners pre-embedded in concrete foundations, form an integral stress structure with the foundation through the pouring process. They provide precise and firm connection points for subsequent equipment installation and steel structure fixing, and are core components for realizing the rigid combination of "foundation and superstructure".
I. Materials and Performance: Material Selection Adapting to Loads and Environments
The material of embedded bolts should be determined according to the bearing load, service environment (such as temperature, humidity, corrosiveness) and service life requirements. Common types include:
- Carbon structural steel: Mainly Q235 steel, with low cost and moderate strength. It is suitable for civil buildings or light equipment foundations with small loads and no special anti-corrosion requirements, such as factory enclosure structures and small machine tool fixing;
- Low-alloy high-strength structural steel: Such as Q355 steel, which improves strength and toughness by adding alloying elements such as manganese and silicon. It can bear large tensile and shear loads and is often used in heavy load scenarios such as large steel structure columns and bridge supports;
- Alloy structural steel: Such as 40Cr, 35CrMo, etc. After quenching and tempering, it has high strength and wear resistance, and is suitable for occasions with extremely high requirements on precision and bearing capacity, such as wind power equipment foundations and heavy machinery fixing;
- Stainless steel: 304 and 316 stainless steel have excellent corrosion resistance, and are suitable for humid environments (such as underground projects, sewage treatment plants), coastal high-salt-fog areas or industrial scenarios with chemical corrosion, which can avoid connection failure caused by bolt rust.
Some embedded bolts will undergo surface treatment (such as hot-dip galvanizing, dacromet coating) to further enhance anti-corrosion performance and extend their service life in harsh environments.
II. Structural Characteristics: Design Logic from "Embedding" to "Connecting"
The structural design of embedded bolts needs to take into account both the grip with concrete and the convenience of subsequent connection, mainly consisting of the following parts:
- Screw rod: A cylinder with external threads. One end is embedded in concrete, and the other end is exposed on the foundation surface for connecting equipment or components. The thread accuracy must meet the tight fit with the nut to ensure the fastening effect;
- Anchoring section: The part embedded in concrete is usually designed with hooks, ribs or anchor plates. For example, L-shaped and J-shaped hooks can increase the mechanical bite force between the bolt and concrete; ribbed screws improve friction through surface concave-convex lines; welded anchor plates (square or circular steel plates) enhance the pull-out resistance by expanding the stress area to prevent the bolt from being pulled out;
- Exposed section: The length of the part exposed to concrete should be designed according to the thickness of the connecting component, and usually a 5-10cm adjustment margin is reserved to facilitate adjusting the component position during installation; some bolts will be processed with hexagon heads or reserved lifting holes on the top to facilitate positioning and fixing during embedding.
This structural design enables embedded bolts to evenly transmit the upper load to the concrete foundation, while resisting horizontal force and torque, ensuring the overall stability of the connection part.
III. Core Uses: Basic Links for Building Rigid Connections
The core function of embedded bolts is to pre-set connection points during the concrete pouring stage, providing a precise and firm fixing foundation for subsequent structures or equipment. The specific applications are reflected in:
- Steel structure fixing: In the installation of factory steel columns, bridge steel components, curtain wall keels, etc., embedded bolts connect the steel structure with the concrete foundation, transmit vertical loads and horizontal forces, and prevent structural overturning or displacement;
- Equipment installation: Heavy machine tools, generator sets, pumps and other equipment need to be fixed on the concrete foundation through embedded bolts to avoid displacement due to vibration during operation, ensuring the operation accuracy and safety of the equipment;
- Prefabricated component connection: In prefabricated buildings, prefabricated wall panels, composite beams and other components are connected with cast-in-place concrete through embedded bolts to realize rigid butt joint between components and improve the seismic performance of the overall structure;
- Infrastructure anchoring: In the foundations of outdoor facilities such as lamp posts, signal towers, and billboards, embedded bolts can firmly fix the upper structure, resist lateral loads such as wind and earthquakes, and prevent 倾倒 (toppling).
From industrial plants to civil buildings, from large-scale projects to small equipment, embedded bolts are the key to realizing the integrated connection of "foundation-structure-equipment".
IV. Installation Process: Key Steps for Precise Embedding
The installation quality of embedded bolts directly affects the stability and accuracy of subsequent connections, and the following processes must be strictly followed:
- Positioning and setting out: Mark the position of bolts on the formwork or steel skeleton according to the design drawings, and use a total station or level to ensure that the positioning deviation does not exceed ±2mm and the elevation error is controlled within ±5mm;
- Fixing bracket: Fix the bolts through steel brackets and angle steel positioning frames. The brackets must be firmly welded to the foundation steel bars to prevent bolt displacement during concrete pouring; for group bolts (multiple bolts used in combination), the bolt spacing and diagonal error must meet the design requirements to ensure the smooth installation of components;
- Embedded in place: Put the bolts vertically into the reserved holes of the positioning frame, adjust the verticality (deviation not greater than 1/100), and then fix the bolts with the bracket by spot welding or binding; the anchoring section must be completely embedded in concrete to avoid insufficient grip due to exposure;
- Pouring and curing: During concrete pouring, avoid direct impact of the vibrator on the bolts to prevent displacement or deformation; after pouring, cure in time to ensure that the concrete strength meets the standard, so that the bolts and the foundation form an integral stress structure;
- Re-inspection and cleaning: After the concrete solidifies, remove the positioning frame, check the bolt position, elevation and thread integrity, clean the concrete residues on the thread surface, and apply anti-rust oil for protection if necessary.
V. Precautions: Ensuring Long-term Reliable Connection Performance
To ensure the connection effect and service life of embedded bolts, the following points should be noted:
- Anti-corrosion treatment: The exposed thread part should be coated with anti-rust paint or covered with a protective cap to prevent rust or damage during construction; in humid environments, stainless steel or hot-dip galvanized bolts are preferred;
- Load matching: Select bolts of appropriate material and specification according to the design load to avoid fracture due to insufficient bolt strength or cost waste due to excessive specifications;
- Precision control: The spacing and verticality of group bolts must be strictly controlled, otherwise it may lead to failure to install components or uneven stress, causing excessive local stress;
- Later maintenance: During equipment or structure maintenance, check the fastening status of bolts, and tighten loose nuts in time; if thread damage or severe bolt rust is found, replace them in time to ensure connection reliability.
Summary
Although embedded bolts are "invisible connectors" hidden in concrete, they bear the safety responsibility of structures and equipment. Based on precise embedded positioning and guaranteed by high-strength materials, they transmit scattered loads to the foundation and are the core link of building rigid connections. In engineering construction, only standardized installation processes, reasonable material selection and strict precision control can make embedded bolts truly play the role of "anchoring" and provide long-term guarantee for structural stability and safe operation of equipment.
