A seated connection, also known as a seated beam-to-column connection, is a type of structural connection used to join steel beams to steel columns. It involves the use of seat angles or seat plates attached to the beam and column, creating a secure and rigid connection. Seated connections provide both moment resistance and vertical load transfer. They are commonly used in steel structures such as buildings, bridges, and industrial facilities.
Here is a step-by-step procedure for making a seated connection:
- Design and Preparation:
- Determine the required strength, load-bearing capacity, and desired level of moment resistance for the connection based on the structural requirements.
- Select the appropriate seat angles or seat plates, bolts, and other connection components based on the design specifications, considering factors such as material strength, size, and corrosion resistance.
- Ensure that the beam and column surfaces are clean, smooth, and free from any debris, rust, or paint.
- Alignment and Positioning:
- Position the beam and column in their designated locations, ensuring proper alignment and fit.
- Use temporary clamps or tack welds to hold the beam and column in place, preventing movement during the connection process.
- Marking and Drilling:
- Mark the positions for the bolt holes on the beam and column, following the specified spacing and pattern.
- Use a drill press or portable drilling machine to drill holes through the marked positions on both the beam and column. Ensure that the holes are aligned and perpendicular to the surface.
- Deburring and Cleaning:
- Remove any burrs or sharp edges around the drilled holes using a deburring tool or file.
- Clean the holes and surfaces of the beam and column to remove any debris, oil, or grease that may affect the connection’s integrity.
- Attaching the Seat Angles or Seat Plates:
- Position the seat angles or seat plates on the beam and column, aligning the holes with the drilled holes.
- Insert bolts through the holes in the seat angles or seat plates, beam, and column, ensuring a proper fit.
- Place flat washers and nuts onto the exposed ends of the bolts.
- Tightening the Bolts:
- Begin tightening the bolts using an appropriate wrench or torque wrench.
- Tighten the bolts gradually and evenly in a crisscross pattern to distribute the load and prevent distortion of the connection.
- Follow the recommended torque specifications provided by the bolt manufacturer or the design engineer.
- Welding (Optional):
- In some cases, additional welding may be required to enhance the connection’s strength and rigidity.
- Welds may be applied between the seat angles or seat plates and the beam, as well as between the seat angles or seat plates and the column.
- The welding process should be carried out by qualified welders, following the applicable welding codes and standards.
- Final Inspection:
- Inspect the connection to ensure that the seat angles or seat plates are securely attached to the beam and column.
- Check for any gaps, misalignment, or visible signs of damage or distortion.
- Verify that the bolts and nuts are properly seated and tightened.
Example and Application: An example of a seated connection is the connection between a steel beam and a steel column in a building frame. The seat angles or seat plates are attached to the beam and column, and bolts are used to secure the connection. This type of connection provides moment resistance and vertical load transfer, contributing to the overall stability and strength of the structure.
Applications of seated connections include:
- Multi-story buildings, where seated connections are commonly used to connect beams and columns, providing support and load transfer between different levels.
- Bridge structures, where seated connections between girders and piers ensure the structural integrity and load-bearing capacity of the bridge.
- Industrial facilities, warehouses, and manufacturing plants, where seated connections are employed to connect beams and columns in heavy-duty steel frames.
Seated connections offer robustness, flexibility, and ease of construction. They are widely used in steel structures where strong and reliable connections are essential for withstanding various loads and ensuring structural stability.
