A bolted tension joint is a type of connection used in steel structures where the connected members are subjected to tensile forces. The bolts in a tension joint are tightened to a specified preload, ensuring that the joint can withstand the applied tension without failure. Here is a step-by-step procedure for creating a bolted tension joint:
- Design the Joint: Determine the required number of bolts, their size, grade, and spacing based on the applied tensile loads, member dimensions, and design requirements. Consider factors such as the ultimate tensile strength of the bolts, the required preload, and the load transfer capacity of the joint.
- Prepare the Members: Ensure that the ends of both members to be joined are clean, free from any rust, paint, or debris that may affect the connection’s integrity. If necessary, clean the surfaces using wire brushes or other suitable methods.
- Align the Members: Position the members so that their ends are in direct contact, ensuring that the faces are properly aligned. Use temporary clamps or fixtures, if needed, to hold the members in place during the assembly.
- Mark Hole Locations: Use a center punch or other marking tool to mark the hole locations on both members. Ensure the hole spacing is uniform and follows the specified bolt pattern. The hole spacing and size depend on factors such as the bolt diameter, load transfer requirements, and connection strength.
- Drill Holes: Use a drill machine and appropriate drill bits to create holes through both members at the marked locations. The hole diameter should match the bolt diameter precisely to allow for a snug fit and optimal load transfer.
- Remove Burrs: After drilling the holes, remove any burrs or sharp edges from the holes using a deburring tool or a suitable method. This ensures that the bolts can be inserted smoothly without interference.
- Insert Bolts: Place the bolts through the holes, ensuring that they pass through both members. The bolts should be long enough to extend beyond the nuts by an appropriate amount to allow for proper engagement and tensioning.
- Add Washers and Nuts: On the opposite side of the joint, place washers over the bolt ends, followed by the nuts. Tighten the nuts by hand until they are snug, but do not apply full torque at this stage.
- Tension the Bolts: Use a calibrated torque wrench or a hydraulic tensioning device to apply the specified preload to the bolts. The preload is the initial tension applied to the bolts, which ensures that they remain under tension even when the structure is subjected to external loads.
- Verify the Preload: After tensioning the bolts, use a calibrated tension measuring device or ultrasonic equipment to verify that the specified preload has been achieved. This step is essential to ensure that the bolts are properly tensioned and can withstand the applied tensile forces.
- Inspect the Joint: Visually inspect the joint to ensure that all bolts are properly tightened and under tension. Check for any signs of gaps, misalignment, or other potential issues. Perform a thorough inspection to verify the integrity and load-carrying capacity of the tension joint.
Example of Application: A typical application of bolted tension joints is in the connection of steel cables or rods in cable structures, suspension bridges, or bracing systems. These tension joints are crucial in transmitting the applied tensile forces and maintaining the structural integrity of the system. The bolts used in these joints are specifically designed to withstand the high tensile loads and are tightened to the required preload.
It is important to note that the above steps provide a general guideline, and the specific procedures may vary depending on the design requirements, bolt specifications, and construction practices. Always refer to the relevant codes, standards, and manufacturer recommendations for the proper installation of bolted tension joints in steel