Fig 11 shows a cross-section through a steel corner bracket that joins two rectangular hollow-section tubes at a right angle. The bracket forms part of a la...
Question 1 Report
Fig 11 shows a cross-section through a steel corner bracket that joins two rectangular hollow-section tubes at a right angle. The bracket forms part of a larger structural framework for an outdoor storage shelter. The fig shows the bracket fixed to both tubes using mechanical fixings.
The mechanism that opens the shelter door is attached to one of the tubes with bolts.
(a) Name one type of permanent mechanical fixing suitable for joining the steel bracket to the tubes in this structure. [1]
(b) Give one reason why a permanent fixing is preferred over a temporary fixing for this structural joint. [1]
(c) Give two reasons why bolts are suitable temporary fixings for attaching the door mechanism to the steel structure. [2]
Answer Details
(a) A suitable permanent mechanical fixing for joining the steel bracket to the tubes is a rivet (or pop rivet). [1] Rivets are inserted through pre-drilled holes and deformed to lock the bracket permanently in place. Welding is also acceptable, though it is a joining process rather than a discrete fixing component.
(b) A permanent fixing is preferred over a temporary fixing for this structural joint because it ensures the joint cannot loosen or come apart under the loads and vibrations that the outdoor storage shelter will experience over its service life. [1] A structural frame joint that loosens could cause the shelter to distort or collapse, so permanence is essential for safety and long-term rigidity.
(c) Two reasons why bolts are suitable temporary fixings for attaching the door mechanism to the steel structure: [2]
- Bolts allow the door mechanism to be removed for maintenance or replacement without damaging the structural tube, since the bolt simply unscrews from its nut. [1]
- Bolts can be tightened to a specific torque to resist vibration while still being removable, providing a secure but adjustable connection that can be re-tightened or repositioned if needed. [1]
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