Structural FAQ
Why do suspension bridges sway?
Controlled sway is an intentional engineering feature. By allowing the deck to move laterally within specific tolerances, the structure dissipates aerodynamic kinetic energy rather than resisting it until brittle failure occurs.
What causes metal fatigue in rivets?
Micro-oscillations under live loads (like passing trains) create cyclical stress. Over decades, this causes microscopic crystalline fracturing in steel rivets, necessitating continual ultrasonic inspection.
What is resonance in structural terms?
Resonance occurs when an external frequency (like wind or synchronized marching) matches the structure's natural frequency, multiplying the amplitude of vibrations exponentially. Tuned mass dampers are often installed to mitigate this.
Why choose cable-stayed over suspension for a 1km span?
For spans between 500m and 1km, cable-stayed bridges offer superior rigidity and faster construction times, as they do not require deep subterranean anchorages for main cables.