The beauty of the Golden Gate Bridge, the iconic aesthetics of the Brooklyn Bridge, and marvel of modern engineering that is the Akashi-Kaikyo Bridge. Suspension bridges are a method of bridging the gap that has existed in its current form since the early 1800s. Since their inception, suspension bridges have always stood out as a stunning design. Towering pillars with wire rope that hangs in the air like a spider’s web – it’s almost staggering to imagine just how sturdy they genuinely are. It’s only through careful design rooted in physics and geometry that these structures are at all possible.
What Makes Suspension Bridges So Special?
In its class, suspension bridges contend with the stayed-cable bridge. They both sport very similar features, a pathway flanked by foundations, punctuated beginning and end with tall support towers, and cables running along its length. However, the engineering behind suspension bridges allows for much longer spans with the same materials. Suspension bridges have the longest spans possible compared to any other kind of bridge. How exactly is this done?
The answer lies in how the thick wire cables are utilized to support the weight of the entire bridge. In a stayed-cable design, wires radiate from the tops of each of the support towers. Each cable runs from the ground level at regular intervals and tethers themselves to the tops. In this design, these stay cables bear a significant brunt of the overall weight, and they are put under a tremendous amount of stress. With so few cables supporting the weight of the entire bridge, forces can become imbalanced very, very quickly.
The suspension bridge makes a marked improvement over cable-stayed bridges in that they distribute the tension more appropriately. The cable draped between the two towers (the main cable) is supplemented with many smaller suspenders – attached to the deck. The weight on deck is distributed more evenly across these suspenders, and in turn to the towers. The foundations themselves also play a much more significant role in supporting the bridge, grounding it at either end. With these forces more evenly spread across each of the elements, engineering can achieve longer spans using less material than ever before. Suspension bridges take two idioms to heart – “many hands make light work” and “work smarter, not harder.”
In older iterations of suspension bridge design, the materials used for the suspenders were chains or bars – mostly steel. The drawback with these, though, came down to safety and strength. Chains, in particular, were comprised of hundreds of moving parts, all grinding on each other with every gust of wind. Every link was a potential point of failure, and every bar posed the threat of buckling or snapping in the cold. In wire rope designs, though, the flexibility and redundancy offered were absolutely unparalleled. It was no longer a death sentence if some strands snapped – the rest of the hundreds of suspenders was its own safety system.
The design of wire rope made each strand much stronger, as well. Long, continuous strands of metal braided with one another dwarfs chains or bars in terms of both tensile and torsional force. To break it down simply, because the wire is twisted and braided on itself, it has more “room” to stretch and bend before breaking.
Your Wire Rope Source
Wire rope is a material you can trust in everything from the Golden Gate Bridge to the simple, practical applications in stage rigging, elevators, construction, and more. For your local source of quality wire rope, you can rely on Silver State Wire Rope and Rigging. Learn more about our capabilities and explore our product catalog. If you’re ready to get started on your next project, all you need to do is contact us today!