This has never been done before on a large bridge. A much more elegant, and economical, alternative was to design the stay cables to overlap over almost a quarter of each 650-metre-long main span, which effectively adds greatly to the stiffness of the deck without increasing its size. This can be countered, for example, by making the central tower larger and stiffer, making the deck much deeper and stiffer, or by tying the tower tops together with additional cables. This stems from a peculiarity of three-masted cable-stayed bridges: as the central tower is not connected to a stiff back-span structure (which would reduce any twisting), an out-of-balance live load on just one of the main spans can cause large deflections in the central tower and deck, and large bending movements in the tower. The design’s most distinctive – and unusual – feature is the crossover of the cables at the middle of each span. The bridge’s form sits in harmony with its two well-known neighbours, each representing the pinnacle of bridge engineering of its generation. The final design was developed in a joint venture between Ramboll, Sweco, and Leonhardt, Andrä und Partner, while construction was the responsibility of Forth Crossing Bridge Constructors (FCBC).Ī cylindrical caisson for the tower foundations is floated out by barge and lowered into place on the seabed by shear-leg crane © Transport Scotland The design for the new bridge was initially developed by Transport Scotland’s (TS) consulting engineers Jacobs Arup, led by Arup’s global bridge design practice leader Naeem Hussain (who was awarded the Royal Academy of Engineering’s Prince Philip Medal in 2012 for his groundbreaking work on bridges, including Queensferry).
The clincher was Beamer Rock, a natural outcrop in the middle of the Forth that provided the ideal location for the central tower of a three-towered cable stayed bridge. A modern cable-stayed bridge was far cheaper and quicker to build than a tunnel or a suspension bridge, and a location close to the existing bridge made connections into the existing road network far easier. Although many options were considered, the choice was straightforward in the end. The Forth Road Bridge has been successfully carrying road traffic across the Forth estuary since 1964, but with loads now weighing many times more than what it was designed for and concerns that cable corrosion would force premature closure, a replacement became an urgent necessity. Engineer and writer Hugh Ferguson spoke to Michael Martin, Project Director with main contractor Forth Crossing Bridge Constructors, David Climie, Project Director with client Transport Scotland, and Peter Curran, Director with Forth Crossing JV – the three engineers who were most closely involved in the bridge’s construction. The 2.7-kilometre-long crossing is the world’s longest three-towered cable-stayed bridge, Britain’s tallest bridge, and Scotland’s largest construction project in the 21st century. The Queensferry Crossing, Britain’s first major new bridge for a generation, is due to open later this summer. A Level Editor is also included so you can create your own levels and trade them with others.The near-complete Queensferry Crossing alongside its two neighbours © Transport Scotland The Bridge Construction Set includes many types of bridge building levels in varying degrees of difficulty from simple to complex with a tutorial section to get you started. The 3D graphics allow you to view your bridge from any angle including a first person train view - its like being strapped to the front of the train when your bridge is first tested (if this happened in real life I think we might have engineers checking all their bridges in a simulator).
The robust physics deployed in the Bridge Construction Set let you build a wide variety of bridges that can span the river.
If they plummet into the river you know you need to go back to the drawing board. When test vehicles pass over your bridge and make it safely across you know you've succeeded. In the Bridge Construction Set you design and build bridges and then stress test them to see how your creations hold up under pressure. In The Bridge Construction Set, Building a bridge that doesn't break is what its all about, although watching your bridge creation break and plunge a train into the watery depths below can be half the fun.
0 kommentar(er)
