Question $2$: $(60\%)$

Design a bridge that will span over the river shown in Figure $3.$ Assume that on the banks on either side of the river there is bedrock that will allow you to support$/$anchor any foundation$/$support needed. In addition, in the middle of the river there is a small island that you could potentially utilise $($if needed$)$ for supporting your bridge. Your objective is to select a design that will allow your bridge to be relatively lightweight. The width of the bridge should allow the introduction of $2$ traffic lanes along the deck.

Assume that the structure is subjected to:

$($i$)$ Dead Loads: linked to the mass of the construction materials used;

$($ii$)$ Traffic loads: normal traffic load in accordance to Load Model $1($see Eurocode $2$ Part $2$: Traffic loads on bridges$)$

$($iii$)$ Wind loads: assumed to cause uplift and act as a uniformly distributed load $(1k\frac{N}{m^2})$ along the deck.

$($iv$)$ Snow Loads: assumed to cause uplift and act as a uniformly distributed load $(0\mathrm{.}8k\frac{N}{m^2})$ along the deck.

Describe the structural system you have selected using sketches. Justify the selection. Show the path that the loads will follow from the point of application to the foundations. advice: choose a determinate structure for your design.

Sketch a $2$D structural model of your bridge. Consider the appropriate load combinations and design key components of your structure adopting the permissible stress approach. Identify the key components $($critical cross$-$sections$)$ that you will consider when designing the bridge. Carry out structural analysis to calculate the design values of the internal actions developing along key structural members $($you can use Linpro to carry out your structural analysis$),$ select the appropriate materials, identify and design the critical cross$-$sections,

Provide some simple sketches showcasing your design solution.

Through a series of sketches describe the construction process you would follow.

Briefly discuss how you would maintain the structure.