User:Mferna20/Helgeland Bridge draft

Introduction
The Helgeland Bridge (Helgelandsbrua in Norwegian) is a cable-stayed road bridge crossing the Leirfjorden in Sandnessjøen, Nordland, Norway. The diamond-shaped towers, fan-shaped cables, and extremely slender deck make this a unique structure among Norwegian bridges.

Structural Description
The Helgeland Bridge was designed by Holger S. Svensson and began construction in 1989, and was completed in 1991 for 200 million NOK (35 million USD). In 2012, the cost would be approximately 373.3 million NOK (65.5 million USD). The bridge is composed of reinforced concrete in the towers, pre-stressed concrete in the deck, and is completed by steel cables. The main span (of a total of 12) reaches 1394 feet, and the towers reach a height of 453 feet. The total length of the bridge is 3494 feet. The bridge's foundations extend to a depth of 31 meters (101 feet). Due to the extreme climate, namely the nearby mountains and the bridge's proximity to the North Atlantic, there is a very heavy wind load on this bridge. Wind gust speed at the deck level is 70 m/s (156.6 mph).

Qualification as Structural Art
The Helgeland Bridge is successful as a work of structural art in many respects. It is perhaps not as iconic as other bridges across the globe, but it is structurally sound and effective in its use of materials as well as being aesthetically pleasing and serving an important social function. It is a sleek example of the balance between form and function and it complements its surroundings.

Scientific
From a scientific standpoint, the self-load of the towers puts them in compression, while the deck is bending and the cables are under tension. Any load the bridge finds itself under makes its way back to the towers and straight down from there, avoiding a complicated load path through arches, trusses, etc. The minimalism of the bridge’s design ensures that materials are used efficiently. The concrete used in the bridge is reinforced in the pylons and prestressed in the deck, thereby lending sturdiness to the structure and allowing for some bending. However, the deck is very thin – only 1.2 meters – so its stiffness alone would not be sufficient to keep the bridge from falling apart. The bridge's steel cables help to rectify this problem. Although it is light on materials, the Helgeland Bridge is indeed sturdy enough to stand up to dead, live, and extreme lateral loads.

Social
A structure in a low-traffic area like the Helgeland Bridge would not get as much traffic as a bridge in an urban area. This might detract from its social function in respect to structural art. However, what the bridge lacks in traffic it makes up for in moderate cost-effectiveness and practicality. It certainly serves an important social function, as Norway’s coastline is riddled with fjords, making bridges an absolute necessity in order to traverse the landscape. The cost of the Helgeland Bridge is comparable to others in Norway such as the Skarnsund Bridge (200 million NOK in 1990) and the Osterøy Bridge (308 million NOK in 1997).

Symbolic
The Helgeland Bridge somewhat differs structurally from most of the other bridges in Norway. On one hand, minimalism seems to be a common theme in Norwegian bridges including Helgeland, with the plain towers of bridges such as those in Askøy and Osterøy resembling, say, Othmar Ammann’s Bronx Whitestone Bridge. However, the Helgeland Bridge avoids having such large empty spaces in its design. Instead, the diamond-shaped pylons taper outward from their highest point to the bridge’s deck, then taper just slightly inwards until reaching the base. The steel cables add substance to the stark vertical towers and extremely thin deck by forming a fan shape. The design is simple without looking flimsy, fitting in with the pristine Norwegian landscape. The aesthetics of the bridge employ plenty of triangular shapes in the fanning of the cables and the towers themselves. Compared to other bridges in Norway, the design is perhaps a bit unusual compared to the standard suspension or arch bridge, but that may indeed be to its benefit.