Travel: Dom Luis Bridge, Oporto

It’s been quite awhile since I’ve managed to haul my ass out of bed this early in the morning. Oporto is a 2-hour drive from my prior location of Fatima, and I wanted to get the sites in before retiring early for the night due to an early AM flight. Yes, Alas, the time has come for me to bid adieu to my short time in Portugal and move on to the next destination on my European Adventure.

Once again, the weather is not being agreeable, in the sunlight you could no doubt see the old world charm of this century old city. However, amidst the gray skies, damp air, and churning brown waters, the city itself seemed to be sighing in sorrow. Fortunately, for the most part, the skies were generous enough to withhold a downpour of rain, and we merely had to deal with the pitter-patter of irregular drizzling.

2013-04-10 05.32.04My first official view of Porto happened while I was still in a dreary state, our bus was crossing a bridge parallel to a well-known sign of the city. It was in this fuzzy mindset that I first witnessed the historic Dom Luis Bridge.

You’ll understand my fascination with this span when you consider my background (see About Me). I was just enthralled by the structure, and it was difficult to withhold the continuous stream of design considerations and analysis methods required from zip-lining through my head.

2013-04-10 05.27.48

The arched form of the bridge results in a degree of non-linearity when considering how the structural elements resist the applied loads. This is difficult to describe in a non-technical sense, but it simply means that as the structure deforms  (changes shape) the strength and capacity of the bridge actually increases, as opposed to the logical assumption that it’s carrying capacity would decrease.

For a brief historic background: The government held a competition for the design of this land connection between Porto and Vila Nova de Gaia that would span the Douro river. Téophile Seyrig claimed this honor, and construction began in 1881, and the bridge officially opened in 1886. At the time, it was the longest bridge of its type at a span of 172 m.

 

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