The Bridge of Wood

Hi, you know that my name is Rodolfo and I have the intention of creating a building with different materials and building systems, but all of them have to have been already used in some construction, if not, How will I know that it really works?

What is difficult is deliver me from the newspapers, they follow me wherever I want to go, sometimes it is a problem being so well known... I feel like a character of Agatha Christie´s books being aware of the possibility that it is caught, and when they do … It cannot believe!! At last, to get to the point. that I have other things to do.

Second stop: the pedestrian bridge of wood

They say that it is the highest pedestrian bridge in the world, which I put in doubt, but I am sure that is highest in Singapure... I was already invited to the inauguration in 2008, but I was being to do and could not attend, so that the Prime Minister was angry... I speak, of course, of the Henderson wave pedestrian bridge, linking the hills of Mount Faber, Telok Blangah Hill and Kent Ridge Park, which are the three beautiful parks.

The most showy thing, beside the gardens before mentioned, of the highway Henderson Road (below the bridge) and the sights of the city, I mean, they are seven wavinesses that form the bridge and that simulate the waves of the sea for the most romantics and the silhouette of a serpent for the others (here I am). The design was gained by IJP Corporation and RSP Architects, Planners and Engineers in an international contest summoned by the Authority of Urban Development (URA).

Here are the dates. The materials used in construction were three: reinforced concrete pillars that sustain the catwalk, Steel as structure for support and acting as catenary (giving the characteristic shape of the bridge) and the wood that covers the entire walkable surface and that rises in the upward sections; the bridge has a length of 274 metres and a width of eight meters; in total there are more than 1,500 square meters of wood surface and there are areas where it appears doubly curved; the highest tower reaches a height of 38 metres.

Well, I have come here only to see the wood, which is unique in the world since it only found in the South-East Asia, called yellow Balau.

Characteristics and uses of Balau wood

The Balau wood is a tropical high density fiberboard, compact and with a high content of oils and tropical resins, it belongs to the Dipterocarpaceae family (award to who memorize it). It is appreciated for its robustness and resistance, and for his behavior with the water, which mades it very popular in shipbuilding and (guess) bridges, also it has excellent mechanical properties.

Currently the yellow or red Balau wood (the two existing varieties) is used in the construction of outdoor furniture, pergolas and parquet flooring. We must make sure that the wood comes from a provider of trust, since if the drying of wood is done incorrectly if not it can crack and warp; It is important to buy sealed wood: wich will avoid to lose its natural oils. Still I have not decided where I will use it in my future construction, but I am sure of one thing: it will be innovative.

Association between wood and steel

A critical point in this type of structure is the bond between the steel and the wood. It is not easy because of the large differences between the two materials, especially when they act outdoor and in what corresponds to the differences in dilation. Never forget that wood is an anisotropic material (different mechanical properties in different directions) and steel a homogeneous material (same properties in different directions).

The union will be made with self-drilling screws to transfer both materials. As you can see in the Henderson Wave bridge, very clearly, the different wooden slats are less separated lengthways (lengthwise) that in the transverse (to wide), this is because the wood fibers dilate more on its thickness than in its long, therefore "they are stretched" more in width than length..

As a last note, if you have the temerity to cross this bridge, remember that you can not smoke in it, for people who smoke. Good bye.