Learning at the Golden Gate

There is no more perfect North American example to learn about fire science history and earthquakes than at the city of San Francisco. Even a centennial after the 1906 quake and fire, the effects still resonate within the city in both its new infrastructure and the character of its constructions.

Coit Tower overlooking San Francisco. The structure was built

Coit Tower overlooking San Francisco at sunrise. The depression era structure was built using funds from the bequest estate of Lillie Hitchcock Coit in the early 1930s. Lillie, a wealthy socialite, was a fire chaser in the late 1800s. She was known to even had participated in fighting fires. Arguably she could be considered one of the first women fire-fighters (though most certainly held in high regard with San Francisco’s fire-fighters). Her will left a third of her estate to beautify the city – this was used to construct this tower. Today the structure helps make a very tranquil walk as the sun rises over the bay in the morning.

I had a wonderful opportunity to visit San Francisco this week for the Fire and Materials conference. There I presented results of optical strain measurements of fibre reinforced polymers at high temperature. That paper possesses a long winded title but a very interesting and curious high temperature behavior to discuss. The conference like its predecessors was well run, and as always, the experts attracted (students, scientists practitioners, educators, consultants, code writers, fire-fighters etc.) were jewels to chat and debate with about today’s relevant fire themes and advances. Even several Edinburgh crew of my alumni were there for our usual Tom Foolery and science chats (be sure to check their blog entries of the recent Czech building fire tests).

However the city’s character does call to the engineer to explore. This is today’s blog focus – which despite the location and atmosphere actually isn’t a fire blog per say but more of a civil engineering one.

Venturing under the bridge

Venturing under the bridge…

Prior to the conference I wanted to see the Golden Gate Bridge – I’ve never had time when I was there last . Naturally the easiest way to see the bridge is to bus it, or even bike it. Neither appealed to me as I like a good walk. I started my journey at Pier 39 (I had wanted to see the extent of its sprinkler systems there on the board). I decided to walk along the shore line afterwards. A feature of that walk is the gorgeous splendor of the dunes which precede the bridge.

A seismic isolator on the bridge

A seismic connection

Before urbanization of San Francisco the whole area was this natural vegetative wet land. A tiny sliver of that is preserved today. It attracts hundreds to the area though. When you get up to the bridge you have an option of just cutting to the top and crossing. However there is a very interesting path to follow (meant actually for bikes). You can go under the bridge (towards the west) which provides you a lesson in structure vibration just hearing the roar of the traffic above. Walking further you encounter a curious plateau with two objects: a buckled steel column, and a seismic isolator (pad). With these are descriptors (pictured below).

Much of what you need to know about the seismic features of the Golden gate bridge can be learnt just next to the bridge. While difficult to identify from this photo, you can see three seismic pads just under the bridge deck and on the supports

Much of what you need to know about the seismic features of the Golden Gate Bridge can be learnt just next to the bridge on the south side.

For the architect and engineer the marvelous thing is that it explains how the new beam and truss members were designed for seismic conditions, while still preserving the heritage appearance of the original member. If you are clever you can spot the new and old members on the bridge after reading the descriptor. Viewing the illustrative seismic pad, then allows you to see how the bridge has been retrofitted. The goal of the pad is to allow a degree of movement in the event of an earthquake. Of course the standard high tension ropes (which everyone knows I love to study) can be seen everywhere. The whole expedition from walking there, looking around and getting back to Pier 39 took about 4 hours.

Shown hear is a engineered beam constrcuted for seismic, while still keeping true to the original appearance of the bridge.

Shown here is a engineered beam constructed for seismic, while still keeping true to the original ‘truss’ like appearance of the bridge.

Incredibly fun, but probably not for the same reasons as visiting the bridge. In San Francisco you can also see the Coit Tower (descriptor above), which some allege resembles a San Francisco Fire hydrant shooting to the sky. Though quick inspection does show it to be depression era. The views and paintings being fantastic to take in. And of course the downtown core growing ever so quickly with urbanization – so if you want to see examples of tall structures in seismic zones they are there. The city is a treat to the engineer and architect. Though I do have an raised eyebrow about the ‘next one’.

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