The Salesforce Tower will soon be completed and overtake the Pyramid as San Francisco’s newest and tallest building. I had a great oppertuinity to take a stroll through the construction area early this month and decided to highlight a few aspects of what i learnt and saw.
To me when i see cities like this, i am filled with creative inspiration. Its very easy to predict what the future skyline of San Francisco will look like. Where the tall buildings will appear (note that for now special planning approval must be given in San Fran), where the heritage will be conserved etc.
We have two papers being presented by students at this year’s Fire and Materials Conference in San Francisco:
Comparing timber adhesive shear strength properties after fire damage
Laminated veneer lumber plated connections in fire
Engineered timber is built up using adhesives. These adhesives tend to begin to break down at temperatures around 200C. The first paper presented will represent an critical evaluation of adhesive break down from heat beyond
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.
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.
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.
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).
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.
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’.