Blue Twizzlers?
Why, this might look like nice big piece of tasty candy. But don't be fooled! It is actually a piece of epoxy-coated post-tensioning strand steel. Show 'n tell in this class (Durability Design of New Concrete Infrastructure) is fun. Other items passed around today were reinforcing bars for concrete made of glass-, aramid- (Kevlar), and carbon fiber-reinforced plastic. Wild stuff.
The professor actually covered some cool stuff today--a crash course in how pre-tensioned and post tensioned concrete work, to bring up the non-structural civil engineering guys up to speed. In that link above, check out Figure 1.9--it's a pretty wild construction technique. They first make a central column. Then they build the bridge deck out as a cantilever on both sides, alternating to keep it in balance, until it meets the cantilever deck coming from the adjacent column. Pretty wild stuff.
Also, in reading some course material, I found out something cool. Have you ever driven by bridge highway overpasses at night, and there's a big enclosure or tarp around the median, and there's this godawful hissing racket coming out of it? I always wondered what that was--are they sandblasting? heating? Well, my best guess now is that they are steam curing the concrete--making it set up faster, to put it back in service. Yeah, geek geek geek.
In very unfortunate news, it appears that the authentic New York style bagel shop that I mentioned earlier is closing down. Dammit. No way I'm staying for a PhD now. [grin]
Definitely starting to worry about the term now. Presentation and assignment due a week from now. Then a week plus trip to Vancouver for work (consulting work with my advisor). Well, it's technically not work, since I'm not getting paid for it--long story--but overall, I don't mind going. Except for the fact that I have a midterm a three days after gettting back. Then a three day trip to Richmond (another consulting trip). And two weeks after that, it goes into end of term (final project and final exam). Good news, though, is that I will be back in Boston by December 16th at the latest--hopefully a few days before that.
Oh, and a small victory this evening--I was poking around the Jazz Real Book that I own, and found out they have Linus and Lucy (i.e., the Peanuts theme, by Vince Guaraldi). I had noodled it out before, but looking at the book chording, I could figure out, "Dammit! That's why that chord never sounded quite right!" It made me happy.
posted by Bats @ 9:58 PM
2 comments
2 Comments:
The picture you show of the bridge seems to be what they're doing in building the new eastern span of the Bay Bridge. They've got the posts rising out of the water, and cranes associated with each one, and it seems like they're building out from the posts, so do you think it's the same technique, or am I smoking crack?
Oh, and coolness on the Linus and Lucy chords - I've tried figuring those out a couple times, and it never ever sounds right.
Yeah, it sounds pretty close. Actually, they're probably using the method shown in Figure 1.11--instead of casting the sections of the bridge deck in place, they are lifting in precast concrete segments. These cantilever methods are pretty necessary when building falsework (i.e., supports) underneath would be a big pain, such as over an active highway, or over water.
I couldn't find any current construction photos, but according to the East Span News Spring 2002, it sounds like this method: In summer 2003, the first concrete segments for the Skyway deck will arrive for installation. Each segment will be as big as a three-story building, at 30 feet high, 80 feet wide, and 25 feet long. The sections will be barged in and then hoisted in place with large cranes. Each concrete segment will be built outward from the piers until it reaches the segment coming from the opposite pier. Also, this method uses a crane at each pier; I have photos of the construction from previous visits, with big tower cranes set up this way.
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