Infrastructure Projects - Construction Technology
A Practical Guide to Construction Techniques and Practice
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Here's the morning after the steel erection. Three beams have been installed and I think that is excellent progress, considering this was their first night shift. When the first beam is erected, because it is so long and slender. It's considered unstable. The ends are braced, but an additional tower is provided to carry some of the dead load of the beam, and also to support the top flange and brace it against rotating. That made the first beam stable. After that, the second beam was raised and joined to the first beam by means of intermediate diaphragms. Then the pair of beams was stable, and subsequent beams could be erected and joined to the previous beam with intermediate diaphragms. A lot of people use a figure of 15 minutes to set a steel beam, but that's completely unrealistic under these circumstances. It's time-consuming to set up the crane and then to dismantle the crane. I think three pieces per shift under these conditions are very good production.
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![]() The fascia form is made of wood, supported on brackets. You can also see this wood handrail, and on top of the fascia form, there's a screed pipe. That's supported on adjustable screws. You need to set this pipe at a higher elevation than the finished elevation to accommodate dead load deflections. You also should use the finishing machine to make passes over the rebar and make sure you're really achieving the correct cover over the rebar.
You want to cover it as soon as possible to prevent the escape of any moisture, and especially in the summer, it's critical to get on it immediately. The requirement on this project is to keep that curing blanket moist for 14 days. You do that with perforated hose or sprinklers. The other observation, there's over a dozen people here, but most of them are bystanders. They are celebrating the day when they are finally pouring the bridge. It's been a troubled project and it must be a relief to everybody to finally see the bridge concrete being placed.
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