Changing the face of Charleston : The unbuilding of the Grace and Pearman Bridges
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(Apr 10)
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(Jul 10 2006)
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(Feb 17)
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(Apr 3)
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(Apr 3)
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(Mar 27)
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(July 23 2006)
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(Mar 13)
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(Mar 13)
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(Feb 28)

November 14, 2005:
More innovation and Harvesting girders

Bob McCabe's group (Jack Foley and Scott BIllingsley) is at it again with more innovation. Here is the worksite and note that the current work area for removing roadway and girders is over a sensitive wetland area

The problem: how to remove the roadway with minimal debris falling into the water below? Bob's team came up with the idea of using the concrete saw and making longitudinal cuts along the middle of the underlying concrete girders. While the experts said it could not be done, Bob's team had an idea. On the top of each girder are rows of stirrups, each an inverted U, that is for tying rebar between girders and forming the grid used to strengthen the concrete. As an example, here is the rebar grid for the Morrison St ramp.

The innovation was figuring out how to cut exactly down the middle of each concrete girder and then make transverse cuts so as to make rectangles of roadway. A 345 grapple pulls on the precut segments until the remaining rebar fails allonging removal of the roadway segment. This harvesting procedure (I hope to catch maybe tomorrow) results in a stack of harvested segments as shown here.

Here is a girder with one sling attached and one loose end

and Stan and Nathan making their way out to secure the sling

This time the man basket brought a team up to assist in wrapping the sling around the girder

which was much more efficient

With the sling attached to the yoke at each end - the girder is ready to lift - almost.

First, Jack brings is 345 shear in and breaks the attachment at this end

then gently bites the girder and the lifting begins

and more lifting

The crane (below) rotates the girder so that it can be placed on the roadway surface

and lowers it into place - in order to release the slings.

shown here. For an animated view of this click here for an 8 Mb mpg I stiched together from the individual photos

In comes Jack

to take a bite. I stiched together another mpeg video (6 Mb) illustraing Jack's eating habits

then the segment is passed to Scott.

who transports it

to the open air barn where the harvest is kept

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Attribution: C. Frank Starmer and Sparky Witte from