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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(Mar 27)
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(Feb 28)

August 17, 2005 A short progress report

Can you image the Pearman bridge without traffic? My Sunday morning bicycle rides were never like this - even at 7am!

Today's lesson - These guys exhibit the skills of a surgeon and dentist. Imagine, having to remove these bridges and extract the supporting structures with minimal disturbance. Yesterday, you saw from Sparky's photos that the Pearman girders end up in a vertical position.

From a distance it seem like we are building our own version of Stonehenge. Today I asked Pio Monsini how they did this and, as with other Testa skills, it turns out not to be an accident but rather a detailed procedure for dropping the girders. After the roadway between girders is removed, the structural integrity of the girder is broken near one pair of piers. The weakened girder then rotates down using the other cap as the point of rotation. Eventually, the structural integrity of the attached end is weakened sufficiently that the girder breaks loose and falls, almost vertically. Apparently this reduces the complexity of removing the girders as well as protecting the region around the girders

These are some of the members of our surgical team

and these are their surgical instruments

and a closer look at the shear (left) And Pio, Ken and one of the surgeons (I later discovered through his wife that this is Michael Hebb)

Here is a view of the Pearman caps - extending almost all the way to the steel superstructure.

We all see the Testa guys working on the road surfaces, but unable to see what is actually happening. Here you can see how they use their shears and grapples to chip away at the roadway between supporting girders. Once the between-girder roadway has been removed, the girder can be prepared for removal and dropped (vertically) into the sandy base under the bridge. Again, the surgical precision of the removal operation is impressive. Note near the middle of the image, the relative position of the girders dropped near one of the supporting columns of the Ravenel bridge approach. There is about 4-5 feet of clearance between the Ravenel support and the dropped girder. Neurosurgeons at work here!

To stabilize the segments east of the expansion joint, it is welded together thus providing additional stability to the remaining segments.

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Attribution: C. Frank Starmer and Sparky Witte from http://oldcooperriverbridge.org