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