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FABRICATION OF THE ENGINEERED BAMBOO STRUCTURES AND FLOOD PROTECTION FOR THE ASSEMBLY BUILDING
MATERIALS Materials for the structures will be sourced in Asia where most of the giant bamboo grows. Strip 40' long strips will be milled from the stalks to about 1.25 cm x 2.54 cm (0.5 x 1.00 inches). The strips are dipped in boric acid and shipped by cargo container to the shipyard. After being kiln dried, they will be stored in the West Shed.
JIGS The jigs for the girders will be channel steel with a 2” flange and a 6” web. These will be set, outside to outside, at the width of the girder which is currently at 30 cm. The bottom jig will be he “back fence” of the assembly jig and will be welded with straps and braces to a long table at three feet in height off the floor. The jig will be angled so that it matches the engineered design.
GIRDER DESIGN The girder will be 390 m long by 30 cm thick. At the apex, the depth of the web will be about 1 m and will taper to each end to 60 cm. In order to glue the strips, starting with what will become the bottom of the girder, we need to place the longest, continuous strips along the bottom which will be in tension. The strips need to be continuous across the vertex. The “top “ jig will be free to move and will have a hinge at the mid-point to accommodate the ever increasing angle. Since the top will be in compression, it will take the ever increasing shorter strips to thereby increase the angle to achieve a 4 to 12 pitch.
LAY-UP Strips will be laid-up by sticking the first layer to the bottom jig with adhesive which allows for the strip to be easily removed from the jig. A layer of glue is applied and the next trip is laid in. Glue will be applied to the exposed edge and flat of the already installed strip. Strips, firmly placed first by hand, then will be compressed by an long tubular air bag. The bag will rest between the bamboo and the “top” jig which is moveable and can be pinned so as to take the PSI of the bag. The bag is inflated and presses, uniformly, against the bamboo strips. We will need some way to put pressure down on the edges of the strips along the run of the girder in assembly. The easiest will be to use 2” straps with ratchets and a block with a hump in the middle to help exert pressure uniformly. The straps will be placed on 2' intervals
GLUE The choices include one part and two part glues. The one part, polyurethane allows for a long pot time and about 2 – 3 hours assembly time. The shorter the assembly time, the shorter the pot time. Another choice is a heat set glue. That works on laminate, but doubtful it would work on 30 cm bamboo. There is very little moisture in the bamboo to help transmit the heat. Inquiries to glue manufacturers have been sent. DWELL TIME There may be a significant dwell time between lay-up sessions. We need to use the same workers in making stanchions and gerts. Similar jigs and air bags will be used to form these structures.
CENTER OF GRAVITY AND ASPECT RATIO By using wood for the superstructure and steel for the foundation frame, the center of gravity should be as low as possible. Further the floor of steel cross members under the concrete slab (or wood) will lower the center of gravity. The forklift and the MTE will add weight as will the construction materials.
The sheds add another 24' to the sides of the main sector, thus giving the building stability in the event a flood causes the building to float.
REGISTRATION PILES At each corner, long piles will be driven well into the subsoil in an attempt to hit rock. These piles will be about 45 cm in diameter with very heavy walls. The source will likely be oil well casings. The “free board” above the finished grade should be about 5' above the 500 year flood level.
REGISTRATION BRACKETS Registration brackets will maintain the registration of the floating Assembly Building as it rises and falls with the flood waters. The bracket, made out of channel one inch thick with a four inch flange and a four inch web is square and allows for installation of 4 inch solid steel rollers on pins attached to ears welded to the top of the flanges in the middle of the same. The surface of these rollers are held back about an inch or two from the pile to allow for expansion and contraction of the steel frame and other misalignment. Each corner has a bracket.
ANCHOR LINES In the remote possibility that the flood waters exceed the 500 year flood level and the building floats up and above the end of the piles, an anchor line needs to be available at each corner. This cable with a large hook on the end is “reeled” by a large “Grip Puller” which is manually operated with a 46” handle. JET's specs are: Model JG-300, Part 186530K, pulling capacity: 11,000 lbs, ASA wire rope is 5/8” by 66', speed is 10 FPM and weight is 123 lbs (pg. 9 of Shop Material Handling Shop Tools, Air and Hand Tools, 2001-2003 Catalog www.powermatic.com) This machine does not use a spool and thus can handle a wire rope of any length and is portable. A hole can be cut in the top of the pile so that the hook (with keeper) can be attached and the bracket used as a fairhead. Thus, under even the most extreme circumstances of flood, each of the four cables attached to the top of their respective pilings will keep the floating building from washing away. As the flood waters recede, the grip puller re-positions the brackets over the top of the emerging pile and the cable detached once full contact is made between the pile and the bracket rollers.
WALKWAYS, PADS The building needs standing room for workers to access the Grip Puller at each corner. Thus a walkway needs to be install across the each end of the building or a pad created at each corner. In such event, each worker will be required to wear a life vest and a safety harness with a reel and attached to the building with a line.
SHEDS Two sheds with sloping roofs anchored at 12 feet up on each side of the building, and running the length of the building, will be built. The bottom outside of the long side of each shed will rest on the outside steel I-beam foundation, thus making the foundation 102' wide. The length, including the walkway on the north end will be 260 +2' for a total of 262 feet in length. Pads can be created for the corners of the south end of the building to avoid crossing in front of the hanger door. The ceiling height on the low side will be 8' and on the high side, 12'. The east shed will house the lumber milling equipment and the west shed will house the lay-up equipment and finishing. The girders will be built on the floor of the assembly building on a 3 foot stand.
Jim Miller 6-2-2011
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