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Re: Holes for galvanized bolts

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About ten years ago , we took a contract to design and build a portable
steel truss bridge , to be used in an area where there was a probability
of avalanches in rivers and destruction of existing bridges. When we
spoke to the galvanizing plant , they assured us that we needed to make
the holes 1/8" larger , and even showed us some samples.  The result was
a disaster : as all of the connections were of the bearing type , we had
to substitute all of the bolts for custom made ones 1/16" larger. When
we did the first assembly , the bridge was just too flexible , because
of the slight lack of restraint in the joints. You should not go larger
than 1/16".


Juan Carlos Gray