[TheForge] Re: Speaking of shops...

[Mike Spencer]

> Wood framing is pretty forgiving.  It has what we call a "running
> factor".  When you hear it crack and see it deflect, you run.
>
>Messing around with structural concrete and structural steel framing
>is dangerous.

My rant about just who it is "the code" protects was specifically with
regard to the right of people to provide their own shelter and take
their own risks.

Public buildings and, in particular, steel structures, are a whole
'nother thing.  We have a notorious case here in Atlantic Canada.

My steel supplier, from '69 and for 30 or so years, was Robb
Engineering.  Nice, helpful guys, various pre-cutting services
available, great about arranging delivery, good employer.  But they
had also had a busy fabrication trade, especially of truss-type steel
joists, where all that laid-back congeniality was a liability. After
many years and many thousands of feet of joist installed, some roofs
collapsed.

    One of the more startling statistics that was reported in the
    [official investigation report] was that 8.3% of all joists
    inspected had one or more broken welds, which was based upon
    almost 7000 inspected joists. These weld cracks appeared quite
    randomly in both their location relative to the joist and their
    location relative to the building, although in some buildings, the
    cracks occurred in groups of consecutive joists. In addition to
    the weld cracks, there were numerous other weld flaws such as
    porosity, under cut, lack of fusion, etc. Virtually every joist
    inspected contained welds which were grossly deficient in
    comparison to the requirements of CSA W59 Welded Steel
    Construction. Then there was the "Puddle Weld", a pool of weld
    metal that was deposited on the ends of web members where they
    joined in the top chord. This non standard weld detail occurred at
    least at every second top chord panel point, and is depicted in
    the sketch below as a "Web Splice Joint". [1]


In this case, the builders were building to code but the truss
fabricator was ignoring engineering specs and procedures with wild
abandon.  The dangerous results, once past (putative) QC and out the
door, would have been caught only by a knowledgeable person with a
good eye.

At this point, nobody knows for sure how many building are at risk.
>From my own selfish POV, however, it's a shame that Robb is gone, all
the helpful, friendly guys are retired and I have to buy my iron from
a tendril of a big and impersonal corporation.



- Mike


[1] PDF, includes descriptions and diagrams of the failed-weld details
    at:

        http://www.pegnl.ca/documents/document_104.pdf 

    or google "Robb Engineering"

-- 
Michael Spencer                  Nova Scotia, Canada       .~. 
                                                           /V\ 
mspencer at tallships.ca                                     /( )\
http://home.tallships.ca/mspencer/                        ^^-^^