old bowstring truss reinforcemen

huangyhg

old bowstring truss reinforcement
my client has a warehouse which he wishes to sell with 70' span bowstring trusses, several of which are broken.  the top chord is 4-2x6s flat, apparenetly nail laminated together as no bolts are visible.  the bottom chord is a single 6x6 spliced in the middle.  the webs vary from 3x3 to 3x4.  the panel point connections are a u plate configuration with a single bolt through each web and the wings of the "u" and two bolts through the base of the "u" and through the chord, top or bottom.  the heel appears to be a thrust plate receiving the top chord  and welded to two side plates bolted through the bottom chord.
i would really appreciate any insigths into these trusses, particularly in the analysis of this type of panel point system.  thanks!
sounds like a real can of worms.  under uniform load, the web members carry virtually no load because the top chord closely follows the bending moment curve.
baretired:  depending on the age of the trusses, the 35 foot length of the 6x6's is possible.  difficult, but possible even today with a special order.   but that is $$$$$$$$$$$$$.
i would ask:
mike:
i would ask:
a photograph or two wouldn't hurt.   
ba
truss pic
truss pic 2 of 4
truss pic 3 of 4
truss pic 4 of 4
one more pic showing the typical panel point configuration which was a main part of my original query.  thank you all for your interest and support.
the first two look like tension failures of the bottom chord - the first at a knot???  and the second at a vertical hole for a tension rod -
the third and fourth look like a bending/tension failures of the top and bottom chords.
did you notice any rot in the failure areas?
the fifth picture shows the joint with added holes beyond the connection holes for the sprinkler system.
i wonder if these holes were considered in the original design.  any record of what the live load was that these trusses were originally designed for?  have there been any serious snow overload conditions in recent years?
doesn't the owner have insurance on the building?  if so, why  haven't the repairs been done yet, assuming the problem has been there a while?     
mike mccann
mmc engineering