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truss members

truss members

truss members

(OP)
we design trusses for the final load condition. but is there a minimum memeber size requirment for lifting? thanks

RE: truss members

That would depend on where you lift from and the resulting stresses.

RE: truss members

In that most roof and floor trusses see in the range of 80 plf on the average on the top chord, and there is a wide variation here, you would do well to consider adding another load condition to your repertoire of load conditions if you pick anywhere but at the design support points.  Chances are that it will not, or should not better to say, govern your design.  Neverthelsess it would be good to check.

Mike McCann
McCann Engineering

RE: truss members

(OP)
OK, I as an engineer on record always designed the final condition. my notes always say something like it is the  contractor's responsbility to put everything to where they suppose to be. I guess there is not a requirement for the sizes then. Thanks.

RE: truss members

I worry more about long span trusses -- say 35' and over..

They can buckle if not picked correctly.  Spreader bars are definitely a must.

RE: truss members

Mike is right - the longer span trusses can get tough to erect and sometimes its good to visit with the contractor/steel-erector prior to design to get a good understanding on how they would lift them into place.

I once did a 378 ft. long bowstring truss - took something like six or seven cranes to lift.

RE: truss members

BCSI-03 from WTCA covers all of the lifting requirements for trusses up to 80' span. Book only costs $7. It is well worth it.

RE: truss members

BCSI-06 is now available.

woodengineer

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