huangyhg

restoring existing roof bracing
hi guys
i have a situation where we are retrofitting an existing building that was built in the 1970's. as a result we need to strengthen the roof bracing, we have decided to install some additional roof bracing to go along with the existing 12mm (1/2") rod roof bracing.
the existing connection is such that the w-beam (ub) rafter has an l-shape cleat welded to the web, a small penetration provided through the web and the rod is unslackened by tightening the nut (i assume, don't know whether turnbuckles are there because the ceiling space is very cluttered with services).
what i want to do is provide new more conventional bracing on the other side of the rafter, however this will clash with the existing l-plate cleat.
my idea is as follows:
1. un-bolt the existing rod
2. saw cut and grind flush the l-plate cleat
3. site weld new cleats to accept the new bracing
4. restore all surface treatments
does this approach seem logical or would there be an easier way to construct this?
is saw-cutting the best way to remove the existing l-plate or is there another more effective method?
is there anyway i can re-use the bracing? for example, cut the rod bracing to the new size and site weld a turnbuckle and cleat?
any comments will be appreciated.
you wouldn't be able to get a saw right against the web. more a job for a grinder. you could reuse the rods, but that might cost more than just having new pieces fabricated in the shop.
flame cutting is acceptable, just keep the cut on the clip and don't gouge the w section. then grind the last bit of the clip away. repair any gouges that occur by welding and grinding.
make sure the welders are certified for the positions of the welding, the welding process, and the electrodes to be used.
thanks hokie and ron
any chance of engaging the roof deck for lateral restraint?
dik
we use metal sheet roofing as a membrane/cladding. i notice there is much talk on this forum about using the roof deck as a flexible diaphram but that isn't a typical assumption we use. i have attached typical roof sheeting that you can find on sites, i don't think it will be a valid assumption to rely on it structurally to act as a diaphram.

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