Gewinkelt Truss

in case your deadhangs are straight downward, the forces on points A and B can be calculated the same way as on a horizontal truss. You just have to project your loads straight downwards, and calculate with the new distances/positions. (gravity always works only straight downwards, otherwise your truss would move to the side all the time... )

just an example: if your truss is 15 meters long and hanged in an 45 degree angle,
the downward projection will just be around 10,6 meters [=15m / sqrt(2)] long)
So your calculation will be based on a shorter distance with loads placed closer together, but your deadhangs are picking the "virtual" truss further outwards!
In case your loads are not uniformly distributed, completely new results may occur.

Attention: this calculation will just cover the loads on points A and B, and does in no way refer to the mechanical capabilities of your truss!!!
Please keep in mind that this angled hanging method could reduce the maximum swl of your truss seriously!

So far for theory, now to the practical issue:

the new distance for your deadhangs (straight downwards!) on the truss can be calculated by dividing the distance beween your points in the roof by cos alpha.

e.g. for an angle of
==> 30 degrees in the shown example the new distance on the truss will be 5m / cos(30°) = 5,77m
==> at 45 degrees 5m / cos(45°) = 7,07m (which is sqrt(2) x 5m, the diagonal through a square, so the calcultion seems to be correct.)
crosscheck with pythagoras: (7,07m)² - (5m)² = 25m² = (5m)² - voila!
==> at 60 degrees 5m / cos(60°) = 10m

hi Goran,

the bending moment and shear forces of a diagonal truss are the same as bending moment and shear forces of a horizontal truss.
if the truss is diagonal, there will be normal forces. this arising normal forces are not relevant for the construction of trussing, mostly.

i have never calculated the internal forces (forces of bracing etc) of a diagonal gribbeted framework .. but now i will do and i'am interested in the results.

free informations of diagonal beams:
http://www.vieweg.de/freebook/978-3-519-35025-5_l.pdf

best regards,
martin