roof truss
roof truss
(OP)
a roof truss with a span of 35 meters ,it will be supported on two concrete columns , the design was carried out assuming one support is pin and the other is roller ,but in the construction drawings 'the attached drawing' both ends are bolted down ,,is that ok , I have some concerns about this as the temperature changes are high in my place ,,moreover, the members near the support are not concentric, is that ok.
Finally is there any standard procedure to test the truss.
Finally is there any standard procedure to test the truss.






RE: roof truss
RE: roof truss
I would make sure the extended top chord (at end) can resist a moment from the support to the first upper pannel joint.
RE: roof truss
RE: roof truss
Typically, you have to restrain the ends to prevent uplift and displacement. It is standard practice that they be bolted and/or welded to supports, however the support conditions frequently allow rotation and some axial length changes. Be sure the bolted connections do not fix the ends from rotation due to deflection of the truss.
-On a typical span of 35 meters, with L/240 deflection, you should expect 14 cm deflection, with a corresponding shortening of truss span of a few millimeters.
-The thermal expansion due to a 20 C change of a mild steel on a member 35 m long will be on the order of 1 cm.
-I would imagine that the columns will allow a small amount of deflection, but this will vary significantly based on the geometry.
As far as loads not being concentric, I don't understand the loading scheme, and cannot comment specifically. If the loading is placed on the top chord by eccentric supports, you need to avoid inducing local bending. If the truss acts in a spandrel manner, there are special torsion and bracing issues which need to be addressed.
RE: roof truss
Determine what moment is induced in the concrete column due to this horizontal movement. If it is a tall, slender, flexible column, it may be OK. If it is a short, fat, stiff column, it may not be able to accomodate the movement.
DaveAtkins
RE: roof truss
RE: roof truss
BA
RE: roof truss
out of all the nodes to have an eccentric connection, the first diagonal away from bearing is probably the least desirable place to have one. PLEASE pay special attention to the design of that truss bearing seat.