Metal truss structure

A metal truss structure which is characterized by chord and web members formed of rectangular tubing and with the chords of double construction to take advantage of the weight and cost savings and high torsional strength of rectangular tubing and arranged for easy and inexpensive fabrication by avoiding precise cutting and difficult welding requirement. This metal truss structure comprises chords, each including a pair of laterally spaced-apart rectangular tubing members positioned flat against opposite sides of the rectangular tubing web members at one corresponding end and welded exclusively by weld lines extending along the longitudinal intersections of the chord members with the web members for simple and automatic welding.

The present invention relates to a metal truss structure. 
A metal truss structure essentially includes a pair of spaced-apart chords 
and web members rigidly joined at their opposite ends to the chords 
respectively. Many different types of metal trusses have been proposed so 
far. For instance, in one previously proposed type of metal truss 
structure, the chords and even the web members are made of angle or tee 
members. In another previously proposed type of metal truss structure, the 
chords are each made of a single square tubing and the web members are 
also of square tubing abutting endwise against the square tubing chord 
members and welded thereto. In either case, the fabrication of such 
trusses is time-consuming and relatively expensive due to the precise 
cutting and fitting required for the web members and to manual welding in 
places of difficult access. 
In the case of trusses made of angles and tees, the latter inherently have 
a low torsional stiffness greatly limiting the maximum stresses allowable 
in such members. 
In the case of square tubing trusses, an improved performance is obtained, 
such as reduced weight and costs, increased torsional stiffness and a 
higher grade steel inherent to rectangular tubing; 50 KSi yield as 
compared to 44 KSi yield for the angles and tees. However, the square 
tubing trusses produced so far comprise chords each made of a single 
square tubing chord member and with square tubing web members arranged in 
the plane of the opposite chord members and in endwise abutment at the 
opposite ends with the two chord members respectively. 
Such arrangement results in chords which are often subject to overstressing 
and deformation due to the relatively thin wall of the square tubing and 
to the practical limitation in the maximum size of the chord members. 
It is a general object of the present invention to provide a metal truss 
structure which substantially avoids the above-mentioned disadvantages. 
It is more specifically a general object of the present invention to 
provide a metal truss structure wherein all the structural members are 
each proportioned for the stress to which it is subjected and such that 
every part of the structure is subjected to the same substantially uniform 
stress of the maximum desired magnitude and to thus utilize only the 
material that is necessary. 
It is another generally stated object of the present invention to provide a 
metal truss structure which, by efficient use of material, effects 
considerable savings in material, thus concurrently reducing the costs of 
the material and of shipping, since both of these are proportional to the 
weight. 
It is a more specific object of the present invention to provide a metal 
truss structure wherein any compression chord or member is made of 
rectangular tubing to take advantage of the weight saving and high 
torsional stiffness inherent to such structural tubing member. 
It is another object of the present invention to provide a metal truss 
structure which is simpler and more economical to fabricate by requiring 
less precise cutting and allowing easier and automatic welding. 
It is a further object of the present invention to provide a metal truss 
structure which, by doubling of the chord members, allows to build 
stronger trusses for larger spans and/or heavier loads, as compared to a 
single chord truss.

In FIG. 1, there is illustrated a metal truss structure formed of a pair of 
upright wall sections 1 and a pair of roof sections 2. Each truss section 
1 has its narrower end resting on ground plates 3, its outer chord 4 
extending vertically and its inner chord 5 upwardly extending inward. The 
roof sections 2 have their narrower and fixed endwise one to the other at 
the roof line and have their larger end fixed to the inner chord 5 of the 
corresponding wall section. 
Each metal truss structure or section 1 or 2 has each of its two chords 
made of double construction; that is, having two chord members 7. The two 
chord members 7 of each chord are laterally spaced apart one from the 
other and separated by the web members 8. 
Each chord member 7 and web member 8 is of rectangular tubing and the chord 
members 7 are fixed flat against opposite sides respectively of the web 
members 8 and at the opposite ends of the web members. 
Both ends of web members 8 are cut so as to extend substantially parallel 
to chord members 7. 
The chord and web members 7 and 8 are welded one to another by weld lines 9 
and 10 at the inner side and outer side of chord members 7, respectively, 
said weld lines extending along all the longitudinal extensions between 
the chord members 7 and the web members 8. Thus, all the weld lines extend 
longitudinally of the truss structure and may be automatically produced.