US851304A - Lattice-truss. - Google Patents

Description

PATENTED APR. 23, 19o?. J. o. MOKEOWN.

LATTICE Huss.

APPLICATION FILED FEB. 25, 1907.v

ency to buckle them laterally, it is obvious UNITED STATES PATENT OFFioE.

JOHN C. kMCKEOWN, OF CHICAGO, ILLINOIS.

LATTICE-reuse.

ySpecification of Letters Patent.

j ratentea April es, 1907.

v appunti@ iialrebrutry 28,1907. seriaiii. 359.295.-

Illinois, have invented certain new and use-l ful. Im rovements in Lattice Trusses, of which t ie following is a specic'ation.

This invention relatesrtotrusses, such as roof and bridge trusses, and relates particularly to lattice trusses of the familiar type comprising a curved, usually substantially circular, upper chord, a. straight lower chord andlcro'ssed lattice or web -members which connect said upper and lower chordsat in* tervals between their ends and .which are rigidly secured together where they cross each other. In trusses of this type it is a simple engineering problem to figure out 'the -maximum and minimum tension and commembers willbe constructed, to make them adequately strongv to carry `their respective maximumloads. The lattice or web members, however, are usually larger in cross section in the plane of the truss than crosswise theretoL. and, vas compression stresses in said lattice or web members willproduce a tendthat the capacity of said lattice or web members to withstand the buckling stresses to which they are subjected will determine the real vresistance or strength of the truss as a whole. viously subjected to no buckling stress, and it'is also obvious that the buckling stress in any compression member can be largely overcome by rigidly connecting it with the tension members which it crosses, or by thus connecting crossed compression meinbers,-an

, averagebuckling stres produced therein.

The primary object f my invention is to provide a truss of this general type in which the lattice or web members will cross each other at relatively short and substantially uniform intervals and in which each lattice o`r web member will be crossed by a relatively i compression stresses therein.

To this end, my invention consists in disposing' the lattice or web members of the A member, when in tension, is ob' l truss at substantially uniform angles to the upper or curved chord, say forty-five degrees, instead 0f to the' lower, straight chord in the manner heretofore common.

A further object of the invention is to provide 'a ,composite top chord for -a truss of this l type,lthe elements ofwhich will be rigidly connected throughout the length of said chord, whereby tthe elements of said chord will be .flexedor bowed uniformly, thus maintaining the upper edge thereof, which receives the joists .ir other transverse supports, even throughout. To this end the elements of the top chord are provided with interlocking longitudinal tongues and grooves, which 'operatein an obvious manner to cause said .elements to bend uniformly and to maintain the ed es thereof even.

In't e accompanying drawing, in'v which my invention'ds fully illustrated,-Figure 1 is a side view of a roof truss embodying my invention; and Fig. 2 is an enlarged transverse sectional view of the top chord thereof, showing lattice or web mem ers and a joist in elevatiom for purposes of concrete illustration, I have shown a truss of m invention as applied for su orting a roof, represents the walls of a b ding, B the roof thereof, comprising joistsb, and a covering b1, C the upper chor of the truss, D the lower chord thereof and E the lattice or web members. Both theup er chord C and the lower chordD are refera ly made in two sections between Whic the ends of the lattice or web members E are rigidly secured. a Each section of the curved top chord C consists of a plurality of elements, as shown two elementsrl and 2, which are secured together by longitudinal interlocking tongues 3 on one thereof, and ooves 4 on the other, which will cause said e ements 1 and 2 to bend uniformly, so that the top ed es 5 thereof will be flush with each other an will tice or web members E, instead ofibeing disppsed at a uniform a le to the lower chord are disposed at a uniform aigle, say fortyfive degrees, to the top chord that is, to `a said lattice or we members are respectively secured thereto. With the lattice or web members E dis osed at uniform angles to the top chord, as escribed, it is found that said `web members cross each other at substantially-uniformintervals, whereas with the Referring novr to the drawings, in which,

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form-an even seatforthe joists b. The lattangent to said to chord at the points where IIO sitely inclined lattice or web member than in a trus'sfof the same size in which the lattice or web members vare'disposed 'at the same angles to theA lowerj'chord. Thus by secilringv the .saidjlattice or Web members together where they cross each other, which may be done any desired manner as by means of bolts or spikes, it is obvious that the lattice orweb members fmy improved truss vvillbe supported against lateral buckling stresses at substantially'uniform intervals and at an in creased number'of Qin-ts,ufa's compared ,With asubstantially si a'r truss in which the lattice or web vmembers are disclosed at uniform angles to thelowerchord, thus effectin-g`the-gobject of feature.

Iclaimk- 1. A trussqcomprising 'a curved u per chord, a lowerychord and lattice memers which connect said chords, said lattice mem-1 bers being disposed at substantially uniform my invention `as relates'to this angles to the ulpper chord at their respective polnts of attac unent thereto. u n

2. .A truss comprising a curved :upper chord, alwer chord and ,lattice members which. connect said chords, said lattice members being disposed at angles of substantially fortyf-five degrees to the upper chord at then' vrespective points of attachment thereto.

3.. A truss comprising a curved upper chord comprising a lurahty of elements provided With longitudpinal interlocking tongues and grooves, a lower chord and lattice members which connect said chords, said lattice members being disposed at substantially unlform angles to the 'upper chord at thelr respective points of attachment thereto.'

4. Av truss comprising a curvedupper chord comprisingv a 'pluralityV of elements provided with. longitudinal interlockmg tongues and grooves, a vlower chord and lattice members Which connect said chords.

n :In testimony, that I claim the foregoing as *myy invention, I afiix my signature 1n Lpres- AYVitnesses CHARLES B. GILLsoN, K. A.. COSTELLO.

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