Cyclopedia of architecture, carpentry, and building : a general reference work . the distance betweentrusses 16 feet; and let it be required to compute the stresses in L^U, and L, U,. Here P= (40 X 16 X 60) -- 8 = 4 800, and the stresses will be: Li U^ (0. 87 X 4 800) X 2. 10 = + 8 350 U^ (2 .60 X 4 800) X = +18 700 pounds. In addition tothe above condi-tions, shafting,heating appara-tus, small cranes,and electric war-ing and other con-ductors are oftenattached to thelower chord of thetruss. These causeadditional stress-es. The case isthat of a concen-trated load orloads at the
Cyclopedia of architecture, carpentry, and building : a general reference work . the distance betweentrusses 16 feet; and let it be required to compute the stresses in L^U, and L, U,. Here P= (40 X 16 X 60) -- 8 = 4 800, and the stresses will be: Li U^ (0. 87 X 4 800) X 2. 10 = + 8 350 U^ (2 .60 X 4 800) X = +18 700 pounds. In addition tothe above condi-tions, shafting,heating appara-tus, small cranes,and electric war-ing and other con-ductors are oftenattached to thelower chord of thetruss. These causeadditional stress-es. The case isthat of a concen-trated load orloads at the lowerchord, and thestresses may becomputed by themethods given inStatics. For example, let a 5-ton hoist be connected as showTi in Fig. 40This hoist runs longitudinally of the shop, or perpendicularly to theplane of the roof truss. The maximum stress in the truss due to thiscause will occur when the hoist is directly beneath the truss. Thestresses will be those caused by a load of 10 000 pounds at the secondpanel point of the lower chord. Fig. 40 gives the stress diagram for. o,2-r + 6100 ,Y /^\ 0 5000 / <^ 0 X / 0CO00 0 000 J^^ + 13700 : C^ ^- 2-7 Fig. 40, Fink Truss Loaded with 5-Ton Hoist; alsoStress Diagram of Same. 238 ROOF TRUSSES 25 TABLE VIHoist Stresses in Fink Truss Member 5tre5S Member Stress L0U4- -15 350 UU4- + IZ50G LoLz + 13 700 U4. Lo - 6 900 Lz Lo + 6 100 All Others 0 this condition, and Table VI gives the stress record. From this it isseen that the hoist docs not affect all members of the truss. Thestresses due to the hoist should be added to those caused by the 40pounds per square foot of horizontal projection, and the memberdesigned accordingly. Of course, if the stress caused by the hoistdecreases the stress caused by the 40 pounds, the member must be de-signed for the stress due to the 40 pounds. Note that concentrated loads, as in the case of the hoist, causedifferent stresses in symmetrical members on the two sides of thetruss. In the final design, th
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