. Practical structural design; a text and reference work for engineers, architects, builders, draftsmen and technical schools;. m and symmetricalloadings for this case, or the loads may be followed from the pointof zero shear in cases of unsymmetrical loading, or the shear methodmay be followed. In Fig. 82 (c) is shown a truss with a subvertical and sub-diagonal at each end. Such an arrangement involves the con-sideration of an additional triangle in which half the weight isadded to the load at h and is then carried to a, the other half beingadded to the load at c. This arrangement offers no d
. Practical structural design; a text and reference work for engineers, architects, builders, draftsmen and technical schools;. m and symmetricalloadings for this case, or the loads may be followed from the pointof zero shear in cases of unsymmetrical loading, or the shear methodmay be followed. In Fig. 82 (c) is shown a truss with a subvertical and sub-diagonal at each end. Such an arrangement involves the con-sideration of an additional triangle in which half the weight isadded to the load at h and is then carried to a, the other half beingadded to the load at c. This arrangement offers no difficulty whenfigured by the shear method,.but sometimes causes trouble and 128 PRACTICAL STRUCTURAL DESIGN confusion when an attempt is made to trace out the loads fromthe middle panel, or point of zero shear. Some trusses have nonparallel chords. The shapes vary fromthose higher at one end, as in Fig. 82 (a), to those approaching anarch form as at (b). Part of the shear is carried by the slopingchord. When the chord stress is found by one of the precedingmethods it is the horizontal stress. For a sloping chord the hori-. Fig. 82—Various Types of Trusses zontal stress must be multiplied by the inclined length and theproduct divided by the panel length, the result being the axial(longitudinal) stress in the inclined member. In the Warren truss (Fig. 83) the stresses in the web membersare alternately tension and compression, the light lines indicatingtension and the heavy lines compression. Each panel is an equi-lateral triangle and in the figure the truss is a single system. Byusing another set of triangles and placing the trusses side by sideso one triangle overlaps another by half the width, we obtain adouble system. Similarly, we may use a triple-system or a four-system truss. When two or more systems are used the result isa Latticed Truss, (Fig. 84). Let W = total load on the truss, uniformly distributed,P = load on each triangle,n = number of triangles in the primary sin
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