. An encyclopaedia of architecture, historical, theoretical, & practical. New ed., rev., portions rewritten, and with additions by Wyatt Papworth. 3 oak,25 fir, and 2*0 elm. Fairbairn considerstbat theaddition of the timber on each side oftheplate gives increased stiffness, and renders it less liable to warp under strain. It is called asandwich beam. He states tliis beam to be weak, comparing the results with those ofthe simple plate girder; and its elasticity, although considerable, is nevertiieless so imper-fect as to render it inadmissible for the support of great loads, whether proceeding
. An encyclopaedia of architecture, historical, theoretical, & practical. New ed., rev., portions rewritten, and with additions by Wyatt Papworth. 3 oak,25 fir, and 2*0 elm. Fairbairn considerstbat theaddition of the timber on each side oftheplate gives increased stiffness, and renders it less liable to warp under strain. It is called asandwich beam. He states tliis beam to be weak, comparing the results with those ofthe simple plate girder; and its elasticity, although considerable, is nevertiieless so imper-fect as to render it inadmissible for the support of great loads, whether proceeding from adead weight, or one in motion over its surface. With riveted angles or flanges, the timberson each side might have been useful in preventing lateral flexure, but they would not liavecontributed, in any great degree, to the vertical bearing powers of the beam. (Application,&c., p. 284-5.) Rolled flat irons can now be obtained about 13 to 14 inches deep, frotn2 inch to an inch in width, up to 30 feet in length, and for special cases somewhat «. The muthod of trussing a beam is explained in Cakpentrv (par. 2021, et scq.).. Ftg- CI3s. Fis- Gist. and I629w. The formulajfor finding the strength for examples V.,_^_V. 675.,are—=A;V/ 2+-^ = s. Here Z length in feet; d depth in feet—both measured from the points of intersection of the stay, tension rod, and top beam ; W load in tons uniformly dis-tributed; h horizontal thrust on beam in tons ; and s strain on inclined pait of tension rodin tons. When the truss has more than one stay, h, /, and (/ will represent the same ; andA, tensile strain on the horizontal portion of the rod. The strain on the inclined tie rodwill be —.\/1--ru-d^ — s; n the number of times that the horizontal distance between the pier and the nearest stay is contained in I. If any load be placed on the middle, the sraiiih will he doubled. If any load be placed en each of the stays, then I will represent thedistance of each loaded stay
Size: 2305px × 1084px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, booksubjectarchitects, booksubjectarchitecture
