Figs. 169 to 174 show general features and details of a build ing of the shed type.
Fig. 169 shows the side framing, the openings. diagonal brac ing, eave strut and columns.
Fig. 170 shows a plan of the columns and trusses, and the bracing between. Fig. 172 shows the end-wall framing, and Fig. 171 is a cross-section showing the type of trusses and the bracing to the columns.
Fig.173 shows a detail of the walls and the columns. These -walls are for protection against weather only, and are not designed to stiffen the steel frame which is sufficiently braced together itself.
Fig. 174 shows the anchorage of the ends of the trusses if solid walls were used in place of the steel wall columns.
Figs. 175 to 177 show a machine shop steel frame with pin connected trusses. Generally trusses of this character are riveted, but occasionally they are pin connected.
Fig. 175 shows the cross-section with low wings along the side walls and a high central portion to provide room for a travel ling crane. This central portion is lighted by a monitor at the top as shown ; the windows in the end walls arc also indicated.
The columns are braced together and to the trusses and the whole frame is self-supporting. The crane runs on a track girder which is supported by a separate column. This is of advantage because it allows the column to be placed directly under the load instead of on a bracket which would-cause heavy eccentric load ing.
Fig. 176 shows a partial elevation of the side. The columns are placed under every other truss only; the intermediate cross trusses are therefore supported by longitudinal trusses shown by Fig. 176. These trusses serve also to give the necessary lateral stiffness to the frame.
Fig. 177 shows a detail of the ends of these trusses and the connection to the columns and of the bracing to the columns and trusses.
Figs. 178 to 183 show the outlines and some details of a light mill building having a double pitched roof as shown by the eleva tion, Fig. 178. This elevation has letters indicating the positions of the different types of purlins shown by Figs. 179 to 182.
As there are skylights on this roof, purlins B" have special framing. The regular puffin is " A," and " D " shows the wind struts between the columns ; there is also a wind strut at the ridge.
Fig. 183 is a detailed elevation of one-half of the main truss, and of the connection of the purlins to the truss.
Figs. 184 to 187 show general features and details of a com bined wood and steel frame mill build' ug. This form is used quite extensively. The main columns, trusses and girders arc of steel ; the roof purlins and floor beams of wood, and the walls of brick.
Fig.185 shows the detail for securing the wood purlins to the trusses.
Fig. 186 shows the main column which carries a bracket for a light crane. This column, on account of the eccentric crane connection, is made of the two channels latticed as shown; in order to get a stiff connection of roof truss to the upper section of column, and also, because of the light load, a column of four angles and a web was desirable. This upper column, therefore, sets down inside of the channel column and is riveted to it as shown by the details.
Fig. 187 shows the connection of the girders in the wings to the columns ; the double beams coming at right angles to the web made it necessary to use deep shear plates across the flanges of the column in order to give support to the bracket and provide for the eccentric strains.
The following definitions apply to pieces often met with in detailing and should be fully understood.
Lag Screws. These are used for connecting wooden construc tion, and their principal use, so far as the structural draftsman is inter ested, is for fastening guard rails to plank flooring on highway bridges, or to cross ties on railroad bridges, or wood purlins on roof trusses Bolts. This term is applied to bolts used to con nect parts of a member, or to connect members to each other, prior to riveting. The bolts are removed and rivets driven in their stead. In making out the shop lists where work is to be erected, a number of these bolts must be included, and about 10% more should be ordered than will appear to be necessary, in order to allow for waste. Fitting-up bolts are used in the shop during the assembling of the parts of any member of a structure.