Engineering Wonders of the World
Volume I

10 ENGINEERING WONDERS OF THE WORLD. is hardly less than marvellous. The Baltimore American Newspaper Building, destroyed by fire in 1904, was replaced by Speed Records. , , £ . i a new structure ot twelve stories in the space of five and a half months. The Farmers’ Bank Building, Pittsburg, an edifice 350 feet high above the pavement, 140 feet long, 120 feet wide, and containing nearly 5,000 tons of steel, went up in six months from the time of completing the foun- Fig. 20.—DIAGRAM OF PROGRESS IN RECONSTRUC- TION OF THE “BALTIMORE AMERICAN” BUILDING, 1904-5. dations. The steel cage of the New Phelan Building, San Francisco (329 by 296 by 205 feet), was erected in seventy-five working days ; and in the same city even more sensational records have been made. In Figs. 20 and 21 we give graphical representations of the pro- gress made on the two buildings first named. The mention of San Francisco naturally turns our thoughts to the earthquake and fire Fig. 21.—DIAGRAM OF PROGRESS IN CONSTRUC- TION OF FARMERS’ BANK BUILDING, PITTSBURG, 1904. of 1906, and suggests inquiry into the suit- ability of steel-frame buildings to resist severe shock and prolonged exposure to fierce heat. We will deal first with the question of earth- quakes. Fig. 22 contains curves a, b, c, and d, illus- trating the oscillations in buildings affected by (a) (b) (c) (d) Norma! Position I'1Movementi Cr Reversal 2ndReversal 3rd Reversal Fig. 22.—DIAGRAM OF VERTICAL EARTHQUAKE MOVEMENTS. the horizontal movements which are the most destructive features of earth- quake shocks. The normal Earthquakes, position of the building is here represented by a vertical line, and its form at each oscillation by a curved line. Now let us consider, with the aid of Fig. 23, what would be the effect of similar contortions on an ordinary brick wall. The first move- ment, a, breaks all the joints on one face, RrMovement I’1Re versa I 2 Reversal 3rdReversal Fig. 23.—DIAGRAM SHOWING EFFECT OF EARTH- QUAKE MOVEMENTS ON BRICK WALLS. absolutely destroying the bond of the mortar ; the first reversal, b, shuts up the joints on the right-hand face in the lower half of the wall, but opens those on the top left-hand face ; the second reversal, c, threatens immediate collapse ; and the third reversal, d, is even more threatening. Although purely diagrammatic, these sketches are sufficient to show that an ordi- nary building could not possibly survive more than one or two movements of the kind, and that it would very soon come tumbling down like a house of cards. By way of contrast, we give in Fig. 27 a sketch showing the effects of a severe shock