Engineering Wonders of the World
Volume I

12 ENGINEERING WONDERS OF THE WORLD. ^vall and floor loads naturally came best out of the ordeal, the damage from earthquake consisting merely of cracks in tile partitions and brick walls, and some .damage to stone be inferred from the diagrams, Figs. 47-56, page 397. Many inadequately protected steel-frame buildings have been destroyed by fire in the Figs. 29 and 30.—Sections of columns protected by wire netting or metal lathing coated in plaster of Paris, and held away from the surface of the columns by V-shaped strips of sheet iron or by vertical rods gripped by clamps projecting from the columns. Fig. 31.—Improved method. Double, envelope of plaster or metal lathing, with intervening air space. Note.—Plaster of Paris being readily destroyed by fierce heat, its use is not to be recommended. Fig. 32.—Column encased by wood lagging, covered out- side by sheet iron and concrete. Figs. 33, 34, and 35.—Improvement on last. Columns en- cased in concrete. Figs. 36 to 40.—Protection by terra-cotta blocks, of shapes varied to suit the cross section of the columns. Figs. 41 and 42.—Double terra-cotta casing. Figs. 43 and 44.—Wrong ways of leading steam, water, gas, and other pipes inside column casings. Leakage tends to corrode the metal, and repairs to the pipes necessitate the removal of part of the casing. . Figs. 45 and 46.—Proper methods of enclosing pipes in separate compartments of the casing. facing. As for the cage construction itself, wo need only repeat the general conclusion arrived at by the Committee of the American Society of Civil Engineers that “ the damage to steel frames was almost negligible.” Let us next consider briefly the most effec- Protection against Fire. tive methods for protecting steel-frame buildings against fire. The various systems of encasing columns are shown in Figs. 29-46. Floor, roof, and other girders are pro- tected in a manner similar to columns, as will United States. Consequently, far greater at- tention has been devoted in recent years to methods for the protection of steelwork, and especially to the employment of fire shutters, wired glass, water screens, and other devices for preventing exterior flames from gaining access to the inside of buildings. If columns and girders be thoroughly encased in concrete or terra-cotta, and doors, window-frames, etc., be made of metal, a fire is localized through sheer want of fuel. The San Francisco fire proved that, where proper precautions are