STEEL

Evening Star, Issue 19784, 7 February 1928, Page 2

STEEL

HISTORY OF ITS USE [By Ernest M'Culloi'gh.] The use of steel skeleton framework in buildings is such a common affair that it is interesting to review occasionally the history of the material. Just when iron was used first by man is uncertain. It is known that the Egyptians made it 3,700 years ago; but nothing remains of iron made then, for it was destroyed by rust. It is reasonable to suppose that iron was used contemporaneously with bronze towards the end of the bronze age, but the iron was destroyed by rust, while the bronze remained. But,'outside of minor uses, such as dowel pins, cramps to hold stone and wood together, bars, etc., iron was not used as a structural material until the eighteenth century. Legends have come down to these days of the use of cast iron water pipe as columns to support wooden girders prior to 1779. In that year, however, a cast iron arch bridge was built at Colebrookdale, England. The experience gained on that bridge led to the making of cast iron columns, girders, lintels, and joists. In the year 1801 a cotton mill was built in Manchester, England, with a complete interior framework of cast iron members, supplanting wood, which had heretofore been used in such factories. The exterior walls were of brick and stone, with cast iron lintels over door and window openings. This became common practice. The advent of passenger-carrying steam railways in 1825 brought about the use of iron, first in cast sections, later in wrought sections, for bridges. Cast iron was found to be objectionable because of its brittleness and because it was about three times as strong in compression as in tension. This great difference made a theoretically correct section impossible; for as there were many casting difficulties with the best possible sections, the excess weight was considerable. In 1843 (or 1845 or 1846, according to different authorities) cast iron girders were abandoned in buildings in favor of sections made up of plates and angles of wrought iron. This_ was in England; hut as was common in those days, the United States was never far behind, so that in 1850 some wrought iron girders wore used in this country. In 1849 a rolling mill in Paris rolled the first wrought iron joists (small beams) with narrow, tapering flanges. Wrought iron joist sections were rolled first in 1860 in England and about the same time in the United States. It is stated by English authorities that the first steel sections were rolled in England by Dorman, Long, and Co., fn 1886, but steel sections were rolled in the United States as early _as 1874, for the arches of tho Eads bridge at St. Louis.

Very little structural steel, however, was used in the United States before 1800, the great development of metal framed buildings that commenced in the ’Bo’s having much to do with the supplanting of wrought iron by steel. Carnegie, Phipps, and Co. commenced the rolling of steel sections instead of wrought iron early in the ’9o’s. It being a common idea with engineers that wrought iron was less liable to attack by rust than steel, insistence upon the use of wrought iron continued until it was no longer possible to obtain rolled wrought iron sections. This is the reason why many designers, builders, and writers in magazines and newspapers continue to use the word “iron” when they are talking, unknowingly in the majority of cases, about steel.

Mild steel, the only ferrous structural material used to-day in steel framework, is twenty times as strong as wood, ten times as strong as stone, four or five times as strong as the best cast iron, while it possesses toughness and ductility not possessed by any of these materials. It has practically equal strength in tension and compression, and has no weakening grain. In the year 1873 a French architect named Saulnier designed and supervised the construction of a chocolate factory at Noisiel-sur-Marnc, France, the building being described in the 1874 edition of ‘ L’Encyclopedie d’Architecture.’ The foundations consisted of four masonry piers in the river Marne, turbines being placed between the piers. Large girders spanned the openings betwen the piers and these girders supported the wrought iron framework that consisted of H sections, bolted and riveted together. It differed in no essential detail from a skeleton steel framework of to-day, and Monsieur Saulnier is entitled to be called the “ father of the skeleton frame building.” Many American engineers and architects had studied in French and German schools, so it is not credible that the design of the French chocolate factory was not familiarly known. The wails of the factory were of hollow brick, the object being to reduce the weight and thus make it possible to use-light wrought iron sections. ' Between 1880 and 1883 George Post, a Now York architect, used cast iron columns to support the walls of the inner court of the Equitable Life Building in New York City. After this experiment had been made the firm of Burnham and Boot. Chicago, designed the Western Union Building in Chicago in 1883, carrying the thin walls of the interior court on spandrel beams at each floor. In the year 1883 W. L. B. Jenney, a Chicago architect, designed a building for the Home Insurance Company in that city. The original design was for a ten-story building, but it was built to a height of twelve stories. This building brought to Mr Jenney the title of “father of the sky-scraper,” but in many essentia,ls_ it was not a real skeleton frame building. In the controversy that raged from 1888 to about 1895 his scheme of framing was referred to as “cage construction,” the true metal framework fastened together rigidly being termed “skeleton frame construction.” Mr Jenney used cast-iron columns supporting wrought-iron girders and beams for the interior, something that had long been common practice. He was the first (after Saulnier) to use framing in the exterior walls, with the walls carried on spandrel beams, this innovation saving weight in the walls, giving more rentable space because of thinner walls, and making considerable saving in the size and cost of foundations.

The exterior columns were of castiron with, brackets at each_ floor to carry the wrought-iron floor girders and side' brackets to carry cast-iron lintels over the windows. The columns carried all of the floor and wall loads, baling encased m brack pteas, so desigpgd

that they carried merely their own weight. The framework was lacking in rigidity in the connections. _ tn 1886 the Tacoma Building, Chicago, was designed by Holabird and Roche, architects of that city, the erection being completed in 1887. It was twelve stories high, on a corner lot 80ft by 125 ft, and the two street fronts, with all the interior frame,_ complied in all respects with the principles of true steel-framed construction. It was not, however, a complete building of this type, for the two party walls were oldfashioned bearing walls. For many years designers were dependent upon steel companies for designing handbooks, of which several were in common use up to within quite recent years. Structural steel was rolled in the forms of angles, channels, and I sections, the latter being, known as “joists” in Great Britain. Standard sections wore adopted finally after the various companies bad tried the experiment of rolling certain standard sections and a few specials of their own. For many years before the “junior” light rolled' sections appeared . there were on the market built-up sections of pressed sheet steel. . Derisively termed “tin joists,” they justified their right to exist, and the deserved popularity of these light sections led to 'the experiments which resulted in the rolling of sections lighter than the standard sections of the day. . ' Pressed steel joists developed from pressed steel channels used first for making partitions.' Two channels bolted together made an 1 section, tho sizes increasing until they now may be procured in all of the standard depths. Welding has supplanted riveting on many sizes. There are on the market light joists of steel rods formed into trusses. Tho rods are of a form that gives a large section, the argument being that rust is not likely to claim a largo percentage of the strength. The open spaces in the trusses afford room for putting in wires and all of the pipes and conduits so necessary in modern buildings. The light steel partition channels and pressed steel angles, channels,' and 1 sections have brought about steel framing for complete houses. Many such houses have been erected, and the companies engaged in promoting the idea report great interest. The light rolled sections . also have been and are being used in residence construction. In Great Britain there was difficulty in building houses fast enough after the war. The shipbuilders had little to do, and in casting about for means to keep their yards going developed the steel house. Two methods of welding arc in common use—namely, by the electric arc and the oxy-acetylene flame. The methods of design wall not be affected, for welding is welding. In addition to tho elimination of noise, welding makes a saving in material. When tension pieces are riveted together . they must be made wider than is strictly necessary for strength, by adding the width of a strip equal to the diameter of the rivet, or rivets. Gusset plates and connection angles must be larger than would be necessary otherwise. When joints are welded the full area of each piece may be utilised. One interesting phase of the welding of structural steel is the revival of the idea of using tubular sections. It has long been an axiom that an area of steel in the form of a hollow steel tube is stronger than the same area in any other form. Many inventors have failed financially, and. caused other men to fail, because of the difficulty of making good connections in joining two tubes together. The welded joint for trusses of tubular sections appears to be a success. The use of steel, however, is not limited to the framing of buildings. On the walls of many low-cost houses steel sheet siding is employed, some of it with plain surfaces broken with plaster and trim, some of it pressed to imitate clapboarding and rustic. Pressed steel garages, filling stations, and similar . structures are good examples of this type of steel work. j It is used in the form of solid plates I in warehouses and industrial plants; in the form of grille and latticed plates in power plants where light otherwise would be shut out, as well as to present as little interference as possible with the circulation of air and tho accumulation of dust. In some of the construction used in modern power plants the open flooring is utilised as stiffening. Metal lath, of course, cannot be neglected in a review of steel as a structural material. It has . been a common item for many years in buildings, and is used for interior partitions as well as the exterior of Walls. It acts as a reinforcement in plaster and converts plastered surfaces into strong slabs. Protected by the plaster it is highly fire resistant, and the use of this "material has greatly advanced fire resistant construction. It is even used as reinforcement in thin concrete floor slabs resting on joists. Within recent years great advance has been made in the production of stronger steel, and the next event will be the production of structural steel very highly, .if uot completely, resistant to corrosion.