Big Building Devices
MECHANICAL WONDERS AND ENGINEERING FEATS COMBINE IN THE REARING OF THE MODERN SKIY SCRAPER
This article is one of the most interesting of the building series which readers of MacLean's Magazine have had the pleasure of reading in recent months. Mr. Holt has dealt with many phases of the building problem in his articles, but no feature has presented more fascinating points than the modern devices of construction outlined in this treatise. Just as we have advanced to the age of steel and concrete in building so we have progressed in the development of mechanical devices which render great modern engineering feats possible. The most notable of these are described in this last word on big building.
AN American friend of mine who bought an old manor-house in Warwickshire desired to put in a new garden door in one of the ground floor rooms. “I dessay I could do it for yer if yer reaaly want to ’ave it,” said the local builder after examining the spot and taking measurements, “but it’ll be more of a passage-like than a hordinary doorway . . . The wall’s eight foot thick just where you wants to
make the ’ole in it.” At another point the wall was eleven feet thick, but that was at the foot of a tower and included a bit of a buttress; in most places there was no more than an eggshell of three or four feet of solid limestone between the inhabitants of the house and the weather.
“All!” say s t h e enthusiast, gazing admiringly at the window embrasures of such a house. “Those were the
days when men knew how to Build” On the contrary, it was because of what they did not know about building that those grand old castles and wonderful old houses came into existence. Grand old houses, marvellous walls, fit to endure the assaults of ages, but the product neither of scientific nor economic building. They were built when material was cheap and labor cheaper.
We build better, but—if you will forgive the paradox—we are never likely to build anything half so good. Our days will be the “bad old days” from the viewpoint of the antiquarian a thousand years hence for our cities will be tangled webs of rusty steel, our suburban residences will hardly leave a mound to
mark their sites, still—well, we make preby good buildings all the same.
POSSIBILITIES AND LIMITATION'S.
Never before has building had greater possibilities and fewer limitations. A very few years ago it was ridiculously
limited. Height, span, form were all subject to a thousand restrictions of material. Even things that were theoretically possible were practically out of the question. This was rather fortunate considering the architectural taste of the greater part of last century. If builders had been able to work as solidly as in Tudor times or on as magnificent a scale as in the present, imagine what monstrosities,
terrible in their size and appearance, would cumber our streets.
However, with modem methods has come a revival of that mysterious quality “good taste.77 Even our factories are being built with some slight regard for appearan/ es and our h lusc.i and cil v buildings are becoming more and more fit to look at as well as mere shelters from the weather.
First, came improvements i n transportation and then greater possibilities of using materials brought from a distance
that were better than local product; then came machinery to help eke out the limitations of manual labor in the work of erecting a building; next, the wider
choice of building
material, the use of cast iron, wrought iron, steel, and
eventually concrete, reinforced concrete, new forms of brick and terra cotta, ariiieial stone — a host of materials which in one way by making things possible that were impossible before, and in another by cheapening work and, therefore, allowing more and better work to be done, increased the scope of building to an enormous extent.
In all forms of building Canada has kept pretty well abreast of the rest of
the world. Some things, naturally, have been too big for a young country to tackle, and again it is only natural that a growing country should have neglected the quality of permanency— what use is there in building more than a temporary shack when a year piay see the need of replacing it with something better? But within the last few
years big things have come within Canada’s reach and permanency too, and Canada can look the world in the face without blushing for her building achievements. The most striking and spectacular development of modern building has, perhaps, been in the matter of steel construction. There is something fascinating about the human towering steel structures which are arising in every Canadian city as they have arisen in every city in the United States; skyscrapers, which turn from gaunt ribbed skeletons to vast buildings decently clothed with
a flesh of brick or stone or terra cotta almost before one realizes that the ori.ce imposing five-storey buildings they replace have been torn down.
They are fascinating from their size and height, but they are still more fascinating from their very simplicity, for they are extremely simple. Think of what a huge tower such as the Traders Bank Building in Toronto would have meant in the middle ages. Its building would have been counted not in days or even years but in generations; vast blocks of stone would have been quarried for its base and its walls, supported by their massive buttresses, would have risen course by course at mighty cost of human labor, each a little mountain, as it were, of solid stone. ■
We might almost be back in middle ages still had it not been for steel : The beginning came in the ’fifties when attempts were made to make greater use of iron in combination with masonry. It is obvious of course that the wall of a building has to carry considerable weight; the weight of the roof, of the various floors and their loads and its own weight. That is why, in primitive building, an enormously wide base and massive buttressing was necessary to
prevent the wall from collapsing under its own strain or buckling under pressure of the various outward “thrusts.” The first use of iron in building goes back a long way since bars or stringers of iron were used in the 16th century and earlier to “tie” the walls of a building together and thus counteract the buckling tendency. The real ancestor of the modern steel building, however, was the iron column built into the masonry of the wall to carry the weight of the various floors and leaving the wall to carry its own weight alone. This was devised in answer to the demand for greater height in buildings and it did allow of a considerable increase in height, but after a building had risen a few storeys more than was previously possible the old limitations again asserted themselves; the iron might have gone higher, but the brickwork could not have reached the limit at which it could continue to support its own weight.
So by natural evolution the iron columns were made to support the walls as well as the floors and the “degree of limitation” was transferred from masonry to the strength of iron. Cast iron,
wrought iron and eventually steel increased the limit till to-day the strength of steel gives possibilities that are practically limitless.
The modern steel building always seems to me to be more akin' to the primitive tená than to the primitive stone Jhut. \ Tt is a twentieth century wigwam, a framework of steel poles over which is hung a curtain of masonry. When all allowances are made for comparative sizes it is far simpler than a wig' warn to construct.
The mediaeval buildim — almost any pre-railway
building for that matter—was necessarily built of local stone or bricks burnt from local clay. With the modern building the materials may, and often do, come from the other side of the world. The steel for most of our big steel buildings comes chiefly from the States, but also to a great extent from England and from Germany. In far away shops the girders are rolled and shaped to definite shop drawing measurements; in some cases they arrive ready to be fitted together at once ; in others they are cut and fitted by some local concern. Most important are the columns, the great uprights on which depends the whole weight of the building and these are made of the
“softer” grades of tough steel. For the transverse girders and the struts and stays which hold the building rigid and stable, medium grades are permissible, steel that is more brittle and not so capable of bearing the enormous strain imposed upon the columns.
The difficult problems of the work
are not, as a rule, evident in the ordered tangle of steel girders into which the spectator stares from his position on the sidewalk. They lie underground in the depths of the excavation which has been dug out and deepened and made ready months before the first girders of the superstructure have peeped above the surrounding hoarding. The problem of the skyscraper is not in fitting it together, that is all reduced to a formula long
ago, the problem lies in finding something for the great tower of brick and steel to stand upon.
Where there is bed rock within reach there is, of course, no difficulty, but, more often than not, bed rock is inaccessible. In this case the usual course is to found the supporting columns on great masses of concrete, the weight of the whole being distributed over a large area on a huge web of steel “grillage.”
The building stands on the more or less soft subsoil steadily and without sinking exactly as a m a n stands by means of snowshoes on the soft surface of the snow.
In other cases where there is a great deal of soft soil through which water freely percolates and where it would be impossible to “float” the building safely on “snowshoes” elaborate caisson methods
have to be employed. Roughly, the caisson is a huge tank which sinks through the soft soil by its own weight. Inside it, work the laborers digging out the soil of the pier hole, which is hoistup a central They work presveral
senses, for the caisson is filled with compressed air with the object of keeping out the soft soil and water, which otherwise would force itself into the gradually growing excavation. Eventually, when the wet layer of soil has been penetrated and a hard basis arrived at the great shaft of the caisson is filled with cement. A succession of these make a solid foundation on which the steel superstructure can be reared. But the variations from the usual plan to fit special circumstances are innumerable. Many steel buildings are
based upon a system of humble wooden piles; in some cases the expensive plan has been resorted to of actually freezing the liquid mud through which the pier holes had to be sunk, the mud being made hard enough for excavation by being pierced by a ramification of little pipes through which freezing mixture was run. These problems of foundation apply not to steel buildings alone but to any buildings of great size and weight.
Any of these processes may be in course of operation in the excavations
of which you catch glimpses when the wagon loads of earth and rock come staggering up the incline into the street. With most of the big Canadian buildings the problem of foundation has been simple enough, though in two or three cases in Montreal the expensive .-caisson system has had to be used, notably with the new additions to the Windsor station. Naturally the ordinary passer-by does not see these operations since they go far deeper than the great pit revealed to the casual glance, which is dug out over the whole site and which merely represents the one or two, or possibly three or four basement storeys which balance the fifteen or
twenty storeys above. Deeper still is the elevator pit for that must go down the same number of storeys as the building rises above it. It is made by means of a steel shaft, sunk easily enough through soil and clay with the aid of a little bit of water washing soil from under it. When it reaches rock, shot and sharp edged gravel are poured down and rolled and worked about under the end of the shaft till a hole is cut and scoured through. It is into this narrow pit that the shaft of the hy-
draulic elevator descends as it drops from floor to floor with its passengers.
MODERN CONSTRUCTION DEVICES.
The basement excavation becomes the site of quite a little factory during the building operations, for machinery has taken the place of most of the hand labor of the past and an engine room in some central position is one of the prime requirements. Even before the excavation is made, machinery comes into play. Very often, for example, a steam plough does the work of breaking up the ground and it is becoming the rule rather than the exception for a steam shovel to replace the human “wops”
who were wont to drape themselves picturesquely along the sidewalk edge during the lunch hour. A steam shovel specially designed for compactness ¡3 to be brought into play on the excavations for Eaton’s big new building in Toronto —for the first time, it is said, in Canada. Then concrete is mixed by machinery ; machinery is necessary for the hoists and the air compressors and in a dozen different ways.
The big steam crane is the rule1'* of the roost. Perched in its convenient central position in the excavation it lifts the first huge girders into place and gradually rises storey by storey with the building which is fitted together around it. The steam crane on the C.P.R. building in Toronto—a good typical example of the Canadian skyscraper--can lift up to 12 tons and swings bundles of girders up to a couple of hundred feet above the street level as though they were so many sticks of wood. For a sixteen storey building such as the C.P.R. office it would handle 2,000 or more tons of steel in the course of the work and would then have to deal with a couple of million bricks for the walls. When all is finished it comes to pieces and descends from the top of the building it has picked up bit by bit from the ground, ready to get to work on another one.
Here and there in the steel framework chatter the pneumatic riveters. Close to where a new girder is to be swung into position by the crane, a little portable forge perches on a platform. It is attended by the “Heater” who feeds it with rivets and sees that they get properly red hot. One by one, as they are needed they are taken from the glowing forge by the “Thrower” who tosses them accurately to the “Sticker,” one of the three men clustered at the end of the great steel beam. The “Sticker” thrusts the rivet through the holes awaiting it ; instantly the “BuckerUp” has his heavy “dolly” pushed hard against the glowing head and the “GunMan” jams the nozzle of his “gun” over the little red-hot projecting end of
the rivet. Chatter, chatter goes the “gun” as the compressed air in its snaky tube jerks the plunger in the nozzle backwards and forwards two hundred times a second ; after a moment the gun is drawn away and the end of the rivet is revealed neatly mushroomed out to correspond with the head upon the other side. As the rivet cools it contracts and draws the two girders it joins still closer together. Meanwhile the riveter and its crew are at work upon the next one.
After the riveters, come the men who protect the steel from its most dangerous enemies, rust and fire. Every girder is very carefully cleaned and scaled and then painted and encased in asbestos, terra cotta or some other material or cement. The last is the common method nowadays since it has been found that cement sticks to smooth steel, protects it absolutely against rust and minimizes more than other materials the danger of its buckling under the action of heat. All the steel girders and columns have to be covered in some way against the attacks of their enemies and the more completely this is done, and inflammable material eliminated from the interior fittings, etc., of the building, the more fire-proof it is.
Even before the steel work is all riveted together and finished, the masons and bricklayers may he at work on the lower storeys. The steel work, as T have said, carries the whole weight of the building, walls and all, so work may be in progress on several storeys simultaneously. Usually the walls are simply brickwork built in the ordinary way from the girders of one floor to meet the girders of the one above. Where there are balconies or cornices the girders project for their support and the protruding portion is built on them or hung from them as desired. Terra cotta and artificial stone are coming into more and more favor every year in replacing brick as a “curtain” with which to fill the interstices of the great Steel skeleton and with both of them it
is possible to get very excellent effects architecturally.
STEEL AND CONCRETE.
The usefulness of steel in building has not begun and ended with purely steel construction ; far from it. It is used in conjunction with brick and stone and almost every other building material to a greater or less degree and has proved invaluable in a thousand different ways. Its most important d e -velopment has been its use within the last decade, in conjunction with concrete. Reinforced concrete is beginning to appropriate a pretty big share of the honors of the modern building.
Reinforced concrete, as anyone knows, is simply concrete strengt hened with steel, usually in the form of bars or meshwork, and designed, therefore, to combine the strength and advantages of both these materials.
After all, when you come to think of it, the casing of the columns of a steel building in concrete for protection against rust and heat is a step towards reinforced concrete and it is not surprising to find the new material largely replacing steel pure and simple in the construction of big buildings.
There is not the same apparent ro-
mance for the spectator in watching a reinforced concrete building going up, but it is fascinating nevertheless since the building operations look so absurdly simple and also since the building has an air of solid permanency from the very outset of its construction.
Foundation problems are practically the same for all types of buildings and
may always be difficult of solution, but once the foundations are well and truly laid a reinforced concrete building can go up storey by storey with astonishing rapidity, far more simply and rapidly even than a steel structure.
A concrete building appears to build itself up out of the dust. Here are no huge piles of material, stacks of bricks, blocks of stone, great tiers of beams of any of the preparations one associates with the making of a big building. Bit by bit the materials come to the site in the form of waggon loads of unimpr e s s i v e looking steel rods, commonplace sacks of cement and mere ordinary sand and gravel. Down in the basement are a few insignificant looking concrete mixers at work, those curious coneshaped machines which lately have become so familiar. Busily the cones revolve and the sand, gravel and cement are transmitted into the thick, pasty
semi-fluid which will harden into solid stone.
Where the walls are gradually rising, the builders are arranging “forms,” the bottomless troughs or moulds into which the concrete is poured. Above the forms project a bristle of ends of steel, the bars or webbing or whatever form the reinforcement may take which is erected inside the forms ready for the concrete to settle and harden around it. As with the walls so with the supporting columns scattered at proper intervals about the interior of the building ; the forms are arranged in a precisely similar way differing only in their thickness and the strength of their reinforcement.
Ten days to a storey is a usual allowance of time for erection. On one day the columns are “poured” and on the next the floors. As each storey “sets” firm and hard the one above is started, and thus a five or six storey building may arise from its foundations in as little as two months. Often a building is only framed in concrete, exactly as a steel building is framed of steel, the curtain walls being built of brick or other material. But there is a growing tendency to use concrete exclusively for floors, walls and everything else and thus to make a building practically equivalent to one hewn out of solid rock—with the additional advantage that the “rock” is provided with tough steel fibres and sinews.
Of course concrete has its disadvantages. Like the little girl, when it is good it is very very good, but when it is bad it is horrid. Bad concrete made of inferior materials or mixed in the wrong proportions may crumble away like unburnt clay, but good concrete has the astonishing property of getting harder and better every year of its life. Advantage is taken of this quality of good concrete in rather a singular way. A building of say four or five storeys is made and left as such for a couple of years. At the end of that time the concrete has hardened and strengthened to such a degree that it is possible to add
an additional storey without any strengthening of the substructure as would be necessary with any other class of building.
In Canada, so far, concrete reinforced or otherwise, has been used chiefly in the construction of factories and similar buildings. There have been a few office buildings made of it and numerous smaller buildings such as dwelling houses, but in its experimental stages its use has been characterized by a certain heaviness and clumsiness which has created some prejudice against it, when appearance has to be studied. This heaviness is not by any means necessary; concrete is capable of considerable lightness and grace and naturally by the use of well designed moulds on the outside walls of the forms, it has great possibilities of ornamentation. But at any rate it is well that factories jvith their great demands of strength, fire-resistance and so on should have seen it through its early stages and it could have no better introduction to the world in general than the enthusiastic testimony it has received from manufacturers.
REMARKABLE BUILDING FEATS.
Even though the purely steel structure no longer has the field of big, economical, and rapid building all to itself it is responsible for most of the miracles the modern builder has accomplished. And not only has it made miracles of construction possible, but of reconstruction also. Quite a commonplace feat of steel, for instance, is the creation of one building a-straddle of another.
The case of the Bank of Hamilton’s head office in that city is a good example. The Bank was housed in an old three-storey building and desired, without changing its site to move into a modern structure of nine storeys. No temporary premises were available in the town and it was therefore necessary to add another six storeys to the existing building without shifting or disturbing the business of the bank carried on therein.
In a very ingenious way the foundations of the old building were, bit by bit removed and replaced by much more extensive concrete foundations fit to carry the weight of the extra six storeys. Naturally enough, there were many difficulties about this work, since it had to be carried out in the dark and confined space of an excavation underneath the old structure. Still, it was successfully accomplished and on the new foundations a steel framework was based, the columns of which were carried upwards through the old building to support the new. Thus the six new storeys were built, so to speak, on a steel bridge spanning the old building and resting on the same foundations. When all was ready¿ the old and new walls were joined and a nine storey building was the result in which the two lower storeys of the old building were left practically untouched. The three unique illustrations which accompany this article show in a striking manner, three stages of the work.
Similar operations have been carried out in many parts of Canada; in Toronto, the other day, three storeys were added to a building in almost exactly the same way and indeed there is hard-
ly any limit to the resources of the building engineer with modern materials and methods at his command.
Still, with all the wonders that steel has made possible, it is refreshing to the conservative mind to see good old-fashioned masonry still holding its ground and to watch even the biggest types of buildings going up brick by brick, course by course, on exactly the same principle as that wherewith Balbus builded his wall and the federated nations on the plains of Babylon started their abortive skyscraper.
Only the principle is the same; the methods and materials are very different. Of bricks, for instance, there are now many kinds in use for different purposes and there is unbounded wealth of choice in tiles and terra cotta and artificial stone. Still the ancient principle remains. The bricks, or blocks, or slabs are slung by cranes or derricks, or carried by immemorial hodmen to their appointed places in the wall and bonded together with mortar. Even concrete conforms in some instances to old tradition ; instead of moulding itself into a monolithic mass it allows itself to be shaped into blocks and built up in the good old-fashioned way.