The Building of Manhattan, page 11
Here the developer and his architect express their own sense of personal pride and creative ability by designing a space that is meant to be individual and different.
The IBM atrium is airy and welcoming with its bamboo plantings and opportunities for the visitor to sit and relax; the Trump Tower is opulent, and extravagant in its use of space and materials. Citicorp Center’s atrium and plaza create their own lively neighborhood, busy and fast paced. The Equitable Center provides a branch of the Whitney Museum of American Art. Tiny in comparison, the Philip Morris street galleria also entices the public with its exhibitions of art from the Whitney. Wherever they’re found, these public spaces add immeasurably to the human enjoyment of the city.
For the developer there is an added incentive. Under the zoning code he may be able to increase the height of his building, with more rentable space, in exchange for having provided this public convenience.
For the architects and engineers these great open street-level spaces are a test of their abilities. Not only must the supporting columns be designed to carry all the weight of the entire building above them, but the supporting beams spanning the open space must be capable of withstanding enormous stresses. Concrete has been used to spectacular effect in archways, domes, and complex structures, but there is one material that is preeminent in spanning great distances with a minimum of volume.
It is steel.
STEEL
The steel skeleton of a big building is put together piece by piece, creating a latticework of metal in the open spaces above the city. The man who raises the steel beams, wrestles them into position, and bolts them solidly into place is the ironworker.
From the streets below he is seen walking along narrow beams of metal, in defiance of common sense.
There is nothing but his confidence, concentration, and sense of balance to prevent his falling hundreds of feet earthward to the streets of the city. The steel skeleton of the skyscraper is his handiwork.
STEEL
Girders, columns, beams, trusses, sheet metal . . . all kinds of shapes and sizes . . . in steel.
The big pieces are trucked to the construction site resting on wooden blocks so the lifting cables or slings can be easily slipped under and around the heavy metal.
Such as the 125-foot-long girders, each weighing 70 tons, for the Marriott Marquis Hotel in Times Square.
Sixty thousand tons of steel for the Empire State Building.
More than 200,000 tons of steel for the World Trade Center.
Steel: iron ore melted at high temperature, alloyed with carbon.
The basic metal can be transformed into hundreds of different steels—each for a specific use—by the addition of minerals or chemicals, and by precise heat treatment. Beams, columns, and the other steel members of the skyscraper must be fabricated to the exact shape and size needed, and ordered months in advance of use. The steel may come from a foreign country or from a nearby state, depending on the cost and when it is needed.
Some high-strength steel used in the World Trade Center is rated to withstand an ultimate strain of 100,000 pounds per square inch. Few steel pieces require such strength, which is determined by the structural engineers and built into the metal exactly according to their specifications.
Now the steel has been formed and drilled according to the engineer’s working drawings. It has been shipped to the ready yard—usually just across the Hudson River in New Jersey—until the day and hour it is needed.
AND IRONWORKERS
Legend attributes to the American Indian the ability to work at dizzying heights without fear. Many of the men who work the steel in Manhattan—all are called ironworkers—are indeed Native Americans. It is said that Canadian Indians first helped put up a high-water bridge over the St. Lawrence River, beginning this tradition of Native Americans working steel at great heights.
Manhattan’s ironworkers are journeymen, moving from job to job, wherever work is available.
The top man is the connector. He is the man high up on a girder, usually with a partner, wrestling a dangling steel beam into place. With the pointed end of his spud wrench he lines up the holes so he can punch in a bolt to hold the beam in place. Then he shinnies out on the beam and releases the wire cables that lifted it into position.
Next, other ironworkers put in and ram tight the rest of the bolts with compressed air guns once they have made sure that the steel is level and true. Later, the decking gang puts down the corrugated steel floors. Overseeing it all is the foreman.
Down on the street level, wire cables are placed around another beam that’s about to be lifted. The tag-line man hooks a rope to the end of the beam to guide it and keep it from swinging about as the crane lifts it skyward.
LOOK OUT BELOW!
This mighty beam is being lifted to a temporary resting place somewhere on the construction site. Later in the day or early the next day it will be lifted into place on the building’s framework.
Down below at street level the traffic has been halted, stopped for a few minutes by the flagman, as the steel is swung up off the delivery truck. Now the crane operator has it under his control and the big truck will move out fast. freeing the unloading area for the next delivery.
Space to unload and store material is always a problem at any building site in Manhattan. The city regulates any encroachment on its sidewalks and streets. It’s always a tight fit to unload material as the rush of traffic squeezes by. Yet the construction crews must have their equipment available as the building takes shape.
The city also requires safety precautions for the general public at all construction sites. The threat of a multi-million-dollar lawsuit against a negligent construction company is an added incentive to avoid accidents. To guard against accidents, each large construction project–specified as being at least 200 feet high, or 15 floors, or covering a lot area of at least 100.000 square feet–must have a qualified site-safety supervisor who is responsible for identifying and correcting any safety hazard or violation.
SPUD WRENCHES
The shiny steel spike with the wrench on one end is the ironworker’s indispensable toot—his spud wrench. It comes in different sizes, to fit the need. It is polished to a high finish by constant handling. The tapered end is jammed into empty bolt holes to force a beam or girder into position so a bolt can be inserted into the lined-up holes. Then, with the wrench end, the ironworker tightens the nut on the bolt.
His spud wrench is not a straight piece of metal: the wrench end is offset, allowing hand room when tightening a nut. Usually two spud wrenches hang from his belt to meet that day’s requirements.
His work belt, separate from the belt that holds up his pants, may weigh as much as 30 pounds or more. His leather or canvas pouch is his carryall. Nuts and bolts, clamps to lock wire cables together, anything he’ll need, all go into his pouch. The coiled rope is his safety rope, used to tie himself to a support in an especially dangerous work position.
His friction lighter, or striker, hangs from his belt. It’s used to light an acetylene torch if he has to trim away a bit of excess metal, which happens from time to time. The wonder is that it doesn’t happen more often. Blueprints are drawn in New York City for steel that is fabricated and drilled with holes hundreds, perhaps thousands, of miles away.
When the heavy metal arrives in Manhattan and is hoisted into position high up on the building’s skeleton, it has to fit. The ironworker’s job is to wrestle it into position, and to bolt it in place. Sometimes a hole has to be enlarged with a tapered reamer, right on the job.
There are times when a loud clanging hammering noise reverberates through the city’s streets. Very rarely it might be a dropped wrench bouncing off steel beams on its way down to a lower level. More likely, two large pieces of steel do not line up exactly, and a drift pin is driven in to align the holes. Then the ironworker pounds the metal beams or columns with a heavy sledgehammer. He must move the metal beams just enough for the pin to be loosened and the bolt inserted and rammed home.
FROM BEAM
Two ironworkers, connectors working as a team. are at a new height, the highest yet of the building’s steel framework. They have just temporarily bolted two horizontal beams to the upright column where they are perched. About them, at their level, are more tops of unconnected steel columns.
Now it is time to join these columns together by bolting horizontal beams to their tops, creating a new floor level of the building’s construction.
Below the ironworkers lie the beams that are to be lifted into place. They were placed there earlier when and where space was made available, in accordance with the time schedule. The foreman has consulted his drawings and checked the numbered markings on each piece of steel at this lower level. There are shouted words—the beams are facing in the right direction but are not in the correct order for lifting by crane. There is quick action as loud curses fill the air. Other ironworkers attach cables to the out-of-place beam, guide the tower crane operator with hand signals, and get the sequence right.
A new beam is hoisted to the men waiting above. One ironworker has guided the beam end into place, while the other has inserted his spud wrench in one of the predrilled holes, lined up the two pieces of metal, and shoved in a bolt. His partner walks the suspended beam to its opposite end, forces it into position, and puts in a temporary bolt. They signal for the next beam. They may stay up on the beams, moving along each time they create a new place from which to work, until all the upright columns of that section have been connected.
The columns and beams are now connected and the “bolters-up” have put bolts in all the rivet holes. They are still called rivet holes even though rivets are no longer used this way. The nuts on the bolts are loosely tightened. But are all the uprights perfectly vertical? And all the horizontals true? To assure that this is so is the job of the surveyors, with their precision instruments. It is also the job of the “plumbers-up” to check the positioning of the columns and beams. They will have to physically adjust any piece of metal that is out of plumb. They stretch heavy wire cables with giant turnbuckles between the upright columns of steel. The surveyor’s crosshairs, fastened to the top of the column upright, must line up with the surveyor’s sight to have the steel upright truly vertical. His hand signals tell the ironworker to loosen or tighten the turnbuckles, until perfect alignment is achieved. One way to determine a true vertical is with the plumb bob—a a pointed weight suspended on a string or wire—in use since the days of the ancient Egyptians. When any piece of metal is found to be off-line the turnbuckles are adjusted and the wire cables stretched taut, holding the columns true while the bolts are tightened.
TO BEAM
These steel columns, which have just been temporarily bolted, are each two floors tall. They will now be checked for vertical alignment and be permanently bolted, welded, and inspected. Steel Q-decking will be laid on top to provide a floor on which to store the steel for the next upper levels.
As the crane lifts steel up to the new top level, stores it there, and then positions each piece for the ironworkers to temporarily bolt in place, the floor just below is being worked on. It was bypassed. Now it is its turn to be permanently bolted, welded, inspected, and to get its Q-deck flooring. This jumping of floors speeds up the construction of the building’s framework.
The four-inch layer of concrete for the floors will be poured on top of the Q-decking later, from the bottom floor on up to the top.
THE WELDER
Weldiers can he seen anywhere on tie building’s skeleton, with the blinding light from their arc welding rods showing where another permanent bond is being joined in the steel beams and columns.
Welders are enveloped in protective clothing: large leather gauntlet gloves, leather aprons, and shoulder and arm guards. These prevent painful skin burns from the blinding arc of electricity given off at the tip of the welding rod. Special eye goggles and protective head masks protect their eyes and faces, for the electric arc gives off invisible untra-violet and infrared rays as well as intensely brilliant light.
The arc welder gets his low voltage, yet concentrated electricity, from a portable generator. It is so powerful that it can create a temperature of 10.000 degrees Fahrenheit at the tip of the slender welding rod, which melts and flows at the joining of the separate pieces of steel to create a permanent bond.
The electric current from the generator flows through the cable to the electrode in the welder’s hand. It jumps a short gap as an arc to the piece being welded on the building’s steel framework. The current passes harmlessly through the building’s framework back to another terminal in the generator, completing the circuit of electricity.
The finished welds are each tested for imperfections with a portable ultrasonic device that sends high-frequency sound impulses through the metal. Any air pockets or imperfections in the weld show up on a testing meter, requiring that the weld be redone.
THE FLOORS TAKE SHAPE
Work ork proceeds simultaneously on different floor levels below the ironworkers. From below, areas may seem temporarily abandoned, but electricians, plumbers, sheet-metal workers—an the many trades that will build the interior of the building—are working according to schedule.
Now the concrete floors must be laid. The top unfinished floor shows corrugated steel lengths, called Q-decking, fitted on top of steel cross beams. The floor below that has wire mesh covering the Q-decking. A raised frame outlines the edge of the entire floor, and will hold in the concrete when it is poured.
The floor below that has a layer of four to five inches of concrete on top of the Q-decking. The wire mesh strengthens the concrete. Metal ducts for heating, air conditioning, and other services will soon be suspended from ceilings beneath the finished concrete floors. Conduits for electricity, telephones and plumbing had already been placed and capped in the concrete floor.
THE OUTER SKIN
Since the outer surfaces of today’s skyscrapers do not have to support the weight of the building, they may be thin sheets of glass, thin slabs of granite or stone, panels of aluminum, stainless steel, ceramic tile, or prefabricated concrete. This outer skin, or curtain wall, is suspended in front of the structural frame. It is bonded by special adhesives and bolted to the framework of the building, whether the building is of reinforced concrete or of steel construction.
The choice of which material to use can be based on esthetic reasons, as well as on the cost of the materials, ease of installation, and future maintenance.
Architects may set up test panels of the material they plan to use at the job site, to judge its visual effect and to test its desirability. The marble used for the curtain wall of the IBM Building in 1983 cost $8.6 million. It came from a quarry in Canada and was chosen carefully for its color, beauty, and resistance to weather.
In addition to keeping out rain and snow, the outer skin must act as insulation, keeping out heat in summer and cold in winter. It should also act as a soundproofing wall, minimizing street noises from the outside. It must meet standards of fireproofing. For example, aluminum will melt in extreme heat, so it requires additional safety precautions: steel fasteners and a fire-resistant back-up panel.
There is a wide range of anchoring devices and methods of installation. In some buildings grids are formed by attaching metal strips vertically to the building’s framework and fastening horizontal pieces between these verticals. Wall inserts, and then the windows, are installed in the resulting open spaces.
In other buildings large panel units, often with window openings, are fastened directly to the building’s structure to form a continuous outer surface.
All outer-skin materials are dependent on their anchorages, which fasten them to the building and by which the weight of the outer skin is transferred to the building itself. The weight of each piece, of whatever material, is never stacked one on top of the other. Rather, it is crucial that each piece be independently supported by its own devices connecting to the building’s frame.
TRADES AND UNIONS
Once the framework of a building has been erected, whether it is of steel or of concrete construction, and the outer skin has been put in place, it looks as though most of the work has been done. On the lower floors, office workers may have already moved their equipment and furniture in and are going about their business.
Yet up above their heads, on other levels, very little may be ready except for the floors and the outer walls. It may take as much time or more to complete all the interior work on a skyscraper as it did to build the foundation and erect the framework.
Now that the vital services are in—utilities that are hidden: heat. air conditioning, electricity, water, plumbing, telephones—a wide variety of men and women workers finish off the interior details. Room partitions have to be installed, plastering, painting, paneling has to be done, tile and carpeting put down, toilet facilities constructed, doors hung, lighting fixtures connected—all the carefully done detail work that hides the basic structure of the building and puts the finishing touches on the completed skyscraper. Perhaps sixty or seventy different trades and unions will be involved in the construction of a major large building in Manhattan.
Manhattan construction is practically all unionized. Most construction workers are journeymen; they do not work for a specific company, they work from job to job. Their union is their link between work and unemployment. between management and worker. If a worker needs a credit reference to get a mortgage and buy a house, he gets it from his union. Most importantly, the union is the worker’s bargaining agent to establish working conditions.
