Welding taking over from Rivets in Skyscraper construction
THE PASSING OF THE RIVET - Those who have lived within earshot of the pneumatic riveters used in the construction of steel-frame buildings will earnestly wish success to the movement to substitute for these the noiseless processes of electric welding. Engineers who are interested in this new method are predicting for it a great future, we are told in the Cleveland Times. Altho the practical application of electric are welding to the building industry is scarcely ten years old, many of the larger structural steel fabricating companies are applying it, we are told by this paper. Notable instances are plentiful where the welding process has replaced riveting building joints. We read:
Today much of the equipment which plays an important part in the make-up of large buildings is made possible by welding, and instances of important structural repairs and building additions are plentiful where welding has been applied.
The ultimate replacement of riveted by welded sections in large buildings is inevitable, because of the tremendous saving which will result from the fact that there is no loss of strength at the joints welded, while the loss of strength on riveted sections runs from 30 to 50 per cent.
Where welding is applied to the supporting members of a structure, this, of course, means that the necessity of having great, heavy steel pieces in the lower stories of a building in order to carry the load higher up, as required on riveted jobs, is eliminated.
The Times quotes I. F. Lincoln, vice-president of the Lincoln Electric Company, of Cleveland, which has been active in this new development, as saying:
Every riveted joint, if it is depended on
to hold the parts together against stress,
must be made from material very much
heavier than would be necessary if a joint
were made by arc welding between the two
pieces of steel, the joint being as strong as
the steel, itself. What the saving from the
use of welding means is staggering in its
total.
When one considers such undertakings
as tall buildings, where rivets have been
used in the past, and remembers that millions of tons of steel are used for them each
year, it is easy to appreciate the savings to
be accomplished through the use of arc
welding at the joints.
The weight of the parts of a tall building
can be reduced at least one-third as an
average where the arc welding method is
used in place of riveting.
In the case of a tall building the difference
between the 100 per cent. joint possible
through welding, and the 50, 60 or 70 per
cent. joint possible through the various
types of riveted construction, is of much
greater importance because the effect
of the heavier parts which must be used in
order to get the strength at the riveted
joint becomes cumulative.
It is obvious that the change from the
riveted to the arc-welded joint is simply
a matter of time. But for the conservatism of many of our present-day engineers
the change would have come much more
rapidly than it has thus far. While we
in this country pride ourselves on our forward look, yet it takes us a long time to
change our ideas on many things having
to do with engineering.
That the attitude toward the use of welding instead of riveting is changing is well illustrated, the Times reporter tells us, by an instance in Detroit, Michigan. One of the largest firms of architects and engineers there specified that all joining of steel members for an industrial building to be erected for an automobile manufacturer could either be estimated on the basis of using rivets or on the use of arc welding. He goes on:
In the same city a twelve-story addition
has just been erected and joined to the
main building of a department-store structure in the business district. In this case
the engineers specified that the 103 girders
of the old and new structure should be
joined through the use of the arc welder.
On the department-store job, to satisfy
the building department, tests were made
on the welded sections, and it was shown
that they carried nine times the stress which
was to be imposed upon them in actual
usage. Reports to the Cleveland manufacturers show that the job cost several
thousand dollars less than would have been
involved had it been necessary to use
riveting.
Within buildings themselves the use of
the arc welder has long been an important
factor, the records of the Cleveland manufacturing firm show. Applications are in
successful use on such important parts as
passenger elevators, major pipe-lines, stocks,
boilers, tanks, and a host of other parts and
important pieces of structural equipment.
Massillon bar joists, joined through the
use of the welder are used in a great variety
of structures. Tests show that in every
case they have stood loads far above those
for which they are rated, and there has
been not a single instance of the failure of
the welded portions, it is stated.
In its own plant the Lincoln Electric Company has put the welder to a severe test.
Welded steel braces have been successfully erected between the office and the
factory buildings to prevent sagging of
steel beams and the pulling apart of the two
units of the structure.
For a number of years the units of the
Lincoln plant had been gradually pulling
apart, bringing about a sag in the roof and
endangering the entire plant, it is stated.
Sagging had resulted from the fact that
the plant is on made ground with a four-foot fill, which, as it settled down at the
rear of the property, tended to pull the
factory away from the office building.
A great deal of money and time were
spent in the past trying to correct this situation. Riveted steel members could not
be made to correct the situation, but
through the use of steel-ridge construction
welding there has been no further sagging.