TESTS SHOW STEEL COLUMNS STRENGTHENED BY BRICK WALL
Steel-frame buildings, from modest structures of just a few floors to the tallest skyscrapers, may be built more economically with the use of less steel as the result of facts discovered by research at the U.S. Bureau of Standards.
This study, which was carried out in the Engineering and Mechanics section of the Bureau under the direction of Dr. A.H. Stang, consisted of tests in the worlds largest testing machine of the strength of vertical steel columns of the kind used in the steel skeletons of buildings. Its results have upset the basis of an engineering practice that forms an important part of the countrys building codes.
Science News headlines, in your inbox
Headlines and summaries of the latest Science News articles, delivered to your email inbox every Thursday.
Thank you for signing up!
There was a problem signing you up.
This portion of the codes requires that a steel column, even though encased in brick as most of them are, must be strong enough to support its load if it were not surrounded by the brick. The question of whether enclosing a steel column in brick increases its strength has been a matter of controversy in engineering circles, to which this Bureau of Standards research gives an answer.
The first part of the research consisted of testing three 6-inch H columns, each 23 feet long and weighing 20 pounds to the foot, a kind often used in construction. These columns carried loads of 23,900, 23,000, and 23,100 pounds per square inch before they failed by bending at mid-height.
Subscribe to Science News
Get great science journalism, from the most trusted source, delivered to your doorstep.
Then each of six other columns of the same kind and size was built into the center of a brick wall, 14 inches thick, about 22-1/3 feet high and 6 feet wide. These columns were tested to loads of 40,000, 41,500, 40,700, 38,800, 42,100, and 41,100 pounds per square inch before they crumpled at the projecting end. These maximum stresses are practically equal to the yield point values for the steel and also to the compressive strengths of short H-sections of about the same length as that of the encased portion of the long columns. The brick wall evidently prevented the columns from failure by bending and effectively strengthened them so that the encased portion failed by yielding.
NEW METHOD MEASURES SIZE OF GERMS TOTALLY INVISIBLE
Germs so small that they cannot be seen with the most powerful microscopes have nevertheless been measured and their size has been determined by a new method developed by Prof. H. Bechhold and Dr. M. Schlesinger of the Frankfort Institute for Colloid Research in Germany.
It was found by the new method that the germ of smallpox is from 21- to 23-hundredths of a micron in diameter. One micron is one-thousandth of a millimeter, which in turn is about one-twenty-fifth of an inch. The germ of chickenpox is smaller, having a diameter of from 12- to 13-hundredths of a micron, which makes it only about a half as large as the germ of smallpox.
LEAD SHOT KILLS DUCKS EVEN THOUGH HUNTERS FIRE AND MISS
From Bear Lake, in southern Minnesota, comes the astonishing news that although hunters shoot and miss, they kill ducks just the same. Four hundred ducks died at the lake during the past season from shot that did not hit them. To explain this paradox, Dr. T.B. Magath of the Mayo Clinic made an investigation. He said lead poisoning was responsible.