Report of progress on accelerometer for recording earthquake‐shocks

Abstract

In the summer of 1930 the Civil Engineering Department of the Massachusetts Institute of Technology undertook to design and construct an accelerometer capable of recording an earthquake‐shock at a point comparatively near the epicenter. Mills W. Braunlich was appointed Research Associate in the Department to carry out this project. The instrument is essentially a torsion‐pendulum, the “inertia‐mass” being mounted eccentrically on a taut wire similar to that used in the Wood‐Anderson seismometer. The particular form of the inertia‐mass is that suggested by Dr. Frank Wenner of the Bureau of Standards. It consists of a rectangular metal loop about 1 inch by 3/8 inch, the longer side being attached to the supporting wire, which is 4 inches in length. The free‐period is one twenty‐fifth of a second. That side of the loop which is farthest from the torsion‐wire is made of sheet copper one‐hundredth of an inch thick, bent into a curve so that it can vibrate between the poles of a magnet. The air‐gap is one thirty‐second of an inch. In the experimental instrument an electromagnet was used in order to permit variations in the damping‐action; this will be replaced later by a permanent magnet. In addition to the magnetic damping, it was found necessary to use special damping to reduce lateral (“violin‐string”) vibrations of the wire. This was accomplished by placing bits of felt, soaked in oil, just above and just below the inertia‐mass.

Digital Technologies in the Architecture, Engineering and Construction (AEC) Industry—A Bibliometric—Qualitative Literature Review of Research Activities

“…The phenomenon of DTs has been emerging since the 1930s, and with the passing of time, new technologies, possibilities and growth have been seen in the AEC industry [ 142 ]. Compared to the 20th century, the 21st century is well ahead in terms of technology, innovation and digitalization, and is also on the rise [ 55 , 143 ].…”