MECHANICAL AND ACOUSTICAL VIBRATIONS OF A BUILDING
GENERATED BY WEAVING LOOMS
ABSTRACT
Dynamic excitations and the resulting stresses in a weaving mill can affect its functioning
in many different ways. Possible consequences of service vibrations include emission of
acoustic waves, reduction of product quality, damage of non-structural elements (especially
partition walls and cladding) and the disturbance of the activity in buildings placed in close
vicinity. It is difficult to identify the influence of the vibrations on the production, on the
weaving shed and on the neighborhoods. In 2004, an Italian company has rented in Romania
6000 square meters in a huge, one level industrial building, in order to lay out a weaving mill.
Connected to this building there is a small five level office building having 256 square meters in
plane. Two categories of weaving looms were installed, air-jet based type and rapier based type.
One may say that it was another well-known classical result of the acquisition of second hand
equipment. This situation was often encountered in Romania in the last twenty years due to the
poor economic situation of the country and to the set up of various private companies which
could not afford new equipment. It was not the case, as the Italian company supplied the
weaving factory with last generation weaving looms. When the machines started to operate,
severe vertical vibrations were generated in the industrial building and annoying acoustical
vibrations were induced in the office building, felt especially at the fifth floor. Practically,
nobody could stay for more than 10 minutes in any room of that floor. In addition, the high
intensity of the vertical vibrations affected the operation of sensitive electronic equipment and, as
a result, a business center located at the fifth floor closed its activity. This made the owner lose a
big amount of money obtained by renting the spaces. The owner of the building, together with
the Italian company, asked R.N.C.E.E.V. to identify the source of the annoying vibrations and to
find a technical solution in order to avoid them. As such a case is not frequently encountered and
the technical literature is very poor on the subject, the author considers it of interest to be
presented. In the paper, the entire process carried out in order to solve this spectacular case of
annoying vibrations will be presented.
1. INTRODUCTION
1
The object of this paper is the study of severe vibrations that were generated by weaving looms
in an industrial building and of the annoying acoustical vibrations that were induced in the adjoining
office building. The first complaint of the owner dated October 12, 2004. In the address sent to the
Italian company, the owner stated that in the office building there was a high level of noise and
excessive tremors which started to damage the walls of the first floor. The second complaint dated
April 27, 2005, when the Italian company was notified that the computers of a business center, located
at the fourth and fifth floors, were out of order and, more than that, cracks started to appear in the
walls. The next complaint, dated June 22, 2005, informed that in three rooms located at the first floor
the partitioning walls collapsed and all the business companies had computer malfunctioning
problems. The Romanian National Center for Earthquake Engineering and Vibrations (R.N.C.E.E.V.)
was employed to solve the problem.
During the first visit at the industrial site it became clear that the work would not be an easy
one. The investigation team led by the author of this paper established, first of all, that a complex
program of instrumental investigations appeared to be necessary in order to identify, if possible, which
type of the weaving looms was responsible for generating the annoying acoustical vibrations. Using
Kinemetrics vibration equipment, the rapier weaving loom type was found responsible for the
permanent acoustical vibrations in the office building. The next step was to establish a solution for
avoiding the vibration problems. To accomplish the task, the technical assessment of the “source” (the
rapier type weaving looms) and of the “system” (consisting of the two buildings) became necessary, in
order to establish the best solution for minimizing the cost of the intervention.
