| Vol 33 No 1 | CONTENTS |
April 2005 |
Control of Eccentric Building Vibration with Base Isolation
Helen Wu, Bob Fitzell & Bijan Samali
An Inexpensive DIY Impact hammer for Vibration Analysis of Buildings
Carl Howard
Some Current Issues in Computer Modelling for Room Acoustic Design
Young-Ji Choi & Densil Cabrera
Measurement of the Effect on Violins of Ageing and Playing
Ra Inta, John Smith & Joe Wolfe
A Code of Ethics for the Australian Acoustical Society
Fergus Fricke
Obituary
Book Reviews
News
Letters
FASTS
Meeting Reports
New Products
Future Meetings
Diary
New Members
Acoustics Australia Information
Australian Acoustical Society Information
Advertisers Index
Vol. 33, No. 1 pp 7 - 12 (2005)
ABSTRACT: Base isolation is found effective in reducing torsional response of structures
with mass eccentricity when subjected to earthquakes. In this study, dynamic characteristics
of an eccentric five-storey benchmark model, isolated with laminated rubber bearings (LRB) and
lead core rubber bearings (LCRB), were examined using a shaker table and four different ground
motions. The earthquake-resistant performance of LRB and LCRB isolators was evaluated. It was
observed that both transverse and torsional responses were significantly reduced with the
addition of an LRB or LCRB isolated system regardless of ground motion input. However, the LRB
was identified to be more effective than LCRI3 in reducing relative torsional angle, model
relative displacements, accelerations and angular accelerations, and therefore, provided a better
protection of the superstructure and its contents.
Vol. 33, No. 1 pp 13 - 18 (2005)
ABSTRACT: The characterisation of vibration in buildings often involves exciting the building
structure with a force and measuring the vibration response. The two common non-destructive
force excitation methods are the use of an instrumented impact hammer or an electromagnetic
vibration shaker. This paper contains a discussion on how to build a low cost instrumented
hammer, and compares the performance of the hammer with a commercially available impact hammer
and a commercially available electromagnetic shaker for vibrating buildings. The merits and
disadvantages of each of these three instruments are discussed and it is the opinion of the
author that for the vibration analyses often conducted in semiconductor manufacturing facilities,
laboratories, and offices, the use of an instrumented impact hammer can provide higher quality
measurements at a lower cost than the use of an electromagnetic shaker.
Vol. 33, No. 1 pp 19 - 24 (2005)
ABSTRACT: This paper deals with several aspects of the application of computer
modelling in room acoustic design in order to promote understanding of this design tool. The
first section of the paper describes the results of the three international round robin tests
of the validity and limitations of current computer modelling techniques. The second and last
sections are concerned with the validity of computer modelling and auralization for the
prediction of the acoustic quality of two concert halls in Australia. The importance of
assigning suitable values of diffusion coefficients to obtain reliable prediction results, and
the validation of computer generated auralizations compared with real recorded music in actual
halls, are also investigated.
Vol. 33, No. 1 pp 25 - 29 (2005)
ABSTRACT: This is a report on the first three years of a long-term experiment designed to
measure how two very similar violins change with time. After being constructed in parallel,
one is stored under controlled conditions in a museum and is played infrequently, while the
other is played regularly by a professional musician. Vibro-acoustic measurements were performed
on the instruments and parts thereof during and after construction. Playing and listening tests
by a panel of experienced violinists were conducted at completion, after three years with no
adjustment, and then after minor adjustments were made to the played violin only. Panels of
players and listeners rated the two violins at all stages, and all results are consistent with
the null hypothesis: at present there is no significant preference for either instrument over a
range of categories.