Lateral Instability of Long-Span Prestressed Concrete Beams on Flexible Bearings

This theme, addressed by John Graham (Verulam, 2 January 2001)has clearly interested many members, who have provided helpful advice. Martin Elvidge from Bradford writes: John Graham of Quorn, Leics., should take a look at Bruce Irons’ solution to the problem of solving finite element equations. His elegant frontal system cured the problem of limited storage in 1970 using much inferior computers to those available today. It takes advantage of the fact that contributions to variables in the structure matrix are complete unless there are other elements connected to it. It is therefore possible to assemble the matrix and eliminate variables at the same time, thus saving computer storage.

As the dynamic response of structures to dance-type loads is an increasingly important design issue, the frequency range of dance-type loads becomes an important consideration. It has been observed at a number of pop concerts that structural response to dance-type loads is at the beat frequency of the music and at an integer multiple of the beat frequency. Therefore, it is suggested that the frequencies of dance-type loads can be evaluated fmm the beat frequencies of music. Samples of 210 songs have been analysed, covering music fmm the 1960s to 199Os, including dance, indie, pop and rock music. The frequency range and distribution of these songs are given. The results show that 96.2% of the songs analysed fill into the range fmm 1.OHz to 2.8Hz and that there has been a linear increase of about 0.12Hz in the average frequencies of modern music from one decade to the next. Jumping tests have been conducted following music beats, and the frequency ranges for coordinated dance-type loads for individuals, for small groups (aerobics), and large groups ( pop concerts), are provided. The implementation of the results in design is also discussed. D. Ginty, J.M. Derwent and T. Ji

The Government of Orissa (GOO), India, has been constructing health-care infrastructure in collaboration with the UK Department For International Development (DFID), under the Basic Programme. The commonly used building materials in such construction works are laterite and brick, which have a detrimental effect on the environment. Hence, Go0 and DFID decided to try out alternatives to these materials. Peu B. Das and P.K. Das