Dr B. R. Ellis (M) (BRE)
I have been involved with structural dynamics for many years and also with measurements on many grandstands -hence I was very interested in this paper. There were a number of items in the paper which surprised me, in particular its links with the March 1997 version of the ‘Green Guide’. The guide introduced a new regulation which is:
‘Dynamic load effects may be caused by
(a) Excitation by wind.
(b) Excitation by activities of spectators. Where a seating deck has a vertical frequency less than 6Hz or a sway frequency less than 3 Hz, a dynamic evaluation of the structure should be carried out giving due consideration to the mass of the spectators.
(c) Excitation by the activities of the spectators at grounds staging pop concerts or other events involving rhythmic activity, in which case the design loads may be even greater than for category (b)'