Human-structure interaction in cantilever grandstands - Design of a section of a full scale raked grandstand

An accurate load model which accounts for the lack of coherency among a group of people is fundamental to the attainment of comprehensive guidelines for the design and assessment of grandstands. In order for a realistic crowd load model to have validity it must be calibrated using data determined from people in an environment close to that experienced in practice. To this end, a segment of a full scale raked grandstand was designed and built in the structural dynamics laboratory in Oxford University. The grandstand test rig reproduces the correct seating arrangement found in modern stadia - accommodating up to 15 test subjects in a 3 × 5 row arrangement. The raked deck has been designed to be rigid and light weight keeping the natural frequency above a level where internal modes may be excited by a group of jumping people. This will enable an understanding of the fundamental jumping mechanism to be gained. Each of the test subjects on the grandstand jump/bob on a bespoke load plate in time to a musical beat produced by a metronome. The second stage of testing involves the actuation of the deck by means of synchronous linear electric motors to investigate the effect of structure flexibility on crowd coherency.