Floor Vibration. Floor Vibration Induced by Dance-Type Loads: Theory

The end of a 6-year term as a Part 3 examination advisor may be an opportune time to air a few personal thoughts on the past, present and future of this examination. D.J.A. Alsop

This paper describes both experimental tests and numerical calculations which were performed to verify an ancdytical method of calculating floor vibrations induced by dance-type loads. The basic experimental set-up is described, and experiments which were undertaken to investigate the interaction between people and structures are discussed. To demonstrate the accuracy of the analytical load model, measured and calculated load time histories are compared. The response of a structure to dance-type loads is then checked by comparing finite element and analytical solutions and by comparing experimental and analytical solutions. To emphasise the importance of choosing an appropriate load model when calculating response, examples of resonant response caused by the sixth multiple of the dance frequency are provided. Finally, comparisons are made with the results from similar work conducted at NRC, Canada. B.R. Ellis and T. Ji

The basis of the so-called elastic theory is that a stiffened suspension bridge is a linearly elastic statically-indeterminate structure. The theory is appropriate when the stiffening (deck) girder is the primary source of stiffness, as for some 19th century bridges for railways and for some more recent minor structures. Otherwise, gravity stiffness is dominant, as (for example) for recent major suspension road bridges designed by the modern so-called deflection theory (for such structures the elastic theory would overestimate girder bending moments by a factor of two at least, according to Martin). Professor T.M. Charlton