A steel-framed switchhouse, designed for the Central Electricity Generating Board, proved unusually sensitive to wind loading. Calculations show that repeated wind loading, together with random application of live loading, will lead to incremental collapse at a of incremental collapse and alternating plasticity relatively low load factor. The phenomena single and two-storey frames, and the results are first discussed with reference to simple of model experiments are presented. Sample detail calculations are then given for the switchhouse, showing how a practical plastic design may be made for (a) static collapse under vertical loads only, and (b) static collapse with added wind load. The columns having been designed elastically, the whole
structure is then analysed for its sensitivity to incremental collapse and alternating plasticity, and the shakedown load factor is determined.
J. Heyman, R.P. Johnson, P.P. Fowler and I.P. Gillson