The Reconstruction of a Soaking Pit Building

During an inspection of the roof over the stage at the New Theatre, Northampton, it was discovered that the structure had sagged considerably and urgent measures were considered necessary to reinstate it. A.B. Grant

Sir-Our attention has been drawn by Mr. C. F. Fischl, of the Joint Fire Research Organisation, to a simplified method of calculating the fire endurance of timber beams. In the paper referred to* a family of curves is used (Figs. 7 and 8) to obtain the fire endurance (t) for various sizes of beams with different values of the ratio - applied load / ultimate load (v).

A type of Nomogram originally devised by Dr. M. R. Horne for the solution of beam moments in rigid frames has been extended to the determination of stanchion moments and developed to include the effects of instability, and it has been found that this can be achieved without departing from the construction of intersecting straight lines. The solution for the behaviour of a stanchion in the elastic range and in the absence of sway can be seen by merely locating two points on the Nomogram and drawing a straight line, which straight line is the diagram of the restraipt moments. The nomograms can be used to demonstrate with great rapidity the phenomenon of "unwrapping" leading to buckling. It is shown how to construct nomograms for continuous stanchions, and it is hoped that these nomograms will also be of use to those engaged in the more general elasto-plastic research into stanchion behaviour. R.H. Wood