INTRODUCTION This Item provides a guide to the use of the data available in the Stress and Strength Sub-series on struts@ beams and shafts. Many component parts of machines and structures can be idealised as beams or struts so that estimates of their stresses@ deflections@ slopes@ et cetera@ can be obtained. The methods of idealisation of real engineering components into such elements are dealt with in Item No. SS1@ Section 7. The general principles to be followed in the design and analysis of beams@ struts and shafts are the same as those for any class of component. Guidance on the estimation of loads and the various failure modes to be considered is given in Item No. SS1@ Sections 4 and 5. As noted@ these components are particularly susceptible to failure by buckling@ that is@ by rapidly increasing deflection at certain load levels. Therefore@ data on the effects of buckling and deflections are extensively covered in the Data Items described in this Guide.