COMPUTER AIDED DESIGN OF RC BEAMS: AN INTERVAL TECHNIQUE

This paper presents an interval technique to analyse and design reinforced concrete beam sections rapidly without using design charts. The technique can be implemented on most desk top personal computers, to become a powerful, user-friendly design tool. It is so simple to program and converges so rapidly, that it is even possible to use it on programmable calculators. It is based on the following assumptions: (1) the stress-strain relations for concrete and steel are those of British Standard BS 8110, although the method can be used with other stress-strain relations; (2) concrete is crushed when the concrete strain at the extreme compression fibre reaches 0.0035; (3) the tensile strength of the concrete is ignored. The mathematical method used takes account of four possible steel stress conditions, and includes a seven-step procedure for determining the ultimate moment of resistance of a doubly reinforced beam section. An explanation is given, showing designers how to apply these steps. An appendix shows how the interval technique, presented here, can be extended easily to arbitrary beam sections. The concept can be applied to analysing and designing other structural members, such as columns.