With the increase of steel cost the importance of optimum design increases. Many factors affect the design of beam sections such as (unsupported length – allowable stress in lateral torsional buckling- load and support condition–steel grade – section class (compact, non-compact, slender)). Choosing a section empirically or by experience and neglecting the previous factors is not correct. To design a beam section allowable stress may be assumed, the required inertia is too calculated, from sections tables a suitable section is to be chosen. At this step, the effect of unsupported length on the section properties has been neglected. The section may have large inertia but is still slender according to code limits and its properties will be reduced again, on other hand the section may have small inertia but still has considerable allowable stress as compact section. Which section is the best? , which factor has a big effect? And how to satisfy all these factors in one-step. As explained before it is difficult to choose the most economic section. A computer program has been made to select the best section by making many trails to choose the best section satisfying all conditions of the Egyptian code of practice for steel construction for the design of beam sections. After that the results were grouped to know the way to obtain the optimum section with respect to flange width, flange thickness, ratio of flange with to thickness, web height, web thickness and lateral unsupported length.
)
View on SCiNiTO