Optimum design of parabolic steel box arches

An optimization procedure has been prescribed for the minimum weight design of symmetrical parabolic arches subjected to arbitrary loading. The cross section is assumed to be a symmetrical box section with variable depth and flange areas. The webs are unstiffened and have constant thickness. The pro posed sequential, iterative search technique determines the optimum geometr ical configuration of the parabolic arch which includes the optimum depth p rofile and the optimum lengths and areas of the required flange plates corr esponding to the prescribed number of curtailments. The study shows that th e optimum value of rise to span ratio (h/L) of a parabolic arch is maximum at 0.41 for uniformly distributed loading over the entire span. For any oth er loading, the optimum value of h/L is less than 0.41.