Are short span reinforced concrete bridge girders cost effective?

摘要

This study investigated the cost effectiveness of steel girders compared to the conventionalrnreinforced concrete girders used in bridge construction in South Africa. The investigation considered an existingrnbridge which required widening as a result of increased traffic flow in close proximity to an industrial area.rnThe consulting engineer specified the same reinforced concrete cross sections for the 10m abutment and 22mrncentral span girders to maintain uniformity with the existing bridge. To determine the cost effectiveness of thisrnapproach, steel girders were designed for only the 10m abutment span based on the relevant South African codesrnof practice. The analysis was conducted for non-composite as well as composite action between the steel girderrnand the reinforced concrete bridge deck. Based on the steel sections obtained a cost comparison was performed.rnThe investigation revealed that for generally available off the shelf I-sections in South Africa, steel girders arernan economically viable option, even when considering corrosion treatment. For the 10m span, the compositerngirder construction proved to be more economical compared to the reinforced concrete beam over a 5 yearrnperiods. However, for the same period, the non-composite girders were economical for 2 years out of the 5 yearrnperiod. Thus, bridge designers should consider steel girders as an option during the conceptual design stage forrnshort spans, i.e. up-to 10m in length. A survey was also conducted amongst senior bridge design engineeringrnprofessionals to determine the apathy towards using steel sections as girders in bridge construction.