COMPARISON OF HIGH STRENGTH RE-BAR USAGE BY TYPE OF BUILDING STRUCTURE IN KOREA

Excessive arrangement of re-bars in the construction of high rise and long span structure is been considered one of the main reasons that deteriorate the quality of the structural member. To overcome this quality degradation problem that arise from the excessive arrangement of the re-bars, the strengths of the steel materials used in structural members has been increasing steadily in the recent years in consideration of stability and durability of buildings. As a consequence, while using of high-strengths re-bar in the construction of highrise and long-span structures is not only bring an ease to re-bar arrangement but also improve the constructability, reduce the construction periods and more simplified connection details can be obtained. The purpose of this research is to investigate the reduction ratio and applicability of the high-strength reinforcing bars (SD500, SD600) to three types of structural systems (rahmen structure, bearing wall system and flat plate system). The results of this study summaries that the reduction ratio of the high-strength bars on the horizontal members was higher than the vertical members in general. This is because, in the case of the vertical members, the reduction of the amount of the re-bar was governed by the minimum required ratio and spacing rather than the member strengths itself. Among the horizontal members, beam and foundation showed a similar decrease in each structure. On the other hand, in case of slabs, the reduction ratio of the re-bar was large according to the type of the structure. For the mixed-used residential complex building the decreasing ratio of the re-bar was significant when slabs strengths were large. But, in the case of apartment buildings re-bar ratio decreasing was highly governed by the minimum requirement and the spacing of the re-bar, while the amount of the rebar was rather increased due to the restriction of crack spacing in the case of office buildings. Based on the above findings, the use of high strengths reinforcing bars reduces the amount of reinforcement work and shortens the construction period due to the reduced reinforcing bars. Ultimately, the economizing effect is greater if considering the qualitative effects such as the improvement of the workability and the quality improvement of the structure due to the proper spacing of the re-bars.