Effect of base columns spacing to lateral resistant and shear lag of modified diagrid structures

Abstract

Development in highrise building design and construction had lead to the emergence of diagrid system. Diagrid system which is a diagonal grid is widely used for tall building construction due to its efficiency in reducing steel consumption without compromised ability of the structure system to support the load acted to the structure. Full diagrid structure is a structure which has the diagonal members constructed from the ground floor to the top of the building. Full diagrid structure often has the problem of limited spacing for building entrance. In order to solve that problem, vertical base columns were introduced below the diagrid structure. Therefore, this study is carried out to analyse the effect of the addition of vertical columns at ground level to the lateral resistance of the diagrid system. The diagrid was started from the level above the columns and is connected to the columns. Furthermore, the arrangement of the base columns was uniform but the spacing between the columns was varied. The design and analysis of the model structure were accomplished by using STAAD.Pro software. Based on the result from the analysis, it shows that the lateral displacement increases when the spacing between the base column increases. The analysis of shear lag also shows that the base column spacing did not influence the shear lag effect on the axial force. In this study, the optimum spacing between the base column is 6m where the resulted lateral displacement and shear lag effect has small difference compared to the full diagrid structure. Thus, it can be concluded that the implementation of base column can reach the same efficiency as full diagrid structure if an effective design of the spacing between the base column is applied to the building system.