Effect of base columns arrangement to lateral displacement and shear lag of modified diagrid structures

Abstract

Diagrid structural systems are now widely used for tall buildings construction. This system can provide great efficiency and aesthetic value in structure. Until now, all the structures of diagrid systems had been designed with full triangulated members from the ground level to the top of the building. Unfortunately, with that design it will cause limited spacing for entrance at the ground level. To overcome this problem, vertical columns that are constructed at the ground floor and connected with diagonal members at upper levels are proposed. Different arrangement of the position of the vertical base columns will be employed: uniform arrangement, non-uniform but symmetrical arrangement and non-uniform and nonsymmetrical arrangement. The objective of this research is to understand the behaviour of lateral displacements of the building and distribution of axial forces of the columns and diagrid members due to wind load that is applied to diagrid structures system without columns and with columns of different arrangement at the base of the building. In this study, the STAAD PRO finite element software was used to analyse the buildings models. Based on the result form the analysis, it shows that when the spacing between the base columns is further between each other, it will increase the lateral displacement of the structure. In this study, Model 3 is the optimum arrangement with 6.0m spacing and uniform arrangement of columns at base when compared to others modified diagrid models. The comparison of diagrid and modified diagrid structures shows the diagrid structure provides better lateral resistance and efficiency to the building. Besides that, the shear lag effect at bottom of the building between diagrid structure and modified structures were very different. This is because the shear lag effect at the base columns of modified diagrid structures was influenced by the spacing of corner columns, spacing of the internal columns and the uniformity of the column spacing.