Influence of slenderness and aspect ratio on the seismic performance of 3-storey modular diagrid steel structures relative to conventional steel structures: A code-based response spectrum study

A study is carried out to evaluate the influence of slenderness ratio and horizontal aspect ratio on the structural performance of 3-storey module diagrid steel buildings in comparison with conventional moment-resisting steel frames. The study considers buildings ranging from 10 to 20 storeys, with an increment of 2 storeys, and each storey is assigned a height of 3.5 m. The bay length in both directions is maintained at 5 m. A series of analytical models with varying vertical and plan aspect ratios are developed and analyzed using response spectrum analysis under seismic loading. Horizontal and Vertical aspect ratios for 10, 12, 14, 16, 18 & 20 storeys were considered, and key dynamic and seismic response parameters, including fundamental time period, natural frequency, lateral displacement and bending moment are evaluated in both principal directions. The results indicate that the diagrid system generally exhibits higher lateral stiffness and a reduced time period in the X direction, with the performance advantage becoming more pronounced at higher slenderness ratios. In the Y direction of lesser width in aspect ratio, the diagrid structure shows marginally greater flexibility at lower slenderness ratios, while the response converges with the conventional frame as slenderness increases.