Evaluation of the reduction of seismic loads effect in tall buildings through their geometric configuration in plan

Abstract

The research aimed to evaluate the effect of seismic loads on tall buildings through four geometric shapes: square, circle, equilateral triangle, and regular hexagon, around X and Y axis, in three evaluation stages of structural regularity condition and system adopted and three verification phases regarding the story drift limit according to E.030 Peruvian standard. Modelling was conducted in ETABS® v.16.2.1, with reinforced concrete of f’c = 280 kg/cm2 and fy = 4200 kg/cm2, in a minimum area of 400 m2 for ten levels plus a roof terrace with 3.20 m typical story height and with a box for two elevators and integrated stairs located in the centroid of each figure. The spectral modal dynamic seismic analysis was applied with parameters of zone 3, intermediate soil, common use, C value according to pseudo accelerations spectrum and rigid frames/structural walls. Among the figures studied, square one allowed the greatest reduction of seismic loads effect (Wseismic = 4296.8270 ton, Tfundamental = 1.077 s, most decoupled main modal matrix, Ia = Ip = 1 in X and Y, DIX ≈ DIY and SFX ≈ SFY), equilateral triangular one originated the most critical structural irregularity (Ip = 0.75), circular one provided the greatest lateral stiffness (DIX = 0.00512 - DIY = 0.00508) and regular hexagonal one presented the highest and most effective structural stability (SFX = 5.318 - SFY = 4.749) when using structural walls (Ro = 6).