A Stacked-Bulb Exoskeletal High-Rise with Geometry-Driven Structural Efficiency and Passive Coastal Environmental Regulation

Coastal urban environments impose increasingly complex demands on high-rise buildings, requiring simultaneous optimization of structural efficiency, aerodynamic stability, environmental performance, and urban identity. Conventional prismatic tower typologies typically rely on internal frame–core systems and active mechanical control to resist wind and regulate climate, often resulting in high material intensity, elevated energy demand, and susceptibility to wind-induced serviceability issues. This study introduces a stacked-bulb exoskeletal high-rise system, composed of vertically aligned spherical and spheroidal shell segments integrated around a central structural axis, as a geometry-driven alternative for resilient coastal development. From a structural mechanics perspective, each bulb segment functions as a curved compression shell, where gravity and lateral loads are redirected along membrane force trajectories rather than bending-dominated paths. First-order shell theory indicates that spherical and near-spherical geometries inherently favor axial compression, enabling a significant reduction in flexural stresses compared to orthogonal frame systems. Analytical load decomposition suggests that global bending demand in the primary vertical system may be reduced by approximately 30–45%, while axial force utilization within the exoskeleton is increased, improving material efficiency and structural robustness. The vertical stacking of bulb segments creates periodic stiffness variation, enhancing overall stability and mitigating soft-story behavior. Aerodynamically, the bulb-shaped geometry disrupts organized vortex shedding and redistributes wind pressure along the façade. The continuously changing curvature reduces peak pressure coefficients and lowers across-wind excitation, particularly critical in coastal wind regimes. Conceptual wind-response analysis indicates a potential 20–35% reduction in wind-induced base shear and acceleration response relative to planar or uniformly tapered towers of comparable height. These reductions directly contribute to improved occupant comfort and reduced reliance on supplemental damping systems. From an environmental performance standpoint, the stacked-bulb configuration supports buoyancy-driven and wind-assisted ventilation. The expanded mid-sections of each bulb create pressure differentials that enhance vertical airflow, while constricted inter-bulb zones act as acceleration regions, improving ventilation effectiveness. Warm air rises through the interior voids and exhausts near upper bulb crowns, inducing passive cooling in lower levels. The proximity to water bodies further enhances thermal moderation through evaporative cooling and reduced diurnal temperature fluctuations. Solar and thermal performance are intrinsically moderated by the curved shell geometry. Variable solar incidence angles across the bulb surfaces produce self-shading effects, limiting peak solar heat gain during critical morning and afternoon periods. Preliminary energy-balance assessment indicates a 25–40% reduction in cooling energy demand, depending on climate zone, glazing performance, and ventilation strategy. Diffuse daylight penetration is simultaneously enhanced, reducing artificial lighting loads while maintaining visual comfort. At the urban scale, the stacked-bulb form offers a distinctive yet performance-driven skyline presence, integrating structural logic with symbolic expression. The elevated base and articulated lower bulb improve pedestrian-level airflow and thermal comfort, contributing positively to the surrounding microclimate and public realm. Overall, the research demonstrates that architectural geometry can function as a primary structural and environmental regulator, rather than a passive envelope requiring mechanical compensation. The stacked-bulb exoskeletal system provides a scalable, adaptable, and climate-responsive model for high-rise development in coastal cities. The study establishes a robust analytical foundation for subsequent finite-element structural analysis, computational fluid dynamics (CFD), wind-tunnel testing, and material optimization, supporting future real-world implementation and academic validation. Please check the attachment for details