Abstract Summary
In recent decades, height-wise urban development relying on slender high-rise buildings with rectangular floorplans is booming in all major cities worldwide. The construction of such buildings is expected to intensify even more over the next years to accommodate pressing demands for residential and office space due to increasing urbanization trends in ever more congested urban environments with high-premium land. However, as their slenderness (height-to-width) ratio increase, rectangular buildings become susceptible to wind-borne vibrations in the crosswind direction leading to excessive floor accelerations, above building code standards, causing discomfort to the occupants and, ultimately, serviceability failure. This is due partly to the low inherent damping of slender buildings and partly to aerodynamic vortex shedding (VS) effects, that is, resonance of the fundamental natural period of the structure with the period of alternating vortices generated at the sharp corner edges of the building. To this end, tuned mass dampers and, more recently, lightweight inerter-based vibration absorbers (IVAs) have been considered in the literature for vibrations serviceability performance improvement in wind-sensitive tall buildings. Still, for routine slender buildings, serviceability floor acceleration thresholds mandated by building code standards are commonly met in practice by stiffening the lateral load-resisting structural system (LLRS) as the incorporation of dampers and vibration absorbers is considered to be “exotic”. However, LLRS stiffening results in higher material use which increases upfront costs and embodied carbon emissions. In this context, this study investigates the potential of using IVAs for LLRS self-weight reduction in buildings whose design is governed by serviceability floor acceleration (occupant comfort) criteria, ultimately leading to embodied carbon emission savings. This is achieved through a novel multi-objective optimization-driven framework with dual objectives for the integrated design of LLRS equipped with an IVA. The framework utilizes an optimality criteria (OC)-based structural sizing algorithm for weight minimization of the LLRS, and a pattern search algorithm for optimal IVA tuning to meet the code-specified floor acceleration criteria for occupant comfort with least structural weight (objective 1) and IVA inertance (objective 2) possible. The latter is the inertia property endowed to the IVA through the use of an inerter device which resists relative acceleration. The applicability of the framework is illustrated by considering a 15-storey steel moment resisting frame building equipped with a tuned inerter damper (TID) under stochastic crosswind excitation accounting for VS effects. The TID is a well-studied IVA in the literature. It is shown that significant reductions in LLRS self-weight are achieved by the proposed integrated design framework as the inertance property of the TID increases. This further results in considerable embodied carbon emission reduction quantified using the latest data applicable in UK. Thus, the bi-objective optimization formulation provides optimal pareto fronts trading structural self-weight to inertance which is quite promising and innovative approach for reducing the embodied carbon footprint of future slender buildings.
