Analysis of the Impact of Vertical Geometric Irregularity on the Seismic Stability of Buildings with Viscous Wall Dampers and Viscous Fluid Dissipaters

Peru, located in the Pacific Ring of Fire, faces a high seismic risk, especially along its coastline, where a large-Magnitude Event (Mw 9) with the potential for massive structural impact is predicted. Many mid-rise buildings have Vertical Geometric Irregularities (VGI), characterized by abrupt changes in stiffness or mass between levels, such as setbacks, discontinuities in elements, or structural transitions that amplify drifts, accelerations, and internal stresses during an earthquake. This research analyzes the impact of such irregularity on the seismic stability of 6-to 20-story buildings, incorporating Viscous Wall Dampers (VWD) and Viscous Fluid Dampers (FVD) as passive control systems. Seventeen structural configurations were modeled in ETABS and subjected to a nonlinear time-history analysis using three pairs of scaled real seismic records, in accordance with the requirements of the National Building Code (NBC). The configurations included a base structure without devices and models with one, two, and three control elements located at different levels. Lateral displacements, inter-story drifts, peak accelerations, and shear forces were evaluated. The FVDs demonstrated greater efficiency, achieving reductions of up to 74.42% in displacements, 70.02% in drifts, 65.53% in accelerations, and more than 50% in shear forces, especially in buildings with 12 to 17 floors. VWDs also performed well, with reductions of up to 55.75% in displacements and 51.41% in drifts, improving overall stiffness and torsional response. These results, obtained under a realistic and regulatory approach, offer valuable technical criteria for the preliminary seismic design of structures with vertical irregularity, with potential application in highly seismic urban areas such as Lima, Callao, and other coastal cities in the country.