Diseño del sistema de control de respuesta sísmica en edificaciones de mediana altura de acero estructural.

Abstract

This document focuses on seismic control systems implemented in mid-rise structural steel buildings. Implementing these control systems in Ecuador is of vital importance due to the presence of high seismic hazard zones. Therefore, the objective of this study is to design a seismic control system using computational tools and a review of scientific articles to reduce seismic demand in mid-rise buildings in the city of Machala during severe and extreme earthquakes. As a methodology for designing structural elements based on seismic-resistant design, the study follows the AISC 360 standard alongside national regulations such as NEC-Seismic Hazard, NEC-Seismic Risk, and NEC-Steel Structures. Additionally, the Nonlinear Time-History Analysis methodology was used to implement seismic signals, along with acceleration design spectra for earthquakes with return periods of 475 years and 2500 years. This allowed for the evaluation of drift control, displacements, shear forces, and distortions experienced by the structure during seismic excitations. The design methodology for isolators was also applied, considering one-degree and two-degree-of-freedom systems to verify results obtained through computational software. The most significant results obtained were as follows: for the base-isolated building using lead rubber bearings (LRB) with an effective stiffness per isolator of 100 Ton/m under an earthquake with a 2500-year return period, a maximum drift of 0.17% was recorded for dynamic seismic analysis. In comparison, the fixed-base structure exhibited a maximum drift of 0.74% under an earthquake with a 475-year return period. Regarding displacements in the base-isolated structure, evaluated using the 2500-year spectrum and incorporating the BM reduction factor from the building’s torsional period, the maximum displacement in the x-axis was 50.67 cm, while in the y-axis, it was 50.04 cm. Additionally, the average displacements integrating 11 seismic signals in the isolated structural model, including the 2500-year spectrum with the BM reduction factor, resulted in a base displacement of 57.92 cm in the x-axis and 64.52 cm in the y-axis. In conclusion, integrating a seismic control system significantly benefits mid-rise structures in the city of Machala. Although it increases displacements and shear forces, it helps keep the structure outside the range of maximum accelerations from the 475-year and 2500-year design spectra. This system effectively controls the isolation period and reduces accelerations that could negatively impact the building.