A Computer Tool to Calculate Seismic Forces Using the Equivalent Horizontal Force Method

Abstract

The seismic design of buildings in Colombia is governed by the Colombian Earthquake Resistant Construction Regulations (NSR-10), which allow the use of several analysis methodologies focused on the determination of dynamic action in buildings to design their seismic resistance system. One of the most used methodologies nowadays is the equivalent horizontal force method (EHF). Its application is a complicated process; therefore this article presents a Java-based software developed at Universidad de La Salle, which aims to enhance the execution of EHF calculations, minimizing the user intervention to only define the project’s basic parameters. The software is made of three modules: the first module allows the user to calculate acceleration, speed, movement, damage threshold or limited safety spectrums, separating the areas with seismic microzoning. With the second module, the user can calculate seismic forces for each one of the structure’s levels. In the third module, the user can calculate the dynamic period using Rayleigh’s method, adjust said period, and finally, adjust the dynamic shear obtained through the modal spectral analysis or any other dynamic analysis method. The final product of the application is a set of .txt files containing the spectra generated in order to be included in structural design programs when performing modal spectral analysis; a report with data provided by the user and the calculations made by the program in PDF format, which can be included in the calculation protocols