Abstract

The article proposes a technique for taking into account the higher vibration modes under seismic resistance estimation of multi-story steel frames by nonlinear static method. The characteristic point search has also been improved. As part of the study, the proposed method was verified by time history analysis. Proposed technique allows one to significantly reduce the calculation time, while excluding the deficit of seismic resistance.

Highlights

  • About 300 thousand earthquakes occur in the world every year

  • According to 1, when performing calculations of building structures taking into account seismic effects, it is necessary to consider two design situations: Seismic loads corresponding to the "Strength Level Earthquake" (SLE) level; Seismic loads corresponding to the level "Ductility Level Earthquake" (DLE) level

  • To estimate the responses error obtained by the multimodal nonlinear static method, it is necessary tos compare the results with the responses obtained by time history analysis using the acceleration records Erthq[1,2,3]

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Summary

Introduction

About 300 thousand earthquakes occur in the world every year. The epicenter of most of them is located far from settlements, and the magnitude of the impact is quite small. Evaluation of seismic resistance under seismic impact of the DLE level earthquake is carried out on the basis of a time history analysis by integrating the motion equations in the time domain using an accelerations records set. Such calculations require a large time resource, complex software and special qualifications of the engineer. Seismic resistance estimation with a given distribution can be performed only if the modal mass of considered form or effective modal mass (ratio of structure mass involved in the dynamic response for a given direction of the seismic impact) is not less than 75%; Inertial forces pattern, obtained by inertial forces superposition of several vibration modes. The research object is steel single-span multi-story frames

Methods for calculating higher mode of vibration
Results
Discussion
EUROPEAN STANDARD
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