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خانه مقالات-Article مقالات عمران-Civil Articles Assessment of Equivalent Static Earthquake Analysis Procedure for Structures with Mass Irregularity in Height
Assessment of Equivalent Static Earthquake Analysis[taliem.ir]

Assessment of Equivalent Static Earthquake Analysis Procedure for Structures with Mass Irregularity in Height

رایگان!

Sudden changes in structural dimensions and mass irregularities are inevitable in urban buildings. Most building codes have different analysis  and design previsions for such buildings. In this article, such provisions based on the Iranian seismic code of practice (Standard No. 2800),  which is to a great extent similar to UBC-97 model code, are verified in order to assess the provisions for different types of structures. Thus,  four two-dimensional residential type steel structures with 4, 8, 12 and 16 stories and with different forms of mass irregularities in height are  designed using the standard equivalent static procedure per the Iranian Seismic Code of practice. The designed structures, then, were  subjected to different nonlinear static (pushover) and dynamic analyses. Two levels of irregularities, i.e. 150 and 300 percents, located at the  heights equal to 50% and 75% of the overall height of the structures, have been considered. The results show that the static procedure  adapted in the code results in much higher internal forces, story shears and overturning moments in various parts of the structures compared  to the dynamic results. Also, this study shows that lateral inter-story drifts obtained using the equivalent static procedure and  dynamic analyses are quite comparable for short buildings. For taller buildings, in contrast, dynamic analyses showed less inter-story drifts. It is  also observed that mass irregularities in height could be responsible for more contribution of higher modes in seismic response of such  structures

توضیحات محصول

ABSTRACT

Sudden changes in structural dimensions and mass irregularities are inevitable in urban buildings. Most building codes have different analysis  and design previsions for such buildings. In this article, such provisions based on the Iranian seismic code of practice (Standard No. 2800),  which is to a great extent similar to UBC-97 model code, are verified in order to assess the provisions for different types of structures. Thus,  four two-dimensional residential type steel structures with 4, 8, 12 and 16 stories and with different forms of mass irregularities in height are  designed using the standard equivalent static procedure per the Iranian Seismic Code of practice. The designed structures, then, were  subjected to different nonlinear static (pushover) and dynamic analyses. Two levels of irregularities, i.e. 150 and 300 percents, located at the  heights equal to 50% and 75% of the overall height of the structures, have been considered. The results show that the static procedure  adapted in the code results in much higher internal forces, story shears and overturning moments in various parts of the structures compared  to the dynamic results. Also, this study shows that lateral inter-story drifts obtained using the equivalent static procedure and  dynamic analyses are quite comparable for short buildings. For taller buildings, in contrast, dynamic analyses showed less inter-story drifts. It is  also observed that mass irregularities in height could be responsible for more contribution of higher modes in seismic response of such  structures.

INTRODUCTION

The existing nonlinear approaches are of great accuracy for evaluation and estimation of seismic demands, but due to complexities involved in  developing the model, are not generally addressed. The equivalent static analysis is one of the common approaches used for seismic  demand analysis of structures, which deemed as one of the fastest and most practical methods in most codes. This procedure is used for  common structures (residential buildings with moderate height). Thus, it is necessary to investigate this approach in terms of structural  considerations and the effect of different parameters on structural response in addition to the comparison between its analysis results and  actual response of the structure .Given the reasons noted above, validity and results of the equivalent static analysis for different types of  structures is unavoidable. In this study, the limitations of this approach cited in the Iranian Code of Practice for Seismic Resistant Design of  Buildings (Standard 2800) are addressed.

Year: 2011

Publisher : Sixth National Congress on Civil Engineering

By : Saleh Malekpour, Farhad Dashti, Amir Kiani

File Information: English Language/ 10 Page / size: 234 KB

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سال : 1390

ناشر :ششمین کنـگره ملی مهنـدسی عمـران

کاری از : صالح ملک پور ، فرهاد دشتی ، امیر کیانی

اطلاعات فایل : زبان انگلیسی / 10 صفحه / حجم : KB 234

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