INVESTIGATION OF IRREGULAR EFFECTS IN HEIGHT ON CONCRETE STRUCTURES BEHAVIOR COEFFICIENT
DOI:
https://doi.org/10.32461/2226-3209.1.2018.178677Abstract
Abstract. The behavior of structures at the time of the occurrence of large earthquakes enters the
nonresponsive range, and their design requires a nonresponsive analysis, but due to the costly nature of this method and its effect to enhance the effect of nonresponsive behavior and energy dissipation due to hysteresis behavior, The damping and the effect of the excessive strength of the structure transform this reactionary force by the coefficient of reduction of resistance or the coefficient of behavior into the design force. Determining the magnitudes of these coefficients in earthquake regulations is mainly based on performance observations of building systems in past earthquakes and based on engineering judgments. One of the cases that has a significant effect on the behavior of structures is irregularity in height, which according to researchers many expressed their concern about the lack of reasonable behavioral coefficients based on research studies and computational backing and emphasized on the
correction of these coefficients based on scientific studies. In this study, using finite element software, irregular effects in the defense is studied on the coefficient of behavior of concrete structures studied is. In the present study, 30 flexural concrete frames have been studied regularly and irregularly in structures with 3, 6, 9, 12, 15 floors in elevations with different openings of 4, 6 and 8 meters. The structures were selected for elastic analysis in order to design, model, and load. After this stage, the structures were modeled for non-elastic analysis (nonlinear static analysis with increasing lateral loading) and then the coefficient of structure behavior was calculated. According to the results, in most cases, the coefficient of reduction due to ductility (R μ ) in regular concrete structures at altitude is
more than that of irregular structures, in other words, in structures with the same number of floors and openings, concrete structures regularly, they have better fitting height than irregular structures at elevation. In particular, it can be said that the coefficient of reduction due to irregular structure (Rμ) in irregular structures at elevation is 91% of its value in the structure regularly in height, in this study, with increasing the number of floors from 3 to 6, the resistance coefficient is decreasing further, but from 6 floors to then, in structures 9, 12 and 15, there is no significant change in the resistivity coefficient. Also, the regular or irregularity of the structure did not make any difference in the change in the value of this coefficient. The overall behavior of the structure (R) also affects the
regular concrete structures at altitude there is a greater amount than the irregular structures at elevation. The regular structures with the number of floors and the size of the span have a higher coefficient of behavior than the irregular structures at elevation. The results showed that the coefficient of behavior obtained from nonlinear dynamic analysis the linear average is about 15% higher than the values obtained by nonlinear static analysis with making side are increasing and there is little difference between the two methods.
Keywords: Structural behavior coefficient -irregularity at height-concrete structures.
References
Taheri Behbahani, Ali Asghar; A Philosophical Attitude to Computational Criteria for Building against
Earthquake, Journal No. 239, Building and Housing Research Center, 1997
Management and Planning Organization of the Seismic Rehabilitation of Existing Buildings, Journal No. 360,
Office of Technical Affairs, Developing Standards and Reducing the Risk of the Earthquake, 2006.
- Mahmoudi Sahebi, Moses; The effect of alternating time and resistance on the need for seismicity-non-
resilient concrete bending frames; Phd dissertation, Structural engineering, Tehran, Faculty of Engineering and
Engineering, Tarbiat Modares University, 1998
Mwafy, A. M. and Elnashai, A. S. (2002), “Calibration of Force Reduction Factors of RC Buildings”, Journal
of Earthquake Engineering, 6(2), 239-273.
Newmark, N. M. and Hall, W. J. (1982), Earthquake Spectra and Design.Earthquake Engrg. Res. Inst., El
Cerrito, Calif.
ATC, (1995), Structural Response Modification Factors, ATC-19 Report,
Applied Technology Council, Redwood City, California.
Uang, C. M. (1992), Seismic Force Reduction and Displacement Amplification Factors.” Proceedings of the
th World Conference on Earthquake Engineering, Balkema, Rotterdam, 5875-5880.
Rahgozar, M. A. and Humar, J. L. (1998), “Accounting for Overstrength in Seismic Design of Steel
Structures.” Canadian Journal of Civil Engineering, 25-1-15.
Kilar, V. and Fajfare, P. (1996), “Simplified Push-Over Analysis of Building Structures.” Proceedings of the
th World Conference on Earthquake Engineering, Acapulco, Mexico, Paper No.1011.
Freeman S.A., "On the Correlation of code forces to earthquake demands".Proc.4thU.S. Japan Workshop on
the Improvement of Building Structural Design and Construction Practices, ATC-15-3, pp. 245-268, 1995
Cosenza E, Manfredi G. Seismic design based on low cycle fatigue criteria. In: Proceedings of XI world
conference on earthquake engineering (CD), Acapulco, Mexico; 1996.
Vaseghi Amiri, Javad, Abdollahzadeh, Gholamreza, Bani Hashemi, Mohammad Reza, The effect of the
indeterminate degree and the type of sections used in the design on the coefficient of behavior of the flexural frame
structures with moderate ductility, the international conference on lightweight plaster, academic jihad Kerman
Province, 2010
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