Investigating the Effect of Earthquake Duration on Concrete Structures by Analyzing the Frequency Content of Acceleration Time History

Document Type : Regular Paper

Authors

1 Shahid Beheshti University

2 Department of Structure & Earthquake, Faculty of Civil Engineering, Shahid Beheshti University, Tehran, Iran

Abstract

The occurred earthquakes in recent years have proved that in some parts of the world, they possess more duration and cause further damage to structures. Due to the fact that major cities of Iran are located in the high seismic areas and also a significant part of existing buildings are concrete structures, it is necessary to study their vulnerability under long duration earthquakes. In this study, the performance of concrete structures affected by earthquakes with different durations (from low to high) has been investigated. In order to investigate the duration of the earthquake, a new index is defined, which is the number of accelerated cycles where their period is close to the structure predominant periods (with 10% difference) and their corresponding acceleration is also higher than the plastic acceleration threshold of the structure. For this purpose, three concrete structures with, 3, 6, and 9 stories were designed with optimal sections and the predominant period and the threshold acceleration for entering nonlinear behavior were calculated. Subsequently, all three buildings were investigated in two-dimensional SeismoStruct software and nonlinear analysis was carried out considering the stiffness deterioration and strength reduction (Takeda model). Each of the 3, 6 and 9 story structures was subjected to 119 earthquake records, durations, distances, magnitudes, and different soil types. Seismic performance of structures such as relative maximum displacement and number of plastic joints were investigated. The results of the analysis show that the use of the index introduced in this study is much more efficient than other definitions of duration for damage to concrete structures. In other words, duration of an earthquake, as defined by the number of cycles whose period is near the predominant period of the structure and accelerated beyond the plastic acceleration threshold of the structure, is very consistent with the rate of damage to the concrete structure. In continuation, the effects of the height and plastic acceleration threshold on various models are discussed in detail.

Keywords

Main Subjects


[1] Raghunandan, M. (2013). Influence of Long Duration Ground Shaking on Collapse of Reinforced Concrete Structures, PhD Thesis.
[2]Chai YH, Fajfar P, Romstad KM (1998). Formulation of duration-dependent inelastic seismic design spectrum. J Struct Eng 124(8): 913-921. doi: 10.1061/(ASCE)0733-9445(1998)124:8(913).
[3] Haftlang, Mahdi (2011). Determination of the interrelationship of the duration of the earthquake with the magnitude of distance and geological conditions, M.Sc. Thesis, University of Water and Power Industry, Iran. http://ganj.irandoc.ac.ir/articles/download_sparse/556907
[4] Capraro I. Damage, (2018). Collapse potential and long duration effects of subduction ground motions on structural systems. University of British Columbia, PhD Thesis.
[5] Chandramohan R. (2016). Duration of earthquake ground motion: Influence on structural collapse risk and integration in design and assessment practice, PhD Thesis.
[6] Tehranizadeh, Mohsen, Hamedi, Farzaneh. (1999). Determination of the duration of Iran earthquakes and its relation to different parameters, 3rd International Conference on Seismology and Earthquake Engineering, Tehran, May 1999.
[7] Page, R.A., Boore, D.M., Joyner, W.B., Caulter, H.W. (1972). Ground Motion Values for use in the Seismic Design of the Trans- Alaska Pipeline System, USGS Cricular 672.
[8] Bolt, B.A. (1969). Duration of Strong Motion, Proc. 4th World Conf. Earthquake Eng., 1304- 1315, Santiago, Chile.
[9] Husid, L. R., (1969). Características de terremotos, Análisis general, Revista del IDIEM 8, Santiago del Chile, pp. 21–42.
[10]Housner, G.W. (1975). Measures of the severity of ground shaking. Proceedings U.S. National Conference on Earthquake Engineering, Ann Arbor, Michigan, 25-33.
 [11] Uang, C.; Bertero, V., (1990). Evaluation of seismic energy in structures, Earthquake Engineering and Structural Dynamics, 19, 77-90.
[12] Shome, N.; Cornell, C.; Bazzurro, P.; Carballo, J. (1998). Earthquakes, records, and nonlinear responses, Earthquake Spectra 14 (3), 469-500.
[13] Rahnama, M.; Manuel, L. (1996). The effect of strong motion duration on seismic demands, Proceedings of the 11th World Conference on Earthquake Engineering, Mexico, Paper No. 924.
[14] Khanzadi, M., Ghodrati Amiri , G., Abdollahzadeh Darzi, G. (2007). Earthquake Duration and Damping Effects on Input Energy, International Journal of Civil Engineerng. Vol. 5, No. 1.
[15] Abdelnaby, A. e. (2012). Multiple Earthquake on Degrading Reinforced Concrete Structures, Ph.D. University of Illinois, USA.
[16] Huang, W., Qian, J., Zhuang, B., Fu, Q. (2012). Damage Assessment of RC Frame Structures under Multi-Earthquake Sequences, Tongji University, P.R.China.
[17] Khoshraftar, Alireza Abbasnia (2006). Study on the Effect of Shock Resistance on Concrete Structures, The First National Conference on Improvement and Reinforcement of Iran, Tehran, National Center for the Rehabilitation of Iran.