Predictive equations for fundamental period of steel moment frames considering the effects of irregularity in the floor plan and height and soil-structure interaction

Document Type : Research Article

Authors

1 Assistant Professor, Department of Civil, Water and Environmental Engineering

2 Department of Civil, Water and Environmental Engineering, Shahid Beheshti University, Tehran, Iran

Abstract

Robust estimation of the fundamental elastic period of the buildings is essential for obtaining realistic seismic base shear. Seismic design codes provide a variety of equations to calculate the fundamental elastic period of vibration for steel moment frame buildings. The empirical equations are mainly based on the building height and do not take into account the effects of irregularity and soil-structure interaction. In this paper, an empirical predictive equation is developed to estimate the fundamental elastic period of steel moment frames. The predictive equation includes parameters that represent irregularity effects and soil-structure interaction. The database used in this study consists of architectural and geotechnical data for 45 building cases. The proposed predictive equation shows satisfactory accuracy. The predicted results are then compared to the values obtained from Iranian 2800 seismic design code, ASCE7-16 and UBC-97. The proposed predictive equation is also verified by 10 fundamental elastic periods obtained from analytical models. The fundamental elastic period was derived using the predictive equations that are specifically more accurate for mid- and high-rise buildings compared to seismic design codes. The values obtained from seismic codes are well below the realistic values for the buildings.

Keywords

Main Subjects


[1] Iranian Code of Practice for Seismic Resistant Design of Buildings, Standard No. 2800-87, 1st ed., Building and Housing Research Center, Tehran, Iran, 1987.
[2] Iranian Code of Practice for Seismic Resistant Design of Buildings, Standard No. 2800-99, 2nd ed., Building and Housing Research Center, Tehran, Iran, 1999.
[3] Iranian Code of Practice for Seismic Resistant Design of Buildings, Standard No. 2800-05, 3rd ed., Building and Housing Research Center, Tehran, Iran, 2005.
[4] Iranian Code of Practice for Seismic Resistant Design of Buildings, Standard No. 2800-14, 4th ed., Building and Housing Research Center, Tehran, Iran, 2014.
[5] Uniform Building Code, U. B. C., International conference of building officials, Whittier, CA,  (1997).
[6] M. Takeuchi, K. Nakagawa, Vibrational characteristics of Buildings, Proceeding of the Second World Conference on Earthquake Engineering, 2 (1960) 978.
[7] A. Aytun, Experimental Determination of Natural Vibration Periods of Structures, in:  Symposium on Earthquake Engineering and Earthquake Related Problems in Turkey, 1972, pp. 2-5.
[8] F. Udwadia, M. Trifunac, Ambient vibration tests of full scale structures, in:  Proceeding of the 5th World Conference on Earthquake Engineering, Rome, 1973, pp. 135-142.
[9] G. C. Hart, R. M. DiJulio Jr, M. Lew, Torsional response of high-rise buildings, Journal of the Structural Division, 101(2) (1975) 397-416.
[10] V. V. Bertero, Fundamental period of reinforced concrete moment-resisting frame structures, John A. Blume Earthquake Engineering Center, 1988.
[11] E. E. Cole, C. V. Tokas, J. F. Meehan, Analysis of recorded building data to verify or improve 1991 Uniform Building Code (UBC) period of vibration formulas, Proceedings of SMIP92, Strong Motion Instrumentation Program, Divisions of Mines Geology, Califorania Department of Conservation, Sacramento,  (1992) 6-1.
[12] A. La Tegala, W. Mera, Theoretical and Experimental Analysis to Define a Simplified Formula for the Determination of the First Period of Vibration of R/C and Steel Buildings, Proceeding of the 7th Conference of the Canadian Association for Earthquake Engineering,Montreal,Canada,  (1995).
[13] R. K. Goel, A. K. Chopra, Evaluation of code formulas for fundamental period of buildings, Proceeding of the 11th World Conference on Earthquake Engineering, Elsevier Science Ltd, Oxford, England, (1127) (1996).
[14] R. K. Goel, A. K. Chopra, Vibration properties of buildings determined from recorded earthquake motions, Earthquake Engineering Research Center, University of California Berkeley, 1997.
[15] L. L. Hong, W. L. Hwang, Empirical formula for fundamental vibration periods of reinforced concrete buildings in Taiwan, Earthquake Engineering & Structural Dynamics, 29(3) (2000) 327-337.
[16] P. Sarkar, A. M. Prasad, D. Menon, Vertical geometric irregularity in stepped building frames, Engineering Structures, 32(8) (2010) 2175-2182.
[17] M. A. Namjooyan, M. R. Karimian, H. Barslani, R. Rahgozar, Presenting a new relationship in estimating the experimental period of steel moment frame, Journal,  (1393) (in Persian).
[18] K. Young, H. Adeli, Fundamental period of irregular momentā€resisting steel frame structures, The Structural Design of Tall adn Special Buildings, 23(15) (2014) 1141-1157.
[19] ASCE, Minimum design loads for buildings and other structures, in, American Society of Civil Engineers, 2016.
[20] J. Stewart, C. B. Crouse, T. Hutchinson, B. Lizundia, F. Naeim, F. Ostadan, Soil-Structure Interaction for Building Structures, Grant/Contract Reports (NISTGCR), National Institute of Standards and Technology, Gaithersburg, MD, 2012.
[21] USGS. 2011. Center for Engineering Strong Motion Data. Retrieved August 2011, from http://strongmotioncenter.org/. in.
[22] M. Schmidt, H. Lipson, Distilling free-form natural laws from experimental data, Science, 324(5923) (2009) 81-85.
[23] Computers and Structures Inc. 2016. ETABS Nonlinear Version 16.2.1. Walnut Creek, CA, USA.