Determining the Maximum Lateral Displacement Due to Sever Earthquakes without Using Nonlinear Analysis

Authors: Mussa Mahmoudi

Abstract:

For Seismic design, it is important to estimate, maximum lateral displacement (inelastic displacement) of the structures due to sever earthquakes for several reasons. Seismic design provisions estimate the maximum roof and storey drifts occurring in major earthquakes by amplifying the drifts of the structures obtained by elastic analysis subjected to seismic design load, with a coefficient named “displacement amplification factor" which is greater than one. Here, this coefficient depends on various parameters, such as ductility and overstrength factors. The present research aims to evaluate the value of the displacement amplification factor in seismic design codes and then tries to propose a value to estimate the maximum lateral structural displacement from sever earthquakes, without using non-linear analysis. In seismic codes, since the displacement amplification is related to “force reduction factor" hence; this aspect has been accepted in the current study. Meanwhile, two methodologies are applied to evaluate the value of displacement amplification factor and its relation with the force reduction factor. In the first methodology, which is applied for all structures, the ratio of displacement amplification and force reduction factors is determined directly. Whereas, in the second methodology that is applicable just for R/C moment resisting frame, the ratio is obtained by calculating both factors, separately. The acquired results of these methodologies are alike and estimate the ratio of two factors from 1 to 1.2. The results indicate that the ratio of the displacement amplification factor and the force reduction factor differs to those proposed by seismic provisions such as NEHRP, IBC and Iranian seismic code (standard no. 2800).

Keywords: Displacement amplification factor, Ductility factor, Force reduction factor, Maximum lateral displacement.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1078545

References:

[1] Uang C., Maarouf A., Displacement amplification factor for seismic design provision, Structural Engineering , 120(8):2423-2436, 1994.
[2] Mahmoudi M., The effect of period and overstrength on seismic - inelastic demand of R/C flexural frames (Persian), A thesis presented for the degree of doctor of philosophy in structural engineering; Tarbiat Modarres University; Iran; 1999.
[3] Riddell R, Hidalgo P., Cruz E., Response modification factors for earthquake resistant design of short period buildings, Earthquake Spectra, 5(3):571-589, 1989.
[4] Nassar A., Osteraas J., Krawinkler H., Seismic design based on strength and ductility demands, Proceeding of the Earthquake Engineering, Tenth World Conference, Balkema, Roterdam, p: 5861-5866, 1992.
[5] Miranda E., Site-dependent strength-reduction factors, Structural Engineering; 119(12), 3503-3519, 1993.
[6] Mahmoudi M., Performance Based Design Using Force Reduction and Displacement Amplification Factors for RCMRF, First European Conference on Earthquake Engineering and Seismology, Geneva, Switzerland, 3-8 September 2006.
[7] Mahmoudi M., The Primary Evaluation of RCMRF With the Aims of Performance Based Design, Journal of Technology & Education, Vol. 1, No. 3, p. 99-106, 2007.
[8] Federal Emergency Management Agency, (1997), NEHRP Guidelines for Seismic Rehabilitation of Buildings, FEMA 273.
[9] NEHRP recommended provisions for the development of seismic regulations for new building, Bldg. Seismic Safety Council; Washington, D.C., 1994.
[10] International Building Code (IBC), International Code Council, 2000.
[11] Iranian code of practice for seismic resistant design of buildings (standard no. 2800), Building & housing research center, 1999.