الفهرس 
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Abstract
The nonlinear seismic behavior of vertically irregular reinforced concrete moment-resisting building frames constructed from Normal-Strength Concrete (NSC with fc` = 25 MPa) and High-Strength Concrete (HSC with fc` =75 MPa) has been studied. The reliability of criteria provided by the studied codes, in order to separate the regular from irregular building frames is also verified. The applicability of the Static Equivalent Lateral Force (SELF) methods used by the seismic codes in Europe (Eurocode 8), in the United States (IBC-2000) and in Egypt (ECL-2003 and ESEE-88) have been examined when applied for moment-resisting building frames vertically irregular in lateral stiffness, mass and setbacks. Six ductile moment-resisting building frames having 12 stories has been assumed as case study (regular frames), and eighty different vertical irregularities have been introduced in the sample frames. Inelastic dynamic analysis computer program has been used to solve the nonlinear equations of motions. Many real and artificial earthquake records with wide ranges of frequency content have been selected as input ground motions, from them two suitable earthquake records have been used in the dynamic analysis. The results showed that the limits in IBC-2000 and ECL-03 aimed at identifying the lateral stiffness irregularities do not result in poor seismic behavior and can be safely reduced by about 10% for the frames with short and long period of vibrations and constructed from NSC and HSC. The limit of story mass irregularity required by IBC-2000 causes severe seismic response comparing with regular frames and needs to be reduced at least by 10%.The limit identifying setback irregularity of frames at the lower 15% of the total height of the frame causes severe seismic response and needs to be considerably relieved. It is proposed to change this limit to be 30% of the total height of the frame. The SELF method of IBC-2000 is not conservative when applied to NSC and HSC frames with mass or setback irregularities. The SELF method of EC-8, ECL-03 and ESEE-88 are conservative when applied to NSC and HSC building frames with short and long period of vibrations and having lateral stiffness, mass and setback irregularities.