Techno Press
Techno Press

Computers and Concrete
  Volume 36, Number 2, August 2025 , pages 127-140
DOI: https://doi.org/10.12989/cac.2025.36.2.127
 


Effect of vertical irregularity of concrete frame systems on the seismic response modification factor
Tarek Salah El-Salakawy, Mosaad El-Diasity, Mina Mounir Naguib and Mohamed Hamdy

 
Abstract
    The analytical model for structures that accounts for all sources of stiffness, P-delta effects, and inelastic response is the most accurate approach for seismic design. The design codes specified factor is known as the response modification factor (R), which represents the ratio between the required base shear forces to keep the structure elastic during the earthquake and the design base shear force considering its inelastic behavior. This study aims to estimate the over strength modification factor (R) for various irregularly of reinforced concrete dual systems at failure using the pushover analysis through the finite element method and compare them with those recommended by the design codes. The structures under investigation were divided into three different heights of 5, 10 and 15 stories. These structures were a dual structural system. Two types of vertical irregularities, classified according to American Society of Civil Engineers (ASCE)/SEI 7-16, have been investigated; soft story and weight (mass). The two types of vertical irregularities were located at three different locations for each type, bottom story, 1/3 from structure height, and 2/3 from structure height. It was concluded that the R coefficient values presented in the current study was not align with those derived from Egyptian or other structural codes.
 
Key Words
    pushover analysis; soft story irregularity V1; weight (mass) irregularity V2
 
Address
Tarek Salah El-Salakawy, Mosaad El-Diasity and Mina Mounir Naguib: Civil Engineering Department, Faculty of Engineering at Shubra, Benha University, Benha, Qalubiya Governorate, Egypt
and Mohamed Hamdy: Civil Engineering Department, Faculty of Engineering at Badr, Badr University, Cairo, Egypt
 

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