TY - JOUR ID - 4901 TI - Investigation on Deflection Amplification Factor for Special Moment Resisting Frames with Soft Story JO - Amirkabir Journal of Civil Engineering JA - CEEJ LA - en SN - 2588-297X AU - Mirza Alian, Mohammad Amin AU - Yakhchalian, Masood AD - Department of Civil Engineering, Qazvin Branch, Islamic Azad University, Qazvin, Iran AD - aDepartment of Civil Engineering, Qazvin Branch, Islamic Azad University, Qazvin, Iran Y1 - 2023 PY - 2023 VL - 54 IS - 11 SP - 4365 EP - 4382 KW - Displacement amplification factor KW - Steel special moment resisting frame KW - Soft Story KW - Inter-story drift ratio KW - Roof drift ratio DO - 10.22060/ceej.2022.21159.7652 N2 - One of the most common irregularities in structures is the irregularity in height and lateral stiffness. Due to the commonness of the use of irregular structures and also the different seismic responses of this type of structures, in comparison with regular structures, investigating the seismic response of irregular structures has always been the subject of several research studies. The structures designed for the reduced base shear, under the design earthquake, have inelastic response. To calculate the real (inelastic) displacements of structures under the design earthquake, the displacements obtained from the reduced base shear, are amplified by the deflection amplification factor (Cd). Seismic codes have dedicated a Cd for each structural system. But different studies have shown that the dedicated Cd by the codes cannot accurately estimate the real displacements. The main purpose of this research is to propose the Cd values for more accurately estimating the maximum inter-story drift ratio (MIDR) and maximum roof drift ratio (MRDR) in steel special moment resisting frames (SMRFs) with the soft story. The number of stories and the location of the soft story are the variables considered in this research. The results show that the use of Cd = 5.5, recommended by the 2800 standard and ASCE 7-16 for steel SMRFs, underestimates the real MIDR and also MRDR, under the design earthquake. It is shown that by increasing the number of stories, the mean Cd obtained from the analyses increases. The reason for this issue is the P-Δ effects that increase by increasing the number of stories. In addition, it is shown that a specified trend cannot be found between the location of the soft story and the mean Cd values in the stories of the structures. Thus, for more accurately estimating MIDR in the considered structures, under the design earthquake, Cd = 8.5 is proposed. Furthermore, for more accurately estimating MRDR, Cd roof = 8.0 is proposed. UR - https://ceej.aut.ac.ir/article_4901.html L1 - https://ceej.aut.ac.ir/article_4901_b46bbb97e7833096c474cf8aa44bae8f.pdf ER -