Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 54 5 2022 07 23 Evaluation of the behavior factor of vertically irregular moment resisting reinforced concrete frames considering the influence of masonry infill walls Evaluation of the behavior factor of vertically irregular moment resisting reinforced concrete frames considering the influence of masonry infill walls 2005 2030 4477 10.22060/ceej.2021.20089.7340 FA Abas Moradi Department of Civil Engineering, Kermanshah ACECR Institute of Higher Education, Kermanshah, Iran Mehdi Izadpanah Department of civil engineering, Kermanshah university of technology, Kermanshah, Iran 0000-0002-3208-8321 Journal Article 2021 05 25 Although infill panels are considered as non-structural elements in the analysis and design process of building frames, these members may significantly affect the seismic performance of the frames. Nowadays, the tendency to design and construct irregular buildings has increased. Behavior factor (BF) plays an important role in the seismic design of buildings. Seismic codes usually present the same BF for the regular and irregular lateral load-carrying systems. In this investigation, the influence of masonry infill walls on the behavior factor of the vertically irregular moment resisting reinforced concrete frames was evaluated. To do so, 3-, 6-, 9- and 12-story moment resisting reinforced concrete frames with various types of vertical irregularities were considered. These frames were assessed with/without considering the influence of infill walls. The capacity curves of the frames were derived using incremental dynamic analysis using 14 acceleration ground motions and then the BFs were achieved. Outcomes demonstrated that infilled frames present higher BFs and more efficient performance in lateral load-carrying rather than bare frames. For the regular frames, considering infill walls effects increased the behavior factor between 18 to 25%. For the irregular frames, due to considering the influence of infill walls, the highest and lowest enhancements of BFs were 3 to 25% (for 3-story frames), 13 to 25% (for 6-story frames), 18 to 25% (for 9-story frames) and 14 to 22% (for 12-story frames). Furthermore, comparing the BFs of regular and irregular frames indicated that vertical irregularity made 14 to 32% reduction in the BF of considered moment resisting reinforced concrete frames. Eventually, two approximate relations were developed to acquire the behavior factors of bare- and infilled- vertically irregular moment resisting reinforced concrete frames. Comparing the behavior factors achieved using the developed approximate relations and an analytical method for three new irregular frames showed that the error of the proposed relations was lower than 7%.  Although infill panels are considered as non-structural elements in the analysis and design process of building frames, these members may significantly affect the seismic performance of the frames. Nowadays, the tendency to design and construct irregular buildings has increased. Behavior factor (BF) plays an important role in the seismic design of buildings. Seismic codes usually present the same BF for the regular and irregular lateral load-carrying systems. In this investigation, the influence of masonry infill walls on the behavior factor of the vertically irregular moment resisting reinforced concrete frames was evaluated. To do so, 3-, 6-, 9- and 12-story moment resisting reinforced concrete frames with various types of vertical irregularities were considered. These frames were assessed with/without considering the influence of infill walls. The capacity curves of the frames were derived using incremental dynamic analysis using 14 acceleration ground motions and then the BFs were achieved. Outcomes demonstrated that infilled frames present higher BFs and more efficient performance in lateral load-carrying rather than bare frames. For the regular frames, considering infill walls effects increased the behavior factor between 18 to 25%. For the irregular frames, due to considering the influence of infill walls, the highest and lowest enhancements of BFs were 3 to 25% (for 3-story frames), 13 to 25% (for 6-story frames), 18 to 25% (for 9-story frames) and 14 to 22% (for 12-story frames). Furthermore, comparing the BFs of regular and irregular frames indicated that vertical irregularity made 14 to 32% reduction in the BF of considered moment resisting reinforced concrete frames. Eventually, two approximate relations were developed to acquire the behavior factors of bare- and infilled- vertically irregular moment resisting reinforced concrete frames. Comparing the behavior factors achieved using the developed approximate relations and an analytical method for three new irregular frames showed that the error of the proposed relations was lower than 7%.  https://ceej.aut.ac.ir/article_4477_d03a857a23b5285736c4d55e0bb067c8.pdf