Abstract
Setback irregularities are considered where discontinuity between adjacent stories is excessive. This irregularity caused the probability of high damage at structures subjected to strong earthquake motion. For this purpose, this study was conducted by modeling the steel special moment frame (SMF) structures using a finite element calculation program with nonlinear static analysis compared to Padang city’s response spectrum. The buildings are also modeled with two types of setbacks: single and multiple setbacks. The results of this paper are discussed including the explanation of many parameters that relate to elastic and inelastic seismic responses of steel special moment frame (SMF). Based on the results, the setback irregularities, both single and multiple setbacks, the inelastic seismic responses are adequately sufficient to SNI 1726 2019 regarding drift limit. The other seismic responses are also discussed in terms of fundamental periods, inter-story drifts, story stiffness, and base shear. Referred to Indonesian Seismic Provision, SNI 1726 2019, it is found that single setback building has more adequate than multiple setbacks in terms of seismic responses. Then, the seismic assessments between these setbacks are explained to address the recommendations about future prevention toward damages and failures in steel buildings.
Highlights
Vertical irregularities are found in some constructions such as multi-story or high-rise buildings and industrial plants
The fundamental period is influenced by mass and stiffness which means structural configuration takes part in determining this value
The longer the fundamental period of the building, the more flexible structure will deform. It affects the value of base shear and structure’s displacements
Summary
Vertical irregularities are found in some constructions such as multi-story or high-rise buildings and industrial plants. Stiffness, and strength are the main parameters to determine that vertical irregularities exist in multi-story buildings. The existence of the setback irregularities is determined as the sudden change of mass, stiffness, and strength due to the discontinuity of the adjacent story. According to the seismic provision in Indonesia, SNI 1729:2019, The setback irregularities are determined as a comparison the length of bays between adjacent stories is higher than 130%. Throughout the year, most of the researches in reinforced concrete and steel buildings considering setback irregularities has stated the seismic responses of these buildings. Research from Karavasilis et al [4] revealed the parameters that need to be concerned in buildings with setbacks such as the number of stories, geometrical irregularity, and beam-column strength ratio
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