Earthquake ground motions are affected by the earthquake magnitude, topographic features, and the geological structure of the ground, as well as the distance of the area under the earthquake to fault. The ground motions close to the fault are quite different from ground motions away from the seismic source. The ground motions, which are at about 20 km from the rupture are generally named as near-fault (NF) ground motions [1][2][3][4]. Some recent earthquakes like as Northridge 1994, Kobe 1995, 1999 Chi-Chi etc. are known as a short-duration impulsive motion that exposes the structure to high input energy at the beginning of the motions [5]. These motions have velocity pulse amplitude. This specialty cannot be seen in records obtained far-field (FF) regions [6]. The velocity pulse duration must be larger than 1.00 second and also the ratio of the peak ground velocity (PGV) to the peak ground acceleration (PGA) must be larger than 0.10 second [7].Two main categories of the NF ground motions are fling-step and forward-directivity, respectively. The fling-step motions cause permanent static displacement in ground, whereas directivity effects do not create permanent displacement. Comparison to the FF ground motions, directivity-effects having the long-period and high-density and the fling-step effect causing permanent static ground displacements, are destructive for structures [8].
Steel braced frame systems (SBFs) having both high stiffness and high strength are commonly utilized due to resisting lateral seismic forces in regions with high seismicity. In the study, concentrically braced frames (CBFs) having different bracing configurations are used to obtain the significance of the pulse period associated with near-fault (NF) ground motion by time-history dynamic analysis. Besides, far-fault (FF) ground motions are also used to compare with NF ground motion results according to chancing bracing configurations. To achieve dynamic responses of steel frames with different concentric bracings under NF ground motions, which especially have small, medium, and long pulse periods, 3-story and 4-span CBFs having different bracing configurations were selected as an example. 4 far-fault and 12 near-fault ground motions having different pulse durations were chosen to evaluate the dynamic response of concentrically braced frames. The results showed that peak ground acceleration (PGA) could be identified as a key parameter that controls the response of braced frames under far-fault ground motions. In addition, the ratio of the pulse duration to the first mode period (Tp/T1) is the dominant parameter when Tp/T1 is only greater than 1.0 under the NF ground motions
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.