چكيده به لاتين
Although code design buildings are expected to perform seismically well in terms of safety, the amount of structural damage can be such that it leads to an irreparable building or requires a high cost to repair. To improve this situation, a new structural system was introduced in 2007 called Linked Column Frame system (LCF). This structural system consists of two parts: 1) two columns connected in height by replaceable links, and 2) the secondary moment frame which carries the gravity loads. The function of the links, which act as fuses, is to deform during the moderate and strong intensity earthquakes to absorb the seismic energy and to protect other load-bearing members in the structure. The interchangeability of the links in this system provides the ability to return to the level of service performance. In this study, the effect of the number and length of links on the seismic behavior of LCF system is investigated. For this purpose, 3, 6 and 9 storey buildings with LCF system with two links and three links in the height of each floor and also with different lengths of links were considered. First, these buildings were designed in 3D in ETABS software, and then the frames with LCF system in OpenSEES software were modeled in two dimensions. Under the influence of 20 earthquake records, including horizontal and vertical components, with two types of far-field and near field, these frames were dynamically analyzed according to FEMA p695 regulations at both DBE and MCE levels. To evaluate the behavior of this system, the drift values, the internal forces of the members and the base shear were compad to the ones in moment frame system. Based on the results, it can be seen that in general, the weight of the LCF system is less than the special moment frame system. Furthermore, the base shear in LCF system, especially with three links, is less than the special moment frame system which results in economic design of the structure and foundation. Generally, increasing the number of links improves the performance of these structures. All the linked coulmn frame structures operate at the level of life safety performance. For 3-story structures, the longest shear link, and for 6- and 9-story structures, the links operating in the moment range are more appropriate. Near-field earthquakes have more destructive effect on structures, and the addition of a vertical earthquake increases the axial force of the columns.
