جستجوی مقالات مرتبط با کلیدواژه « linked-column frame » در نشریات گروه « عمران »

The linked column frame (LCF) system is a new steel lateral load resisting system that is developed with the aim of creating the capability of quick and simple repair of buildings after earthquakes. The LCF system is a combination of a primary linked column (LC) system and a secondary moment frame (MF) system that together resist lateral loads. On the other hand, more recent studies have shown that the linked column (LC) system individually has the ability to resist lateral loads and provides sufficient seismic capacity. Therefore, due to the importance of presenting the seismic performance factors of response modification coefficient (R), over strength factor (Ω0 ) and deflection amplification factor (Cd ) in seismic codes and the need for these factors for the seismic analysis and structural design using a linear analysis method, in this research the quantification of the values of these seismic factors for the linked column system (LCS) is discussed. Moreover, a comparison of the value of materials used in the skeleton of models designed with different structural systems is made, which examines the weight of elements in each system separately, and it compares the LCF and LCS system with other common structural systems in terms of steel used in the structure. The results show that the response modification coefficient of the linked column system (LCS) is equal to 8, similar to the linked column frame (LCF) and moment resisting frame (MRF) systems. But the over strength factor of the LCS system is slightly lower than the LCF and MRF systems, which is equal to 2.7. Also, the deflection amplification factor of the LCF system is the same as the moment resisting frame system, but in the design of the LCS system, using a linear analysis, a larger interstory drift can be allowed in the upper half of the building, because for the design of linked column (LC), the rotation of links is usually a critical criterion for design.

This paper evaluates the "Response Modification", "Reduction due to ductility" and "Over-strength" factors for steel frames with "Linked Columns Frame" as dual systems. Since, LCF is a relatively modern lateral load resisting system, the necessity of a more comprehensive study is felt for performance evaluation of these frames under strong ground motions. In this regard, steel frames equipped with the linked column frame with 3, 5, 7, 9, and 11 stories are designed based on the Iranian earthquake design code (Standard No. 2800, 4th version) and implemented in Opensees software. Response modification factor (R factor) is calculated based on the result of incremental dynamic analysis (IDA), linear and nonlinear dynamic analysis under far-field earthquakes which have been presented in FEMA-P695. For a more accurate assessment, the shear and flexure performance of link beams is investigated in this study. The results show that R factors change in the height of steel frames with LCF. However, the mean values of the R factor do not necessarily increase or decrease as the number of stories increases. In most cases, R factors for LCFs with shear links are larger than the related result of steel frames containing flexural links. Also, the R factor does not need to consider more than 6.0 for regular LCFs with studied shear link beam.

The linked column frame (LCF) as a seismic resistant system with the ductile behavior using shear fuse will reduce the damage to other members of the structure at different hazard levels. In this paper, the seismic behavior of the LCF systems designed by Shoaib and Malakoutian procedures has been evaluated. In order to improve the seismic performance of the designed samples, a new and optimal system with the pattern of the double linked columns has been proposed. For this purpose, a 3-story model of SAC buildings with two linked beam bays and four- moment frame bays has been designed by the procedures. The studied models include: 1-The model designed by Malakoutian procedure (MaM), 2- The model designed by Shoaib procedure (ShM) and 3- The LCF with double-linked column pattern (DLCF). Models have been evaluated using incremental dynamic analyses according to FEMAP695 instructions in OPENSEES. The results show that the model designed by Shoaib procedure (ShM) has “50%” and 14% more capacity than the model designed by Malakoutian procedure and the DLCF model respectively. Also the average link beam capacity in the ShM model is “50%” higher than the MaM model. Finally the results show that compared to the MaM model the new pattern of the linked column in the DLCF model has considerably increased the structure’s capacity, the link beam capacity in energy absorption and base shear capacity by an average of 30%.

Recent studies show that aftershocks can intensify structural damage and even lead to collapse of the structures. Among the structural systems, moment frames show desirable ductility, but in such systems damage spreads in many structural elements. Accordingly, it is possible for these systems to experience more severe damage during an earthquake. Recently, Linked-Column Frame (LCF) is introduced to limit structural damage in moment frames which can prevent formation of plastic hinges in major structural members. However, only a limited number of investigations are carried out on this systems and there is a lack of study that investigates post-mainshock performance of this system. The aim of this study is to investigate the influence of mainshock-afteshshock (MS-AS) sequence on LCF system and compare the results with conventional moment frames. For this reason, SAC 3-story building, which is designed according to UBC-94, is modeled and analyzed in OpenSEES software package. In the first step, behavior of these structures is investigated using nonlinear dynamic analysis. In the next step, incremental dynamic analysis is employed for different performance levels including IO, LS, and CP states to gain a better insight about the behavior of these structure in MS-AS sequences. Results show that MS-AS sequences can lead to increase in drift response of the frames with both systems. However, LCF shows a superior performance during seismic sequences.