This paper deals with numerical study of a newly developed seismic load resisting System called “ Linked Column Frame ((LCF)) System” which can be used to dissipate the earthquake energy and aids the structure to quickly revert to the serviceability level Dominant behavior of this System resembles that of the ductile link beam and as the shear fuse, it mitigate structural damages in various seismic events. In order to investigate the structural behavior of this in the event of near and far-filed earthquakes, after validationg the models by means of laboratory models, 3, 6 and 9-storey buildings were deigned making use of performance based design approach and then, the earthquake-induced responses were investigated by applying near and far-field earthquake records. Based on the results derived from the nonlinear dynamic analysis, the maximum inter-storey drift developed by the near and far-field earthquakes are equal to 3. 91, 1. 08, 1. 65% and 1. 74, 3. 91 and 4. 06, respectively. These values are related to the lower half of the building’ s height and in compliance with the comparison between maximum displacement and inter-storey drifts obtained by the method proposed by Shoeibi and Malakoutian et al; the structure takes advantage of the controlled maximum and inter-storey drifts.

In this research, seismic response of Linked Column with simple Frame System is evaluated as a new structural System. Linked Column with simple Frame (LCS) is a new idea of a structural steel Frame System that has a suitable seismic performance against the earthquake. Achieving to the fast and simple repair of buildings with replacing some members after the earthquake is purpose of designing this System. In this research, elastic behavior of the new structural System is compare with the other common structural steel Frame Systems in the same conditions, and special Linked Column with simple Frame System (LCS) response, compare with special concentrically braced Frame System (CBF) and special moment resisting Frame System (MRF) in 1 to 9 story models. The results of the model analysis are presented as graphs of base shear, steel weight, uplift force, period of time, maximum story drift and maximum lateral displacement (roof displacement) of 1 to 9 story models of researched structural steel Frame Systems. Based on these results, the elastic response of LCS is similar to other structural Systems and its design is possible using linear analysis methods. Then, inelastic capacity and seismic performance parameters of Linked Column with simple Frame System is evaluated by the use of pushover curves of models. This result discloses that behavior factor of 8 (Ru=8), overstrength factor of 2. 7 (Ω, 0=2. 7) and deflection amplification factor of 5. 5 (Cd=5. 5) is appropriate for this System. Eventually, the capacity of structural stability and collapse mechanism of LCS models has been evaluated by using nonlinear dynamic time history analysis under the 14 ground motion records that scaled to the base design earthquake. The coming results are indicated base on maximum interstory drift for LCS models. Based on these results, mean value of maximum interstory drift for all LCS models is below 2 percent and this System has the capability of structural stability against the earthquake records. The plastic hinges spreading and beginning (collapse mechanism) in nonlinear analysis shows that LCS System has the capability of creation design targets. After evaluation of Linked Column with simple Frame System with different types of structural analysis, the seismic performance of this System is acceptable as a new structural steel Frame System. This System is so appropriate for 1 to 6 story buildings or buildings with maximum height of 20 meters. Also, this System has the capability of realizing its main feature, which is achieving a fast repairable building right after the earthquake with replacing some members, as if the building will have the capability of resisting earthquake after the fast simple repairing. Thus, Linked Column with simple Frame (LCS) in a primary evaluation of seismic response is presented as a new structural steel Frame System. Naturally this System needed to more research in all necessary fields. The results of this study and comparison can display the proper views and assumptions from behavior of the all steel structural Systems that have been investigated. Also, the results show can expect an appropriate nonlinear behavior from structures when following provisions code in designing models with using a linear analysis.

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 Shoeibi 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 Shoeibi procedure (ShM) and 3-The (LCF) with double-Linked Column pattern (D(LCF)). Models have been evaluated using incremental dynamic analyses according to FEMAP695 instructions in OPENSEES. The results show that the model designed by Shoeibi procedure (ShM) has “ 50%” and 14% more capacity than the model designed by Malakoutian procedure and the D(LCF) 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 D(LCF) model has considerably increased the structure’ s capacity, the link beam capacity in energy absorption and base shear capacity by an average of 23%.

This study investigates the effect of different link beam lengths in the Reinforced Concrete (RC) Frame retrofitted with the Linked Column Frame ((LCF)) System. It also investigates the ratio of the link beam length (e) to the span length of the RC Frame (L) from 0 to 1. 5 for the 9 models of the RC Frame retrofitted by the (LCF) System has been investigated. In addition, it studies the formation of plastic hinges in the RC and Linked Column (LC) Frame, distribution of stiffness between the RC and LC Frame and the ratio of the structural displacement with the formation of the first plastic hinge in the member of the RC Frame at the collapse prevention level (Dp (LCF)) to the structural displacement with the formation of the first plastic hinge in the link beam (Dy (LCF)) has been studied. Based on the nonlinear static analysis results, the model with the ratio of e/L= 0. 45 has a better performance than other different lengths of the link beam. In this model, the stiffness of the LC Frame has increased about 78% in comparison with the model with the ratio of e/L that is more than 0. 6. Also, the ratio of Dp (LCF) to Dy (LCF) for the model of e/L = 0. 45 in comparison with two models of e/L = 0. 3 and 0. 6 is more about 14% and 22%, respectively. It means that, the model of e/L = 0. 45 has more potential to reach the performance level of Rapid Repair (RR) to occupancy.

One of the newest fields of study in the field of structural and earthquake engineering is the achievement of structural Systems that quickly return to their pre-earthquake state and service after an earthquake. One of the newest of these Systems is the Linked Column Frame ((LCF)) System, which protects the vertical loadbearing System during earthquakes by having the replaceable link beam members as a fuse member. The relative low cost and easy repair process in these Systems lead to the rapid return to occupancy after an earthquake. In this System, the replaceable link beams used initially provide the initial rigidity of the System and then exhibit soft nonlinear behavior and ductility with energy dissipation resulting from the yield. In this paper, the behavior of the Linked Column Frame System for retrofitting of the RC Frames in two structures of 5-and 10-storeys were investigated. Based on the results of the nonlinear static analysis of the two 5-and 10-storey reinforced concrete structures retrofitted with (LCF) System, the amount of bearing capacity and the energy dissipation capacity of the structure retrofitted increased by an average of 3. 1 times compared to the structures without retrofitting. The plastic hinges were first formed in steel Frames (LC Frames) and the RC structure remained in an elastic state. Furthermore, the maximum and minimum shear absorption of seismic force percentage of the LC Frames were approximately 80% and 13% in the lower and upper storeys, respectively.

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.

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.

In this research, the seismic performance of a Linked Column System is evaluated as a secondary lateral resisting System. The Linked Column is a new idea of the lateral resisting System that can be used in seismic rehabilitation of existing buildings and increases the lateral load-carrying capacity of buildings against the earthquake load. Moreover, this research used the Linked Column System for the seismic rehabilitation of existing buildings, which do not have adequate lateral load resisting capacity. For this purpose, several models are designed in 3, 6 and 9 stories with 40, 60, and 80 percents of the required lateral load resisting capacity in a special concentrically braced Frame and special moment-resisting Frame Systems. Then, the Linked Column as a secondary lateral resisting System was added to the first models for supplying the required lateral load-carrying capacity. After the evaluation of rehabilitated models with nonlinear static pushover analysis, the results show that the increased capacity of models using the Linked Column System is possible, and rehabilitated models have adequate capacity for lateral loads. In the next part, the capacity of structural stability and collapse mechanism of rehabilitated models have been evaluated by using nonlinear dynamic time history analysis under the 14 ground motion records that scaled to the base design earthquake. The coming results are indicated based on the maximum inter-story drift of models. Based on these results, the mean value of maximum inter-story drift for all models is below 2 percent, and rehabilitated models have the capability of structural stability against the earthquake records. The plastic hinges spreading and beginning (collapse mechanism) in nonlinear analysis show that the secondary Linked Column System has a good interaction with the first System of models. Based on these results, Linked Column System has the capability to provide an increase in the lateral load-carrying capacity of buildings in an optimum design with high energy absorption and dissipation, while low space occupancy is considered and also without requirement of changing or retrofitting structural members. Thus, the Linked Column System is presented as a convenient choice for the existing buildings seismic rehabilitation.

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 (LCF)s 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 (LCF)s with studied shear link beam.

In recent years, special truss moment Frames (STMFs) have been widely used as a relatively new steel Frame System for seismic hazard zones. These Frames dissipate seismic energy through special ductile segments embedded near the middle of the span of the truss beam. In this study, the seismic behavior of STMFs with Truss Columns was investigated by nonlinear static analysis (pushover), cyclic static analysis, and time history analysis and compared with the common STMFs reported in the literature. To achieve this goal, two 2D models with the same characteristics were converted into a nonlinear model based on seismic design criteria, design and with the help of the concentrated plasticity method. the results showed that STMFs with Truss Columns have a better seismic performance than STMFs with filled-web Columns. Compared to ordinary STMFs, ductility and energy dissipation were enhanced, hinges were more distributed at higher performance levels, and drifts were more evenly and uniformly distributed on stories for STMFs with Truss Columns. In addition, STMFs were more affordable due to their lower weight and can be used to install pipes through Web Columns.