Journal of Civil Engineering Researchers
Volume:1 Issue: 4, 2017

In this paper, the effect of base isolator on the seismic response demands of 12 story reinforced concrete buildings with moment resistant frame which are designed for soil typesII and III according to fourth edition of Iran seismic code (2800) is investigated. The nonlinear time-history analysis is carried out on two buildings with different soil types in two states with and without base isolator under 7 near field earthquakes which are scaled for two performance levels of life safety and collapse prevention. The seismic responses with respects to base shears and inter-story drifts are compared according to the installation of LRB isolation systems in the frame building.The main function of the base LRB isolator is to extend the period of structural vibration by increasing lateral flexibility in the frame structure, and thus ground accelerations transferred into the superstructure can dramatically decrease.Therefore,Baseisolation system is able to achieve notable mitigation in the base shear. In addition, they make a significant contribution to reducing inter-story drifts distributed over the upper floors.

In the last few decades the wide of usage of the deformable system or dampers increase significantly. Dampers are the elements that reduce the vibration of the lateral load which are caused by earthquake or wind. Dampers play the vital role todecrease the absorption of the lateral load.[1] this paper have compered the results of technical and economical of the 30-story steel structure with two options including, special moment frames (SMF) plus friction dampers, and special moment frames without using of dampers. This two structure classified with 26-story above the ground and 4-storyunderground. Shear walls have been implemented its 4-story of basemen. In addition, soil behind the shear walls has been compacted.

Base isolation is a design method for reducing response of a structural system under ground motion. With progress of science and technology in recent years, enhancing safety and performance of buildings during the earthquake, is exceedingly considered important. Today there are two methods for resisting earthquake forces: first, improvement of structural seismic capacity by for example using of lateral resistant systems such as moment frames and shear walls and bracings. Second, reducing the structural seismic demand by base isolation system.In this paper we investigated the effect of base isolation system on behavior of a 10 stories steel frame, in comparison of using ordinary systems. We studied some cases such as base shear, period, drift and structural member sections.

One of the methods for reduction of dynamicalresponse of structure against the seismic loads is to use the frictional dampers which, today, very extensive application of these dampers havebeen expanded greatly in designation of new building and/ or resistant-making of the available building. In these dampers, mechanism of performance is in such a way that value of input energy into the structure is absorbed and depreciated. Thus, this tool has an appropriate influence on the seismic behavior of the structure. In the current research, using analysis of non-linear time history, a 8-story structure equipped with frictional dampener and diametrical member is to be modeled in the Opensees software through two-dimensional form and compared with lack-of-dampener structure. Finally, the results suggest appropriate influence of the frictional damper on decrease of the lateral displacement of the structure and reduction of the knots/nodes against the lack-of-damper frame.

Earthquakes cause severe damages to large-scale infrastructures. Conventionally, structures are designed to resist dynamic forces through a combination of strength, deformability and energy absorption. These structures may deform well beyond the elastic limit. In order to avoid such critical damages, structural engineers are working to figure out different types of structural systems that are robust and can withstand strong motions. Alternatively, some types of structural protective systems may be implemented to mitigate the damaging effects of these dynamic forces. These systems work by absorbing or reflecting a portion of the input energy that would otherwise be transmitted to the structure itself. The concept of structural control isto absorb vibration energy of the structure by introducing supplemental devices. Varioustypes of structural control theories and devices have been recently developed and introduced to large-scale civil engineering structures. Viscous dampers, when used in high-rise buildings in seismic areas, should reduce the vibrations induced by both strong winds and earthquakes. In the present study, a residential building with 20 floors is analyzed with columns; columns with viscous dampers at different locations were for all the 2 cases. The building is analyzed in Zone 3 & Zone 5 with three soils in both static & Dynamic Analysis using software ETABS. Moments, Shear, Displacement was compared for all the cases. It is observed that the deflection was reduced by providing the viscous dampers.