Far-fault Earthquakes Research Articles

Three-Mass Structural-Isolating-Damping Model Subjected to Near- and Far-Fault Earthquakes

ABSTRACTSeismic base isolators and dampers are commonly used as control tools in building frames to mitigate earthquake damage. This study proposes and investigates a structural system consisting of a central fixed core and an isolated section, the two parts of which are connected to each other by a damper. In new structures, called partially isolated (PI) structures, the interaction between conventional frames with fixed bases and frames equipped with control tools including isolators and dampers is measured using a three-mass model by three simplified differential equations of motion. Validating the proposed model provided good results. The model with various modes of partial isolation and certain mass ratios was subjected to seven near-fault and seven far-fault earthquakes to be evaluated. The mean displacement, acceleration, and shear responses of the structural-isolating-damping model were compared with those of fully isolated (FI) and fully fixed (FF) structures. The results showed that by connecting the two parts, responses of the fixed part to FF structure and those of the isolated part to FI structure significantly improved. Under near-fault earthquakes, the displacement response reduction of the fixed part to FF model was estimated to be about 20% and the response of the isolated part to FI model was about 50%. Due to the functional weaknesses observed in FI structures including large displacement of the structure base, poor performance of the isolator in near-fault earthquakes, and high costs of preparing and installing the isolation system, these points were significantly resolved in PI structures.

Inelastic displacement demand for non‐degrading bilinear SDOF oscillators with self-centering viscous-hysteretic devices

The self-centering viscous-hysteretic device (SC-VHD) is an innovative self-centering system developed recently by the authors to improve structural seismic resilience. The goal of this research is to develop an inelastic displacement ratio Ci spectrum as well as inelastic displacement estimation methods for non‐degrading bilinear SDOF oscillators with SC-VHDs. Statistical analysis is conducted on non‐degrading bilinear SDOF oscillators with self-centering viscous-hysteretic devices (SC-VHDs) to investigate the effect of the design parameters of the bilinear oscillator and the SC-VHD on the constant-ductility inelastic displacement ratio Ci spectrum under the near-fault pulse-like earthquakes (NFPE) and the far-fault earthquakes (FFE). Results indicate that, except in very rare cases, the mean Ci spectrum under the NFPE is always larger than that under the FFE. Besides, the mean Ci spectrum has a significant and clear dependence on the ductility ratio, the ratio of preload to yield strength, the ratio of loading stiffness to elastic stiffness, the ratio of unloading stiffness to loading stiffness, and the viscous damping ratio. When estimating the Ci spectrum, both decreasing the ductility ratio and increasing the viscous damping ratio can cause a reduction in record-to-record variability. Based on the statistical data, a formula about ductility ratio and period considering the effect of the design parameters of the SC-VHD and earthquake motions is proposed and verified for the mean Ci spectrum. Then, a Ci spectrum method and an equivalent linearization method estimating the inelastic displacement demand of the bilinear oscillator with the SC-VHD are proposed, verified by comparing the estimation results and the statistical results, and evaluated through adopting an error measure. Finally, these two methods are adopted to estimate the maximum roof displacement of a two-story steel moment-resisting frame (MRF) with SC-VHDs, which demonstrates their application.

Teaching-Learning Based Optimization of Nonlinear Isolation Systems under Far Fault Earthquakes

Seismic isolation systems exposed to far-fault earthquakes can reduce floor accelerations and story drift ratios to acceptable levels. However, they exhibit different structural performances in each earthquake due to different excitation frequency contents. By optimizing the isolation system parameters, their performance may be maintained at the best level under different far-fault earthquakes. In this study, the optimization of the parameters of the nonlinear isolation system of a 5-story benchmark building is performed by Teaching-Learning Based Optimization (TLBO) algorithm to minimize peak floor accelerations under historical far-fault earthquakes with and without exceeding a specified base displacement limit. According to the results of the analyses, it can be said that TLBO algorithm is a robust algorithm with low standard deviations for determining optimum nonlinear isolation system parameters.

Evaluation of the relative and absolute cumulative input energy time history in the near-fault earthquake with visible pulse in acceleration time history, using the relative and absolute energy reflection spectral approach

Several studies have been carried out to evaluate the impact of near-fault earthquake with fling-step motion effects. The obvious feature of such earthquakes is the existence of a pulse with a significant amplitude in the velocity accelerograms. In this article, in order to investigate the effect of pulse-type near-fault earthquakes on the elastic demands of steel moment frames, a 15stories was simulated. After verifying the modelling process, under the influence of 20 near-field and 2 far-field records were analysed. The relationship between effective cyclic energy, ECE, and the displacement, velocity and hysteretic curve of SDOF systems in near- and far-fault earthquakes was evaluated. Then, studying the energy of relative and absolute cumulative input energy with kinetic energy in one section and maximum inter-story drift for 4 different levels of nonlinear behaviours (R = 1.0, 2.0, 4.0, 6.0) in the other section, the effect of higher modes was evaluated. Studying the inter-story drift profile for two near-fault earthquakes, with and without accelerated pulses, indicates the formation of the maximum drift, IDRmax, in upper stories for low nonlinear degrees (R=1.0 and R=2.0) in Records with visible pulses that verify the participation of higher modes. However, in accelerated pulse-free records, in addition to intensifying the IDRmax in the upper stories, a large-scale demand is imposed in the lower stories. In other words, in the lower stories, the first mode is mainly involved in these records.

Performance limits of base-isolated liquid storage tanks with/without supplemental dampers under near-fault earthquakes

In order to ensure the continuity of the production process and avoid health, security, and ecological problems, the protection of the liquid storage tanks (LSTs) in industrial complexes against earthquakes is vital. Although base-isolation is successful in protecting LSTs from the detrimental effects of far-fault earthquakes, it is challenged by large-amplitude and long-period velocity pulses observed in near-fault earthquakes which may cause large isolator and sloshing displacements. Employing supplemental damping in the isolation system may reduce isolator displacements but the improvement in the superstructure response may be limited if not worsened. Thus, determining the performance limits of base-isolated LSTs with/without supplemental damping in terms of both isolation system and superstructure responses through a systematic examination considering different levels of earthquake magnitude and different fault distances is essential. Since the period and the amplitude of the ground velocity pulse is dependent on the earthquake magnitude and the closest fault distance, such an examination will also help reveal the influence of the characteristic properties of near-fault pulses on the responses of these structures. Therefore, here, a benchmark LST with different base-isolation systems with/without supplemental viscous dampers, located at different fault distances are subjected to synthetically generated near-fault earthquake records with different levels of moment magnitudes. Various isolator and viscous damper characteristics are taken into account. Non-linear time history analyses are conducted to obtain isolator displacement, sloshing displacement, and isolation system shear force responses and the performance limits of the benchmark LST with different base-isolation systems with/without supplemental dampers are presented in a comparative manner.

Investigation of the Structural Response of the MRE-Based MDOF Isolated Structure under Historic Near- and Far-Fault Earthquake Loadings

Fixed base structures subjected to earthquake forces are prone to various issues, such as the attraction of greater forces to structure, amplified accelerations to non-structural components, expensive design for better seismic performance, and so forth. Base isolation applied at the foundation of vulnerable structures is a radical bypass from the conventional approaches utilized by structural engineers. However, the practical implementation of passive base isolation is constrained by factors such as large displacements at isolation level, uplifting forces at isolators, and vulnerability to unpredictable and versatile earthquakes. This study is focused on the evaluation of the smart base isolation system under various harmonic and earthquake loadings. The proposed system employs a magnetorheological elastomer (MRE)—a class of smart materials, based on an adaptive isolation layer under the building structure for its vibration control. The building is idealized as a five-degree-of-freedom (DOF) structure with the mass lumped at each storey. The stiffness of the MRE isolation layer is adjusted using the linear quadratic regulator (LQR) optimal feedback control algorithm. A total of 18 simulations have been performed for the fixed base, passively isolated, and MRE-based isolated structures under a series of earthquake loadings of both a near-fault and far-fault nature for analyzing a total of 306 responses of the structures. The simulation results indicate that MRE-based isolation has significantly reduced all the responses compared to the passively isolated structure for both the near-fault and far-fault earthquake loadings. For harmonic loading, however, the passively isolated structure outperformed the MRE isolated structure in terms of storey drift and acceleration responses.

Seismic Fragility Analysis of Base Isolated Structure Subjected to Near-fault Ground Motions

In order to better evaluate the performance of the base isolated structure under the near-fault earthquakes, this paper takes into consideration an existing engineering case study in China as the prototype, and uses OpenSEES platform to establish the nonlinear finite element model of the base isolated structure. The nonlinear response of the isolated structure under the near-fault earthquake is analyzed. The incremental dynamic analysis (IDA) method is used to calculate the damage probability of the structure under the near-fault earthquake, and the fragility curve of the base isolated structure is established. The fragility equation is obtained by nonlinear regression, and the error of fragility equation is analyzed. The results show that the maximum value of the inter-story drift of the upper structure under the action of near-fault earthquake is significantly greater than that under the action of far-fault earthquake. With the increase of seismic intensity, the damage probability of base isolated structure increases nonlinearly, and the maximum response value of horizontal displacement of bearing and inter-story drift of superstructure increases generally. In addition, the exceeding probability of the fragility curve based on PSDA is greater than that based on EDP criterion. When the sample points of the two methods are the same, the exceeding probability points calculated based on PSDA can be regarded as accurate values. The fragility curve based on PSDA may overestimate the exceeding probability to some extent, and the overestimation may be enlarged with the increase of failure stage.

Effect of loading history on axial cyclic behaviour of RC prisms representing wall boundary zones

Susceptibility of flexure-dominated reinforced concrete walls to premature compression failure modes (global lateral instability, local rebar buckling, etc.) was exposed during the recent past earthquake events in Chile and New Zealand. Numerous experimental studies have been conducted since then on isolated columns representing wall boundary zones to study critical parameters influencing these compression failure modes. However, a specific study including the effect of different loading histories, particularly in terms of cycle content (strain range and corresponding cycle count), is missing in the literature. In this study, uniaxial cyclic tests were performed on six doubly reinforced prisms idealised as the boundary elements of rectangular flexure-dominated walls to evaluate the effect of various loading histories on different compression failure modes. The uniaxial cyclic loading histories applied to these specimens included a conventional loading protocol (obtained directly from lateral cyclic loading test of a prototype wall) as well as two earthquake loading histories comprising cycle content representative of the cyclic demand expected from near-fault and far-fault earthquakes. In some of these tests, the level of compressive strains in the adopted loading protocol was reduced to study their impact on the compression failure modes. Although results re-affirmed the influence of imposed tensile strain on the global lateral instability and rebar buckling phenomena, the effect of variation in the number and amplitude of the strain cycles in the loading history was also displayed. Furthermore, results not only highlighted the impact of compressive strain variation on the global out-of-plane buckling response but also revealed the detrimental effects of rebar buckling on the low-cycle fatigue life of the specimens.

Seismic behaviour of reinforced concrete frames with steel-plate shear walls

This paper describes an investigation carried out on the behaviour of buildings with a dual lateral load-resisting system, comprising a reinforced concrete (RC) moment frame and steel plate shear walls (SPSW), subject to near-fault (NF) and far-fault (FF) earthquakes. Experimental validation of a one-bay, three-storey, RC frame with SPSWs was done using structural analysis software. The seismic performance of four buildings with various numbers of storeys was then compared using finite-element software. The non-linear dynamic behaviour of the four building was also modelled. Based on the results, it was found that the standard seismic design spectrum defined by Iranian Code of Practice for Seismic Resistant Design of Buildings does not satisfy all structural demands developed by NF earthquakes. The spectrum should be modified, especially for areas near active faults. The results also revealed that the impact of FF earthquakes on low- to mid-rise structures is more profound compared to that of NF earthquakes. Conversely, it was also found that NF earthquakes have greater impacts on taller buildings than that of the FF motions.

Three dimensional seismic deformation-shear strain-swelling performance of America-California Oroville Earth-Fill Dam

Structural design of the vertical displacements and shear strains in the earth fill (EF) dams has great importance in the structural engineering problems. Moreover, far fault earthquakes have significant seismic effects on seismic damage performance of EF dams like the near fault earthquakes. For this reason, three dimensional (3D) earthquake damage performance of Oroville dam is assessed considering different far-fault ground motions in this study. Oroville Dam was built in United States of America-California and its height is 234.7 m (770 ft.). 3D model of Oroville dam is modelled using FLAC3D software based on finite difference approach. In order to represent interaction condition between discrete surfaces, special interface elements are used between dam body and foundation. Non-reflecting seismic boundary conditions (free field and quiet) are defined to the main surfaces of the dam for the nonlinear seismic analyses. 6 different far-fault ground motions are taken into account for the full reservoir condition of Oroville dam. According to nonlinear seismic analysis results, the effects of far-fault ground motions on the nonlinear seismic settlement and shear strain behaviour of Oroville EF dam are determined and evaluated in detail. It is clearly seen that far-fault earthquakes have very significant seismic effects on the settlement-shear strain behaviour of EF dams and these earthquakes create vital important seismic damages on the swelling behaviour of dam body surface. Moreover, it is proposed that far-fault ground motions should not be ignored while modelling EF dams.

Estimation of Seismic Damage Induced by Near- and Far-Fault Earthquakes Using Modified Equivalent Linearization Method of Mid-Rise RC Buildings

For the seismic design of a mid-rise reinforced concrete (RC) building considering the damage control, the main purpose of this work is to propose a simplified method that can be used to estimate the damage index or damage state induced by the near-fault and far-fault earthquakes. In addition to the maximum deformation response, the hysteretic energy dissipation induced the earthquakes is also considered in the damage index quantification based on the modified equivalent linearization method (MELM). Based on the damage index model in terms of the maximum deformation response and hysteretic energy dissipation under an earthquake, this work provides a convenient method by which an engineer can determine the damage-controlling minimal ductility requirement to ensure that the damage index remains under a specified value. For a mid-rise RC building structure, an engineer can also apply the simplified formula proposed in this work to obtain the damage-controlling yielding strength for a specified ductility capacity.

Microtremor measurements and 3D dynamic soil–structure interaction analysis for a historical masonry arch bridge under the effects of near- and far-fault earthquakes

For rational solutions against seismic excitations of masonry bridges, the capability of 3D soil–structure interaction (SSI) modeling with experimental evidence has been insufficiently researched up to now. This is also valid for the effects of near- and far-fault earthquakes. Hence, the spectral responses measured by microtremors have been compared with the ones of 3D SSI analysis under the effects of near- and far-fault earthquakes for a historical masonry arch bridge in this article. The 3D SSI modeling of bridge and substructure soil was built with elastic finite element model using solid element and viscous boundary. The SSI analysis has been performed by direct approach using time-history analysis. The earthquake motions (near fault, far fault) were selected in accordance with the tectonic setting of the bridge’s region. From the study, it is possible to confirm that microtremors are able to detect spectral responses of the bridge by the presence of SSI influences. By the evidence of amplifications and soil–structure resonance, the microtremor measurements experimentally promise that: (i) the bridge can be adequately identified by SSI analysis compared to fixed base, (ii) the elastic model can satisfactorily provide information about the bridge’s responses (amplitudes, spectral response, stress distribution) under earthquake effect, and (iii) the far-fault motion especially due to SSI modeling is significant for the seismic responses. The study indicates that regarding the SSI influences into seismic computation has become quite efficient for determination of a possibility of various adverse effects (high displacements, critical stresses, resonance). Moreover, diagnosing the historical bridge well as a result of microtremors together with SSI modeling strongly proposes protection of the bridge with an appropriate retrofitting.

Prof. Comparing H2 and H∞ Algorithms for Optimum Design of Tuned Mass Dampers under Near-Fault and Far-Fault Earthquake Motions

In this study, the robust optimum design of Tuned Mass Damper (TMD) is established. The H2 and H∞ norm of roof displacement transfer function are implemented and compared as the objective functions under Near-Fault (NF) and Far-Fault (FF) earthquake motions. Additionally, the consequences of different characteristics of NF ground motions such as forward-directivity and fling-step are investigated on the behavior of a benchmark 10-story controlled structure. The Colliding Bodies Optimization (CBO) is employed as an optimization technique to calculate the optimum parameters of the TMDs. The resulting statistical assessment shows that the H∞ objective function is rather superior to H2 objective function for optimum design of TMDs under NF and FF earthquake excitations. Finally, the robustness of the designed TMDs is evaluated under a large set of natural ground motions.

Study and Comparison of Seismic Behaviour of Isolator-Damper Hybrid Control System with Conventional Structural Systems

In this paper, in addition to introduce a hybrid structural system contained local isolators and dampers, its behavior and functional capabilities were studied on a conventional structure. For this purpose, an RC frame building with six-story was designed based on valid codes and then, in four cases based on the number of spans, it was split into two separate adjacent frames. Base isolation was done underneath the columns of one frame, while the bottom connections of the other frame’s columns were remained fixed and viscous dampers provided the connection of two adjacent frames on the same floors. Nonlinear time history analysis (NTHA) under three near-fault and three far-fault earthquakes and frequency-domain analysis are performed. Displacement, drift, acceleration and shear forces of the stories in the four proposed hybrid cases with two limited cases, full base-isolated and full base-fixed frames, as well as nonlinear hysteresis behavior of a damper and an isolator are assessed. The results showed that using the novel hybrid control method in most cases can mitigate deteriorating effects of all types of seismic motions observed in the conventional structural systems. However, among them, two cases (2 isolated columns -5 fixed columns and 3 isolated columns -4 fixed columns) had the best significant influence on seismic performance and structural response reduction. Furthermore, frequency response functions of displacement and acceleration with respect to ground acceleration demonstrated that the two proposed cases further suppress the responses of the limited cases, over a wide range of frequencies including all natural frequencies. Due to decrease about 50-70% in the number of base isolators (compared to full isolation) lead to considerable construction cost savings. In spite of the limitation of ASCE7-10 code on separately using base isolators and dampers on structure, applying the proposed combination technique of these two dissipating devices can overcome the limitation.

A comparative study of floor accelerations of different structural systems with lead-rubber-bearing (LRB) isolators

Seismic base isolation technique has been successfully used to protect structural as well as nonstructural components from the damaging effects of earthquakes by reducing floor accelerations and inter-story drifts for many decades. The level of floor acceleration is a key issue in the protection of acceleration-sensitive nonstructural components. The intensity of floor acceleration varies depending on the vibration characteristics of the structural system. Furthermore, the viscous damping devices sometimes are used to improve the performance of the superstructure as well as the base isolation system. The characteristics of the ground motions are also influential in the performance of the viscous damping devices. In this paper, the floor acceleration performance of seismically isolated buildings with different lateral load resisting systems such as moment resisting frame, dual system, moment resisting frame plus viscous wall dampers, and dual system plus viscous wall dampers is investigated under near-fault and far-fault earthquake ground motions. Moreover, the effectiveness of supplemental viscous damping devices equipped in parallel with lead-rubber-bearing isolators is studied. It is inferred from the study that the most effective way of reducing floor accelerations is to provide more rigidity to the superstructure. Utilizing supplemental viscous dampers along with lead-rubber-bearing isolators having about 20% of effective damping ratio is meaningless or harmful in relation to floor acceleration and base shear.

Seismic performance of double skin semi-base-isolated structures

Base isolation technology is a popular and powerful isolation technology. This technique can greatly reduce the seismic response of the structure, so as to reduce the damage to the structure. Base isolation method decouples the superstructure from the base by installing a flexible layer under each column to reduce dynamic response in the earthquake and elongate the time period of structures due to its inherent flexibility. However, the long time period causes large displacement. In addition, base isolation devices are highly vulnerable due to uplift forces produced by lateral force resisting systems (LFRS). In this study, an adjustable structure with a new configuration, namely double skin semi-base-isolated (SBI) structure is presented to solve the above problems. The LFRS is omitted in the proposed SBI structure and the time period and displacement are reduced compared to the conventional base-isolated structure. The forcedeformation behavior of an isolator is modeled as bi-linear hysteretic behavior which can be effectively used to model all isolation system in practice. This study investigates the seismic performance of 10-story double skin SBI reinforced concrete (RC) structure under far-fault earthquake ground motion by numerical method. Results demonstrate that the SBI system is significantly adjustable with the use of RC coupling beams between the inner core and outer frames. By increasing or reducing the number of connected floors in the SBI system, dynamic behaviors of the SBI system can be changed. The adjusted structure can be created by adding and removing RC coupling beams at every arbitrary floor level.

Optimization of Linear Seismic Isolation Parameters via Crow Search Algorithm

In this study, isolation parameters of a seismic isolated structure were optimized via crow search algorithm (CSA). A shear frame model was generated with a base isolation system. The aim is to obtain isolation system parameters that result the minimum roof acceleration without exceeding the isolator displacement limits. The Matlab program was used for optimization operations and the SAP2000 program was used for structural analysis. The open application-programming interface (OAPI) was employed for the two programs to work together. Time history analyses were conducted using recorded near- and far-fault earthquake ground motions. Within the content of the study, linear isolator system parameters, which are the isolator period and damping ratio, were optimized through the linear time history analyses results by achieving the predefined aim. The analyses were performed for various isolation displacement limits and damping ratio ranges. The optimum results were determined at the range of various displacement limits and damping ratios by attaining the specified upper limits for displacement in all cases. Since higher damping ratios cause increased floor accelerations, optimum isolation parameters were achieved generally at the intermediate damping ratios well below the upper limits. Therefore, optimum isolation parameters are crucial for obtaining minimum floor accelerations. The verification of the optimum isolator parameters, which are achieved by the crow search algorithm employed, was made by comparing them with the results of a previous study.

Major Parameters Affect the Non-Liner Response of Structure Under Near-Fault Earthquakes

Near-fault ground motion can be identified by the presence of a predominant long duration pulse in the velocity traces mainly due to directivity effect. This pulse exposes the structure to high input energy at the beginning of the earthquake which leads to a higher response in comparison with the ordinary ground motions. This paper investigates 79 earthquake records with different properties to achieve three goals: the first aim is to compare between the linear and nonlinear response of SDOF systems under near-fault and far-fault earthquakes. While the second objective is to examine the parameters that control the characteristics of near-fault earthquakes. Two factors have been studied which is PGV/PGA ratio and pulse period. Finally, the seismic code provisions related to the near-fault earthquakes were evaluated in term of the elastic acceleration response spectrum, the evaluation is adopted for American Society of Civil Engineers code ASCE 7 and Uniform Building Code UBC. The results lead to the following conclusions: with respect to a specific PGA, the near-fault earthquake imposed higher response in comparison with far-field earthquakes. The near-fault earthquakes become severe as the PGV/PGA and pulse period increase. The interested seismic codes can cover the actual behavior based on the average response of a certain amount of data, while it may become non-conservative relative to an individual record.

Seismic Behavior of Frames with Bolted End Plate Connections Rehabilitated by Welded Haunches Under Near- and Far-Fault Earthquakes

A retrofit method for bolted end plate connections is the use of haunches. This method needs no change or replacement of connection components. The optimum selection of rehabilitation parameters like thickness or haunch-beam angle is of great importance for designers. Besides, one of the important factors for designers to select this retrofit method, is the efficiency of retrofitting by haunches and the effectiveness of retrofit parameters on behavior of retrofitted frames in near- and far-field earthquakes. The results of 2D numerical modeling of the frames shows that rehabilitation of the weak end plate connections using haunch improves the seismic behavior of the weak frame relative to the reference frame with connections designed according to AISC code. For example, the roof displacements are reduced by 8% averagely and the maximum story drifts in near and far-field earthquakes are reduced by 22% and 12% in the rehabilitated frames compared to those of the reference frame. The results of 3D substructure numerical models, after verification by experimental results, showed that the increase of haunch thickness from 12 to 18 mm did not significantly increase the moment capacity and initial rotational stiffness. However, the pinching in moment-rotation hysteresis is decreased. The increase of haunch angle from 30 to 60 resulted in shift of plastic hinge to haunch internal area and 100% reduction of energy absorption and initial rotational stiffness compared to those of the reference specimen. Since the change of retrofit method parameters results in change of stiffness and natural time period of the structure and the affecting parameter on structure dynamic behavior is “the ratio between structure main time frequency to earthquake predominant time period”, the selection of the first haunch thickness with an angle of 30 degree toward the beam that satisfy the requirements of FEMA350 will be economic and optimized.

A simple structural control model for earthquake excited structures

The biggest challenge and criticism on active control systems in earthquake engineering applications point out the issues that could occur because of a possible power loss of the active controller system during an earthquake. The power supply of an active control system can be disabled during an earthquake. This study is written to introduce a simple structural model to overcome the challenges defined above, and to investigate the performance of this system. The integrated active and semi-active control system is named as “INASA.” The proposed control method of the INASA system both minimizes integrated active and semi-active control energy, as well as the structural energies. A building with an active tendon controller system, with the integration of an MR damper, is considered as an example structure. For numerical validation of the INASA system, near-fault and far-fault earthquakes are used. The electrical current need for operation of the MR damper as well as the time-delay effects of the active tendon controllers are also taken into account for more realistic dynamic simulations. The dynamic performance of the INASA system under different earthquakes is compared to the building equipped with the MR damper the conventional uncontrolled structure. The results showed that the INASA system could work without any stability problems under both earthquakes. Time-delays did not have a negative effect on the system. And a reasonable reduction in uncontrolled response is achieved with very small power requirement. In the possible case of a power loss, the deactivation of the active tendon control system did not lead to a discrepancy, because the MR damper continued to operate with a very small power requirement and showed a good performance.