Proposed Isolation System Research Articles

Shaking table tests on seismic performance of a five-story reinforced concrete frame structure with MoS2 sliding bearings and steel dampers

The seismic performance of friction isolated structure is greatly affected by the friction coefficient, and the combination of low friction material and limit device is an available option. Via the Motion State module simulating the friction conditions and the Bouc Wen model describing the restoring characteristic of the steel dampers, a single-degree-of-freedom model was established to investigate the influence of the friction coefficient and limit stiffness on the isolation effect. Then, for the evaluation of the seismic performance of the proposed isolation system with molybdenum disulfide (MoS2) sliding bearings and steel dampers, the shaking table tests of a 1/5 scaled five-story reinforced concrete frame structure model, subjected to three ground motions with different peak ground acceleration, were implemented to obtain the isolation layer drift, absolute acceleration, inter-story shear and damage energy of the structure under the testing conditions of free sliding, limited sliding, multi-dimensional seismic excitation, and top additional layer sliding. It is found that the ideal friction coefficient for sliding isolated structure is 0.03–0.07, and the corresponding reasonable elastic stiffness of steel dampers is (0.2–0.5) Ks that is the stiffness of the structural standard story, and the proposed MoS2 sliding bearing presents remarkable low-friction characteristic with a friction coefficient of 0.04–0.05. The appropriate steel dampers can reduce the isolation layer drift without obviously increasing the acceleration. The low-frequency components in the ground motion significantly increase the isolation layer drift, while the high-frequency components cause the superstructure acceleration to show a K-shaped distribution along the height. Moreover, the proposed isolated system can be effectively used for structural protection under multi-dimensional earthquakes, the sliding additional layer on the roof can be considered as the second defense line in the structural seismic design, and the seismic energy the superstructure bears can directly estimate the seismic isolation effect that is consistent with the analysis result of dynamic response.

Seismic Isolation of Fragile Pole-Type Structures by Rocking with Base Restraints

Pole-type structures are vulnerable to earthquake events due to their slender shapes, particularly porcelain cylindrical equipment in electrical substations, which has inherent fragility and low strength in its materials. Traditional base isolation designs configure the bottom of the pole-type equipment as hinges with restraints. It fully relies on the restrainers to re-center the pole-type equipment, posing a risk of tilting and functionality failure after earthquakes. This study proposes a solution to this challenge by introducing a restrained rocking mechanism at the base of the structure. The design leverages the self-centering nature of rocking motion and uses restrainers to control the amplitude of rotation. Hence, it can effectively avoid tilting of the pole-type structures after earthquakes. Experimental investigations conducted on a 1:1 full-scale specimen revealed that the proposed restrained rocking design can achieve a reduction in seismic internal forces of over 50% while maintaining equipment in an upright position. Furthermore, an analytical model for the proposed isolation system of pole structures was developed and validated through comparison with experimental results. This paper introduces a novel solution for seismic isolation of pole-type structures through restrained rocking, specifically addressing the research gap regarding a reliable self-centering mechanism under seismic excitation. This advancement significantly enhances the seismic resilience of fragile pole-type structures and provides practical design methodologies for the seismic isolation of slender structures.

Experimental study on a cable-stayed bridge isolated with the combination of elastoplastic cables and fluid viscous dampers in the transverse direction

It is usually challenging to design an effective transverse isolation strategy that needs both large restoring force and large deformation capacity for cable-stayed bridges to meet the requirements under regular operation and earthquakes. The authors proposed a novel transverse isolation device that combines elastoplastic cables and fluid viscous dampers (FVDs) to address this challenge. The elastoplastic cables are adopted to control the relative displacements at the girder-pylon connections in the transverse direction under both regular operation and earthquakes. FVDs are responsible for dissipating input seismic energy. To further validate the effectiveness of the proposed isolation system under both far and near-fault ground motions, shake table tests were conducted for a cable-stayed bridge with a scale ratio of 1/20. Details of the scaled model for the isolated and fixed systems, including dimensions of the components, additional mass arrangement, instrumentations, and boundary conditions, are briefly described. Seismic responses are recorded for each test case, such as accelerations and displacements of the pylons and girder, hysteretic responses of the combined devices, and strain responses of the pylon rebars. The experimental results indicate that the transverse boundary conditions have significant effects on the seismic responses of the girder, and the high-mode content of ground motions mainly dominates the seismic responses of the pylons. In addition, the isolated system effectively reduces the seismic responses at the bottom of the pylons, and the effectiveness of the isolation is becoming more evident with an increase in the PGA of the ground motions.

Optimizing base isolation system parameters using a fuzzy reinforced butterfly optimization: A case study of the 2023 Kahramanmaras earthquake sequence

This study aims to obtain the viable parameters of base isolation systems that are utilized in buildings with seismic isolation and specially located in Turkey. To provide a more accurate representation of real-world scenarios, the study accounts for severe ground motion records simultaneously during the dynamic response analysis of the structure. Three records are taken from the 2023 Turkey earthquake (records for Elbistan, Nurdagi, and Pazarcik). The optimization model's objective function is to minimize the ratio of the roof acceleration to the peak ground acceleration. To ensure realistic outcomes, certain isolation parameters are constrained, such as maintaining the damping ratio and period within a predetermined range as well as the maximum lateral drift of the structure. An upgraded variant of the Butterfly Optimization Algorithm, known as the Fuzzy Butterfly Optimization Algorithm (FBOA), is employed to address the presented optimization model. The FBOA technique incorporates a fuzzy decision-making mechanism that adjusts its search strategy according to the prevailing conditions of the present problem. In addition, the FBOA method utilizes a new auxiliary vector called virtual butterfly, which provides information on the entire population based on each agent's quality. Consequently, FBOA transforms into a self-regulating search algorithm, eliminating the requirement for any external parameters. Results have verified the effectiveness of FBOA in detecting optimal parameters of the proposed isolation system.

A novel isolation system with enhanced QZS properties for supporting multiple loads

Various quasi-zero stiffness (QZS) isolators with high-static and low-dynamic stiffness (HSLDS) play an important role in effectively attenuating vibrations within the low-frequency range. Most existing QZS isolators can effectively achieve low-frequency vibration isolation under a certain load capacity, but cannot achieve excellent isolation performance for other load capacities. Hence, in this study, a novel isolation system composed of n series-arranged rhombic QZS elements for different supporting loads is proposed to explore its benefits in achieving ultra-low frequency vibration isolation. The novelty of the present design lies in the ability to support multi-load levels while maintaining multiple enhanced QZS properties by conveniently connecting QZS rhombic elements in series. The piecewise static stiffness responses are theoretically analyzed for multiple enhanced QZS characteristics. Nonlinear restoring forces are simulated by ADAMS to verify the theoretical results, which demonstrates that the static behavior of the proposed isolation system has multiple enhanced QZS behaviors. By employing the harmonic balance method (HBM), the nonlinear dynamic equation is formulated and subsequently solved to determine the vibration transmissibility. The vibration transmissibility of the novel isolation system with multiple QZS properties under different key parameters including the supporting load or static equilibrium position, base excitation amplitude, and damping coefficient are calculated. Numerical results demonstrate that the proposed isolation system can achieve superb ultra-low frequency and even full-band vibration isolation performance with a guaranteed stable equilibrium for different loads. The presented design provides new insights into ultra-low frequency passive vibration isolation required in various engineering fields.

Seismic performance of isolated buildings with friction spring damper

The main objective of this paper is to introduce a new combination of passive seismic response control devices containing Friction Spring Damper (FSD) and Pot Bearing (PB) for buildings and compare this system with conventional seismic isolators such as Lead Rubber Bearing (LRB) and Friction Pendulum System (FPS). For this purpose, two benchmark buildings with different structural systems have been considered for implementing the devices. To capture the flag-shaped and self-centered behavior of FSD, new uniaxial material has been developed for OpenSees, and numerical verification of the material has been done based on a past experimental study. Nonlinear dynamic time-history analyses have been used to extract the seismic responses of models, including fixed-base structures, and isolated structures by FSD along with PB, LRB, and FPS. The results show that not only the proposed isolation system has the capability of reducing base shear and inter-story drift as well as both conventional seismic isolation systems compared to fixed-base structures, but also the system has even better performance than the isolated structures with LRB. Moreover, due to the self-centered behavior of FSD, the residual displacement of the proposed system is much lower than conventional isolation systems, which can lead to lower maintenance costs of isolators.

Seismic performance improvement using bolt-on isolators on interconnected slender electrical equipment

The slender electrical equipment in substations is fragile to damage during earthquakes owing to the seismically sensitive structure, low material strength, and coupling effects from interconnected equipment. To improve the seismic performance of the slender electrical equipment in the interconnected circuit system, the design and characterization of an assembled isolation system were recommended. The solution was based on a novelty combination application of bolt-on isolators and a support block by reducing the bending stiffness of slender equipment to achieve vibration isolation function. The isolation function test was performed on isolators from characteristics of stiffness variation and damping. Finally, the effectiveness of the proposed isolation system was proved in seismic performance improvement of interconnected slender electrical equipment using a comparison shaking table test, which was performed on a full-scale interconnected circuit, consisting of two ±800kV composite pillar insulators connected by a tubular busbar. Therefore, thus isolation system can provide effective seismic protection for interconnected slender equipment in proper design.

A three-axis modular horizontal vibration isolation system with adjustable stiffness: Design, analysis and experimental validation

In this study, a modular vibration isolator design is introduced in which the horizontal stiffness of the system can be adjusted in three axes (translational stiffness in the horizontal x and y axes and torsional stiffness about the vertical z-axis) by changing the compressive forces on the leg modules, which are composed of elastic stepped columns and a string. A novel multi-string tensioning mechanism is developed to change the axial compressive forces on all the elastic stepped columns simultaneously, which in turn vary the translational and torsional stiffness of the system. Consequently, the translational and torsional natural frequencies of the system can be tuned to a targeted value by increasing/decreasing the tension forces in the strings for light/heavy payloads. With the use of multiple leg modules in the isolator, the torsional natural frequency can be kept close to the translational natural frequencies at any value of the tension forces in the strings even if the payload masses vary over a wide range. To investigate the relationship between the tension forces and natural frequencies, a leg module is produced. Analytical and finite element models of the leg module are formed, and the results of these models are found to be in good agreement with the experimental results. It is shown that the translational and torsional natural frequencies of the isolator with multiple leg modules can be adjusted to 0.5 Hz and 0.6 Hz, respectively, keeping the lower limits of the isolation bandwidth in the translational and torsional axes less than 1 Hz. Moreover, the upper limit of the isolation bandwidths can be kept above 135 Hz. Therefore, the proposed isolation system has a very wide isolation bandwidth at low frequencies.

Analysis and design of a semi-active X-structured vibration isolator with magnetorheological elastomers

This paper proposes a semi-active X-shaped vibration isolation (XSVI) system with magnetorheological elastomer (MRE) based on its field-controlled variable properties. The conceptual design of the proposed system is constructed by embedding an MRE-based device into a X-shaped structure, instead of the original XSVI’s linear spring. The proposed system could fulfill tuning capability stiffness for effective vibration mitigation in random low-frequency excitations. The theoretical modeling is developed and the static analysis of the proposed MRE-based XSVI system is studied. The dynamic equation of proposed isolation system is established and solved by harmonic balance method. The influence of key geometrical parameters and field strength on the proposed system characteristics are detailly studied and discussed, and the tunable frequency-shift properties are presented. Under the harmonic excitations in a single frequency, the displacement of the isolated objective can be reduced by 22.5% with the field strength of 0.7 T. In the presence of double-tone (2 Hz mixed with 5 Hz) external loading, the reduction ratio of excited and isolated objectives’ displacements by semi-active control are respectively 63.95% and 18.77% by comparing the passive-off state. Additionally, compared with the original XSVI system and MRE isolator, the proposed MRE-based XSVI system in semi-active controller presents outstanding isolation performances. This study indicates that the proposed MRE-based XSVI system could provide a potential method for vibration isolation tuning in wide-band low-frequency range.

Active isolation tests of metamaterial-based barriers and foundation

This study investigates the performance of novel metamaterial-based barriers and foundation on mitigating waves transmitting from a vibrational source to the surrounding soil. An active isolation system is a wave barrier built close to the vibration source to reduce the wave radiating from the source of vibration on the structure to surrounding soil. This research reports the efficacy of the proposed isolation system using an active excitation field test, thereby expanding the applicability of such wave barriers beyond passive isolation. The test barrier is a trench barrier infilled with a layered periodic metamaterial that is composed of alternating layers of polyurethane and reinforced concrete (RC). Tests are also conducted on an empty trench for comparison. A mobile shaker mounted on top of a steel frame is utilized to simulate an active vibration source. By mechanically reorienting the shaker, active isolation tests can be conducted in all three directions (vertical, horizontal inline, and horizontal crossline). Motions on the ground surface, periodic barrier, foundation, and steel frame are monitored using three-dimensional (3D) geophones and 3D accelerometers. The effects of the barrier length, the infilled material, and the total number of barriers on the isolation behavior at various exciting frequencies, and excitation directions are investigated. Tests also include the scenario where the wave barrier is used along with a metamaterial-based periodic foundation. Experimental studies show that vibrations generated from the shaker mounted on top of the steel frame are effectively restrained by a metamaterial-based foundation. The performance of the periodic barriers is better than that of an empty trench within certain frequency ranges. The wave isolation performance is enhanced with the increasing barrier length. This research provides the benchmark for the future design of periodic barriers and periodic foundations in buildings or other vibration-sensitive facilities.

Investigation of five different low-cost locally available isolation layer materials used in sliding base isolation systems

The isolation systems based on sliding friction have gained the attention of researchers recently due to their low cost and high efficiency. The isolation layer plays a vital role in the energy dissipation and enhancement of the seismic capacity of an isolation system and is one of the crucial components of the friction-based isolator, thus needs to be designed carefully. Therefore, in this study, five different low-cost and locally available materials were utilized to fabricate the isolation layer and studied analytically, experimentally, and verified numerically. The isolation system under study consists of a low-lateral stiffness material with specific thickness, placed on the surface of low friction Teflon sheet having 3 mm thickness and is sandwiched between the superstructure and foundation. Furthermore, vertical rebars were distributed throughout the isolation layer to ensure the re-centering process. The cyclic behavior of all isolation layer materials was studied by conducting cyclic loading tests, for which the proposed isolation layer materials were sandwiched between two hollow concrete blocks. As friction is the primary source of energy dissipation, so standardized testing methodology was adopted to find the friction among the sliding interface. A detailed analytical study and modal analysis were conducted to identify the response of fixed and isolated models and some important parameters such as fundamental time-period, frequencies, and mode shapes. Based on the experimental study, the rubberized mortar among the others was found as a feasible material for the isolation layer. Later on, a detailed numerical study was conducted in Abaqus by creating a fixed-base and isolated models, whose dynamic behavior was studied under multiple seismic excitations. From the numerical study, the acceleration response reduction of 40%–53% was noticed at the top floor level of an isolated model as compared to the fixed-based model. The low cost and higher effectiveness of the proposed isolation system make it more robust to be used for low-rise masonry structures in developing countries.

High Damping Passive Launch Vibration Isolation System Using Superelastic SMA with Multilayered Viscous Lamina

Whole-spacecraft launch-vibration isolation systems are attractive for achieving the goal of better, faster, cheaper, and lighter small satellites by reducing the design-load and vibration-test specifications for on-board components. In this study, a three-axis passive launch-vibration isolation system, based on superelastic shape memory alloy (SMA) technology, was developed to significantly attenuate the dynamic launch loads transmitted to a small satellite. This provides a superior damping characteristic, achieved by superelastic SMA blades stiffened by multilayered thin plates with viscous lamina adhesive layers of acrylic tape. The basic characteristics of the proposed isolation system with various numbers of viscoelastic multilayers were obtained through a static load test. In addition, the effectiveness of the design was validated through a launch environment simulating sine and random vibration tests.

Seismic retrofitting of a historic building by using an isolation system with a weak restoring force

Historic buildings and cultural relics are valuable and must be preserved carefully. However, such structures may be destroyed during earthquakes owing to the deterioration of their structural performance over time. Therefore, retrofitting protection measures must be adopted. The typical structural style of ancient buildings in China and East Asia involves timber structures. Due to the diversity of the construction environment, the site conditions of such buildings are often unfavorable. Moreover, several important cultural relics in historic buildings exhibit low integrity, and therefore the primary structure must not be influenced during retrofitting. To overcome these problems, this paper proposes the use of an isolation system with a weak restoring force and post-earthquake recentering capacity. The proposed isolation system consists of elastic sliding bearings, laminated rubber bearings, viscous dampers and jack reaction joints. To better isolate lightweight structures under soft soil conditions, the stiffness of the isolation layer must be designed to have a low value, and therefore, the self-recentering ability cannot be realized. Thus, in this work, jack reaction joints were used to recenter the structure after a rare earthquake. Moreover, a performance index was introduced that is suitable for the seismic isolation protection of typical East Asian historic buildings. The proposed isolation system was applied to a famous historic timber building in Shanghai, namely, the Yufo temple, to improve the seismic performance of the translocated structure and nonstructural members. The underpinning system of translocation facilitates the use of the isolation system. The analysis results indicate that the proposed isolation method can help improve the performance of the structure involving both historic buildings and cultural relics and that the superstructure remains unaffected by the reinforcement measures. In addition, this approach can provide guidance for the protection of other cultural historical buildings that have different styles.

Investigation on low-cost friction-based isolation systems for masonry building structures: Experimental and numerical studies

Masonry structures do not exhibit adequate seismic performance but they are still the most commonly constructed buildings across the globe. To enhance their seismic capacity and to protect them from the damaging effects of earthquakes in seismic active regions, an innovative low-cost friction-based seismic isolation system is developed in this study. The proposed isolation system, installed between the foundation and superstructure is made up of a 50 mm thick isolation layer material having low lateral stiffness, which is sandwiched between two 4 mm thick Teflon sheets and is further reinforced by vertical rebars. To establish the mechanical properties of the isolation system, experimental trials were performed using weak mortar, asphalt cushion, steel balls enclosed in mortar, coarse sand mortar, and rubberized mortar as an isolation layer material, and the proposed isolation system is installed between two hollow concrete blocks for testing purpose. Cyclic load tests were performed on the specimens and force-deformation curves were achieved. Two numerical models, one with a fixed base and another with the proposed isolator were developed using finite element analysis approach and analyzed against five different ground motions input. The isolation layer material used in the numerical model was selected based on friction coefficient and cyclic loading tests. In case of low seismic excitation, the isolation system does not activate to ensure structural integrity, however, when the lateral forces exceed the permissible limit then the isolation system permit deformation in both horizontal directions to dissipate seismic energy through friction while the vertical reinforcement ensure the re-centering mechanism of the structure. It is observed that the proposed isolation system considerably reduces the transmission of earthquake energy to the superstructure over a variety of ground motions. Depending upon the type of ground motion, an overall 45% − 56% reduction was observed in the absolute acceleration response of the top roof level of the isolated structure.

Seismic protection of unreinforced masonry buildings by means of low cost elastomeric isolation systems

Thousands of rural houses in developing countries with high seismicity were built without adequate seismic protection due to economical reason. This paper discusses a possibility to improve the seismic protection of typical unreinforced masonry in developing regions using low cost base isolation devices. The proposed isolation system involves fibre reinforced elastomeric isolators (FREIs) having small dimensions and few layers of rubber pads to reduce the fabrication cost. A series of 3D FE simulations are carried out to investigate the performances of the proposed FREIs utilised in the isolation of a one story masonry house prototype. The model is assumed subjected to several accelerograms to have an insight into the sensitivity of the isolation system against different earthquakes. The results reveal that the proposed low cost FREI system provides significant damage mitigation to the masonry house with good applicability of the FREI devices.

Development of the passive vibroacoustic isolation system for the path matched differential interferometry based fiber-optic sensors

Fiber-optic interferometric sensor arrays are very attractive for many applications. One of the common used interrogation approaches for fiber-optic sensor arrays is the path matched differential interferometry (PMDI). It allows to interrogate a large number of multiplexed fiber-optic sensors by using an auxiliary compensation interferometer (CIF). This approach with using the phase modulator allows to implement the phase-generated carrier demodulation for multiplexed fiber-optic sensors. However, this approach has the significant disadvantage, which is that environmental vibroacoustic impacts on the CIF produce undesirable phase signals from the sensor array. It leads to increasing the noise floor level of the measuring system. In this paper the development methodology and results of the experimental investigation of the passive vibroacoustic isolation system for the CIF in the PMDI-based fiber-optic interferometric sensor are presented. The proposed isolation system is implemented by using acoustic absorbing layers and the special mechanical suspension system for the CIF mounted in the single rack unit. It is shown that the proposed approach for the CIF isolation allows to reduce its sensitivity to vibroacoustic impacts by up to 30 dB in the frequency range up to 500 Hz. It is also demonstrated that potting of the CIF fiber-optic components reduces its isolation efficiency by an average value of 8.3 dB in the considered frequency range, that is not applicable for interferometric sensors. The presented methodology and obtained results might be used in PMDI-based fiber-optic interferometric sensors to improve their performance characteristics.

Multi-level SMA/lead rubber bearing isolation system for seismic protection of bridges

In performance-based seismic design, bridges are expected to satisfy specific performance objectives under several levels of seismic hazard. In this paper, a multi-level SMA/lead rubber bearing (ML-SLRB) isolation system was proposed to ensure both isolation efficiency and capability to limit excessive bearing displacements under different levels of earthquake excitations. The ML-SLRBs also offer advantages such as the ability to provide re-centering forces and good fatigue and corrosion-resistant. The ML-SLRB isolation system consists of three groups of SMA cables, each is designed to be activated at a certain seismic hazard level, and a conventional lead rubber bearing. First, the design and working mechanism of this new isolation system were described in detail. Then, a design procedure was proposed for seismic isolation of bridge structures with ML-SLRBs. Next, the hysteretic response of ML-SLRBs was simulated in a general-purpose structural engineering software. A four-span continuous box-girder bridge was designed and modeled with different isolation systems including ML-SLRBs. Nonlinear dynamic analyses of the isolated bridges were conducted under both far-fault and near-fault earthquakes. Results show that compared to isolations systems that do not adapt their stiffness according to increasing seismic demand, e.g. the isolators with a bilinear force–displacement response, the proposed isolation system exhibits high isolation efficiency at small or moderate earthquakes, while effectively limits the bridge displacements to avoid pounding and girder unseating under extreme earthquakes.

Active stabilization of unmanned aerial vehicle imaging platform

The advancement in technology has seen a rapid increase in the use of unmanned aerial vehicles for various applications. These unmanned aerial vehicles are often equipped with the imaging platform like a camera. During the unmanned aerial vehicle flight, the camera is subjected to vibrations which hamper the quality of the captured images/videos. The high-frequency vibrations from the unmanned aerial vehicle are transmitted to the camera. Conventionally, passive rubber mounts are used to isolate the camera from the drone vibrations. The passive mounts are able to provide reduction in response near the resonance. However, this comes at the cost of amplification of response at the higher frequency. This article proposes an active vibration isolation system which exhibits improved performance at the higher frequencies than the conventional system. The active isolation system consists of a contact-less voice coil actuator supported by four springs. Experiments are carried out to study the effect of vibrations on the quality of images captured. The characterization of drone vibrations is also carried out by recording the acceleration during different flight modes. The performance of the proposed isolation system is experimentally validated on a real drone camera subjected to the recorded drone acceleration spectrum. The isolation system is found to perform better than the conventional rubber mounts and is able to reduce the vibrations to a factor of one-fourth. It can be effectively used to improve the image acquisition quality of the unmanned aerial vehicles.

Multi-Degree of Freedom Isolation System With High Frequency Roll-Off for Drone Camera Stabilization

The technological developments in the field of image based sensing have led to a vast growth in the use of drones in various domains. The drone is usually equipped with an image sensor (camera) which collect images over the target area. These images are then post-processed to extract the important information. Efficiency and accuracy of the image based sensing are largely dependent on the captured image quality. Therefore, it is important to prevent the transmission of the drone vibrations to the camera. Most of the current camera mounting systems use passive rubber mounts for isolation. However, these mounts are effective only in vertical direction and essentially adds damping to the system which degrades the performance of the isolation at high frequency. In this paper, a multi-degree of freedom isolation system, based on a Stewart platform configuration, is proposed for drone camera stabilization. The important features of the proposed isolation system are — (i) high frequency roll-off, (ii) no use of flexible joints, (iii) uses non-contact voice coil actuator thus avoiding spurious resonances of the legs, (iv) adjustable stiffness, (v) 3D printed lightweight parts and (vi) centralized control using a single sensor (inertial measurement unit). A prototype of the proposed system has been manufactured and validated experimentally. The proposed isolation system is found to reduce the response of the isolation system near resonance without compromising performance at high frequency. The application of the isolation system can be easily extended to other fields which require high quality image acquisition.

Seismic protection of unreinforced masonry buildings by means of low cost elastomeric isolation systems

Thousands of rural houses in developing countries with high seismicity were built without adequate seismic protection due to economical reason. This paper discusses a possibility to improve the seismic protection of typical unreinforced masonry in developing regions using low cost base isolation devices. The proposed isolation system involves fibre reinforced elastomeric isolators (FREIs) having small dimensions and few layers of rubber pads to reduce the fabrication cost. A series of 3D FE simulations are carried out to investigate the performances of the proposed FREIs utilised in the isolation of a one story masonry house prototype. The model is assumed subjected to several accelerograms to have an insight into the sensitivity of the isolation system against different earthquakes. The results reveal that the proposed low cost FREI system provides significant damage mitigation to the masonry house with good applicability of the FREI devices.