Bidirectional Seismic Excitation Research Articles

Average spectral acceleration (AvgSa) for high-confidence probabilistic seismic demand modeling of urban highway bridge portfolios: What period range and damping ratio shall we use?

The average spectral acceleration (AvgSa), i.e., the geometric mean of spectral accelerations over a period range, has attracted widespread recognition as one of the most promising intensity measures (IMs) for probabilistic seismic demand modeling of structures. As AvgSa is a structure-related spectral IM, a pivotal step in calculating AvgSa is to determine an appropriate period range and damping ratio. Whilst optimal AvgSa has been well documented for buildings, consensus on the period range and damping ratio of AvgSa for urban highway bridges is yet to be reached. To this end, a pool of AvgSa candidates with different combinations of lower and upper period bounds and damping ratios are assessed to identify the optimum combination(s) for straight and curved urban highway bridge portfolios against bidirectional seismic excitations, in terms of peak pier drift ratio, peak bearing displacement, and residual pier drift ratio. Results indicate that for the peak demand parameters, optimal AvgSa is characterized by a damping ratio of 0.2 and a period range of [Tf, 1.5Tf], where Tf is the structural fundamental period, for bridges with relatively short piers; and the optimal period range becomes [Tf, 2Tf] for medium to tall-pier bridges. Besides, the optimal period range for the conventional 5%-damped AvgSa is also detected, where [0.5Tf, 1.5Tf] is the optimal range for bridges with relatively short piers, while [0.5Tf, 2Tf] is recommended for medium to tall-pier bridges. Regarding the residual pier drift ratio, averaging spectral accelerations over any examined period ranges does not outperform traditional spectral accelerations at specific periods.

Estimating structural response to bidirectional seismic excitation using spectrum compatible motions: Performance of a pair of companion spectra

AbstractBidirectional analyses covering a range of incidence angles for several records are essential yet challenging for routine design. Recent studies have shown that the response to bidirectional shaking may be estimated per straightforward unidirectional analysis in the most preferred orientation in conjunction with the orthogonal combination rules, and this can also remove the need for various incidence angles. Further, it is well known that the mean response can be estimated with reduced dispersion using fewer spectrum‐compatible records. Combining the advantages of both, a pair of companion spectra independent of period and orientation has recently been developed. While the basis of the companion spectra is established therein from a sound mathematical perspective, the applicability of the proposed spectra to real structures may be revisited, especially to structures sensitive to bidirectional interaction, before recommending the companion spectra for practical design. To achieve this end, following a brief scrutiny of the companion spectra, the performance of the same is critically examined for idealized SDoF analogues and real structures such as bridge piers representative of SDoF systems and buildings with asymmetry using single storey and multistorey models (MDoF systems). The results show that the response of the real structures to bidirectional seismic loading can be reasonably estimated with reduced dispersion using fewer records compatible with the pair of the companion spectra. As such, the critical response parameters may be computed by actual bidirectional analyses or by combining responses to unidirectional analyses under fewer spectrum compatible records. Hence, the pair of companion spectra that can be used as “target” to independently match two components of a chosen record is useful for practical design.

Nonlinear seismic response of seabed with terrain variation and seawater-seabed coupling

Understanding the seismic characteristics of submarine sites and conducting seismic response analysis for such locations are crucial for the safety of marine engineering. However, due to a shortage of strong motion records, the ground motion of offshore earthquakes has not yet been fully characterized. The actual seabed conditions are highly intricate, necessitating consideration of factors such as the dynamic coupling effect between seawater and seabed, the strong nonlinearity of seafloor soft sediments, and the diverse nature of natural submarine terrain. In this study, the modified Davidenkov dynamic constitutive model is used to simulate the nonlinear behavior of the soil. The Coupled Acoustic-Structure method is utilized to simulate the interaction between seawater and seabed. Three typical and simplified terrains, namely flat terrain, valley terrain, and hilly terrain, are individually modeled. The measured seafloor ground motions with different frequency components are used as bidirectional seismic excitations input from the bedrock. The amplification factor in terms of CAV is introduced to evaluate the amplification of seismic ground motion characteristics at seabed surface with respect to those at the bedrock surface. The acceleration response spectra in both horizontal and vertical directions, as well as the corresponding vertical-to-horizontal response spectral ratios, at the representative points are obtained, respectively. Several key findings are consistent with the features of the observed offshore and onshore earthquake ground motions. Numerical examples are presented to illustrate the different influence rules of terrain condition, overlying water depth, and seismic intensity on the nonlinear seismic response characteristics.

Seismic Response Analysis of Multi Span Hyperbolic Brick Arch Thin Shell Structure

The research objective is to investigate the multi-span hyperbolic brick arch thin-shell structure located in Changleyuan, Baoji City, Shaanxi Province. The study utilizes on-site dynamic testing and finite element numerical simulation methods to analyze the dynamic characteristics of the thin-shell structure and its seismic response under various seismic waves and directions. The simulation results indicate the following findings: Vertical earthquakes cause more severe damage to structures compared to horizontal earthquakes. Bidirectional seismic excitation has a greater impact on the structure than unidirectional and three-dimensional seismic excitation. The obtained results provide a scientific basis for the seismic protection, reinforcement, and repair of this multi-span double-curved brick arch thin-shell structure.

Performance of masonry infills in reinforced concrete moment resisting frames under bidirectional seismic excitations

Performance of masonry infills in reinforced concrete moment resisting frames under bidirectional seismic excitations

Shake table testing of a half-scale stone masonry building aggregate

AbstractMasonry aggregates have developed throughout city centres of Europe due to a centuries-long densification process that generally lacked consistent planning or engineering. Adjacent units are connected either through interlocking stones or a layer of mortar. Without interlocking stones, the connection between the units is weak, and an out of-phase response of the units can lead to separation and pounding. Modelling guidelines and code instructions are missing for modelling the interaction of such adjacent units because of scarce experimental data. Therefore, in this study an unreinforced stone masonry aggregate was tested on the bidirectional shake table with an incremental seismic protocol as a part of the SERA AIMS—Adjacent Interacting Masonry Structures project. The aggregate was constructed at half-scale with double-leaf undressed stone masonry without interlocking between the units. Floors were built with timber beams and one layer of planks, with different beam span orientation for each unit. After significant damage, one of the units was retrofitted by anchoring the timber beams to the walls to prevent out-of-plane failure and testing was continued. Significant interaction between the units was observed with specific damage mechanisms. Cracking and separation were observed at the interface in both longitudinal and transverse direction, starting at lower intensity runs and progressively increasing. Bidirectional seismic excitation affected the unit separation, with friction forces seemingly playing a role in the transverse direction. Signs of pounding at the interface were observed during higher intensity runs, together with the formation of a soft storey mechanism at the upper storey of the higher unit. The mechanism involved an out-of-plane response of the shared wall, with a horizontal crack at the height of the interaction. These findings contribute to a better understanding of the seismic behaviour of masonry aggregates.

Nonlinear seismic response analysis of layered seabed considering seawater-seabed coupling effects

Earthquake in the sea area is an important factor affecting the safety of marine engineering construction, seabed site seismic response analysis is an important preliminary work for marine engineering construction. Based on a fluid-solid weak coupling model which could simulate seawater-seabed interaction, four typical borehole sections along the proposed tunnel at Qiongzhou strait are selected to establish layered seabed models for studying the seabed site seismic responses affected by the seawater, seabed soft sediments and bedrock earthquake motion under bidirectional seismic excitation, in which the dynamic nonlinearity of the seabed soft soil is simulated by a generalized non-Masing constitutive model (DCZ model). The result shows: the suppression effect of seawater on seabed seismic motion exists only in the shallow range of seabed (< 50 m), and the suppression effect on the vertical seismic response is higher than that along the horizontal direction; the suppression effect of seawater on the seabed surface seismic motion and the frequency response phenomenon of “high frequency suppression, low frequency amplification” of seabed seismic response is positively correlated with seawater depth; The mean lines of the horizontal and vertical spectrum β obtained by numerical calculation are higher than the design spectrum in the land code within several period ranges, and the possibility of adverse effects induced by seawater and seabed soft sedimentation on the seismic resistance of marine engineering should be considered.

Numerical Analysis and Experimental Study on Seismic Coupling Response of Pipe-Soil System Under Bidirectional Seismic Excitation

The seismic response of buried pipeline is significantly affected by the soil around the pipeline. In this study, a numerical analysis model of the pipeline and the soil around the pipeline is built, and the finite element numerical analysis of its seismic response law is conducted to address the problem of pipeline soil seismic coupling response. A shaking table test of the seismic response of buried pipeline under two-way seismic excitation is performed based on the developed two-way layered shear continuum model soil box. The peak strain response at the middle section of the pipeline grows fastest, the peak strain of the pipeline under non-uniform seismic excitation constantly exceeds that under uniform excitation, and the axial strain of the pipeline exhibits more sensitivity to earthquake than the bending strain, as indicated by the results of numerical analysis and shaking table test. The peak value of soil acceleration response under non-uniform excitation exceeds under uniform excitation. The displacement of soil increases with the height. The pipeline soil interaction becomes more intense under non-uniform excitation, and the relative movement between pipeline and soil becomes more significant. The seismic excitation more significantly affects the axial displacement of soil. The peak value of soil acceleration response varies from larger along the pipeline to larger along the axis with the increase of the loading grade. A slight difference exists between the peak value of axial and transverse acceleration response of the pipeline. The peak value of pipeline acceleration response declines in the axial direction than the peak value of soil acceleration response, whereas it rises in the transverse direction than the peak value of soil acceleration response, especially under non-uniform excitation. As revealed by the above results, the effect of bidirectional non-uniform seismic excitation on the lateral pipeline soil interaction is enhanced, and soil is more seriously damaged.

Bond-slip at anchorage under unidirectional and bidirectional seismic excitation: Search for an efficient mathematical model

Reinforcement anchorage slip can significantly contribute to the seismic response of bridge columns, especially to residual deformation. For a reliable numerical model of slip action, the present study evaluates three advanced models, each founded on distinct principles: (a) a macroscopic model (M−I), (b) a microscopic model (M−II), and (c) a mixed model that employed micro-model material properties derived from a macro-model (M−III). The performance of each model under unidirectional shaking has been first validated. The M−I cannot account for bidirectional loading, and as such, the performance of the M−II and M−III has, for the first time, been rigorously examined against the two-component shake table test results. Beginning with the simplified pulses, the responses of representative bridge columns are computed to unidirectional and bidirectional shaking for several near-fault motions. The M−I, M−II, and M−III are fairly similar in mimicking the slip action for unidirectional loading. Also, the M−II and M−III can closely represent the responses to bidirectional shaking. A simple extension of the M−I is proposed to capture the effects of bidirectional loading. The performance of the M−I (extended), M−II, and M−III are shown similar from the viewpoint of representing (i) the seismic fragilities, (ii) the uncertainties of the influential parameters, and (iii) the consequences of a sequence of motions. The detailed scrutiny of a range of models helps select the most appropriate scheme in a specific design context. On the other hand, the less-rigourous model, viz., M−I with the proposed extension, can be used within the limitations of commercial software and can prove useful in routine design for bidirectional seismic action.

Seismic Performance of RC Buildings with Different Positions of Lift Core Wall and Added Shear Walls

Nepal is situated in an area with considerable seismic activity. It is important to choose structural systems that can withstand the lateral loads. In a dual system of reinforced concrete structures, the placement of shear walls optimally increases the stiffness of the buildings. The lateral rigidity of RC buildings may be improved by strategically placing lift core walls. Buildings would be more useful if they had easy access to an elevator and stairs. Torsional irregularity in buildings would be caused by the lift core wall's eccentric location. For these kinds of structures, a bidirectional seismic excitation study is required. In design, IS 1893:2016 is applied. Drift limitations are obtained from FEMA 356 2000 for different damage conditions and median displacement values are taken as per HAZUS 4.2 SP3. This research work presents the vulnerability due to eccentric positioning of lift core in symmetrical reinforced concrete frame. The torsional irregularities are needed to be removed with optimum positioning of extra shear walls. The reduction in vulnerability of buildings due to added walls is also studied.

An Efficient Straightforward Pushover Method for Buildings with Two-Way Unsymmetric-Plan Subjected to Two Components of Ground Motions

ABSTRACT A straightforward pushover method is developed for unsymmetric-plan buildings under bidirectional seismic excitation. To this end, a single innovative torsional-lateral load pattern is introduced based on the response spectrum analysis. The joint contribution of two horizontal seismic excitations and the joint contribution of all considered modes to internal structural forces in forming plastic hinges are considered by implementing the single load pattern. An equivalent dominant mode shape derived from the load pattern is defined to establish capacity spectra in both directions. The accuracy of the proposed procedure in estimating the seismic demands of buildings is demonstrated through two unsymmetric-plan buildings.

Experimental study on rocking blocks subjected to bidirectional ground and floor motions via shaking table tests

AbstractTo provide an insight for reliable seismic risk assessment of small building contents, the rocking response of freestanding wooden blocks subjected to 11 bidirectional horizontal ground motion records scaled to various intensity levels is investigated via shaking table tests. Three prisms and three cylinders with slenderness ratios of 2, 3 and 4, and three prisms having the same slenderness ratio of 3 but different size parameters of 158 mm, 237 mm and 316 mm, are considered. The peak ground acceleration statistics corresponding to rocking and overturning of the blocks are obtained. Shaking table tests to investigate the rocking response of the prisms located on different floors of a full‐scale three‐story reinforced concrete frame structure were also conducted. Experimental fragility curves corresponding to rocking and overturning occurrence of the blocks are finally generated. The experimental results highlight that the minimum rocking accelerations are different for the prisms with the same slenderness ratio but different sizes. Moreover, compared with the prism on the ground, the prism on the top floor has significantly higher rocking demand, while the prism on the second floor may have lower rocking demand. Furthermore, the cylinder has higher rocking and overturning fragility than the prism with the same height and width. The rocking and overturning fragility increases as the block becomes slenderer or smaller. The proposed critical rocking acceleration under bidirectional seismic excitation in real conditions is a half of the theoretical one under unidirectional excitation.

Effect of out-of-plane displacements on the in-plane capacity of lightly precompressed rocking unreinforced masonry piers

Unreinforced masonry (URM) buildings subject to bidirectional seismic excitation are under the effects of simultaneous in-plane and out-of-plane actions. Seismic assessment carried out without considering the combined effects due to these actions could result in non-conservative capacity estimates and inadequate strengthening requirements. Bidirectional effects are not explicitly considered in the seismic assessment of existing URM buildings, owing to the limitations in existing protocols and analytical models and the simplicity achieved in performing the assessment. The current work attempts to quantify the effect of out-of-plane displacements on the in-plane capacity of masonry walls undergoing a flexural rocking mechanism of failure, thereby improving the existing understanding of bidirectional interaction in masonry structures. Response of lightly precompressed masonry piers with different aspect ratios in the presence of out-of-plane displacements, were studied experimentally and replicated using numerical and analytical studies. Results indicate that the interaction problem in URM structures should not be considered only from a force capacity reduction perspective. The force capacity reduction predicted using the interaction equations employing an exceedance of net tensile stress-based approach shall be applicable only for the flexural cracking strength and not the ultimate flexural capacity. The in-plane flexural cracking capacity reduces in proportion to the applied out-of-plane displacements when the applied out-of-plane displacements are in the elastic range. In the inelastic range of out-of-plane displacements, the ultimate flexural capacity corresponding to toe-crushing and also the initial stiffness of the pier was observed to decrease due to the reduction in net area available for compression. Also, even small range of out-of-displacements could result in inelasticity in a URM pier leading to a reduced toe-crushing capacity. Hence, it may not be conservative to define the in-plane restoring shear as the failure capacity for rocking URM piers under bidirectional loading. Accordingly, modifications are proposed for the response of masonry walls undergoing rocking mechanism.

Experimental tests and numerical modeling of full-scale unbonded fiber reinforced elastomeric isolators (UFREIs) under bidirectional excitation

Unbonded fiber reinforced elastomeric isolators (UFREIs) can be used for the seismic protection of structures as a lower-cost alternative to conventional laminated rubber bearings, by replacing internal steel shims with fiber reinforcement and exploiting the frictional mechanism at the rubber-concrete interface to avoid anchorage bolts. In this paper, the hysteretic behavior of full-scale (diameter 620 mm) UFREIs is investigated in both an experimental and a numerical framework when subjected to triaxial loading (i.e., simultaneous imposed displacement along two horizontal directions with concurrently applied vertical load), to account for the inherent multi-directional nature of a real earthquake scenario. Experimental results of UFREIs tested under two bidirectional orbits involving different velocities and amplitudes up to 100% shear strain are presented, and peculiar effects ascribed to the lateral coupling of the devices are identified by comparison with monodirectional test results. Then, an efficient nonlinear phenomenological model is proposed to simulate the isotropically coupled biaxial hysteretic behavior of UFREIs detected from the experiments. This model consists of a set of nonlinear springs arranged in a circular configuration and governed by just three parameters with clear mechanical significance. Novel analytical (closed-form) expressions for the model calibration are ad-hoc developed in this paper. This modeling approach is used to quantify the impact of biaxial coupling of UFREIs on the structural performance of base-isolated structures under bidirectional seismic excitation. To this aim, the seismic response of a three-dimensional reinforced concrete building isolated with UFREIs is numerically simulated. Numerical results show that isolator displacements and superstructure accelerations tend to be higher by using an uncoupled model, calibrated upon monodirectional tests and that neglects bidirectional interaction, as usually performed in practice.

Seismic performance of near-fault geosynthetic-reinforced pile-supported embankment

The seismic performance of embankments is an important consideration for the design and construction of high-speed railways (HSRs) in near-fault areas. Incorporating geosynthetics into embankment soil can improve seismic resistance. However, the effect of different reinforcement methods on the seismic performance of embankments is not well understood. In this study, two 1 : 20 scaled embankment models (full-length-geosynthetic-reinforced pile-supported embankment (FRPE) and turn-back-geosynthetic-reinforced pile-supported embankment (TRPE)) were tested on a shaking table to compare their seismic performance and failure characteristics. The results show that under near-fault bidirectional seismic excitation, the pile foundations of both embankments exhibited bending deformation, with the largest bending moment in the middle of the pile body. The TRPE reduced the vertical dynamic response of the embankment slope but exhibited a more remarkable horizontal dynamic response than the FRPE. Furthermore, the embankment deformation and excess pore water pressure of the TRPE were generally larger than those of the FRPE. Nonetheless, the TRPE has potential application in practical engineering as it ensures earthquake resistance, with higher economic benefits.

Seismic overturning fragility analysis for freestanding building contents subjected to horizontal bidirectional floor motions

The rocking response of freestanding building contents simplified as rigid bodies was usually investigated in two dimensions with ground motions as the input, while their three-dimensional (3-D) rocking response subjected to horizontal bidirectional floor motions needs further investigation in both deterministic and probabilistic views. In this paper, the rocking response of freestanding 3-D rectangular blocks subjected to seismic excitations with two horizontal components are first investigated by shake table tests and finite element (FE) numerical simulation. An incremental dynamic analysis-based overturning fragility assessment method for the blocks within a building subjected to bidirectional ground motions is then proposed, using uncoupled nonlinear FE models of the block-building systems. The overturning fragility of six blocks within a four-story reinforced concrete frame structure is assessed. The influence of excitation directions, floor levels, block slenderness ratios (2.5, 3, 3.5 and 4), block sizes (size parameters of 91 mm, 182 mm and 364 mm) and intensity measurements (IMs) on the overturning fragility of the block is characterized. The experimental overturning fragility curves of three blocks in real conditions under bidirectional seismic excitations are finally obtained from the shake table tests. Rocking-torsional rotations are observed for the block with sliding not allowed. The block rocks around a side or a vertex while overturns around a side. Except the largest block, the block under bidirectional excitations is usually more and sometimes equally vulnerable to overturn in comparison to that under unidirectional excitations. The block on a higher floor is found to be more vulnerable to overturn than that on a lower floor considering the peak ground acceleration-based IM. These observations highlight on the significance of 3-D analysis for the rocking blocks considering floor acceleration amplification. This paper also enlarges the experimental database of seismic rocking response of rectangular blocks under bidirectional horizontal motions.

Engineering analysis of the dynamic characteristics of an electrical jacket platform of an offshore wind farm under seismic loads

From the perspective of the power transmission economy, offshore electrical platforms will be an inevitable choice for developing large-scale offshore wind farms in the open sea. In this study, a finite element numerical model of the electrical platform was built, and the dynamic responses under seismic loads were analyzed. The validity of the numerical model was verified by the corresponding physical model test. On this basis, a time-history analysis of the strain, acceleration, and displacement response of the electrical platform was carried out. The results and trends of dynamic responses under different wave actions were obtained. The influence of water and air environments and unidirectional and bidirectional seismic excitations on the dynamic response of the structure was analyzed. Consequently, the strain peaks of the structures under air conditions are all greater than those under water conditions, with an increment mean of 12.88%, and an increment mean of the peak acceleration of 10.76%. The peak value of the acceleration response is 30.49% higher than that of the unidirectional earthquake, and the peak value of the strain response is 25.78% higher than that of the unidirectional earthquake. It is indicated that bidirectional seismic excitation is more detrimental to the safety of structures.

Probabilistic damage evaluation of base-isolated reinforced concrete structures under near-fault pulse-like bidirectional seismic excitations

In this article, seismic fragility of a base-isolated special Reinforced Concrete (RC) moment frame is investigated under near-fault pulse-type ground motion records. The vulnerability of the displacement-dominated performance of isolator devices to a likely vibration resonance caused by such records is the focus of the study. For this purpose, Lead-Rubber Bearings (LRBs) and Triple Friction Pendulum Bearings (TFPBs) are utilized to represent various isolator behaviorisms in different period ranges. The structures are modelled in three dimensions to account for the axial-bending-bending interaction in the isolator devices. The models are then subjected to IDAs under three sets of near-fault pulse-type ground motion records with different pulse periods. Four different damage states are considered and the IDA results are used for deriving fragilities that express probabilities of exceeding these states at various intensity levels. The study revealed that despite the amplifying effects of the employed records, using isolators is still feasible. That is, even for pulse periods near to the effective period of isolators, resonance has not led to higher failure probabilities in the isolated buildings compared to their fixed-base counterparts. Furthermore, at longer pulse periods, the gradual yielding behavior of TFPBs made them more effective than the LRBs. Results also disclosed that at lower intensities, damage of base-isolated structures is mainly caused due to excessive floor acceleration while at higher intensities the maximum inter-story drift plays the dominant role. This suggest these two response parameters to be alternatively used as the Engineering Demand Parameter (EDP) when defining damage states at the medium and high intensity levels.

Maximum mean square response and critical orientation under bi-directional seismic excitation

Power Spectrum Analysis (PSA) consists one of the seismic analysis methods proposed by modern code provisions. In the context of PSA, the computation of seismic behavior is achieved by a stochastic analysis that yields mean square values. A method that can be used for the determination of maximum or mean square response is the response history analysis. In the present study, analytical formulas are developed for the determination of the maximum mean square value and the corresponding critical incident angle of any scalar response quantity under two horizontal seismic components for any time interval of ground motion within the context of linear response history analysis. An R/C building is analyzed in order to demonstrate the variation of the maximum mean square response with the incident angle. The maximum mean square response values over all incident angles are calculated using the developed formulas. The results show that the application of the earthquake components along the structural axes can underestimate the mean square response.

Adaptive neuro-fuzzy and simple adaptive control methods for full three-dimensional coupled buildings subjected to bi-directional seismic excitations

Attenuation of three-dimensional coupled buildings under bi-directional seismic excitations using semi-active control devices is pursued in this paper. Multiple magneto-rheological (MR) dampers are employed to connect two adjacent buildings at multiple levels for real-time control of the structural responses. The MR dampers are managed by adaptive neuro-fuzzy inference systems (ANFIS) and simple adaptive control (SAC) methods so a comparison between the performance of both controllers can be made. The displacement feedback type is used for both control methods to design the closed-loop action. The structural system modeled as two three-dimensional buildings connected by frame elements in which the MR dampers are implemented. The equations of motions of the three-dimensional model are formulated by assuming that each floor diaphragm is rigid in its own plane but flexible in the vertical coordinate. Each link is assumed to have three degrees-of-freedom two translational and one rotational at its ends. The adaptive neuro-fuzzy inference system is designed based on Sugeno-type model. Seven triangular membership functions are chosen to fuzzify the input crisp data in the fuzzy logic controller. The training data for ANFIS are generated by the Linear Quadratic Regulator (LQR) under white-noise disturbance. For the simple adaptive controller, LQR is also used to generate the desired trajectories of the reference-model. Numerical simulations are carried out for both symmetrical and asymmetrical coupled buildings under eleven pairs of major earthquakes. The results show that both ANFIS and SAC can deal very successfully with modeling complexities associated with full three-dimensional models subjected to multi-excitations. In terms of seismic responses reduction, both methods have shown a great potential in enhancing the structural performance under seismic activities.