Frame and rocking wall(FRW)structures have excellent resilient performance during earthquakes.However,the concrete at interfacial corners of rocking walls(RWs)is easily crushed due to local extreme compression during ...Frame and rocking wall(FRW)structures have excellent resilient performance during earthquakes.However,the concrete at interfacial corners of rocking walls(RWs)is easily crushed due to local extreme compression during the rocking process.An innovative RW with a curved interface is proposed to prevent interfacial corners from producing local damage,enhancing its earthquake resilient performance(ERP).The precast wall panel with a curved interface is assembled into an integral self-centering hybrid rocking wall(SCRW)by two post-tensioned unbonded prestressed tendons.Moreover,two ordinary energy dissipation steel rebars and two shear reinforcements are arranged to increase the energy dissipation capacity and lateral resistance.Two SCRW specimens and one monolithic reinforced concrete(RC)shear wall(SW)were tested under pseudo-static loading to compare the ERPs of the proposed SCRW and the SW,focusing on studying the effect of the curved interface on the SCRW.The key resilient performance of rocking effects,failure modes,and hysteretic properties of the SCRW were explored.The results show that nonlinear deformations of the SCRW are concentrated along the interface between the SCRW and the foundation,avoiding damage within the SCRW.The restoring force provided by the prestressed tendons can effectively realize self-centering capacity with small residual deformation,and the resilient performance of the SCRW is better than that of monolithic SW.In addition,the curved interface of the SCRW makes the rocking center change and move inward,partially relieving the stress concentration and crush of concrete.The rocking range of the rocking center is about 41.4%of the width of the SCRW.展开更多
In seismology and earthquake engineering,it is fundamental to identify and characterize the pulse-like features in pulse-type ground motions.To capture the pulses that dominate structural responses,this study establis...In seismology and earthquake engineering,it is fundamental to identify and characterize the pulse-like features in pulse-type ground motions.To capture the pulses that dominate structural responses,this study establishes congruence and shift relationships between response spectrum surfaces.A similarity search between spectrum surfaces,supplemented with a similarity search in time series,has been applied to characterize the pulse-like features in pulse-type ground motions.The identified pulses are tested in predicting the rocking consequences of slender rectangular blocks under the original ground motions.Generally,the prediction is promising for the majority of the ground motions where the dominant pulse is correctly identified.展开更多
The performance of a strapdown inertial navigation system(SINS)largely depends on the accuracy and rapidness of the initial alignment.A novel anti-interference self-alignment algorithm by attitude optimization estimat...The performance of a strapdown inertial navigation system(SINS)largely depends on the accuracy and rapidness of the initial alignment.A novel anti-interference self-alignment algorithm by attitude optimization estimation for SINS on a rocking base is presented in this paper.The algorithm transforms the initial alignment into the initial attitude determination problem by using infinite vector observations to remove the angular motions,the SINS alignment is heuristically established as an optimiza-tion problem of finding the minimum eigenvector.In order to further improve the alignment precision,an adaptive recursive weighted least squares(ARWLS)curve fitting algorithm is used to fit the translational motion interference-contaminated reference vectors according to their time domain characteristics.Simulation studies and experimental results favorably demonstrate its rapidness,accuracy and robustness.展开更多
The development of insertion-type anodes is the key to designing“rocking chair”zinc-ion batteries.However,there is rare report on high mass loading anode with high performances.Here,{001}-oriented Bi OCl nanosheets ...The development of insertion-type anodes is the key to designing“rocking chair”zinc-ion batteries.However,there is rare report on high mass loading anode with high performances.Here,{001}-oriented Bi OCl nanosheets with Sn doping are proposed as a promising insertion-type anode.The designs of cross-linked CNTs conductive network,{001}-oriented nanosheet,and Sn doping significantly enhance ion/electron transport,proved via experimental tests and theoretical calculations(density of states and diffusion barrier).The H^(+)/Zn^(2+)synergistic co-insertion mechanism is proved via ex situ XRD,Raman,XPS,and SEM tests.Accordingly,this optimized electrode delivers a high reversible capacity of 194 m A h g^(-1)at 0.1 A g^(-1)with a voltage of≈0.37 V and an impressive cyclability with 128 m A h g^(-1)over 2500 cycles at 1 A g^(-1).It also shows satisfactory performances at an ultrahigh mass loading of 10 mg cm^(-2).Moreover,the Sn-Bi OCl//MnO_(2)full cell displays a reversible capacity of 85 m A h g^(-1)at 0.2 A g^(-1)during cyclic test.展开更多
This paper presents a single-degree-of-freedom(SDOF)constitutive model for assessing the performance of freestanding block contents of buildings.The model incorporates a bespoke damper to account for energy dissipatio...This paper presents a single-degree-of-freedom(SDOF)constitutive model for assessing the performance of freestanding block contents of buildings.The model incorporates a bespoke damper to account for energy dissipation associated with rocking.It is advantageous in its direct correlation,via energy conservation,to the restitution coefficient for impact during rocking.A comparative study with the existing SDOF rocking models shows that the proposed model significantly improves the accuracy of free-rocking simulations,in which inherent damping predominantly affects response.It provides a promising and efficient tool for computationally intensive performance evaluation of nonstructural components.展开更多
The challenge in the practical application of rocking foundations is the estimation of its performance,particularly the rotation angle,during a strong earthquake.In this study,the dynamic rocking behavior for a shallo...The challenge in the practical application of rocking foundations is the estimation of its performance,particularly the rotation angle,during a strong earthquake.In this study,the dynamic rocking behavior for a shallow foundation considering structural response was evaluated through two analytical approaches:the conventional soil-foundation-structure interaction(SFSI)governing equation of a single-degree-of-freedom(SDOF)structure on a rocking shallow foundation,and the Housner rocking model(i.e.,a rocking rigid block on a rigid base).Both approaches were validated with dynamic centrifuge tests.The test models consisted of a soft soil deposit,a shallow rectangular foundation,and an SDOF structure dominated by a bending behavior.A total of 11 foundation-structure systems and six seismic waves,including recorded earthquake signals and sinusoidal waves,were utilized.The results showed that the conventional SFSI equation well predicted the maximum rotation during strong earthquakes.However,this method was less accurate regarding the rotational phase information and maximum rotation of the foundation during weak earthquakes.On the other hand,although the modified Housner′s rocking model required five parameters relevant to a soil-foundation-structure system,it overestimated the maximum rotation of the foundation when compared with the results from dynamic centrifuge tests.展开更多
Bridges designed following a conventional approach minimize the risk of collapse,but often require challenging,costly,and time-consuming restoration after an earthquake occurs.The new seismic design philosophy require...Bridges designed following a conventional approach minimize the risk of collapse,but often require challenging,costly,and time-consuming restoration after an earthquake occurs.The new seismic design philosophy requires bridges to maintain functionality even after severe earthquakes.In this context,this paper proposes a controlled rocking pile foundation(CRPF)system and numerically evaluates bridges′degree of seismic resilience.The CRPF system allows a pile cap to rock on a pile foundation and dissipate seismic energy through inelastic deformations of replaceable bar fuses that connect a pile cap and piles.Following the conceptual design of the CRPF system,two analytical models were developed for a bridge pier utilizing the CRPF system and a pier designed to develop a plastic hinge in its column.The analytical results indicate that,after experiencing a severe earthquake,a conventionally designed bridge pier sustained substantial damage in its column and exhibited significant residual displacement.In contrast,a pier using the CRPF system showed negligible residual displacement and maintained elastic behavior except,as expected,for bar fuses.The damaged fuses can be rapidly replaced to recover bridge seismic resistance following an earthquake.Therefore,the CRPF system helps to achieve the desired postearthquake performance objectives.展开更多
Cross-laminated bamboo(CLB)have a high strength to weight ratio and stable bidirectional mechanical properties.Inspired by the investigation on cross-laminated timber(CLT)rocking walls,CLB rocking walls with conventio...Cross-laminated bamboo(CLB)have a high strength to weight ratio and stable bidirectional mechanical properties.Inspired by the investigation on cross-laminated timber(CLT)rocking walls,CLB rocking walls with conventional friction dampers(CFDs)are studied in this paper.To investigate the mechanical properties of the CLB rocking wall,seven tests are conducted under a cyclic loading scheme,and different test parameters,including the existence of the CFDs,the moment ratio,and the loading times,are discussed.The test results show a bilinear behavior of the CLB rocking wall.The small residual displacements of the CLB rocking wall demonstrate an idealized self-centering capacity.The cumulative energy dissipation curves indicate that the energy dissipation capacity of the CLB rocking wall can be greatly improved with CFDs.The limit states of the CLB rocking wall under a lateral force are proposed based on the strains,stress,and damage level of the CLB material and posttensioned rebar.In addition,an analytical model of the CLB rocking wall is developed based on the proposed limit states of the CLB rocking wall to evaluate the hysteretic response of the CLB rocking wall,and the model is validated by the experimental data.The comparison results show the potential value of the analytical model for engineering design.展开更多
A multiple rocking wall-frame(MRWF)system,in which the wall panels are directly connected to the adjacent beams and foundation is presented herein.In the MRWF system,the unbonded post-tensioned(PT)tendons are used to ...A multiple rocking wall-frame(MRWF)system,in which the wall panels are directly connected to the adjacent beams and foundation is presented herein.In the MRWF system,the unbonded post-tensioned(PT)tendons are used to promote the self-centering ability,and O-shaped steel dampers are applied to enhance the energy dissipation capacity and reparability of the structure.First,analytical equations are proposed to determine the behavior of the O-shaped dampers.Then,the MRWF system is numerically evaluated for five different models consisting of rocking walls with varying numbers and arrangements while keeping the total effective width of wall panels constant.The numerical results show that with an increase in the number of wall panels and a decrease in the wall width,the hysteretic behavior of the MRWF system tends to the ideal flag-shaped pattern,resulting in little damage to the beams,insignificant strain in the wall toe,negligible residual drifts and damage index of less than 0.2 under severe earthquakes.In contrast,the conventional model demonstrates extensive damage to the structural elements due to undesirable wall-to-frame interaction,which leads to a damage index of 0.78 and residual drifts of 0.42%under seismic loads.展开更多
In this study, sacrificial components were incorporated into self-centering railway bridge piers to improve the lateral stiffness. The seismic response of this new detail was investigated. First, the method to compute...In this study, sacrificial components were incorporated into self-centering railway bridge piers to improve the lateral stiffness. The seismic response of this new detail was investigated. First, the method to compute the initial uplift moment of the self-centering pier is given. In addition, shaking table tests were conducted on a free-rocking pier without sacrificial components, which was used to validate a two-spring numerical model. Good agreement was obtained between the numerical results and experimental data. Furthermore, the validated model was employed to investigate the influence of sacrificial components on the seismic response of rocking piers. For this purpose, two models were developed, with and without sacrificial components. Nonlinear response history analysis was then performed on both models under three historical motions. The results showed that compared to the one without sacrificial components, the rocking pier with sacrificial components has comparable displacement at the top of the pier, and maximum uplift moment at high amplitude motion. Therefore, incorporating sacrificial components into the rocking pier can increase the lateral stiffness at service load and low amplitude frequent earthquakes but can produce comparable response at high seismic excitation. These results provide support for performance-based seismic design of self-centering rocking piers.展开更多
A controlled rocking concentrically steel braced frame(CR-CSBF)is introduced as an alternative to conventional methods to prevent major structural damage during large earthquakes.It is equipped with elastic post-tensi...A controlled rocking concentrically steel braced frame(CR-CSBF)is introduced as an alternative to conventional methods to prevent major structural damage during large earthquakes.It is equipped with elastic post-tensioned(PT)cables and replaceable devices or fuses to provide overturning resistance and dissipate energy,respectively.Although CR-CSBFs are not officially legalized in globally valid codes for new buildings,it is expected to be presented in them in the near future.The main goal of this study is to determine the optimal design parameters consist of the yield strength and modulus of elasticity of the fuse,the initial force of the PT cable,and the gravity load on the rocking column,considering different heights of the frame,spanning ratios and ground motion types for dual-configuration CR-CSBF.Nonlinear time-history analyses are performed in OpenSees.This study aims to define the optimal input variables as effective design parameters of CR-CSBFs by comparing four seismic responses consisting of story drift,roof displacement,roof acceleration and base shear,and also using the Euclidean metric optimization method.Despite the previous research,this study is innovative and first of its kind.The results demonstrate that the optimal design parameters are variable for various conditions.展开更多
A new rocking constraint device(RCD)is developed for three-dimensional(3D)base-isolated frame structures by connecting a custom-designed cylinder pair to provide vertical damping with replaceable damping components in...A new rocking constraint device(RCD)is developed for three-dimensional(3D)base-isolated frame structures by connecting a custom-designed cylinder pair to provide vertical damping with replaceable damping components installed outside the cylinders when the superstructure undergoes translational motion,and rocking constraint capacity when the superstructure is susceptible to rocking.Theoretical formulas for calculating the damping and rocking constraint stiffness of the RCD are proposed.Two series of sinusoidal loading tests are conducted at different loading frequencies and amplitudes to verify the damping and rocking constraint performance of the RCD.The test results show that the cylinder without orifices on its piston can provide the desired damping with a replaceable damping component,and that the RCD can effectively suppress rocking.Although the vertical stiffness of an individual cylinder is affected by the location of the replaceable damping component and loading frequency,the average vertical stiffness of the two cylinders,which determines the rocking constraint stiffness of the RCD,is independent of the two factors.Comparisons of the test and theoretical results indicate that the errors of the proposed formulas for calculating the damping and rocking constraint stiffness of the RCD do not exceed 12.9%and 11.0%,respectively.展开更多
"Rocking chair"type lithium-ion batteries with lithium metal-free anodes have been successfully com-mercialized over the past few decades.Zinc-ion batteries(zIBs)have gained increasing attention in recent ye..."Rocking chair"type lithium-ion batteries with lithium metal-free anodes have been successfully com-mercialized over the past few decades.Zinc-ion batteries(zIBs)have gained increasing attention in recent years given their safety,greenness,ease of manufacture,and cost-efficiency.Nevertheless,the practical application of ZIBs is largely hindered by the dendritic growth of the Zn metal anode,low Coulombic eficiency,great harm,and existence of various side reactions.Herein,this review provides a systematic overview of emerging"rocking chair"type ZIBs with zinc metal-free anodes.Firstly,the basic fundamen-tals,advantages,and challenges of“rocking chair”type ZIBs are introduced.Subsequently,an overview of the design principles and recent progress of"rocking chair"type ZIBs with zinc metal-free anodes are presented.Finally,the key challenges and perspectives for future advancement of"rocking chair"type ZiBs with zinc metal-free anodes are proposed.This review is anticipated to attracted increased focus to metal-free anodes"rocking chair"type metal-ion battery and provide new inspirations for the develop-ment of high-energy metal-ion batteries.展开更多
A rock concert for kids took to the stage of a theater nestled in a hutong,a narrow alleyway in the traditional residential areas of Beijing,on March 18.Chinese and British performers put on a musical extravaganza tha...A rock concert for kids took to the stage of a theater nestled in a hutong,a narrow alleyway in the traditional residential areas of Beijing,on March 18.Chinese and British performers put on a musical extravaganza that had children stomping their feet,shaking their heads and rocking out to the music.展开更多
基金National Key Research and Development Program of China under Grant No.2018YFC0705602。
文摘Frame and rocking wall(FRW)structures have excellent resilient performance during earthquakes.However,the concrete at interfacial corners of rocking walls(RWs)is easily crushed due to local extreme compression during the rocking process.An innovative RW with a curved interface is proposed to prevent interfacial corners from producing local damage,enhancing its earthquake resilient performance(ERP).The precast wall panel with a curved interface is assembled into an integral self-centering hybrid rocking wall(SCRW)by two post-tensioned unbonded prestressed tendons.Moreover,two ordinary energy dissipation steel rebars and two shear reinforcements are arranged to increase the energy dissipation capacity and lateral resistance.Two SCRW specimens and one monolithic reinforced concrete(RC)shear wall(SW)were tested under pseudo-static loading to compare the ERPs of the proposed SCRW and the SW,focusing on studying the effect of the curved interface on the SCRW.The key resilient performance of rocking effects,failure modes,and hysteretic properties of the SCRW were explored.The results show that nonlinear deformations of the SCRW are concentrated along the interface between the SCRW and the foundation,avoiding damage within the SCRW.The restoring force provided by the prestressed tendons can effectively realize self-centering capacity with small residual deformation,and the resilient performance of the SCRW is better than that of monolithic SW.In addition,the curved interface of the SCRW makes the rocking center change and move inward,partially relieving the stress concentration and crush of concrete.The rocking range of the rocking center is about 41.4%of the width of the SCRW.
基金National Key Research and Development Program,Ministry of Science and Technology of China under Grant No.2022YFC3803004the National Natural Science Foundation of China under Grant No.51838004。
文摘In seismology and earthquake engineering,it is fundamental to identify and characterize the pulse-like features in pulse-type ground motions.To capture the pulses that dominate structural responses,this study establishes congruence and shift relationships between response spectrum surfaces.A similarity search between spectrum surfaces,supplemented with a similarity search in time series,has been applied to characterize the pulse-like features in pulse-type ground motions.The identified pulses are tested in predicting the rocking consequences of slender rectangular blocks under the original ground motions.Generally,the prediction is promising for the majority of the ground motions where the dominant pulse is correctly identified.
基金supported by the National Natural Science Foundation of China(41174162).
文摘The performance of a strapdown inertial navigation system(SINS)largely depends on the accuracy and rapidness of the initial alignment.A novel anti-interference self-alignment algorithm by attitude optimization estimation for SINS on a rocking base is presented in this paper.The algorithm transforms the initial alignment into the initial attitude determination problem by using infinite vector observations to remove the angular motions,the SINS alignment is heuristically established as an optimiza-tion problem of finding the minimum eigenvector.In order to further improve the alignment precision,an adaptive recursive weighted least squares(ARWLS)curve fitting algorithm is used to fit the translational motion interference-contaminated reference vectors according to their time domain characteristics.Simulation studies and experimental results favorably demonstrate its rapidness,accuracy and robustness.
基金supported by the Natural Science Foundation of China (52102312,51672234,and 52072325)the Natural Science Foundation of Hunan Province of China (2021JJ40528)+2 种基金the China Postdoctoral Science Foundation (2020M682581)the Macao Young Scholars Program (AM2021011)the College Student Innovation and Entrepreneurship Training Program (S202210530051)。
文摘The development of insertion-type anodes is the key to designing“rocking chair”zinc-ion batteries.However,there is rare report on high mass loading anode with high performances.Here,{001}-oriented Bi OCl nanosheets with Sn doping are proposed as a promising insertion-type anode.The designs of cross-linked CNTs conductive network,{001}-oriented nanosheet,and Sn doping significantly enhance ion/electron transport,proved via experimental tests and theoretical calculations(density of states and diffusion barrier).The H^(+)/Zn^(2+)synergistic co-insertion mechanism is proved via ex situ XRD,Raman,XPS,and SEM tests.Accordingly,this optimized electrode delivers a high reversible capacity of 194 m A h g^(-1)at 0.1 A g^(-1)with a voltage of≈0.37 V and an impressive cyclability with 128 m A h g^(-1)over 2500 cycles at 1 A g^(-1).It also shows satisfactory performances at an ultrahigh mass loading of 10 mg cm^(-2).Moreover,the Sn-Bi OCl//MnO_(2)full cell displays a reversible capacity of 85 m A h g^(-1)at 0.2 A g^(-1)during cyclic test.
基金Supported by:The Key Program of the CEA Key Laboratory for Earthquake Engineering and Engineering Vibration under Grant No.2019EEEVL0304the Heilongjiang Touyan Innovation Team Program,China。
文摘This paper presents a single-degree-of-freedom(SDOF)constitutive model for assessing the performance of freestanding block contents of buildings.The model incorporates a bespoke damper to account for energy dissipation associated with rocking.It is advantageous in its direct correlation,via energy conservation,to the restitution coefficient for impact during rocking.A comparative study with the existing SDOF rocking models shows that the proposed model significantly improves the accuracy of free-rocking simulations,in which inherent damping predominantly affects response.It provides a promising and efficient tool for computationally intensive performance evaluation of nonstructural components.
基金National Research Foundation of Korea(NRF)Grant funded by the Korean Government(Ministry of Science and ICT)under Grant No.2017R1A5A1014883。
文摘The challenge in the practical application of rocking foundations is the estimation of its performance,particularly the rotation angle,during a strong earthquake.In this study,the dynamic rocking behavior for a shallow foundation considering structural response was evaluated through two analytical approaches:the conventional soil-foundation-structure interaction(SFSI)governing equation of a single-degree-of-freedom(SDOF)structure on a rocking shallow foundation,and the Housner rocking model(i.e.,a rocking rigid block on a rigid base).Both approaches were validated with dynamic centrifuge tests.The test models consisted of a soft soil deposit,a shallow rectangular foundation,and an SDOF structure dominated by a bending behavior.A total of 11 foundation-structure systems and six seismic waves,including recorded earthquake signals and sinusoidal waves,were utilized.The results showed that the conventional SFSI equation well predicted the maximum rotation during strong earthquakes.However,this method was less accurate regarding the rotational phase information and maximum rotation of the foundation during weak earthquakes.On the other hand,although the modified Housner′s rocking model required five parameters relevant to a soil-foundation-structure system,it overestimated the maximum rotation of the foundation when compared with the results from dynamic centrifuge tests.
基金Supported by:National Natural Science Foundation of China under Grant Nos.52008092,U1934205,51908123the China Postdoctoral Science Foundation under Grant No.2021M690034+1 种基金the International Postdoctoral Exchange Fellowship Program of Chinathe Zhishan Postdoctoral Fellowship Program。
文摘Bridges designed following a conventional approach minimize the risk of collapse,but often require challenging,costly,and time-consuming restoration after an earthquake occurs.The new seismic design philosophy requires bridges to maintain functionality even after severe earthquakes.In this context,this paper proposes a controlled rocking pile foundation(CRPF)system and numerically evaluates bridges′degree of seismic resilience.The CRPF system allows a pile cap to rock on a pile foundation and dissipate seismic energy through inelastic deformations of replaceable bar fuses that connect a pile cap and piles.Following the conceptual design of the CRPF system,two analytical models were developed for a bridge pier utilizing the CRPF system and a pier designed to develop a plastic hinge in its column.The analytical results indicate that,after experiencing a severe earthquake,a conventionally designed bridge pier sustained substantial damage in its column and exhibited significant residual displacement.In contrast,a pier using the CRPF system showed negligible residual displacement and maintained elastic behavior except,as expected,for bar fuses.The damaged fuses can be rapidly replaced to recover bridge seismic resistance following an earthquake.Therefore,the CRPF system helps to achieve the desired postearthquake performance objectives.
基金would like to extend their sincere gratitude for the financial support from the Integrated Key Precast Components and New Wood-bamboo Composite Structure Foundation of China(2017YFC0703502)the National Natural Science Foundation of China(51978152)the Fundamental Research Funds for the Central Universities(YJ202061).
文摘Cross-laminated bamboo(CLB)have a high strength to weight ratio and stable bidirectional mechanical properties.Inspired by the investigation on cross-laminated timber(CLT)rocking walls,CLB rocking walls with conventional friction dampers(CFDs)are studied in this paper.To investigate the mechanical properties of the CLB rocking wall,seven tests are conducted under a cyclic loading scheme,and different test parameters,including the existence of the CFDs,the moment ratio,and the loading times,are discussed.The test results show a bilinear behavior of the CLB rocking wall.The small residual displacements of the CLB rocking wall demonstrate an idealized self-centering capacity.The cumulative energy dissipation curves indicate that the energy dissipation capacity of the CLB rocking wall can be greatly improved with CFDs.The limit states of the CLB rocking wall under a lateral force are proposed based on the strains,stress,and damage level of the CLB material and posttensioned rebar.In addition,an analytical model of the CLB rocking wall is developed based on the proposed limit states of the CLB rocking wall to evaluate the hysteretic response of the CLB rocking wall,and the model is validated by the experimental data.The comparison results show the potential value of the analytical model for engineering design.
文摘A multiple rocking wall-frame(MRWF)system,in which the wall panels are directly connected to the adjacent beams and foundation is presented herein.In the MRWF system,the unbonded post-tensioned(PT)tendons are used to promote the self-centering ability,and O-shaped steel dampers are applied to enhance the energy dissipation capacity and reparability of the structure.First,analytical equations are proposed to determine the behavior of the O-shaped dampers.Then,the MRWF system is numerically evaluated for five different models consisting of rocking walls with varying numbers and arrangements while keeping the total effective width of wall panels constant.The numerical results show that with an increase in the number of wall panels and a decrease in the wall width,the hysteretic behavior of the MRWF system tends to the ideal flag-shaped pattern,resulting in little damage to the beams,insignificant strain in the wall toe,negligible residual drifts and damage index of less than 0.2 under severe earthquakes.In contrast,the conventional model demonstrates extensive damage to the structural elements due to undesirable wall-to-frame interaction,which leads to a damage index of 0.78 and residual drifts of 0.42%under seismic loads.
文摘In this study, sacrificial components were incorporated into self-centering railway bridge piers to improve the lateral stiffness. The seismic response of this new detail was investigated. First, the method to compute the initial uplift moment of the self-centering pier is given. In addition, shaking table tests were conducted on a free-rocking pier without sacrificial components, which was used to validate a two-spring numerical model. Good agreement was obtained between the numerical results and experimental data. Furthermore, the validated model was employed to investigate the influence of sacrificial components on the seismic response of rocking piers. For this purpose, two models were developed, with and without sacrificial components. Nonlinear response history analysis was then performed on both models under three historical motions. The results showed that compared to the one without sacrificial components, the rocking pier with sacrificial components has comparable displacement at the top of the pier, and maximum uplift moment at high amplitude motion. Therefore, incorporating sacrificial components into the rocking pier can increase the lateral stiffness at service load and low amplitude frequent earthquakes but can produce comparable response at high seismic excitation. These results provide support for performance-based seismic design of self-centering rocking piers.
文摘A controlled rocking concentrically steel braced frame(CR-CSBF)is introduced as an alternative to conventional methods to prevent major structural damage during large earthquakes.It is equipped with elastic post-tensioned(PT)cables and replaceable devices or fuses to provide overturning resistance and dissipate energy,respectively.Although CR-CSBFs are not officially legalized in globally valid codes for new buildings,it is expected to be presented in them in the near future.The main goal of this study is to determine the optimal design parameters consist of the yield strength and modulus of elasticity of the fuse,the initial force of the PT cable,and the gravity load on the rocking column,considering different heights of the frame,spanning ratios and ground motion types for dual-configuration CR-CSBF.Nonlinear time-history analyses are performed in OpenSees.This study aims to define the optimal input variables as effective design parameters of CR-CSBFs by comparing four seismic responses consisting of story drift,roof displacement,roof acceleration and base shear,and also using the Euclidean metric optimization method.Despite the previous research,this study is innovative and first of its kind.The results demonstrate that the optimal design parameters are variable for various conditions.
基金This study was sponsored by the Scientific Research Fund of the Institute of Engineering Mechanics,China Earthquake Administration(No.2019EEEVL0302)the Open Fund of State Key Laboratory of Disaster Reduction in Civil Engineering(No.SLDRCE18-03)the National Natural Science Foundation of China(Grant No.51978463).
文摘A new rocking constraint device(RCD)is developed for three-dimensional(3D)base-isolated frame structures by connecting a custom-designed cylinder pair to provide vertical damping with replaceable damping components installed outside the cylinders when the superstructure undergoes translational motion,and rocking constraint capacity when the superstructure is susceptible to rocking.Theoretical formulas for calculating the damping and rocking constraint stiffness of the RCD are proposed.Two series of sinusoidal loading tests are conducted at different loading frequencies and amplitudes to verify the damping and rocking constraint performance of the RCD.The test results show that the cylinder without orifices on its piston can provide the desired damping with a replaceable damping component,and that the RCD can effectively suppress rocking.Although the vertical stiffness of an individual cylinder is affected by the location of the replaceable damping component and loading frequency,the average vertical stiffness of the two cylinders,which determines the rocking constraint stiffness of the RCD,is independent of the two factors.Comparisons of the test and theoretical results indicate that the errors of the proposed formulas for calculating the damping and rocking constraint stiffness of the RCD do not exceed 12.9%and 11.0%,respectively.
基金supported the National Natural Science Foundation of China(No.62101296)the Natural Science Foundation of Shaanxi Province(Nos.2021JQ-760 and 2021JQ-756).
文摘"Rocking chair"type lithium-ion batteries with lithium metal-free anodes have been successfully com-mercialized over the past few decades.Zinc-ion batteries(zIBs)have gained increasing attention in recent years given their safety,greenness,ease of manufacture,and cost-efficiency.Nevertheless,the practical application of ZIBs is largely hindered by the dendritic growth of the Zn metal anode,low Coulombic eficiency,great harm,and existence of various side reactions.Herein,this review provides a systematic overview of emerging"rocking chair"type ZIBs with zinc metal-free anodes.Firstly,the basic fundamen-tals,advantages,and challenges of“rocking chair”type ZIBs are introduced.Subsequently,an overview of the design principles and recent progress of"rocking chair"type ZIBs with zinc metal-free anodes are presented.Finally,the key challenges and perspectives for future advancement of"rocking chair"type ZiBs with zinc metal-free anodes are proposed.This review is anticipated to attracted increased focus to metal-free anodes"rocking chair"type metal-ion battery and provide new inspirations for the develop-ment of high-energy metal-ion batteries.
文摘A rock concert for kids took to the stage of a theater nestled in a hutong,a narrow alleyway in the traditional residential areas of Beijing,on March 18.Chinese and British performers put on a musical extravaganza that had children stomping their feet,shaking their heads and rocking out to the music.
