Since masonry structures are prone to collapse in earthquakes,a novel joint reinforcement method with a polypropylene band(PP-band)and cement mortar(CM)has been put forward.Compared with the common reinforcement metho...Since masonry structures are prone to collapse in earthquakes,a novel joint reinforcement method with a polypropylene band(PP-band)and cement mortar(CM)has been put forward.Compared with the common reinforcement methods,this method not only facilitates construction but also ensures lower reinforcement cost.To systematically explore the influence of joint reinforcement on the seismic performance of masonry walls,quasi-static tests were carried out on six specimens with different reinforcement forms.The test results show that the joint action of PP-band and CM can significantly improve the specimen′s brittle failure characteristics and enhance the integrity of the specimen after cracking.Compared with the specimen without reinforcement,each of the seismic performance indexes of the joint reinforced specimen had obvious improvement.The maximum increased rate about peak load and ductility of the joint reinforced specimen is 100.6%and 233.4%,respectively.展开更多
The Code for Seismic Design of Buildings(GB50011-2010)in 2016 and the method of seismic performance-based design for high-rise buildings in the Guide for Performance-based Design of High-Rise Buildings(TBI2017)are com...The Code for Seismic Design of Buildings(GB50011-2010)in 2016 and the method of seismic performance-based design for high-rise buildings in the Guide for Performance-based Design of High-Rise Buildings(TBI2017)are compared.In view of the characteristics and limitations of the seismic performance index set by the Sino-US seismic code,a“three-index”performance index system and evaluation process considering the displacement angle of the structural interlayer,the plastic damage degree of components and the plastic strain of material is put forward;combining the example of time-history analysis of a out-of-code high-rise building under the rare earthquakes is verified.The results show that the method of seismic performance evaluation by using deformation control index in Sino-US seismic code is relatively simple;however,both are lacking in the setting of specific components and the whole structure level respectively.The"three-index"system can comprehensively and quantitatively evaluate the seismic performance of out-of-code high-rise buildings.展开更多
In this paper,the seismic behaviors of precast bridge columns connected with grouted corrugated-metal duct(GCMD)were investigated through the biaxial quasi-static experiment and numerical simulation.With a geometric s...In this paper,the seismic behaviors of precast bridge columns connected with grouted corrugated-metal duct(GCMD)were investigated through the biaxial quasi-static experiment and numerical simulation.With a geometric scale ratio of 1:5,five specimens were fabricated,including four precast bridge columns connected with GCMD and one cast-in-place(CIP)bridge column.A finite element analysis model was also established by using OpenSees and was then calibrated by using the experimental results for parameter analysis.The results show the biaxial seismic performance of the precast bridge columns connected with GCMD was similar to the CIP bridge columns regarding ultimate bearing capacity and hysteresis energy,and further,that it could meet the design goal of equivalent performance.The seismic performance of the precast bridge columns connected with GCMD deteriorated more significantly under bi-directional load than under uni-directional load.A proper slenderness ratio(e.g.,7.0-10.0)and longitudinal reinforcement ratio could significantly improve the energy dissipation capacity and deformation capacity of the precast bridge columns,while the axial load ratio and concrete strength had little influence on the above properties.The research results could bring insights to the development of the seismic design of precast bridge columns connected with GCMD.展开更多
In this article,the seismic performance of box-shaped steel piers embedded with energy-dissipating shells under a multi-directional seismic load is investigated.A finite element(FE)model was accurately established and...In this article,the seismic performance of box-shaped steel piers embedded with energy-dissipating shells under a multi-directional seismic load is investigated.A finite element(FE)model was accurately established and verified by the quasi-static test results.A parametric analysis of the hysteretic behaviour of a novel box-shaped steel pier under eccentric pressure was carried out on this basis.We discussed the influence of the eccentricity,axial compression ratio,thickness of embedded shell,ratio of slenderness,spacing of transverse stiffening ribs on the embedded shell,and width-to-thickness ratio of wallboard on the anti-seismic performance of a novel box-shaped steel bridge pier.The results revealed that the load carrying capacity and ductility coefficient of the specimen are substantially influenced by the eccentricity,variation in the axial compression ratio,and slenderness ratio.The specimen′s plastic energy dissipation capacity can be effectively improved by increasing the thickness of the embedded shell.The spacing of the transverse stiffening ribs only marginally affects seismic performance.In addition,the width-to-thickness ratio of the wallboard exerts a more considerable influence on the deformability of the square-section specimen.Finally,a formula for calculating the bearing capacity of the novel box-shaped steel piers under cyclic loading is proposed.展开更多
Many concrete dams seriously suffer from long-term seepage dissolution,and the induced mechanical property deterioration of concrete may significantly affect the structural performance,especially the seismic safety.An...Many concrete dams seriously suffer from long-term seepage dissolution,and the induced mechanical property deterioration of concrete may significantly affect the structural performance,especially the seismic safety.An approach is presented in this paper to quantify the influence of seepage dissolution on seismic performance of concrete dams.To connect laboratory test with numerical simulation,dissolution tests are conducted for concrete specimens and using the cumulative relative leached calcium as an aging index,a deterioration model is established to predict the mechanical property of leached concrete in the first step.A coupled seepage-calcium dissolutionmigrationmodel containing two calculation modes is proposed to simulate the spatially non-uniformdeterioration of concrete dams.Based on the simulated state of a roller compacted concrete dam subjected to 100 years of seepage dissolution,seismic responses of the damare subsequently analyzed.During which the nonlinear cracking of concrete,the radiation damping of the far-field foundation is considered.Research results show that seepage dissolution will seriously weaken the seismic safety of concrete dams because of the dissolution-induced decrease of effective thickness of the dam body.The upstream surface,dam toe and gallery wall suffer from a large degree of dissolution,whereas it is minimal and basically the same inside the dam body,at a degree of 0.19%within 100 years.The horizontal displacements of dam crest under the design static load and fortification against earthquake increase by 6.9%and 21.9%,respectively,and the dissolution-induced seismic cracking leads to the failure of dam anti-seepage system.This study can provide engineers with a reference basis for reinforcement decision of old concrete dams.展开更多
In this paper,three kinds of shear walls with full sleeve grouting,fully defective sleeve and partially defective are designed for finite element analysis to analyze the influence of defects on the seismic performance...In this paper,three kinds of shear walls with full sleeve grouting,fully defective sleeve and partially defective are designed for finite element analysis to analyze the influence of defects on the seismic performance of shear walls.The research shows that at the beginning of loading(5 s),the three models begin to appear compressive damage at the bottom of the wall in all three models.The damage of the defect-free model develops rapidly,and the damage of the fully defective model is basically the same as that of the partially defective model.With the gradual increase of displacement control(15 s),the compressive damages at the foot of the wall in the defect-free and partially defective grouting model are obvious,with plastic hinge formed in the foot of the wall,and the phenomenon of development along the pier body showing up.When the structure is damaged,the overall compressive damages of the wall in the defect-free and partially defective models are obvious,and the damage on the defective side of the partially defective model is slightly deficient.While the maximum stress of pre-stressed reinforcement in the defect-freemodel is concentrated at the top of the sleeve,themaximumstress of the pre-stressed steel bar in the fully defective model appears at the end of the steel bar in the sleeve.The hysteresis curve shape of the non-defectmodel and partially defective model are basically the same,showing a“shuttle”shape with a sound energy dissipation effect.The hysteresis curve shape of the fully defective model appears an obvious“pinch”phenomenon.The yield displacement levels of the defect-free and partially defective models are smaller than that of the fully defective model structure.The stiffness degradation curves of the three models basically overlap with one another.Before the limit displacement,the stiffness results of the non-defect model and the partially defective model are greater than that of the fully defective model.When the displacement is loaded to 20 mm,the stiffness degradation of the three models is equivalent.展开更多
Variable curvature friction pendulum bearings(VCFPB)effectively reduce the dynamic response of storage tanks induced by earthquakes.Shaking table testing is used to assess the seismic performance of VCFPB isolated sto...Variable curvature friction pendulum bearings(VCFPB)effectively reduce the dynamic response of storage tanks induced by earthquakes.Shaking table testing is used to assess the seismic performance of VCFPB isolated storage tanks.However,the vertical pressure and friction coefficient of the scaled VCFPB in the shaking table tests cannot match the equivalent values of these parameters in the prototype.To avoid this drawback,a real-time hybrid simulation(RTHS)test was developed.Using RTHS testing,a 1/8 scaled tank isolated by VCFPB was tested.The experimental results showed that the displacement dynamic magnification factor of VCFPB,peak reduction factors of the acceleration,shear force,and overturning moment at bottom of the tank,were negative exponential functions of the ratio of peak ground acceleration(PGA)and friction coefficient.The peak reduction factors of displacement,acceleration,force and overturning moment,which were obtained from the experimental results,are compared with those calculated by the Housner model.It can be concluded that the Housner model is applicable in estimation of the acceleration,shear force,and overturning moment of liquid storage tank,but not for the sliding displacement of VCFPBs.展开更多
A staircase provides the main escape way from a building in an emergency.Unfortunately,it may suffer severe damages or even collapse during an earthquake.For improving the seismic performance of staircases,this paper ...A staircase provides the main escape way from a building in an emergency.Unfortunately,it may suffer severe damages or even collapse during an earthquake.For improving the seismic performance of staircases,this paper proposes an innovative staircase isolator with the features of lightweight,costeffective and ease of construction and replacement,which is formed by suitable engineering plastic shims between rubber layers.A connection construction scheme is also proposed for the isolated staircase.Systematic performance tests have been carried out to characterize the isolator in terms of mechanic behavior and ultimate states.The test results show that mechanical properties of the proposed staircase isolator are excellent and suitable for staircase in building structure.In order to investigate the influence of staircase on building structural responses,time history analyses of a typical building structure without staircase(WS),with fixed staircase(FS)and with isolated staircase(IS)are conducted and compared within the environment of SAP2000.Results show that staircase isolation can effectively eliminate the diagonal bracing effect of staircase slab and make structural components uniformly stressed.When the novel isolator is employed for staircase in a building structure,there is no vulnerable position in staircase and the performance of staircase in building structure can be greatly enhanced.展开更多
A utility tunnel system consists of pipes and ancillary facilities.In this paper,a finite element model of a concrete utility tunnel with pipes inside is established.Several tunnel segments were built to simulate a re...A utility tunnel system consists of pipes and ancillary facilities.In this paper,a finite element model of a concrete utility tunnel with pipes inside is established.Several tunnel segments were built to simulate a real utility tunnel,while the pipe was fixed by springs on the brackets in the utility tunnel.Using the discrete soil spring element to simulate the soil-structure interaction,actual earthquake records were adopted as excitation to analyze the seismic responses of pipes in a utility tunnel.Moreover,the influences of different parameters,including soil type,earthquake records,and field apparent wave velocity on the seismic responses of the utility tunnel and the pipes inside were studied.Finally,the seismic responses of buried pipes were analyzed and compared with those of pipes in a utility tunnel to evaluate the seismic performance of pipes for two working conditions.展开更多
A design procedure for improving the seismic performance of unequal-span underground structures by installing isolation devices at the top end of columns is proposed based on the seismic failure mode of frame-type und...A design procedure for improving the seismic performance of unequal-span underground structures by installing isolation devices at the top end of columns is proposed based on the seismic failure mode of frame-type underground structures and the design concept of critical support columns.A two-dimensional finite element model(FEM)for a soil-underground structure with an unequal-span interaction system was established to shed light on the effects of a complex subway station with elastic sliding bearings(ESB)and lead rubber bearings(LRB)on seismic mitigation.It was found that the stiffness and internal force distribution of the underground structure changed remarkably with the installation of isolation devices at the top end of the columns.The constraints of the beam-column joints were significantly weakened,resulting in a decrease in the overall lateral stiffness and an increase in the structural lateral displacement.The introduction of the isolation device effectively reduces the internal force and seismic damage of the frame column;however,the tensile damage to the isolation structure,such as the roof,bottom plate,and sidewall,significantly increased compared to those of the non-isolation structure.Although the relative slip of the ESB remains within a controllable range under strong earthquake excitation as well as frame columns with stable vertical support and self-restoration functions,the LRB shows a better performance during seismic failure and better lateral displacement response of the unequal-span underground structure.The analysis results provide new ideas and references for promoting the application of seismic isolation technology in underground structures.展开更多
Soils with spatial variability are the product of natural history.The mechanical properties tested by soil samples from boreholes in the same soil layer may be different.Underground structure service in surrounding so...Soils with spatial variability are the product of natural history.The mechanical properties tested by soil samples from boreholes in the same soil layer may be different.Underground structure service in surrounding soils,their seismic response is controlled by the deformation of the surrounding soils.The variability of soil mechanical parameters was not considered in the current research on the seismic response of underground structures.Therefore,a random field model was established to describe the spatial variability of surrounding soils based on the random field theory.Then the seismic response of underground structures in the random field was simulated based on the time-domain explicit global FEM analysis,and the soil mechanical parameters and earthquake intensity influencing the seismic response of surrounding soils and underground structures were studied.Numerical results presented that,the randomness of soil parameters does not change the plastic deformation mode of surrounding soils significantly.The variation coefficients of inter-story deformation of structures and lateral deformation of columns are much smaller than that of mechanical parameters,and the randomness of soil parameters has no obvious effect on the structural deformation response.展开更多
When the sliding bearing is fixed only at the top of the middle column of the underground structure,the cracks at the side end of the middle plate should be aggravated while the seismic damage of the mid-column should...When the sliding bearing is fixed only at the top of the middle column of the underground structure,the cracks at the side end of the middle plate should be aggravated while the seismic damage of the mid-column should be alleviated.To enhance the seismic performance of the mid-plate,a new isolation design method has been mentioned while the elastic sliding bearings are set at the top of the mid-columns and between the side end of the mid-plate and the side wall at the same time.By establishing a nonlinear finite element analysis model for the static-dynamic coupling interaction system,the seismic response characteristics of the cast-in-place station structure without a sliding bearing have been analyzed and compared with those of the station structure with the sliding bearing fixed only at the top of the middle columns,and those of the station structure with sliding bearing be fixed between the mid-plate and the sidewall at the same time.The results show that the new isolation station structures suffer fewer earthquake damages at the mid-plate and mid-columns at the same time,which can improve the overall seismic performance of the subway station structure.展开更多
Rod element and shell element were used in finite element software ABAQUS to establish dynamic elastic-plastic analysis model of the structure,the seismic performance of an irregular plane complex overrun structure nu...Rod element and shell element were used in finite element software ABAQUS to establish dynamic elastic-plastic analysis model of the structure,the seismic performance of an irregular plane complex overrun structure numerical simulation,the structure was calculated under different input level and displacement response of the acceleration response,and analyses the force of the wear layer column and the floor of the open hole stress level.The results were compared with the shaking table test to verify the accuracy of the numerical simulation results.The results of numerical calculation were basically consistent with the experimental results,and the finite element model basically reflected the response of the structure under the simulated earthquake.展开更多
Recent developments in earthquake engineering indicate that probabilistic seismic risk analysis (PSRA) is becoming increasingly useful for the evaluation of structural per-formance in accordance with building codes. I...Recent developments in earthquake engineering indicate that probabilistic seismic risk analysis (PSRA) is becoming increasingly useful for the evaluation of structural per-formance in accordance with building codes. In recent years, the field of seismic resis-tance design has been undergoing a critical shift in focus from strength to performance. However, current earthquake resistant design procedures do not relate building performance to probability. A lack of sufficient empirical data has highlighted gaps in this research. This study integrated results from the analysis of structural fragility and seismic hazard in Taiwan to perform PSRA to examine the effectiveness of building code in mitigating the risks associated with earthquakes. Factors taken into account included the effect of construction materials, building height, and building age. The results of this study show that the probability of exceeding damage associated with the CP level in buildings of light steel, pre-cast concrete, and masonry, exceeds 2%. These buildings fail to meet the performance objectives outlined in FEMA-273.展开更多
The seismic performance of a fully fabricated bridge is a key factor limiting its application.In this study,a fiber element model of a fabricated concrete pier with grouting sleeve-prestressed tendon composite connect...The seismic performance of a fully fabricated bridge is a key factor limiting its application.In this study,a fiber element model of a fabricated concrete pier with grouting sleeve-prestressed tendon composite connections was built and verified.A numerical analysis of three types of continuous girder bridges was conducted with different piers:a cast-in-place reinforced concrete pier,a grouting sleeve-fabricated pier,and a grouting sleeve-prestressed tendon composite fabricated pier.Furthermore,the seismic performance of the composite fabricated pier was investigated.The results show that the OpenSees fiber element model can successfully simulate the hysteresis behavior and failure mode of the grouted sleeve-fabricated pier.Under traditional non-near-fault ground motions,the pier top displacements of the grouting sleeve-fabricated pier and the composite fabricated pier were less than those of the cast-in-place reinforced concrete pier.The composite fabricated pier had a good self-centering capability.In addition,the plastic hinge zones of the grouting sleeve-fabricated pier and the composite fabricated pier shifted to the joint seam and upper edge of the grouting sleeve,respectively.The composite fabricated pier with optimal design parameters has good seismic performance and can be applied in high-intensity seismic areas;however,the influence of pile-soil interaction on its seismic performance should not be ignored.展开更多
Large numbers of basic transceiver stations,where the telecommunication room is one of the main components,comprise an important part of the telecommunication system.After earthquakes,considerable economic loss from t...Large numbers of basic transceiver stations,where the telecommunication room is one of the main components,comprise an important part of the telecommunication system.After earthquakes,considerable economic loss from telecommunication systems is often associated with seismic damage and functional loss of the telecommunication room.However,research related to this has been limited.In this study,shaking table tests were conducted for a full-scale typical telecommunication room,including a light-steel house and the necessary communication and power supply equipment.The tests not only focused on the seismic damage to all the structures but also considered the functions of the communication and power supply of the equipment.The interactions between these facilities and their effects on communication function were also investigated.Compared with the damage to structures,the interruption of the power supply due to earthquakes is a weak link.Finally,the damage indexes,together with their threshold values of different damage states for the communication and power supply equipment,were derived from the test results.The results of this research can contribute to the literature gaps regarding seismic performance studies of telecommunication rooms,and can serve as a valuable reference for future research on its seismic fragility and economic losses evaluation.展开更多
In this study, dynamic centrifuge model tests were performed for sand slopes under different earthquake ground motions and slope angle to characterize the seismic performance of slopes. Four groups of tests under vary...In this study, dynamic centrifuge model tests were performed for sand slopes under different earthquake ground motions and slope angle to characterize the seismic performance of slopes. Four groups of tests under varying seismic input amplitude were conducted. Under the action of increasing earthquake intensity, the rigidity of the soil decreases and the damping ratio increases, both of the dynamic response and the predominant period of slopes are increased. Three types of seismic waves with the same seismic intensity were applied in the model tests. It shows that the variability in the ground motion leads to the acceleration response spectra of the slopes being completely different and the Northridge seismic wave with low-frequency component is closest to the predominant period of the slope model. In addition, the effect of slope angle on the seismic performance of slopes were also clarified. The results reveal how the slope angle affects the acceleration recorded on the ground surface of the slope, both in terms of the peak ground-motion acceleration(PGA) amplification factor and the predominant period. Finally, the permanent displacement of the model slopes under different earthquake intensities were further analyzed. Based on the nonlinear growth of the permanent displacement of the slope, the test results demonstrated the failure process of the slope, which can further provide a basis for theperformance-based seismic design of slopes.展开更多
To examine the seismic resistance performance of a steel arch bridge during a strong earthquake,an approach is proposed in this paper to determine the ultimate strain of an arch rib using the static elasto-plastic lar...To examine the seismic resistance performance of a steel arch bridge during a strong earthquake,an approach is proposed in this paper to determine the ultimate strain of an arch rib using the static elasto-plastic large deformation theory.A steel fixed-end deck arch bridge with a span length of 200 m was used as an example in this study.The ultimate strain of the arch rib was calculated using the elasto-plastic finite element model.The seismic responses of the arch bridge exposed to strong earthquakes in two and three directions were also simulated.Moreover,the effect of earthquake motion in the lateral direction on the elasto-plastic earthquake response was discussed,and the seismic resistance of the structure was analyzed.The results show that steel arch bridges have preferable seismic resistance under strong earthquake conditions.While lateral earthquake motion has some influence on the damage to an arch bridge,it has little effect on the displacement,axial force,and bending moment responses of the arch rib.It is feasible to examine the seismic performance of the arch bridge by ascertaining the out-of-plane and in-plane earthquake responses of the bridge.展开更多
The seismic behavior of a structural system composed of pre-stressed concrete stand supporting a retractable steel roof was studied,which is typically based on the prototype of engineering project of Shanghai Qizhong ...The seismic behavior of a structural system composed of pre-stressed concrete stand supporting a retractable steel roof was studied,which is typically based on the prototype of engineering project of Shanghai Qizhong Tennis Center.By elasto-plastic finite element analysis and shaking table test,the following were investigated:the effects of roof configurations in opening and closing,the effect of pre-stress on the structural seismic response,and the failure mechanism of the spatial stand frame systems featured with circularly arranged columns and inverse-cone type stands.It was found thatthe roof status has great effect on the natural period,vibration modes,and seismic response of the whole structure,the stand response to horizontal seismic excitation is stronger in roof opening configuration than in closing state,and the response mode is dominantly translational rather than rotational,though the stand is characterized by its fundamentally torsional vibration mode.The study indicated that the pre-stressed inversecone stands can keep the system from global side-sway collapse under gravity loads,even in the case that most columns loose moment capacity.展开更多
基金National Natural Science Foundation of China under Grant Nos.51968047 and 51608249the Key Research and Development Program of Jiangxi Province under Grant No.20161BBG70058。
文摘Since masonry structures are prone to collapse in earthquakes,a novel joint reinforcement method with a polypropylene band(PP-band)and cement mortar(CM)has been put forward.Compared with the common reinforcement methods,this method not only facilitates construction but also ensures lower reinforcement cost.To systematically explore the influence of joint reinforcement on the seismic performance of masonry walls,quasi-static tests were carried out on six specimens with different reinforcement forms.The test results show that the joint action of PP-band and CM can significantly improve the specimen′s brittle failure characteristics and enhance the integrity of the specimen after cracking.Compared with the specimen without reinforcement,each of the seismic performance indexes of the joint reinforced specimen had obvious improvement.The maximum increased rate about peak load and ductility of the joint reinforced specimen is 100.6%and 233.4%,respectively.
文摘The Code for Seismic Design of Buildings(GB50011-2010)in 2016 and the method of seismic performance-based design for high-rise buildings in the Guide for Performance-based Design of High-Rise Buildings(TBI2017)are compared.In view of the characteristics and limitations of the seismic performance index set by the Sino-US seismic code,a“three-index”performance index system and evaluation process considering the displacement angle of the structural interlayer,the plastic damage degree of components and the plastic strain of material is put forward;combining the example of time-history analysis of a out-of-code high-rise building under the rare earthquakes is verified.The results show that the method of seismic performance evaluation by using deformation control index in Sino-US seismic code is relatively simple;however,both are lacking in the setting of specific components and the whole structure level respectively.The"three-index"system can comprehensively and quantitatively evaluate the seismic performance of out-of-code high-rise buildings.
基金National Natural Science Foundation of China under Grant No.51408360the Natural Science Foundation of Fujian(NSFF)under Grant No.2020J01477the Technology Project of Fuzhou Science and Technology Bureau(TPFB)under Grant No.2020-GX-18。
文摘In this paper,the seismic behaviors of precast bridge columns connected with grouted corrugated-metal duct(GCMD)were investigated through the biaxial quasi-static experiment and numerical simulation.With a geometric scale ratio of 1:5,five specimens were fabricated,including four precast bridge columns connected with GCMD and one cast-in-place(CIP)bridge column.A finite element analysis model was also established by using OpenSees and was then calibrated by using the experimental results for parameter analysis.The results show the biaxial seismic performance of the precast bridge columns connected with GCMD was similar to the CIP bridge columns regarding ultimate bearing capacity and hysteresis energy,and further,that it could meet the design goal of equivalent performance.The seismic performance of the precast bridge columns connected with GCMD deteriorated more significantly under bi-directional load than under uni-directional load.A proper slenderness ratio(e.g.,7.0-10.0)and longitudinal reinforcement ratio could significantly improve the energy dissipation capacity and deformation capacity of the precast bridge columns,while the axial load ratio and concrete strength had little influence on the above properties.The research results could bring insights to the development of the seismic design of precast bridge columns connected with GCMD.
基金National Science Foundation of China under Grant No.51778248Natural Science Foundation of Fujian Province under Grant No.2018J01075+2 种基金Promotion Program for Young and Middle-aged Teacher in Science and Technology Research of Huaqiao University under Grant No.ZQN-PY312Research Trained Fund for Outstanding Young Researcher in Higher Education Institutions of Fujian ProvinceSubsidized Project for Postgraduates′Innovative Fund in Scientific Research of Huaqiao University under Grant No.18013086021。
文摘In this article,the seismic performance of box-shaped steel piers embedded with energy-dissipating shells under a multi-directional seismic load is investigated.A finite element(FE)model was accurately established and verified by the quasi-static test results.A parametric analysis of the hysteretic behaviour of a novel box-shaped steel pier under eccentric pressure was carried out on this basis.We discussed the influence of the eccentricity,axial compression ratio,thickness of embedded shell,ratio of slenderness,spacing of transverse stiffening ribs on the embedded shell,and width-to-thickness ratio of wallboard on the anti-seismic performance of a novel box-shaped steel bridge pier.The results revealed that the load carrying capacity and ductility coefficient of the specimen are substantially influenced by the eccentricity,variation in the axial compression ratio,and slenderness ratio.The specimen′s plastic energy dissipation capacity can be effectively improved by increasing the thickness of the embedded shell.The spacing of the transverse stiffening ribs only marginally affects seismic performance.In addition,the width-to-thickness ratio of the wallboard exerts a more considerable influence on the deformability of the square-section specimen.Finally,a formula for calculating the bearing capacity of the novel box-shaped steel piers under cyclic loading is proposed.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.51709021,52079120)the project funded by China Postdoctoral Science Foundation(Grant No.2020M670387)the Belt and Road Special Foundation of the State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering(Grant No.2019nkzd03).
文摘Many concrete dams seriously suffer from long-term seepage dissolution,and the induced mechanical property deterioration of concrete may significantly affect the structural performance,especially the seismic safety.An approach is presented in this paper to quantify the influence of seepage dissolution on seismic performance of concrete dams.To connect laboratory test with numerical simulation,dissolution tests are conducted for concrete specimens and using the cumulative relative leached calcium as an aging index,a deterioration model is established to predict the mechanical property of leached concrete in the first step.A coupled seepage-calcium dissolutionmigrationmodel containing two calculation modes is proposed to simulate the spatially non-uniformdeterioration of concrete dams.Based on the simulated state of a roller compacted concrete dam subjected to 100 years of seepage dissolution,seismic responses of the damare subsequently analyzed.During which the nonlinear cracking of concrete,the radiation damping of the far-field foundation is considered.Research results show that seepage dissolution will seriously weaken the seismic safety of concrete dams because of the dissolution-induced decrease of effective thickness of the dam body.The upstream surface,dam toe and gallery wall suffer from a large degree of dissolution,whereas it is minimal and basically the same inside the dam body,at a degree of 0.19%within 100 years.The horizontal displacements of dam crest under the design static load and fortification against earthquake increase by 6.9%and 21.9%,respectively,and the dissolution-induced seismic cracking leads to the failure of dam anti-seepage system.This study can provide engineers with a reference basis for reinforcement decision of old concrete dams.
基金The authors are grateful for the financial support received from the National Natural Science Foundation of China(No.52078038)Basic Scientific Research Business of Central University(No.FRF-MP-20-20).
文摘In this paper,three kinds of shear walls with full sleeve grouting,fully defective sleeve and partially defective are designed for finite element analysis to analyze the influence of defects on the seismic performance of shear walls.The research shows that at the beginning of loading(5 s),the three models begin to appear compressive damage at the bottom of the wall in all three models.The damage of the defect-free model develops rapidly,and the damage of the fully defective model is basically the same as that of the partially defective model.With the gradual increase of displacement control(15 s),the compressive damages at the foot of the wall in the defect-free and partially defective grouting model are obvious,with plastic hinge formed in the foot of the wall,and the phenomenon of development along the pier body showing up.When the structure is damaged,the overall compressive damages of the wall in the defect-free and partially defective models are obvious,and the damage on the defective side of the partially defective model is slightly deficient.While the maximum stress of pre-stressed reinforcement in the defect-freemodel is concentrated at the top of the sleeve,themaximumstress of the pre-stressed steel bar in the fully defective model appears at the end of the steel bar in the sleeve.The hysteresis curve shape of the non-defectmodel and partially defective model are basically the same,showing a“shuttle”shape with a sound energy dissipation effect.The hysteresis curve shape of the fully defective model appears an obvious“pinch”phenomenon.The yield displacement levels of the defect-free and partially defective models are smaller than that of the fully defective model structure.The stiffness degradation curves of the three models basically overlap with one another.Before the limit displacement,the stiffness results of the non-defect model and the partially defective model are greater than that of the fully defective model.When the displacement is loaded to 20 mm,the stiffness degradation of the three models is equivalent.
基金Scientific Research Fund of Institute of Engineering Mechanics,China Earthquake Administration under Grant No.2018D03the National Natural Science Foundation of China under Grant Nos.51608016 and 51421005。
文摘Variable curvature friction pendulum bearings(VCFPB)effectively reduce the dynamic response of storage tanks induced by earthquakes.Shaking table testing is used to assess the seismic performance of VCFPB isolated storage tanks.However,the vertical pressure and friction coefficient of the scaled VCFPB in the shaking table tests cannot match the equivalent values of these parameters in the prototype.To avoid this drawback,a real-time hybrid simulation(RTHS)test was developed.Using RTHS testing,a 1/8 scaled tank isolated by VCFPB was tested.The experimental results showed that the displacement dynamic magnification factor of VCFPB,peak reduction factors of the acceleration,shear force,and overturning moment at bottom of the tank,were negative exponential functions of the ratio of peak ground acceleration(PGA)and friction coefficient.The peak reduction factors of displacement,acceleration,force and overturning moment,which were obtained from the experimental results,are compared with those calculated by the Housner model.It can be concluded that the Housner model is applicable in estimation of the acceleration,shear force,and overturning moment of liquid storage tank,but not for the sliding displacement of VCFPBs.
基金This work was supported by the National Key Research and Development Program of China(Grant No.2017YFC0703600)the National Natural Science Foundation of China(Grant Nos.51278138,51978185)+1 种基金Yangcheng Scholar’s Program of Guangzhou Municipal Department of Education(Grant No.1201541630)Innovation Research Program for the Postgraduates of Guangzhou University(Grant No.2017GDJC-D16).
文摘A staircase provides the main escape way from a building in an emergency.Unfortunately,it may suffer severe damages or even collapse during an earthquake.For improving the seismic performance of staircases,this paper proposes an innovative staircase isolator with the features of lightweight,costeffective and ease of construction and replacement,which is formed by suitable engineering plastic shims between rubber layers.A connection construction scheme is also proposed for the isolated staircase.Systematic performance tests have been carried out to characterize the isolator in terms of mechanic behavior and ultimate states.The test results show that mechanical properties of the proposed staircase isolator are excellent and suitable for staircase in building structure.In order to investigate the influence of staircase on building structural responses,time history analyses of a typical building structure without staircase(WS),with fixed staircase(FS)and with isolated staircase(IS)are conducted and compared within the environment of SAP2000.Results show that staircase isolation can effectively eliminate the diagonal bracing effect of staircase slab and make structural components uniformly stressed.When the novel isolator is employed for staircase in a building structure,there is no vulnerable position in staircase and the performance of staircase in building structure can be greatly enhanced.
基金supported by the Ministry of Science and Technology of China(SLDRCE19-B-24).
文摘A utility tunnel system consists of pipes and ancillary facilities.In this paper,a finite element model of a concrete utility tunnel with pipes inside is established.Several tunnel segments were built to simulate a real utility tunnel,while the pipe was fixed by springs on the brackets in the utility tunnel.Using the discrete soil spring element to simulate the soil-structure interaction,actual earthquake records were adopted as excitation to analyze the seismic responses of pipes in a utility tunnel.Moreover,the influences of different parameters,including soil type,earthquake records,and field apparent wave velocity on the seismic responses of the utility tunnel and the pipes inside were studied.Finally,the seismic responses of buried pipes were analyzed and compared with those of pipes in a utility tunnel to evaluate the seismic performance of pipes for two working conditions.
基金the research funding provided by the National Natural Science Foundation of China(NSFC,No.51978333)the SINOMACH Science and Technology Major Project(SINOMAST-ZDZX-2020-03)。
文摘A design procedure for improving the seismic performance of unequal-span underground structures by installing isolation devices at the top end of columns is proposed based on the seismic failure mode of frame-type underground structures and the design concept of critical support columns.A two-dimensional finite element model(FEM)for a soil-underground structure with an unequal-span interaction system was established to shed light on the effects of a complex subway station with elastic sliding bearings(ESB)and lead rubber bearings(LRB)on seismic mitigation.It was found that the stiffness and internal force distribution of the underground structure changed remarkably with the installation of isolation devices at the top end of the columns.The constraints of the beam-column joints were significantly weakened,resulting in a decrease in the overall lateral stiffness and an increase in the structural lateral displacement.The introduction of the isolation device effectively reduces the internal force and seismic damage of the frame column;however,the tensile damage to the isolation structure,such as the roof,bottom plate,and sidewall,significantly increased compared to those of the non-isolation structure.Although the relative slip of the ESB remains within a controllable range under strong earthquake excitation as well as frame columns with stable vertical support and self-restoration functions,the LRB shows a better performance during seismic failure and better lateral displacement response of the unequal-span underground structure.The analysis results provide new ideas and references for promoting the application of seismic isolation technology in underground structures.
基金supported by the Beijing Natural Science Foundation(8212007)the Pyramid Talent Training Project of Beijing University of Civil Engineering and Architecture(JDYC20200311)。
文摘Soils with spatial variability are the product of natural history.The mechanical properties tested by soil samples from boreholes in the same soil layer may be different.Underground structure service in surrounding soils,their seismic response is controlled by the deformation of the surrounding soils.The variability of soil mechanical parameters was not considered in the current research on the seismic response of underground structures.Therefore,a random field model was established to describe the spatial variability of surrounding soils based on the random field theory.Then the seismic response of underground structures in the random field was simulated based on the time-domain explicit global FEM analysis,and the soil mechanical parameters and earthquake intensity influencing the seismic response of surrounding soils and underground structures were studied.Numerical results presented that,the randomness of soil parameters does not change the plastic deformation mode of surrounding soils significantly.The variation coefficients of inter-story deformation of structures and lateral deformation of columns are much smaller than that of mechanical parameters,and the randomness of soil parameters has no obvious effect on the structural deformation response.
基金financially supported by the National Natural Science Foundation of China(Nos.51778290,51978333)。
文摘When the sliding bearing is fixed only at the top of the middle column of the underground structure,the cracks at the side end of the middle plate should be aggravated while the seismic damage of the mid-column should be alleviated.To enhance the seismic performance of the mid-plate,a new isolation design method has been mentioned while the elastic sliding bearings are set at the top of the mid-columns and between the side end of the mid-plate and the side wall at the same time.By establishing a nonlinear finite element analysis model for the static-dynamic coupling interaction system,the seismic response characteristics of the cast-in-place station structure without a sliding bearing have been analyzed and compared with those of the station structure with the sliding bearing fixed only at the top of the middle columns,and those of the station structure with sliding bearing be fixed between the mid-plate and the sidewall at the same time.The results show that the new isolation station structures suffer fewer earthquake damages at the mid-plate and mid-columns at the same time,which can improve the overall seismic performance of the subway station structure.
基金supported by the Visiting Scholar Foundation of Key Laboratory of New Technology for Construction of Cities in Mountain Area in Chongqing University, China
文摘Rod element and shell element were used in finite element software ABAQUS to establish dynamic elastic-plastic analysis model of the structure,the seismic performance of an irregular plane complex overrun structure numerical simulation,the structure was calculated under different input level and displacement response of the acceleration response,and analyses the force of the wear layer column and the floor of the open hole stress level.The results were compared with the shaking table test to verify the accuracy of the numerical simulation results.The results of numerical calculation were basically consistent with the experimental results,and the finite element model basically reflected the response of the structure under the simulated earthquake.
文摘Recent developments in earthquake engineering indicate that probabilistic seismic risk analysis (PSRA) is becoming increasingly useful for the evaluation of structural per-formance in accordance with building codes. In recent years, the field of seismic resis-tance design has been undergoing a critical shift in focus from strength to performance. However, current earthquake resistant design procedures do not relate building performance to probability. A lack of sufficient empirical data has highlighted gaps in this research. This study integrated results from the analysis of structural fragility and seismic hazard in Taiwan to perform PSRA to examine the effectiveness of building code in mitigating the risks associated with earthquakes. Factors taken into account included the effect of construction materials, building height, and building age. The results of this study show that the probability of exceeding damage associated with the CP level in buildings of light steel, pre-cast concrete, and masonry, exceeds 2%. These buildings fail to meet the performance objectives outlined in FEMA-273.
基金This study was supported by the National Natural Science Foundation of China(Grant Nos.52108428,52178446,51978021,and 51908015)the Fundamental Research Funds for the Central Universities(No.2023MS067).We gratefully acknowledge their support.
文摘The seismic performance of a fully fabricated bridge is a key factor limiting its application.In this study,a fiber element model of a fabricated concrete pier with grouting sleeve-prestressed tendon composite connections was built and verified.A numerical analysis of three types of continuous girder bridges was conducted with different piers:a cast-in-place reinforced concrete pier,a grouting sleeve-fabricated pier,and a grouting sleeve-prestressed tendon composite fabricated pier.Furthermore,the seismic performance of the composite fabricated pier was investigated.The results show that the OpenSees fiber element model can successfully simulate the hysteresis behavior and failure mode of the grouted sleeve-fabricated pier.Under traditional non-near-fault ground motions,the pier top displacements of the grouting sleeve-fabricated pier and the composite fabricated pier were less than those of the cast-in-place reinforced concrete pier.The composite fabricated pier had a good self-centering capability.In addition,the plastic hinge zones of the grouting sleeve-fabricated pier and the composite fabricated pier shifted to the joint seam and upper edge of the grouting sleeve,respectively.The composite fabricated pier with optimal design parameters has good seismic performance and can be applied in high-intensity seismic areas;however,the influence of pile-soil interaction on its seismic performance should not be ignored.
基金Key Project of the Key Laboratory of Earthquake Engineering and Engineering Vibration,China Earthquake Administration under Grant Nos.2020EEEVL0502 and 2019EEEVL0304。
文摘Large numbers of basic transceiver stations,where the telecommunication room is one of the main components,comprise an important part of the telecommunication system.After earthquakes,considerable economic loss from telecommunication systems is often associated with seismic damage and functional loss of the telecommunication room.However,research related to this has been limited.In this study,shaking table tests were conducted for a full-scale typical telecommunication room,including a light-steel house and the necessary communication and power supply equipment.The tests not only focused on the seismic damage to all the structures but also considered the functions of the communication and power supply of the equipment.The interactions between these facilities and their effects on communication function were also investigated.Compared with the damage to structures,the interruption of the power supply due to earthquakes is a weak link.Finally,the damage indexes,together with their threshold values of different damage states for the communication and power supply equipment,were derived from the test results.The results of this research can contribute to the literature gaps regarding seismic performance studies of telecommunication rooms,and can serve as a valuable reference for future research on its seismic fragility and economic losses evaluation.
基金This work was supported by the National Natural Science Foundation of China(Nos.41625011,41807284,41831291)。
文摘In this study, dynamic centrifuge model tests were performed for sand slopes under different earthquake ground motions and slope angle to characterize the seismic performance of slopes. Four groups of tests under varying seismic input amplitude were conducted. Under the action of increasing earthquake intensity, the rigidity of the soil decreases and the damping ratio increases, both of the dynamic response and the predominant period of slopes are increased. Three types of seismic waves with the same seismic intensity were applied in the model tests. It shows that the variability in the ground motion leads to the acceleration response spectra of the slopes being completely different and the Northridge seismic wave with low-frequency component is closest to the predominant period of the slope model. In addition, the effect of slope angle on the seismic performance of slopes were also clarified. The results reveal how the slope angle affects the acceleration recorded on the ground surface of the slope, both in terms of the peak ground-motion acceleration(PGA) amplification factor and the predominant period. Finally, the permanent displacement of the model slopes under different earthquake intensities were further analyzed. Based on the nonlinear growth of the permanent displacement of the slope, the test results demonstrated the failure process of the slope, which can further provide a basis for theperformance-based seismic design of slopes.
文摘To examine the seismic resistance performance of a steel arch bridge during a strong earthquake,an approach is proposed in this paper to determine the ultimate strain of an arch rib using the static elasto-plastic large deformation theory.A steel fixed-end deck arch bridge with a span length of 200 m was used as an example in this study.The ultimate strain of the arch rib was calculated using the elasto-plastic finite element model.The seismic responses of the arch bridge exposed to strong earthquakes in two and three directions were also simulated.Moreover,the effect of earthquake motion in the lateral direction on the elasto-plastic earthquake response was discussed,and the seismic resistance of the structure was analyzed.The results show that steel arch bridges have preferable seismic resistance under strong earthquake conditions.While lateral earthquake motion has some influence on the damage to an arch bridge,it has little effect on the displacement,axial force,and bending moment responses of the arch rib.It is feasible to examine the seismic performance of the arch bridge by ascertaining the out-of-plane and in-plane earthquake responses of the bridge.
文摘The seismic behavior of a structural system composed of pre-stressed concrete stand supporting a retractable steel roof was studied,which is typically based on the prototype of engineering project of Shanghai Qizhong Tennis Center.By elasto-plastic finite element analysis and shaking table test,the following were investigated:the effects of roof configurations in opening and closing,the effect of pre-stress on the structural seismic response,and the failure mechanism of the spatial stand frame systems featured with circularly arranged columns and inverse-cone type stands.It was found thatthe roof status has great effect on the natural period,vibration modes,and seismic response of the whole structure,the stand response to horizontal seismic excitation is stronger in roof opening configuration than in closing state,and the response mode is dominantly translational rather than rotational,though the stand is characterized by its fundamentally torsional vibration mode.The study indicated that the pre-stressed inversecone stands can keep the system from global side-sway collapse under gravity loads,even in the case that most columns loose moment capacity.
