A new type of rigid connection of steel girder and reinforced concrete pier of a bridge is proposed. The components in rigid connection are installed by high strength bolts on the spot, which are very convenient in ...A new type of rigid connection of steel girder and reinforced concrete pier of a bridge is proposed. The components in rigid connection are installed by high strength bolts on the spot, which are very convenient in construction. The moment from superstructure can be effectively transferred to substructure, and the plates provided for shear transferring can withstand the majority of total horizontal force. With static cyclic loading test, useful experimental data is obtained on the new type of connection of steel superstructure and concrete substructure. As a result, the stress transfer mechanism of the rigid connection can be made clearly and the seismic performance of this structure can also be clarified. Compared computed strength and ductility with actual results, it can be found that this type of connection has good energy absorption capacity in spite of large displacement and no local buckling arises at the locations where stress concentration occurs. Because of doing away with the expensive bearing, this new type of composite structure can be expected to construct a bridge with high seismic resistant capacity thus saving in total construction cost.展开更多
Due to the wide railway network and different characteristics of many earthquake zones in China,considering the running safety performance of trains(RSPT)in the design of high-speed railway bridge structures is very n...Due to the wide railway network and different characteristics of many earthquake zones in China,considering the running safety performance of trains(RSPT)in the design of high-speed railway bridge structures is very necessary.In this study,in order to provide the seismic design and evaluation measure of the bridge structure based on the RSPT,a calculation model of RSPT on bridge under earthquake was established,and the track surface response measure when the derailment coefficient reaches the limit value was calculated by referring to 15 commonly used ground motion(GM)intensity measures.Based on the coefficient of variation of the limit value obtained from multiple GM samples,the optimal measures were selected.Finally,the limit value of bridge seismic response based on RSPT with different train speeds and structural periods was determined.展开更多
The low-cycle loading test of two staggered slab-column-boundary beam joints was carried out to study their seismic performance.The crack development,load-displacement relationship,displacement ductility,and energy di...The low-cycle loading test of two staggered slab-column-boundary beam joints was carried out to study their seismic performance.The crack development,load-displacement relationship,displacement ductility,and energy dissipation performance of the staggered slab-column joints(SSCJ)were studied.Experimental results reveal that both specimens present short-column brittle shear failure.Furthermore,an obvious hysteretic curve pinching phenomenon occurred.Thus,it can be concluded that the seismic performance of the joints is insufficient.These results suggest that the anchorage of the longitudinal reinforcement of the slab in the joint’s core area should be improved,and attention should be paid to the short-column stirrup configuration of the SSCJ.These results can provide a research basis for the design of such joints in future applications.展开更多
In order to evaluate the seismic behavior of confined RC column-composite beam joints, five interior joints were tested under low cyclic reversed load. The weakening extent of flanges, the number of studs, and whether...In order to evaluate the seismic behavior of confined RC column-composite beam joints, five interior joints were tested under low cyclic reversed load. The weakening extent of flanges, the number of studs, and whether to reinforce weakened flanges were used as parameters in designing these five joints. Failure characteristics, hysteretic curves, skeleton curves, ductility, energy dissipation, strength degradation, and stiffness degradation were analyzed. The test results revealed that the steel beam flanges in the joints were equivalent to the tie rod. Weakened flanges resulted in poor seismic behavior; however, the seismic behavior could be improved by increasing studs and reinforcing weakened flanges. The joint steel plate hoops, equivalent to stirrups, did not yield when the maximum load was reached, but yielded when the failure load was reached for the joints with shear failure. Increasing stud-type joints and reinforcing flange-type joints ensured good seismic behavior and met project requirements. Based on the experimental results, the failure mechanism of the joints was discussed, and the shear capacity equations of the joints was presented.展开更多
To investigate the seismic behavior of connections composed of steel reinforced ultra high strength concrete (SRUHSC) column and reinforced concrete (RC) beam, six interior strong-column-weak-beam connection specimens...To investigate the seismic behavior of connections composed of steel reinforced ultra high strength concrete (SRUHSC) column and reinforced concrete (RC) beam, six interior strong-column-weak-beam connection specimens were tested subjected to reversal cyclic load. Effects of applied axial load ratio and volumetric stirrup ratio on ductility, energy dissipation capacity, strength degradation and rigidity degradation were discussed. It was found that all connection specimens failed in bending in a ductile manner with a beam plastic hinge. The ductility and energy dissipation capacity increased with the decrease of applied axial load ratio or increase of volumetric stirrup ratio. The displacement ductility coefficient and equivalent damping coefficient lay between those of steel reinforced ordinary concrete connection and those of reinforced concrete connection. The applied axial load ratio and volumetric stirrup ratio had less influence on the strength degradation and more influence on the stiffness degradation. The stiffness degraded sharply with the decrease of volumetric stirrup ratio or increase of applied axial load ratio. The experimental results indicate that SRUHSC column and RC beam connection exhibited better seismic performance and can provide reference for engineering application.展开更多
This paper is dedicated to the study of the seismic performance of an existing RC （reinforced concrete） bridge localized in a region of moderate seismicity. The bridge has six spans and piers with very different hei...This paper is dedicated to the study of the seismic performance of an existing RC （reinforced concrete） bridge localized in a region of moderate seismicity. The bridge has six spans and piers with very different heights, three of which are monolithically connected to the deck. To understand the roles of the different pier sizes in the overall behavior, several analyses were carried out in the longitudinal direction： （1） linear dynamic approach; （2） non-linear static approach; （3） non-linear dynamic approach. Linear dynamic analysis was made in order to design the bridge for the ultimate limit state considering the largest value of the ductility factor. No safety verification was made for the other loads. Using non-linear static analyses, sensitivity was performed to check the influence of reinforcement quantities of each pier on the overall behavior of the bridge under Lisbon seismic action. For the non-linear dynamic approach, a series of strong motion records compatible with the EC-8 spectrum for Lisbon area were generated. The very same combinations of reinforcement quantities were studied. Comparisons between static and dynamic non-linear analysis were made to confirm the validity of the first one in the case under analysis, where the period of vibration is quite high.展开更多
The seismic performance of precast reinforced concrete （RC） coupled shear walls is significantly influenced by coupling beams and the beam-to-wall joints during large deformations into plastic ranges. This study inv...The seismic performance of precast reinforced concrete （RC） coupled shear walls is significantly influenced by coupling beams and the beam-to-wall joints during large deformations into plastic ranges. This study investigated the use of engineered cementitious composite （ECC） in the cast-in-place beam-to-wall joints and the upper regions of the composite coupling beams as an innovative method to improve the seismic performance ofprecast RQ coupled shear walls. Two 1/2-scale precast coupled shear walls were tested under reversed cyclic loading and seismic behavior in terms of failure characteristic, mechanical characteristic value, load-displacement hysteresis curves, load-displacement envelope relationship, stiffness degradation, ductility and energy dissipation capacity were evaluated. Research results show that the substitution of concrete with ECC in the critical cast-in-place regions proved to be an effective method to improve the seismic performance of the two-story spatial of precast RC coupled shear walls.展开更多
文摘A new type of rigid connection of steel girder and reinforced concrete pier of a bridge is proposed. The components in rigid connection are installed by high strength bolts on the spot, which are very convenient in construction. The moment from superstructure can be effectively transferred to substructure, and the plates provided for shear transferring can withstand the majority of total horizontal force. With static cyclic loading test, useful experimental data is obtained on the new type of connection of steel superstructure and concrete substructure. As a result, the stress transfer mechanism of the rigid connection can be made clearly and the seismic performance of this structure can also be clarified. Compared computed strength and ductility with actual results, it can be found that this type of connection has good energy absorption capacity in spite of large displacement and no local buckling arises at the locations where stress concentration occurs. Because of doing away with the expensive bearing, this new type of composite structure can be expected to construct a bridge with high seismic resistant capacity thus saving in total construction cost.
基金Projects(U1934207,51778630,11972379)supported by the National Natural Science Foundation of ChinaProject(2020zzts148)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(GJJ200657)supported the Research Project of Jiangxi Provincial Education Department,China。
文摘Due to the wide railway network and different characteristics of many earthquake zones in China,considering the running safety performance of trains(RSPT)in the design of high-speed railway bridge structures is very necessary.In this study,in order to provide the seismic design and evaluation measure of the bridge structure based on the RSPT,a calculation model of RSPT on bridge under earthquake was established,and the track surface response measure when the derailment coefficient reaches the limit value was calculated by referring to 15 commonly used ground motion(GM)intensity measures.Based on the coefficient of variation of the limit value obtained from multiple GM samples,the optimal measures were selected.Finally,the limit value of bridge seismic response based on RSPT with different train speeds and structural periods was determined.
基金The National Natural Science Foundation of China(No.59878013).
文摘The low-cycle loading test of two staggered slab-column-boundary beam joints was carried out to study their seismic performance.The crack development,load-displacement relationship,displacement ductility,and energy dissipation performance of the staggered slab-column joints(SSCJ)were studied.Experimental results reveal that both specimens present short-column brittle shear failure.Furthermore,an obvious hysteretic curve pinching phenomenon occurred.Thus,it can be concluded that the seismic performance of the joints is insufficient.These results suggest that the anchorage of the longitudinal reinforcement of the slab in the joint’s core area should be improved,and attention should be paid to the short-column stirrup configuration of the SSCJ.These results can provide a research basis for the design of such joints in future applications.
基金Supported by the National Natural Science Foundation of China(No.51209094)
文摘In order to evaluate the seismic behavior of confined RC column-composite beam joints, five interior joints were tested under low cyclic reversed load. The weakening extent of flanges, the number of studs, and whether to reinforce weakened flanges were used as parameters in designing these five joints. Failure characteristics, hysteretic curves, skeleton curves, ductility, energy dissipation, strength degradation, and stiffness degradation were analyzed. The test results revealed that the steel beam flanges in the joints were equivalent to the tie rod. Weakened flanges resulted in poor seismic behavior; however, the seismic behavior could be improved by increasing studs and reinforcing weakened flanges. The joint steel plate hoops, equivalent to stirrups, did not yield when the maximum load was reached, but yielded when the failure load was reached for the joints with shear failure. Increasing stud-type joints and reinforcing flange-type joints ensured good seismic behavior and met project requirements. Based on the experimental results, the failure mechanism of the joints was discussed, and the shear capacity equations of the joints was presented.
基金Supported by National Natural Science Foundation of China (No. 50878037)
文摘To investigate the seismic behavior of connections composed of steel reinforced ultra high strength concrete (SRUHSC) column and reinforced concrete (RC) beam, six interior strong-column-weak-beam connection specimens were tested subjected to reversal cyclic load. Effects of applied axial load ratio and volumetric stirrup ratio on ductility, energy dissipation capacity, strength degradation and rigidity degradation were discussed. It was found that all connection specimens failed in bending in a ductile manner with a beam plastic hinge. The ductility and energy dissipation capacity increased with the decrease of applied axial load ratio or increase of volumetric stirrup ratio. The displacement ductility coefficient and equivalent damping coefficient lay between those of steel reinforced ordinary concrete connection and those of reinforced concrete connection. The applied axial load ratio and volumetric stirrup ratio had less influence on the strength degradation and more influence on the stiffness degradation. The stiffness degraded sharply with the decrease of volumetric stirrup ratio or increase of applied axial load ratio. The experimental results indicate that SRUHSC column and RC beam connection exhibited better seismic performance and can provide reference for engineering application.
文摘This paper is dedicated to the study of the seismic performance of an existing RC （reinforced concrete） bridge localized in a region of moderate seismicity. The bridge has six spans and piers with very different heights, three of which are monolithically connected to the deck. To understand the roles of the different pier sizes in the overall behavior, several analyses were carried out in the longitudinal direction： （1） linear dynamic approach; （2） non-linear static approach; （3） non-linear dynamic approach. Linear dynamic analysis was made in order to design the bridge for the ultimate limit state considering the largest value of the ductility factor. No safety verification was made for the other loads. Using non-linear static analyses, sensitivity was performed to check the influence of reinforcement quantities of each pier on the overall behavior of the bridge under Lisbon seismic action. For the non-linear dynamic approach, a series of strong motion records compatible with the EC-8 spectrum for Lisbon area were generated. The very same combinations of reinforcement quantities were studied. Comparisons between static and dynamic non-linear analysis were made to confirm the validity of the first one in the case under analysis, where the period of vibration is quite high.
基金supported by the National Key Research and Development Program of China(Grant No.2016YFC0701703)the Fundamental Research Funds for the Central Universities+1 种基金Project Supported by the Research and Innovation Program for Graduate Students in Jiangsu(Grant No.KYLX16_0257)A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(Grant No.CE02-2-47)
文摘The seismic performance of precast reinforced concrete （RC） coupled shear walls is significantly influenced by coupling beams and the beam-to-wall joints during large deformations into plastic ranges. This study investigated the use of engineered cementitious composite （ECC） in the cast-in-place beam-to-wall joints and the upper regions of the composite coupling beams as an innovative method to improve the seismic performance ofprecast RQ coupled shear walls. Two 1/2-scale precast coupled shear walls were tested under reversed cyclic loading and seismic behavior in terms of failure characteristic, mechanical characteristic value, load-displacement hysteresis curves, load-displacement envelope relationship, stiffness degradation, ductility and energy dissipation capacity were evaluated. Research results show that the substitution of concrete with ECC in the critical cast-in-place regions proved to be an effective method to improve the seismic performance of the two-story spatial of precast RC coupled shear walls.
