Eight high strength concrete (HSC) prisms strengthened with continuous carbon fiber sheet(CFS)were tested.As a result of the confinement provided by CFS,the concrete would fail at a greater strain than the unconfined ...Eight high strength concrete (HSC) prisms strengthened with continuous carbon fiber sheet(CFS)were tested.As a result of the confinement provided by CFS,the concrete would fail at a greater strain than the unconfined and then a significant increase in ductility can be achieved.The lateral pressure exerted by CFS would increase the compressive strength of the concrete,resulting in higher load bearing capacity.This paper proposes the stress strain curve of this kind of hybrid specimen,which agrees well with the test results.Based on the stress strain relationship and the assumptions proposed in this paper,a computer program was developed to analyze HSC columns,confined by CFS,which were subjected to axial compression and biaxial bending.The results shown in this paper indicate that the ductility of HSC column is significantly improved and the strength is also increased by some degree.展开更多
For the purpose of inventing a new seismic retrofitting method for the reinforced high strength concrete （HSC） T-section beam using carbon fiber reinforced polymer （CFRP） sheet, three series, a total of twelve T-s...For the purpose of inventing a new seismic retrofitting method for the reinforced high strength concrete （HSC） T-section beam using carbon fiber reinforced polymer （CFRP） sheet, three series, a total of twelve T-section beams with nine specimens confined by CFRP sheet in the plastic zone and three control beams were conducted up to failure under four-point bending test. The effectiveness of confining CFRP sheet on improving the flexural ductility of tmstrengthened T-section beams was studied. The parameters such as the width and the thickness of CFRP sheet and the type of T-section were analyzed. The experimental results show that ductility and rotation capacity of plastic hinge can be improved by the confinement of CFRP sheet, and the ductility indices increase with the increment of width and thickness of CFRP sheet. A plastic rotation model considering the width of CFRP sheet and the effect of flange of T-section beam is proposed on the basis of the model of BAKER, and the test results show a good agreement with the perdicted results. The relevant construction suggestions for seismic retrofitting design of beam-slabs system in cast-in-place framework structure are presented.展开更多
Twenty-one square concrete columns were constructed and tested. The testing results indicate that bonded carbon fiber reinforced plastics(CFRP) sheets can be used to increase the strength and improve the serviceabilit...Twenty-one square concrete columns were constructed and tested. The testing results indicate that bonded carbon fiber reinforced plastics(CFRP) sheets can be used to increase the strength and improve the serviceability of damaged concrete columns at low temperatures. The failure of the specimens,in most cases,takes place within the middle half of the columns. And the failure of strengthened columns is sudden and explosive. The CFRP sheets increase both the axial load capacity and the ultimate concrete compressive strain of the columns. The ultimate loads of strengthened columns at-10,0 and 10 ℃ increase averagely by 9.09%,6.63% and 17.83%,respectively,as compared with those of the control specimens. The axial compressive strength of strengthened columns is related to the curing temperatures. The improvement of axial compressive strength decreases with reducing temperature,and when the temperature drops to a certain value,the improvement increases with falling temperature.展开更多
The objective of this work is to investigate the fatigue behavior of reinforced concrete(RC) beams strengthened with externally bonded carbon fiber reinforced polymer(CFRP) and steel plate. An experimental investigati...The objective of this work is to investigate the fatigue behavior of reinforced concrete(RC) beams strengthened with externally bonded carbon fiber reinforced polymer(CFRP) and steel plate. An experimental investigation and theoretical analysis were made on the law of deflection development and stiffness degradation, as well as the influence of fatigue load ranges. Test results indicate that the law of three-stage change under fatigue loading is followed by both midspan deflection and permanent deflection, which also have positive correlation with fatigue load amplitude. Fatigue stiffness of composite strengthened beams degrades gradually with the increasing of number of cycles. Based on the experimental results, a theoretical model by effective moment of inertia method is developed for calculating the sectional stiffness of such composite strengthened beams under fatigue loading, and the calculated results are in good agreement with the experimental results.展开更多
To discuss the applicability of advanced composite carbon fiber reinforced polymer(CFRP) and ultrahigh performance concrete reactive powder concrete(RPC) in super-long span cable-stayed bridges, taking a 1 008 m cable...To discuss the applicability of advanced composite carbon fiber reinforced polymer(CFRP) and ultrahigh performance concrete reactive powder concrete(RPC) in super-long span cable-stayed bridges, taking a 1 008 m cable-stayed bridge with steel girders and steel cables as an example,a new cable-stayed bridge in the same span with RPC girders and CFRP cables was designed,in which the cable's cross section was determined by the principle of equivalent cable capacity and the girder's cross section was determined in virtual of its stiffness, shear capacity and local stability. Based on the methods of finite element analysis,the comparative analysis of these two cable-stayed bridge schemes about static performances,dynamic performances,stability and wind resistance behavior were carried out. The results showed that it was feasible to form a highly efficient,durable concrete cable-stayed bridge with RPC girders and CFRP cables and made its applicable span range expand to 1 000 m long around.展开更多
文摘Eight high strength concrete (HSC) prisms strengthened with continuous carbon fiber sheet(CFS)were tested.As a result of the confinement provided by CFS,the concrete would fail at a greater strain than the unconfined and then a significant increase in ductility can be achieved.The lateral pressure exerted by CFS would increase the compressive strength of the concrete,resulting in higher load bearing capacity.This paper proposes the stress strain curve of this kind of hybrid specimen,which agrees well with the test results.Based on the stress strain relationship and the assumptions proposed in this paper,a computer program was developed to analyze HSC columns,confined by CFS,which were subjected to axial compression and biaxial bending.The results shown in this paper indicate that the ductility of HSC column is significantly improved and the strength is also increased by some degree.
基金Project(51121005) supported by the Science Fund for Creative Research Groups of the National Natural Science Foundation of ChinaProject(50878035) supported by the National Natural Science Foundation of China
文摘For the purpose of inventing a new seismic retrofitting method for the reinforced high strength concrete （HSC） T-section beam using carbon fiber reinforced polymer （CFRP） sheet, three series, a total of twelve T-section beams with nine specimens confined by CFRP sheet in the plastic zone and three control beams were conducted up to failure under four-point bending test. The effectiveness of confining CFRP sheet on improving the flexural ductility of tmstrengthened T-section beams was studied. The parameters such as the width and the thickness of CFRP sheet and the type of T-section were analyzed. The experimental results show that ductility and rotation capacity of plastic hinge can be improved by the confinement of CFRP sheet, and the ductility indices increase with the increment of width and thickness of CFRP sheet. A plastic rotation model considering the width of CFRP sheet and the effect of flange of T-section beam is proposed on the basis of the model of BAKER, and the test results show a good agreement with the perdicted results. The relevant construction suggestions for seismic retrofitting design of beam-slabs system in cast-in-place framework structure are presented.
基金Project(04043076) supported by the Outstanding Youth Foundation for Scientific and Technological Research of Anhui Province, ChinaProject(2007jq1035) supported by the Scientific Research Projects for Young College Teachers of Anhui Province, China
文摘Twenty-one square concrete columns were constructed and tested. The testing results indicate that bonded carbon fiber reinforced plastics(CFRP) sheets can be used to increase the strength and improve the serviceability of damaged concrete columns at low temperatures. The failure of the specimens,in most cases,takes place within the middle half of the columns. And the failure of strengthened columns is sudden and explosive. The CFRP sheets increase both the axial load capacity and the ultimate concrete compressive strain of the columns. The ultimate loads of strengthened columns at-10,0 and 10 ℃ increase averagely by 9.09%,6.63% and 17.83%,respectively,as compared with those of the control specimens. The axial compressive strength of strengthened columns is related to the curing temperatures. The improvement of axial compressive strength decreases with reducing temperature,and when the temperature drops to a certain value,the improvement increases with falling temperature.
基金Project(51108355)supported by the National Natural Science Foundation of ChinaProject(2011CDB269)supported by the Natural Science Foundation of Hubei Province,China
文摘The objective of this work is to investigate the fatigue behavior of reinforced concrete(RC) beams strengthened with externally bonded carbon fiber reinforced polymer(CFRP) and steel plate. An experimental investigation and theoretical analysis were made on the law of deflection development and stiffness degradation, as well as the influence of fatigue load ranges. Test results indicate that the law of three-stage change under fatigue loading is followed by both midspan deflection and permanent deflection, which also have positive correlation with fatigue load amplitude. Fatigue stiffness of composite strengthened beams degrades gradually with the increasing of number of cycles. Based on the experimental results, a theoretical model by effective moment of inertia method is developed for calculating the sectional stiffness of such composite strengthened beams under fatigue loading, and the calculated results are in good agreement with the experimental results.
基金National Natural Science Foundation of China(No.51078134)Natural Science Foundation of Jiangxi Province(No.20114BAB206010)Department of Education Foundation of Jiangxi Province(No.GJJ11449)
文摘To discuss the applicability of advanced composite carbon fiber reinforced polymer(CFRP) and ultrahigh performance concrete reactive powder concrete(RPC) in super-long span cable-stayed bridges, taking a 1 008 m cable-stayed bridge with steel girders and steel cables as an example,a new cable-stayed bridge in the same span with RPC girders and CFRP cables was designed,in which the cable's cross section was determined by the principle of equivalent cable capacity and the girder's cross section was determined in virtual of its stiffness, shear capacity and local stability. Based on the methods of finite element analysis,the comparative analysis of these two cable-stayed bridge schemes about static performances,dynamic performances,stability and wind resistance behavior were carried out. The results showed that it was feasible to form a highly efficient,durable concrete cable-stayed bridge with RPC girders and CFRP cables and made its applicable span range expand to 1 000 m long around.
