This paper deals with flexural concrete members reinforced longitudinally but without transverse reinforcement. The conducted experimental investigations have shown that beams without web reinforcement may fail withou...This paper deals with flexural concrete members reinforced longitudinally but without transverse reinforcement. The conducted experimental investigations have shown that beams without web reinforcement may fail without attaining their full flexural capacity and then shear governs their failure. In the paper, there are presented recent results of the author＇s own experiments, which aimed at disclosing some aspects of the propagation of cracks in longitudinally reinforced concrete beams without stirrups. The experimental program has been designed especially to investigate the influence of the shear span-to-depth ratio on diagonal crack propagation and load carrying capacity of tested beams.展开更多
The potential of externally applied FRP （fiber-reinforced plastic） sheets, being employed in retrofitting schemes aimed to repair and strengthen RC （reinforced concrete） structural elements damaged by prototype st...The potential of externally applied FRP （fiber-reinforced plastic） sheets, being employed in retrofitting schemes aimed to repair and strengthen RC （reinforced concrete） structural elements damaged by prototype strong earthquakes, is presented and discussed in this study. The limitation of the debonding mode of failure of these FRP sheets is highlighted and the necessity to develop efficient anchoring devices for these FRP sheets is underlined. The behavior of such a novel HAD （hybrid anchoring device） capable of anchoring CFRP （carbon fiber reinforcing plastic） sheets to RC structural elements, is presented and discussed. The behavior of the device itself was studied through a 3D non-linear numerical simulation at the preliminary design stage in order to establish certain desired features such as the ductile behavior of the device itself as well as the satisfactory performance of the FRP sheets wrapped around this device. This HAD was next applied as part of a strengthening scheme aimed to upgrade the flexural capacity of an RC bridge-type pier specimen subjected to a cyclic seismic-type loading sequence. The obtained results demonstrated an increase in the specimen＇s flexural capacity by 100% as well as a similar increase in its capability of dissipating energy in a ductile manner during the cyclic load sequence. Moreover, the employed 3D non-linear numerical simulation yielded reasonably good agreement between the measured and the predicted cyclic response of this specimen strengthened by CFRP layers, which were anchored by the novel HAD. The successful behavior of this novel HAD, which has been patented with No. WO2011073696, is currently being tried with a number of other retrofitting schemes employing FRP sheets externally attached on RC structural elements.展开更多
Concrete Filled FRP （Reinforced Polymeric Plastic） Tubes （CFFT） and Reinforced Concrete Filled FRP Tubes （RCFFT） are known to have the capability to enhance structural performance in terms of structural stabilit...Concrete Filled FRP （Reinforced Polymeric Plastic） Tubes （CFFT） and Reinforced Concrete Filled FRP Tubes （RCFFT） are known to have the capability to enhance structural performance in terms of structural stability, ductility, as well as chemical resistance when compared with conventional concrete members. In this study, the authors evaluate the structural performance of the CFFT and the RCFFT through flexural tests for the purpose of applying the members as flexural ones. Moreover, the compressive behavior of the CFFT and the RCFFT members was investigated to examine their confinement effects. Based on the experimental and analytical results of the compressive behavior of the members, equations for estimating the ultimate compressive strengths of the CFFT and the RCFFT were proposed. In addition, the degree of improvement on the flexural performance of the RCFFT member strengthened by the FRP was analyzed from the flexural tests.展开更多
文摘This paper deals with flexural concrete members reinforced longitudinally but without transverse reinforcement. The conducted experimental investigations have shown that beams without web reinforcement may fail without attaining their full flexural capacity and then shear governs their failure. In the paper, there are presented recent results of the author＇s own experiments, which aimed at disclosing some aspects of the propagation of cracks in longitudinally reinforced concrete beams without stirrups. The experimental program has been designed especially to investigate the influence of the shear span-to-depth ratio on diagonal crack propagation and load carrying capacity of tested beams.
文摘The potential of externally applied FRP （fiber-reinforced plastic） sheets, being employed in retrofitting schemes aimed to repair and strengthen RC （reinforced concrete） structural elements damaged by prototype strong earthquakes, is presented and discussed in this study. The limitation of the debonding mode of failure of these FRP sheets is highlighted and the necessity to develop efficient anchoring devices for these FRP sheets is underlined. The behavior of such a novel HAD （hybrid anchoring device） capable of anchoring CFRP （carbon fiber reinforcing plastic） sheets to RC structural elements, is presented and discussed. The behavior of the device itself was studied through a 3D non-linear numerical simulation at the preliminary design stage in order to establish certain desired features such as the ductile behavior of the device itself as well as the satisfactory performance of the FRP sheets wrapped around this device. This HAD was next applied as part of a strengthening scheme aimed to upgrade the flexural capacity of an RC bridge-type pier specimen subjected to a cyclic seismic-type loading sequence. The obtained results demonstrated an increase in the specimen＇s flexural capacity by 100% as well as a similar increase in its capability of dissipating energy in a ductile manner during the cyclic load sequence. Moreover, the employed 3D non-linear numerical simulation yielded reasonably good agreement between the measured and the predicted cyclic response of this specimen strengthened by CFRP layers, which were anchored by the novel HAD. The successful behavior of this novel HAD, which has been patented with No. WO2011073696, is currently being tried with a number of other retrofitting schemes employing FRP sheets externally attached on RC structural elements.
文摘Concrete Filled FRP （Reinforced Polymeric Plastic） Tubes （CFFT） and Reinforced Concrete Filled FRP Tubes （RCFFT） are known to have the capability to enhance structural performance in terms of structural stability, ductility, as well as chemical resistance when compared with conventional concrete members. In this study, the authors evaluate the structural performance of the CFFT and the RCFFT through flexural tests for the purpose of applying the members as flexural ones. Moreover, the compressive behavior of the CFFT and the RCFFT members was investigated to examine their confinement effects. Based on the experimental and analytical results of the compressive behavior of the members, equations for estimating the ultimate compressive strengths of the CFFT and the RCFFT were proposed. In addition, the degree of improvement on the flexural performance of the RCFFT member strengthened by the FRP was analyzed from the flexural tests.
