The stress-strain curves of confined concrete were obtained based on tests of seven cross-shaped columns confined by stirrups under axial load. The experiment results showed that the strength and deformation of confin...The stress-strain curves of confined concrete were obtained based on tests of seven cross-shaped columns confined by stirrups under axial load. The experiment results showed that the strength and deformation of confined concrete can be enhanced effectively by stirrups for cross-shaped columns. Compared with the non-confined concrete, when the stirrup characteristic value is in the range of 0.046-0.230, the confined concrete compressive strengths has an increase of 8%-43%, and the strain corresponding to the peak stress of confined concrete has an increase of 25%-195%. According to the test results, the effects of stirrup characteristic and stirrup spacing on the compressive strength and strain of confined concrete were analysed. It is shown that the compressive strength of confined concrete has a linear relationship with the product of stirrup characteristic value and stirrup effective restraint coefficient, and the strain corresponding to the peak stress of confined concrete has a nonlinear relationship with the product of stirrup characteristic value and stirrup effective restraint coefficient. The stress-strain curve equation of confined concrete was proposed for cross-shaped columns, and the calculated curves are in good agreement with the experimental curves.展开更多
Steel corrosion is the main occasion for durability degradation of concrete structures. For existing corrosion-expansion models of reinforcement, effects of stirrups were not considered, thus, they cannot entirely ref...Steel corrosion is the main occasion for durability degradation of concrete structures. For existing corrosion-expansion models of reinforcement, effects of stirrups were not considered, thus, they cannot entirely reflect the actual corrosion and expansion states. Based on uniform corrosion hypothesis and current models, a corrosion-expansion model for steel in concrete members is presented, which considered the effects of stirrups. Verification result of the model by test data indicates its full significance in structural inspection and life evaluation fields.展开更多
The use of Winderen Knee Protection Solution stirrups compared to standard iron stirrups, reveals the following benefits: 1) A reduction of stress or strain time in the order of 14 seconds per minute of activity whils...The use of Winderen Knee Protection Solution stirrups compared to standard iron stirrups, reveals the following benefits: 1) A reduction of stress or strain time in the order of 14 seconds per minute of activity whilst walking and 5 - 7 seconds less whilst trotting or cantering for muscles around the knee. 2) A reduction of stress or strain time in the order of 25 seconds per minute of activity whilst walking and 9 - 10 seconds less whilst trotting or cantering for ligaments around the knee. 3) A significant improvement in the E-score (less time exposed to stress and shock) and ST-score (lower force around the knee) whilst walking. 4) A considerable improvement in rider comfort and feeling of leg stability (self-assessment) compared with the owners current stirrups, whilst riding.展开更多
Reinforced concrete beams consisting of both steel and glass-fiber-reinforced polymer rebars exhibit excellent strength,serviceability,and durability.However,the fatigue shear performance of such beams is unclear.Ther...Reinforced concrete beams consisting of both steel and glass-fiber-reinforced polymer rebars exhibit excellent strength,serviceability,and durability.However,the fatigue shear performance of such beams is unclear.Therefore,beams with hybrid longitudinal bars and hybrid stirrups were designed,and fatigue shear tests were performed.For specimens that failed by fatigue shear,all the glass-fiber-reinforced polymer stirrups and some steel stirrups fractured at the critical diagonal crack.For the specimen that failed by the static test after 8 million fatigue cycles,the static capacity after fatigue did not significantly decrease compared with the calculated value.The initial fatigue level has a greater influence on the crack development and fatigue life than the fatigue level in the later phase.The fatigue strength of the glass-fiber-reinforced polymer stirrups in the specimens was considerably lower than that of the axial tension tests on the glass-fiber-reinforced polymer bar in air and beam-hinge tests on the glass-fiber-reinforced polymer bar,and the failure modes were different.Glass-fiber-reinforced polymer stirrups were subjected to fatigue tension and shear,and failed owing to shear.展开更多
基金Supported by National Natural Science Foundation of China (No. 50878141)
文摘The stress-strain curves of confined concrete were obtained based on tests of seven cross-shaped columns confined by stirrups under axial load. The experiment results showed that the strength and deformation of confined concrete can be enhanced effectively by stirrups for cross-shaped columns. Compared with the non-confined concrete, when the stirrup characteristic value is in the range of 0.046-0.230, the confined concrete compressive strengths has an increase of 8%-43%, and the strain corresponding to the peak stress of confined concrete has an increase of 25%-195%. According to the test results, the effects of stirrup characteristic and stirrup spacing on the compressive strength and strain of confined concrete were analysed. It is shown that the compressive strength of confined concrete has a linear relationship with the product of stirrup characteristic value and stirrup effective restraint coefficient, and the strain corresponding to the peak stress of confined concrete has a nonlinear relationship with the product of stirrup characteristic value and stirrup effective restraint coefficient. The stress-strain curve equation of confined concrete was proposed for cross-shaped columns, and the calculated curves are in good agreement with the experimental curves.
文摘Steel corrosion is the main occasion for durability degradation of concrete structures. For existing corrosion-expansion models of reinforcement, effects of stirrups were not considered, thus, they cannot entirely reflect the actual corrosion and expansion states. Based on uniform corrosion hypothesis and current models, a corrosion-expansion model for steel in concrete members is presented, which considered the effects of stirrups. Verification result of the model by test data indicates its full significance in structural inspection and life evaluation fields.
文摘The use of Winderen Knee Protection Solution stirrups compared to standard iron stirrups, reveals the following benefits: 1) A reduction of stress or strain time in the order of 14 seconds per minute of activity whilst walking and 5 - 7 seconds less whilst trotting or cantering for muscles around the knee. 2) A reduction of stress or strain time in the order of 25 seconds per minute of activity whilst walking and 9 - 10 seconds less whilst trotting or cantering for ligaments around the knee. 3) A significant improvement in the E-score (less time exposed to stress and shock) and ST-score (lower force around the knee) whilst walking. 4) A considerable improvement in rider comfort and feeling of leg stability (self-assessment) compared with the owners current stirrups, whilst riding.
基金The authors wish to acknowledge the research grants from the National Key Research and Development Program of China(2017YFC0703000)the National Natural Science Foundation of China(Grant No.51678430).
文摘Reinforced concrete beams consisting of both steel and glass-fiber-reinforced polymer rebars exhibit excellent strength,serviceability,and durability.However,the fatigue shear performance of such beams is unclear.Therefore,beams with hybrid longitudinal bars and hybrid stirrups were designed,and fatigue shear tests were performed.For specimens that failed by fatigue shear,all the glass-fiber-reinforced polymer stirrups and some steel stirrups fractured at the critical diagonal crack.For the specimen that failed by the static test after 8 million fatigue cycles,the static capacity after fatigue did not significantly decrease compared with the calculated value.The initial fatigue level has a greater influence on the crack development and fatigue life than the fatigue level in the later phase.The fatigue strength of the glass-fiber-reinforced polymer stirrups in the specimens was considerably lower than that of the axial tension tests on the glass-fiber-reinforced polymer bar in air and beam-hinge tests on the glass-fiber-reinforced polymer bar,and the failure modes were different.Glass-fiber-reinforced polymer stirrups were subjected to fatigue tension and shear,and failed owing to shear.
