In order to investigate the mechanical properties and stress-strain curves of concrete at different ages under impact load,the impact compression tests of concrete at age of 1, 3, 7, 14 and 28 d were conducted with a ...In order to investigate the mechanical properties and stress-strain curves of concrete at different ages under impact load,the impact compression tests of concrete at age of 1, 3, 7, 14 and 28 d were conducted with a large diameter split Hopkinson pressure bar, respectively. Based on statistical damage theory and Weibull distribution, combining the analysis of the change laws of stressstrain curves and viscosity coefficient of concrete with age, a damage constitutive model that can reflect the variation in dynamic mechanical properties with age was proposed. The stress-strain curves calculated from the proposed model are in good agreement with those from experimental data directly.展开更多
With consideration of the differences between concrete and steel,three solutions using genetic evolutionary structural optimization algorithm were presented to automatically develop optimal strut-and-tie model for dee...With consideration of the differences between concrete and steel,three solutions using genetic evolutionary structural optimization algorithm were presented to automatically develop optimal strut-and-tie model for deep beams.In the finite element analysis of the first method,the concrete and steel rebar are modeled by a plane element and a bar element,respectively.In the second method,the concrete and steel are assigned to two different plane elements,whereas in the third method only one kind of plane element is used with no consideration of the differences of the two materials.A simply supported beam under two point loads was presented as an example to verify the validity of the three proposed methods.The results indicates that all the three methods can generate optimal strut-and-tie models and the third algorithm has powerful capability in searching more optimal results with less computational effort.The effectiveness of the proposed algorithm III has also been demonstrated by other two examples.展开更多
Combining fiber reinforced polymer(FRP)with seawater sea-sand concrete(SSC)can solve the shortage of river sand that will be used for marine engineering construction.The bond performance of BFRP bars and SSC specimens...Combining fiber reinforced polymer(FRP)with seawater sea-sand concrete(SSC)can solve the shortage of river sand that will be used for marine engineering construction.The bond performance of BFRP bars and SSC specimens is researched by pull-out test in this paper.The effects of the parameters,such as bar type,bar diameter,concrete type and stirrup restraint,are considered.It is beneficial to the bonding performance by the reduction of bar diameter.The utilization of seawater sea-sand has a low influence on the bond properties of concrete.The bond strength of BFRP is slightly lower than the steel rebar,but the difference is relatively small.The failure mode of the specimen can be changed and the interfacial bond stress can be improved by stirrups restraint.The bond-slip curves of BFRP ribbed rebar include micro slip stage,slip stage,descent stage and residual stage.The bond stress shows the cycle attenuation pattern of sine in the residual stage.In addition,the bond-slip model of BFRP and SSC is obtained according to the experimental results and related literature,while the predicted curve is also consistent well with the measured curve.展开更多
基金Project(2010CB732004)supported by National Basic Research Program of ChinaProject(50934006)supported by the National Natural Science Foundation of China
文摘In order to investigate the mechanical properties and stress-strain curves of concrete at different ages under impact load,the impact compression tests of concrete at age of 1, 3, 7, 14 and 28 d were conducted with a large diameter split Hopkinson pressure bar, respectively. Based on statistical damage theory and Weibull distribution, combining the analysis of the change laws of stressstrain curves and viscosity coefficient of concrete with age, a damage constitutive model that can reflect the variation in dynamic mechanical properties with age was proposed. The stress-strain curves calculated from the proposed model are in good agreement with those from experimental data directly.
基金Project(50908082) supported by the National Natural Science Foundation of ChinaProject(2009ZK3111) supported by the Science and Technology Department of Hunan Province,China
文摘With consideration of the differences between concrete and steel,three solutions using genetic evolutionary structural optimization algorithm were presented to automatically develop optimal strut-and-tie model for deep beams.In the finite element analysis of the first method,the concrete and steel rebar are modeled by a plane element and a bar element,respectively.In the second method,the concrete and steel are assigned to two different plane elements,whereas in the third method only one kind of plane element is used with no consideration of the differences of the two materials.A simply supported beam under two point loads was presented as an example to verify the validity of the three proposed methods.The results indicates that all the three methods can generate optimal strut-and-tie models and the third algorithm has powerful capability in searching more optimal results with less computational effort.The effectiveness of the proposed algorithm III has also been demonstrated by other two examples.
基金Project(BE2019642)supported by the Jiangsu Provincial Key Research and Development Program,China。
文摘Combining fiber reinforced polymer(FRP)with seawater sea-sand concrete(SSC)can solve the shortage of river sand that will be used for marine engineering construction.The bond performance of BFRP bars and SSC specimens is researched by pull-out test in this paper.The effects of the parameters,such as bar type,bar diameter,concrete type and stirrup restraint,are considered.It is beneficial to the bonding performance by the reduction of bar diameter.The utilization of seawater sea-sand has a low influence on the bond properties of concrete.The bond strength of BFRP is slightly lower than the steel rebar,but the difference is relatively small.The failure mode of the specimen can be changed and the interfacial bond stress can be improved by stirrups restraint.The bond-slip curves of BFRP ribbed rebar include micro slip stage,slip stage,descent stage and residual stage.The bond stress shows the cycle attenuation pattern of sine in the residual stage.In addition,the bond-slip model of BFRP and SSC is obtained according to the experimental results and related literature,while the predicted curve is also consistent well with the measured curve.
