Corrugated steel web is folded along the longitudinal direction and has the mechanical properties such as axial compression stiffness corrugation effect, shear modulus corrugation effect, similar to that of an accordi...Corrugated steel web is folded along the longitudinal direction and has the mechanical properties such as axial compression stiffness corrugation effect, shear modulus corrugation effect, similar to that of an accordion. In order to study the lateral-torsional buckling of box beams with corrugated steel webs (BBCSW) under the action of bending moment load, the neutral equilibrium equation of BBCSW under the action of bending moment load is derived through the stationary value theory of total potential energy and further, along with taking Kollbrunner-Hajdin correction method and the mechanical properties of the corrugated web into consideration. The analytical calculation formula of lateral-torsional buckling critical bending moment of BBCSW is then obtained. The lateral-torsional buckling critical bending moment of 96 BBCSW test specimens with different geometry dimensions are then calculated using both the analytical calculation method and ANSYS finite element method. The results show that the analytical calculation results agree well with the numerical calculation results using ANSYS, thus proving the accuracy of the analytical calculation method and model simplification hypothesis proposed in this paper. Also, compared with the box beams with flat steel webs (BBFSW) with the same geometry dimensions as BBCSW, within the common range of web space-depth ratio and web span-depth ratio, BBCSW’s lateral-torsional buckling critical bending moment is larger than that of BBFSW. Moreover, the advantages of BBCSW’s stability are even more significant with the increase of web space-depth ratio and web depth-thickness ratio.展开更多
Heliostats are sensitive to the wind load, thus as a key indicator, the study on the static and dynamic stability bearing capacity for heliostats is very important. In this work, a numerical wind tunnel was establishe...Heliostats are sensitive to the wind load, thus as a key indicator, the study on the static and dynamic stability bearing capacity for heliostats is very important. In this work, a numerical wind tunnel was established to calculate the wind load coefficients in various survival stow positions. In order to explore the best survival stow position for the heliostat under the strong wind, eigenvalue buckling analysis method was introduced to predict the critical wind load theoretically. Considering the impact of the nonlinearity and initial geometrical imperfection, the nonlinear post-buckling behaviors of the heliostat were investigated by load-displacement curves in the full equilibrium process. Eventually, combining B-R criterion with equivalent displacement principle the dynamic critical wind speed and load amplitude coefficient were evaluated. The results show that the determination for the best survival stow position is too hasty just by the wind load coefficients. The geometric nonlinearity has a great effect on the stability bearing capacity of the heliostat, while the effects of the material nonlinearity and initial geometrical imperfection are relatively small. And the heliostat is insensitive to the initial geometrical imperfection. In addition, the heliostat has the highest safety factor for wind-resistant performance in the stow position of 90-90 which can be taken as the best survival stow position. In this case, the extreme survival wind speeds for the static and dynamic stability are 150 m/s and 36 m/s, respectively.展开更多
Foundation scour is an important cause for structural failure of sea-crossing bridges. Usually, the sea-crossing bridges operate under the harsh natural environment in which service wind, wave and vehicle loads are st...Foundation scour is an important cause for structural failure of sea-crossing bridges. Usually, the sea-crossing bridges operate under the harsh natural environment in which service wind, wave and vehicle loads are stronger and extreme loads such as earthquake, hurricane, and ship collision, are more frequent. As a result of the foundation scour,the dynamic behavior of bridge under different combined action of service and extreme loads may be further escalated.In particular, this work has investigated the scour effect on a sea-crossing bridge under service wind, wave and vehicle loads as well as extreme seismic loads. The dynamic coupled earthquake-wind-wave-vehicle-bridge(EWWVB) system is established by considering the interactions within the system, and the p-y curve method is used to calculate the loaddisplacement relation of the pile and soil under various levels of foundation scour. After that, a case study has been performed on a cable-stayed bridge with foundation scour. The results indicate that the dynamic characteristics of bridge structure will change after considering bridge scour, and the dynamic responses of bridge and vehicle will be affected to different degrees under service and seismic loads considering bridge scour.展开更多
基金Projects(51408449,51778630)supported by the National Natural Science Foundation of ChinaProject(2018zzts189)supported by the Fundamental Research Funds for the Central Universities,China
文摘Corrugated steel web is folded along the longitudinal direction and has the mechanical properties such as axial compression stiffness corrugation effect, shear modulus corrugation effect, similar to that of an accordion. In order to study the lateral-torsional buckling of box beams with corrugated steel webs (BBCSW) under the action of bending moment load, the neutral equilibrium equation of BBCSW under the action of bending moment load is derived through the stationary value theory of total potential energy and further, along with taking Kollbrunner-Hajdin correction method and the mechanical properties of the corrugated web into consideration. The analytical calculation formula of lateral-torsional buckling critical bending moment of BBCSW is then obtained. The lateral-torsional buckling critical bending moment of 96 BBCSW test specimens with different geometry dimensions are then calculated using both the analytical calculation method and ANSYS finite element method. The results show that the analytical calculation results agree well with the numerical calculation results using ANSYS, thus proving the accuracy of the analytical calculation method and model simplification hypothesis proposed in this paper. Also, compared with the box beams with flat steel webs (BBFSW) with the same geometry dimensions as BBCSW, within the common range of web space-depth ratio and web span-depth ratio, BBCSW’s lateral-torsional buckling critical bending moment is larger than that of BBFSW. Moreover, the advantages of BBCSW’s stability are even more significant with the increase of web space-depth ratio and web depth-thickness ratio.
基金Project(CYB14010)supported by Chongqing Graduate Student Research Innovation Project,ChinaProject(51405209)supported by the National Natural Science Foundation of China
文摘Heliostats are sensitive to the wind load, thus as a key indicator, the study on the static and dynamic stability bearing capacity for heliostats is very important. In this work, a numerical wind tunnel was established to calculate the wind load coefficients in various survival stow positions. In order to explore the best survival stow position for the heliostat under the strong wind, eigenvalue buckling analysis method was introduced to predict the critical wind load theoretically. Considering the impact of the nonlinearity and initial geometrical imperfection, the nonlinear post-buckling behaviors of the heliostat were investigated by load-displacement curves in the full equilibrium process. Eventually, combining B-R criterion with equivalent displacement principle the dynamic critical wind speed and load amplitude coefficient were evaluated. The results show that the determination for the best survival stow position is too hasty just by the wind load coefficients. The geometric nonlinearity has a great effect on the stability bearing capacity of the heliostat, while the effects of the material nonlinearity and initial geometrical imperfection are relatively small. And the heliostat is insensitive to the initial geometrical imperfection. In addition, the heliostat has the highest safety factor for wind-resistant performance in the stow position of 90-90 which can be taken as the best survival stow position. In this case, the extreme survival wind speeds for the static and dynamic stability are 150 m/s and 36 m/s, respectively.
基金Project(51908472)supported by the National Natural Science Foundation of ChinaProjects(2019TQ0271,2019M663554)supported by the China Postdoctoral Science FoundationProject(2020YJ0080)supported by the Project of Science and Technology Department of Sichuan Province,China。
文摘Foundation scour is an important cause for structural failure of sea-crossing bridges. Usually, the sea-crossing bridges operate under the harsh natural environment in which service wind, wave and vehicle loads are stronger and extreme loads such as earthquake, hurricane, and ship collision, are more frequent. As a result of the foundation scour,the dynamic behavior of bridge under different combined action of service and extreme loads may be further escalated.In particular, this work has investigated the scour effect on a sea-crossing bridge under service wind, wave and vehicle loads as well as extreme seismic loads. The dynamic coupled earthquake-wind-wave-vehicle-bridge(EWWVB) system is established by considering the interactions within the system, and the p-y curve method is used to calculate the loaddisplacement relation of the pile and soil under various levels of foundation scour. After that, a case study has been performed on a cable-stayed bridge with foundation scour. The results indicate that the dynamic characteristics of bridge structure will change after considering bridge scour, and the dynamic responses of bridge and vehicle will be affected to different degrees under service and seismic loads considering bridge scour.
