The non-stationary buffeting response of long span suspension bridge in time domain under strong wind loading is computed. Modeling method for generating non-stationary fluctuating winds with probabilistic model for n...The non-stationary buffeting response of long span suspension bridge in time domain under strong wind loading is computed. Modeling method for generating non-stationary fluctuating winds with probabilistic model for non-stationary strong wind fields is first presented. Non-stationary wind forces induced by strong winds on bridge deck and tower are then given a brief introduction. Finally,Non-stationary buffeting response of Pulite Bridge in China,a long span suspension bridge,is computed by using ANSYS software under four working conditions with different combination of time-varying mean wind and time-varying variance. The case study further confirms that it is necessity of considering non-stationary buffeting response for long span suspension bridge under strong wind loading,rather than only stationary buffeting response.展开更多
Compared with general circular flanges, flanges on conical shells have different configurations. In the Chinese national code GBISO, however, there are no related contents about flange design of this kind of type. So,...Compared with general circular flanges, flanges on conical shells have different configurations. In the Chinese national code GBISO, however, there are no related contents about flange design of this kind of type. So, it needs to study loads of flanges of this kind of type. This paper takes the flange connection of a wide angle diffuser in a transonic and supersonic wind tunnel as the background, according to the principles of flange design in Chinese national code GB150, combining the characteristics of flanges of a wide angle diffuser, the loads of flanges have been analyzed, and the equations of loads and their locations have been presented.展开更多
Wind load is one of the main lateral control loads that need to be considered in the design of high-rise building structures. It is also of great engineering significance to study the influence of static wind load or ...Wind load is one of the main lateral control loads that need to be considered in the design of high-rise building structures. It is also of great engineering significance to study the influence of static wind load or time-varying wind load on the dynamic response of structures. In this paper, a high-rise building with a rectangular section (46.8 m × 27 m × 33 m) is simulated based on Ansys18.0 APDL software. The real situation of its response under no lateral wind load and different fluctuating wind load conditions is simulated and the stress and strain response of the building under steady-state and time-varying wind load is given. The results show that the upper strain of the structure under wind load is about 1/1000 of the bottom strain, and the strain of the structure shows obvious accumulation from the top to the bottom, that is, the bottom strain of the building will be higher than the top strain. The influence of time-varying wind load on building structure is related to the loading position of wind load on the structure. The results provide a basis for the structural wind resistance design of this type of building.展开更多
Modern tall buildings are generally built in urban areas, where value of the terrain roughness length is much greater than that of the general terrain areas, therefore wind-induced vibrations become more pronounced. T...Modern tall buildings are generally built in urban areas, where value of the terrain roughness length is much greater than that of the general terrain areas, therefore wind-induced vibrations become more pronounced. The present formulas of numerical analysis of wind-induced response become less accurate. A more accurate expression of along-wind load spectrum matrix is proposed. On the basis of the expression, structural analysis formula of along-wind displacement and acceleration response are developed and programmed. The rationality of these formulas are illustrated in examples.展开更多
A nonlinear finite element model is developed to examine the lateral behaviors of monopiles, which support offshore wind turbines(OWTs) chosen from five different offshore wind farms in Europe. The simulation is using...A nonlinear finite element model is developed to examine the lateral behaviors of monopiles, which support offshore wind turbines(OWTs) chosen from five different offshore wind farms in Europe. The simulation is using this model to accurately estimate the natural frequency of these slender structures, as a function of the interaction of the foundations with the subsoil. After a brief introduction to the wind power energy as a reliable alternative in comparison to fossil fuel, the paper focuses on concept of natural frequency as a primary indicator in designing the foundations of OWTs. Then the range of natural frequencies is provided for a safe design purpose. Next, an analytical expression of an OWT natural frequency is presented as a function of soil-monopile interaction through monopile head springs characterized by lateral stiffness KL, rotational stiffness KRand cross-coupling stiffness KLRof which the differences are discussed. The nonlinear pseudo three-dimensional finite element vertical slices model has been used to analyze the lateral behaviors of monopiles supporting the OWTs of different wind farm sites considered. Through the monopiles head movements(displacements and rotations), the values of KL, KRand KLRwere obtained and substituted in the analytical expression of natural frequency for comparison. The comparison results between computed and measured natural frequencies showed an excellent agreement for most cases. This confirms the convenience of the finite element model used for the accurate estimation of the monopile head stiffness.展开更多
As the span length of suspension bridges increases, the diameter of cables and thus the wind load acting on them, the nonlinear wind-structure interaction and the wind speed spatial non-uniformity all increase consequ...As the span length of suspension bridges increases, the diameter of cables and thus the wind load acting on them, the nonlinear wind-structure interaction and the wind speed spatial non-uniformity all increase consequently, which may have un-negligible influence on the aerostatic behavior of long-span suspension bridges. In this work, a method of advanced aerostatic analysis is presented firstly by considering the geometric nonlinearity, the nonlinear wind-structures and wind speed spatial non-uniformity. By taking the Runyang Bridge over the Yangtze River as example, effects of the nonlinear wind-structure inter-action, wind speed spatial non-uniformity, and the cable’s wind load on the aerostatic behavior of the bridge are investigated analytically. The results showed that these factors all have important influence on the aerostatic behavior, and should be considered in the aerostatic analysis of long and particularly super long-span suspension bridges.展开更多
Dynamic analysis must be performed when the duration of the applied load is short or if the load is dynamic in nature. Wind load, as a random load, can lead to the vibration of the coke tower. In order to study the in...Dynamic analysis must be performed when the duration of the applied load is short or if the load is dynamic in nature. Wind load, as a random load, can lead to the vibration of the coke tower. In order to study the influence to the strength of the coke tower by wind, ABAQUS was used to conduct the transient modal dynamic analysis of the wind load. The response of the structure during loading and unloading was mainly observed. The results indicate that, with the effect of wind, the maximal nodal displacement appears at the top of the tower, which is 0.79 mm; while the maximal stress locates at the node around the skirt, the maximum is 3.26 MPa. Both of the displacement and stress cannot cause the failure of the structure. After loading and unloading, the structure engenders vibration along the loading direction. The frequency is 10 Hz, under the effect of external loads, it may easily cause the resonance of the structure, which can cause damage to the structure. So it must be taken into consideration during the process of design and operation.展开更多
The morphological characteristics and stalk biomechanical properties at the dough stage of wheat were determined using the variety of wheat in the breeding process.Their mechanical responses to wind and rain loads for...The morphological characteristics and stalk biomechanical properties at the dough stage of wheat were determined using the variety of wheat in the breeding process.Their mechanical responses to wind and rain loads for an individual and a group of wheat were simulated using finite element method by ANSYS.The stress and displacement of each finite element can be outputted through stress nephogram and displacement nephogram,respectively.In order to judge whether the wheat could return to its original position after deformation,elastic mechanics theory was utilized to analyze the critical load of instability under both axial rain load and transverse wind load.The large displacement situation was analyzed with large displacement elastic nonlinear theory and the numerical value was obtained by ANSYS.The results show that it is possible to apply various load types on models using ANSYS and the dynamic response can be simulated well under different rain and wind loads.The location of maximum Von Mises stress can be calculated and the variation of stress can be described clearly,which are helpful to predict the wheat lodging under wind and rain loads.展开更多
基金Sponsored by the National Natural Science Foundation of China(Grant No.51408174)Anhui Provincial Natural Science Foundation(Grant No.1408085QE95)+1 种基金China Postdoctoral Science Foundation(Grant No.2013M540511 and 2015T80652)Key University Science Research Project of Anhui Province(Grant No.KJ2016A294)
文摘The non-stationary buffeting response of long span suspension bridge in time domain under strong wind loading is computed. Modeling method for generating non-stationary fluctuating winds with probabilistic model for non-stationary strong wind fields is first presented. Non-stationary wind forces induced by strong winds on bridge deck and tower are then given a brief introduction. Finally,Non-stationary buffeting response of Pulite Bridge in China,a long span suspension bridge,is computed by using ANSYS software under four working conditions with different combination of time-varying mean wind and time-varying variance. The case study further confirms that it is necessity of considering non-stationary buffeting response for long span suspension bridge under strong wind loading,rather than only stationary buffeting response.
文摘Compared with general circular flanges, flanges on conical shells have different configurations. In the Chinese national code GBISO, however, there are no related contents about flange design of this kind of type. So, it needs to study loads of flanges of this kind of type. This paper takes the flange connection of a wide angle diffuser in a transonic and supersonic wind tunnel as the background, according to the principles of flange design in Chinese national code GB150, combining the characteristics of flanges of a wide angle diffuser, the loads of flanges have been analyzed, and the equations of loads and their locations have been presented.
文摘Wind load is one of the main lateral control loads that need to be considered in the design of high-rise building structures. It is also of great engineering significance to study the influence of static wind load or time-varying wind load on the dynamic response of structures. In this paper, a high-rise building with a rectangular section (46.8 m × 27 m × 33 m) is simulated based on Ansys18.0 APDL software. The real situation of its response under no lateral wind load and different fluctuating wind load conditions is simulated and the stress and strain response of the building under steady-state and time-varying wind load is given. The results show that the upper strain of the structure under wind load is about 1/1000 of the bottom strain, and the strain of the structure shows obvious accumulation from the top to the bottom, that is, the bottom strain of the building will be higher than the top strain. The influence of time-varying wind load on building structure is related to the loading position of wind load on the structure. The results provide a basis for the structural wind resistance design of this type of building.
文摘Modern tall buildings are generally built in urban areas, where value of the terrain roughness length is much greater than that of the general terrain areas, therefore wind-induced vibrations become more pronounced. The present formulas of numerical analysis of wind-induced response become less accurate. A more accurate expression of along-wind load spectrum matrix is proposed. On the basis of the expression, structural analysis formula of along-wind displacement and acceleration response are developed and programmed. The rationality of these formulas are illustrated in examples.
文摘A nonlinear finite element model is developed to examine the lateral behaviors of monopiles, which support offshore wind turbines(OWTs) chosen from five different offshore wind farms in Europe. The simulation is using this model to accurately estimate the natural frequency of these slender structures, as a function of the interaction of the foundations with the subsoil. After a brief introduction to the wind power energy as a reliable alternative in comparison to fossil fuel, the paper focuses on concept of natural frequency as a primary indicator in designing the foundations of OWTs. Then the range of natural frequencies is provided for a safe design purpose. Next, an analytical expression of an OWT natural frequency is presented as a function of soil-monopile interaction through monopile head springs characterized by lateral stiffness KL, rotational stiffness KRand cross-coupling stiffness KLRof which the differences are discussed. The nonlinear pseudo three-dimensional finite element vertical slices model has been used to analyze the lateral behaviors of monopiles supporting the OWTs of different wind farm sites considered. Through the monopiles head movements(displacements and rotations), the values of KL, KRand KLRwere obtained and substituted in the analytical expression of natural frequency for comparison. The comparison results between computed and measured natural frequencies showed an excellent agreement for most cases. This confirms the convenience of the finite element model used for the accurate estimation of the monopile head stiffness.
基金Project (No. 502118) supported by the Natural Science Foundation of Zhejiang Province, China
文摘As the span length of suspension bridges increases, the diameter of cables and thus the wind load acting on them, the nonlinear wind-structure interaction and the wind speed spatial non-uniformity all increase consequently, which may have un-negligible influence on the aerostatic behavior of long-span suspension bridges. In this work, a method of advanced aerostatic analysis is presented firstly by considering the geometric nonlinearity, the nonlinear wind-structures and wind speed spatial non-uniformity. By taking the Runyang Bridge over the Yangtze River as example, effects of the nonlinear wind-structure inter-action, wind speed spatial non-uniformity, and the cable’s wind load on the aerostatic behavior of the bridge are investigated analytically. The results showed that these factors all have important influence on the aerostatic behavior, and should be considered in the aerostatic analysis of long and particularly super long-span suspension bridges.
文摘Dynamic analysis must be performed when the duration of the applied load is short or if the load is dynamic in nature. Wind load, as a random load, can lead to the vibration of the coke tower. In order to study the influence to the strength of the coke tower by wind, ABAQUS was used to conduct the transient modal dynamic analysis of the wind load. The response of the structure during loading and unloading was mainly observed. The results indicate that, with the effect of wind, the maximal nodal displacement appears at the top of the tower, which is 0.79 mm; while the maximal stress locates at the node around the skirt, the maximum is 3.26 MPa. Both of the displacement and stress cannot cause the failure of the structure. After loading and unloading, the structure engenders vibration along the loading direction. The frequency is 10 Hz, under the effect of external loads, it may easily cause the resonance of the structure, which can cause damage to the structure. So it must be taken into consideration during the process of design and operation.
基金The authors would like to thank the College of Agriculture,Shanxi Agricultural University,P.R.China to provide wheat for testing.The authors would also like to thank the Research Fund for the Doctoral Program of Higher Education(20060113002).
文摘The morphological characteristics and stalk biomechanical properties at the dough stage of wheat were determined using the variety of wheat in the breeding process.Their mechanical responses to wind and rain loads for an individual and a group of wheat were simulated using finite element method by ANSYS.The stress and displacement of each finite element can be outputted through stress nephogram and displacement nephogram,respectively.In order to judge whether the wheat could return to its original position after deformation,elastic mechanics theory was utilized to analyze the critical load of instability under both axial rain load and transverse wind load.The large displacement situation was analyzed with large displacement elastic nonlinear theory and the numerical value was obtained by ANSYS.The results show that it is possible to apply various load types on models using ANSYS and the dynamic response can be simulated well under different rain and wind loads.The location of maximum Von Mises stress can be calculated and the variation of stress can be described clearly,which are helpful to predict the wheat lodging under wind and rain loads.