Action Of Wind Load Research Articles

Application of Rock Bolt Foundation in the Design of Metallurgical Industry Factory Building

Metallurgical industry factory building is usually high. Under the action of wind load and horizontal crane force, large moment will be induced at the column base. That is to say, the moment acting on the foundation is large. The embedded depth is relatively deep and the size of factory building foundation is relatively big. In the case of foundations based on the natural rock, if the routine design code adopted, the high capacity of the rock can not be fully utilized. The use of bolt at the bottom surface of the foundation integrates the foundation and the natural rock, hence reduces the foundation size and embedded depth to save the investment.

Fatigue Reliability Analysis of the Stay Cables of Cable-Stayed Bridge under Combined Loads of Stochastic Traffic and Wind

The existent studies on cable stays fatigue for the serviced cable-stayed bridge generally only considered traffic or wind load action respectively. The long span cable-stayed bridges are very sensitive to wind load, so the fatigue estimation of cable stays considering traffic and wind load simultaneously is very important for the bridge safety. In the present research, taking an actual bridge as an example, based on linear cumulative damage theory, fatigue reliability of cable stays is analyzed under combined load of vehicles and wind. Firstly, based on the long-term traffic survey and wind speed data, traffic and wind load probability distribution models for the bridge are built respectively. Secondly, an intensive computational work is performed to obtain stress time history of the stay cables in the typical time block by running self-compiled Bridge-Vehicle-Wind interaction dynamic response analysis program. Thirdly, the stress result is updated in accordance with traffic growth and extreme wind speed changing in service period. The stress amplitude and frequency are attained by rain-flow cycle counting method. Finally, the fatigue damage limit state function of cable stays is proposed based on linear cumulative damage theory, and solved by Monte-Carlo method. The analysis result shows that the effect of buffeting wind load on the fatigue reliability of cable stays is significant, the influence degree increases generally in accordance with the order from short cable to long cable. The fatigue life of cable under designed safety probability reduces by the range from 2% to 63%, average 50% compared to only considering traffic load. So fatigue assessment of stay cables should take traffic and wind loads together into account. The proposed analysis framework offers a referenced fatigue assessment approach for conventional long span bridges.

Active Flutter Suppression by Feedback Compensation of Transport Logs

A IRCRAFT wings are deigned to be flexible, and as a consequence of this feature they are known to be continuously oscillating under the action of wind loads leading to the well-known phenomenon of “flutter.” Flutter in wings was conventionally inhibited by passive design techniques based on altering the mass and stiffness distributions of the wing. However, the recent trend in building highly flexible aircraft has demonstrated the inadequacy of passive techniques for inhibiting the occurrence of flutter. To overcome the inadequacy of passive techniques in inhibiting the occurrence of flutter within the design envelope of the aircraft, a new technique, based on feedback control, was developed in the early 1970s, called “active flutter suppression.” Two distinct approaches emerged for the design of the control law for activeflutter suppression, the first based on optimal control, and the second approach [1], emerging from the concept of passivity, considers the energy flowing in and out of the “system.” There are several applications of this method to real aircraft, and [2] is archetypal of these examples. References [3,4] are typical examples in which the techniques based on the modeling methods were applied to the synthesis of optimal and near-optimal control laws for active flutter suppression. In this paper we propose a third approach towards controlling flutter. By careful consideration of the unsteady aerodynamic loading, those components that contribute to the delay in the growth of the loading in response to changes in the wingmotion are isolated. These delays or transport lags are then eliminated by an appropriate control law that ensures the constancy of circulatory component of the unsteady lift. With secondary compensation one could increase the flutter speed, which is the primary objective of active flutter suppression. Furthermore, the constancy of the circulatory component implies that the flow is less likely to separate and the circulation is more likely to remain steady. To evaluate the method we consider the archetypal problem of the typical section and implement such a control law. Themotivation for this work arose from the need to develop smart, flexibly actuated morphing control surfaces for future aircraft wings in low-speed flight. The method described in this paper can be routinely implemented with control surfaces. Morphing control surfaces can be deflected in a multitude of modes and the method itself is based on observations of bird flight.

Behaviour of masts subjected to action of wind load

Behaviour of masts subjected to action of wind load

Nonlinear buckling analysis of hyperbolic cooling tower shell with ring-stiffeners

This paper is concerned with a numerical solution of hyperbolic cooling tower shell, a class of full nonlinear problems in solid mechanics of considerable interest in engineering applications. In this analysis, the post-buckling analysis of cooling tower shell with discrete fixed support and under the action of wind loads and dead load is studied. The influences of ring-stiffener on instability load are also discussed. In addition, a new solution procedure for nonlinear problems which is the combination of load increment iteration with modified R-C are- length method is suggested. Finally, some conclusions having important significance for practice engineering are given.

Buckling of Orthotropic Cylinders Due to Wind Load

In many practical problems, e.g., storage bins, oil tanks, missile shells, launch vehicles, etc., cylindrical shells are subjected to unsymmetrical lateral external load. These shells are usually made of thin sheets of metal; therefore, in many instances these structures have failed due to buckling. In this paper, the stability of cylindrical shells under the action of wind load is investigated. Often these shells are constructed of corrugated steel sheets; therefore, the shells are analyzed by considering the material as orthotropic. This analysis can also be used for other orthotropic materials. The principle of minimum potential energy in conjunction with Ritz's approach is used. The buckling loads, as well as the buckling configurations, are obtained for short cylinders made of corrugated steel sheets subjected to wind pressure. The present study is made on cylindrical shells of various dimensions, which are simply supported at the base and are open or closed at the top. For practical use, buckling load curves for these shells are given for different length‐to‐radius and radius‐to‐thickness ratios.

Wind Action on Simple Yielding Structures

The behavior of simple elastic-plastic structures under the action of wind load is examined by analytical and numerical methods. Approximate analytical expressions are derived for the rate of development of permanent set in lightly damped systems subject to wind load. The analytical solutions, which are based essentially on the elastic behavior of the system, are compared with solutions obtained by numerical modeling of a yielding structure. The results obtained indicate that, for the idealized structures examined, there can be a substantial difference between the velocity of a storm which will just cause some permanent set and the velocity necessary to cause severe permanent damage.