الفهرس | Only 14 pages are availabe for public view |
Abstract The main target of this thesis is to investigate the natural characteristics of wind, methodologies of artificial wind histories algorithms, and dynamic response of wind on the cable stayed bridges. The numerical methods are widely adopted tools for simulating wind histories. The most accurate technique is the wind tunnel test, but it is not the most economical option. Therefore, a lot of researches are concerned with developing those methods to be more accurate, applicable, and to save executed time of analysis. In this research, a comparison was conducted between two algorithms for simulation of stochastic Gaussian processes. These algorithms are autoregressive method (AR) and spectral representation method (SR). For the application of the simulation methods, a MATLAB program was written for the two algorithms. The application of both methods was carried out on a cable stayed bridge with a main span of 670 m to study a set of points along the deck. A comparison between the obtained results for each simulation was conducted. Moreover, the statistical properties were computed to compare and assess the results of both methods accurately. Afterwards, the more accurate method to generate artificial wind on the stonecutters bridge was selected to evaluate the dynamic response. The dynamic response of the bridge was extracted due to the buffeting force and self-excited force. The time domain analysis was performed by a FORTRAN program based on the minimization of total potential energy of the structure using the method of conjugate gradient. This program allowed considering the structural non-linearities as well as calculating the self-excited forces as a function of the structure`s response. The results revealed that, the response of the bridge in existence of dynamic wind load (buffeting force and self-excited force) are much greater than those in existence of static wind. The structural response of the cable stayed bridges has shown to be very sensitive to wind speed. Given that the response could increase tremendously with the increase of wind speed. |