The effect of initial condition and road surface roughness on the dynamic response of bridge deck

Pao Yue-kong Library Electronic Theses Database

The effect of initial condition and road surface roughness on the dynamic response of bridge deck

 

Author: Lai, Wai-pang
Title: The effect of initial condition and road surface roughness on the dynamic response of bridge deck
Degree: M.Sc.
Year: 1998
Subject: Bridges -- Floors
Bridges -- Live loads
Roads -- Riding qualities
Surface roughness
Structural dynamics
Hong Kong Polytechnic University -- Dissertations
Department: Multi-disciplinary Studies
Dept. of Civil and Structural Engineering
Pages: v, 81, [73] leaves : ill. ; 31 cm
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b1460496
URI: http://theses.lib.polyu.edu.hk/handle/200/328
Abstract: A revised program, named as "SIMMAIN" in Quick Basic computer language was rewritten with Matlab computer language, renamed as "MAIN". Due to the relaxation of 640 kbytes internal memory limitation, dynamic responses of a bridge-vehicle system are simulated with smaller time intervals and the vehicle speed can be as low as possible. Therefore, more practical bridge-vehicle interactions are developed. However, the processing time is increased relatively; a powerful computer system is recommended to run the program. The success of the program is confirmed by verifying it with the existing program and good agreement was obtained with experimental results. Further parametric studies identified that the dynamic amplification factor is higher for bridge A. In general, the dimensionless parameters frequency ratio FR and axle spacing parameter ASP are more sensitive than that of mass ratio MR. The middle of the frequency ratio range often occurs a turning point. It gives designers an impression that the natural frequency of a bridge should be designed so that low dynamic amplification factor is maintained for the majority of vehicles. Road surface roughness simulation modules are added in this study. ISO road classes and power spectral density functions are utilized to calculate road surface roughness along the length of a bridge, which in turn incorporated into the program to simulate bridge dynamic responses. Simulation results concluded that dynamic amplification factors are increasing through road classes A to H (good to poor) and simulated results from Inverse Fourier Transform (IFFT) simulation method are higher than those simulated from Monte Carlo method. Also, comparison between Monte Carlo and IFFT methods showed that IFFT simulation method overestimated bridge responses with the presence of road surface roughness.

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