Study On Diaphragm’s Effects On Dynamic Behavior Of Muliple-tablets Simply Supported Beam Bridge

Diaphragm, as the important component of multi-tablets simply supported beam bridge, has played a vital role in remaining and improving its integrity, stability and lateral stiffness. On the basis of studying structural characteristics and diaphragm of multi-tablets simply supported beam bridge, the author came up with simplified model and algorithm to analyze the bridge’s dynamic characteristics and dynamic response under the effect of vehicle-bridge coupling. Those results were then compared to those of dynamic structural analysis based on ANSYS so as to prove rationality and validity of the simplified model and algorithm. Three diaphragm parameters (stiffness, thickness, and location) were set to analyze corresponding changes of the bridge’s dynamic characteristics and responses so that the effect of diaphragm on the bridge’s dynamic characteristics was further studied, which contained certain reference value to bridge condition assessment and strengthening. The work in the thesis was as follows:1) The study on dynamic characteristics of multi-tablets simply supported beam bridge was as follows. On the basis of analyzing diaphragm’s effects upon the bridge, the author came up with a model which simplified diaphragm to spring-quality system and a simplified algorithm which calculated fundamental vibration frequency of the model. Those results were then compared to numerical results of ANSYS so as to prove the validity of simplified model and algorithm. Lastly, the effect of diaphragm parameters (stiffness, thickness and location) on bridge’s dynamic characteristics was studied.2) The basic theory about transverse load distribution factors of multi-tablets simply supported beam bridge was expounded, the corresponding calculation formula was deduced by modal parameter method and those factors were revised by using correlation analysis and correction factor. In this way, multi-tablets beam was simplified to single beam. The effect of diaphragm on bridge’s transverse load distribution factors was analyzed3) Study on dynamic response of multi-tablets simply supported beam bridge was as follows. Firstly, basic theory about vehicle-bridge coupling vibration was explained and displacement expression was deduced when one forth vehicle simplified model went across a single beam. Secondly, response formula of arbitrary single beam under the effect of vehicle load was deduced by applying revised factors to the vehicle-bridge coupling vibration formula. Lastly, the effect of diaphragm parameters (stiffness, thickness and location) on the bridge’s vehicle-bridge coupling vibration response was studied.