Natural Vibration Characteristic Analysis And Practical Calculator Research Of Fundamental Frequency Of The Continuous System Bridge With High-pier And Long-span

With the implementation of reform and opening up policy, China’s bridge constructionhas been rapidly developed. Various types of bridges has been built all over the country,including the world’s leading long-span bridges. As the development of China’s westerndistricts has been paid more attention, continuous system bridge with high-pier and long-spanwith its unique advantages and features, attracted more and more designers and builders.Bridge with high-pier and long-span’s pier is high and soft, which made it vulnerable tovehicle loads, wind loads, earthquake loads and other effects. Therefore, the dynamiccharacteristics of the bridge become the general concern of the bridge builders.Comparing with the old specification, existing " General code for design of highwaybridges and culverts "(JTG D60-2004) and "Code for design of highway reinforced concreteand prestressed concrete bridge and culverts "(JTG D62-2004) made great improvements indynamic characteristics of the bridge, especially in the field of putting forward fundamentalfrequency estimating formula for variety types of bridge, which made designer estimate thefundamental frequency and determine the impact factor quickly. However, JTG D60onlygives the estimation of continuous bridge formula, no mention of continuous rigid framebridge and rigid-continuous girder bridge fundamental frequency estimation formula.In order to made the calculation of fundamental frequency for the continuous rigidbridge and combined continuous-rigid frame bridge more convenient, fast and accurate, thispaper started from the point of structural design parameter of the continuous system bridgewith high-pier and long-span, and researched the effects of different structural designparameters on the continuous system bridge with high-pier and long-span’s natural vibrationcharacteristies (fundamental frequency). This paper found out the design parameters(sensitivity parameter) which impacts the frequency of continuous rigid bridge most: mainspan length, spans, side and mid-span ratio, single or double thin-walled pier, pier height,joining beam setting and so on. The design parameters (sensitivity parameter) which impactsthe frequency of combined continuous-rigid frame bridge is main span length, spans, side andmid-span ratio, depth-span ratio, pier height and so on. According to the sensitivityparameter, this paper established a number of finite element model to calculate thefundamental frequency, and using the principle of multiple linear regression, fitted outempirical formula to calculate the fundamental frequency of the continuous rigid bridge andcombined continuous-rigid frame bridge. Validated with examples, the result shows thefundamental frequency calculated from empirical formula agrees well with the fundamental frequency calculated from finite element model, which indicates that this research method isfeasible and effective.