环境因素对斜拉桥模态频率影响的周期特性

Periodic Characteristics of Environmental Effects on Modal Frequencies of a Cable stayed Bridge

摘要:

利用东海大桥主航道斜拉桥5年的结构健康监测以及收费站数据，从周期性的角度研究了温度、交通荷载对结构竖弯、侧弯基频以及高阶频率的影响规律，并在1年，1周，1天和0.5天模态频率变化的主要周期上通过逐步回归分析比较了温度、交通荷载对结构频率变化的影响程度.结果表明，温度、交通荷载和结构频率的变化存在明显的周期特征，且在不同的时间周期温度和交通荷载对频率变化的影响程度不同.基于长期实测数据的分析有助于加深对结构频率变化特性的理解，并把握其周期性变化规律，从而对结构状态进行更准确地评估.

关键词:桥梁工程; 周期特性; 模态频率; 环境因素; 数据解释

Abstract:

Based on a 5 year field measurement data from the structural health monitoring system and the toll gate of Donghai Bridge (DHB), this study focuses on the dependency of the structural frequencies, including the first vertical/lateral bending modes as well as the higher modes, on the temperature and traffic loading in the prospect of periodic characteristics. The environmental effects on the frequency variation are compared by the stepwise regression analysis on such dominating periods as 1 year, 1 week, 1 day and 0.5 day. Results of this study show that the variations of temperature, traffics and modal frequencies have some long period components, and the relative importance of temperature and traffics is different for each individual period. Based on the long term field measurement data, the analysis herein can advance the understanding on the periodic variation of structural frequencies, and may lead to more reliable assessment of structural conditions.

Key words:bridge engineering; periodic characteristics; modal frequency; environmental factors; data interpretation