环境因素对混凝土简支梁模态参数的影响分析

Environment Effect Analysis on Modal Parameters of Reinforced Concrete Simply Supported Beam

准确的模态参数测试是基于动力特性进行桥梁损伤识别的基础,模态参数受到环境因素的影响产生变化,从而导致无法得到准确的损伤识别结果。因此,分析环境因素对模态参数的影响,明确主要环境影响变量,对桥梁损伤诊断的环境影响剔除具有重要意义。以季冻区中小跨径钢筋混凝土简支梁为例,对试验梁监测数据进行分析和关联度计算,研究环境因素与模态参数的季节性变化规律,定量对比环境因素对模态参数变化的影响程度,确定影响钢筋混凝土简支梁模态参数变化的主要环境变量,进一步明确空气温度与太阳辐射作用下内部温度变化对模态频率的影响规律。

Accurate modal parameter testing is the basis of damage identification based on dynamic characteristics.However,environment factors have been widely demonstrated to produce significantly change in modal parameters that exceed even the effects of structural damage,which will lead to the failure of damage identification techniques.Therefore,it is significant to analyze the environment effect on modal parameters and eliminate its effect on damage identification.In this paper,a reinforced concrete simply supported beam at northeast seasonal freezing area is selected as a subject for study.Based on the monitoring data from a testing beam,seasonal variation of environmental factors and modal parameters is expounded.The influence degree of environmental factors on modal parameters is evaluated quantitatively using grey relational degree method.And the main environmental factors affecting the modal parameters of reinforced concrete simply supported beam are determined.Considering the influence of air temperature and solar radiation intensity on the modal frequency,the influence rule of internal temperature on modal frequency is defined.