Damage detection methods based on natural frequencies, vibration modal shapes and other basic dynamic parameters are deficient, their accuracy and applicability should be improved.Here, damping ratio was proposed as an indicator for damage detection to explore the relationship between damping and structural damage.The relationships among damping, number and width of structural cracks and damage evolution were described theoretically.Through a simply supported T beam bridge test, the free vibration method was used to calculate the bridge system''s damping ratios.The system''s damping ratios under different damage levels were obtained.The results showed that the system''s damping ratios firstly increase and then decrease with increase in damage levels;the difference between damping ratios corresponding to positive displacement and negative one, respectively has the same evolution law;the location with a larger changing rate of damping ratio may have a more serious damage, so the changing rate of damping ratio can be used to realize locating basic damages;compared with natural frequencies and vibration modal shapes of bridges, damping ratios are more sensitive and vivid, so they can be taken as indicators of damage detection for RC bridges, and their changing inflection points can be taken as early warning thresholds of structural reinforcement and maintenance.%基于频率和振型等基本动力参数的损伤识别方法存在不足,准确性和适用性有待改进.提出将阻尼作为损伤识别的指标,探究阻尼与结构损伤之间的关系.论述阻尼与结构裂缝的数量和宽度及损伤演变的关系.通过对一跨简支T梁桥试验,采用自由振动法求阻尼比,获得了不同损伤等级损伤演变下的阻尼比.结果表明阻尼比随着损伤等级的增加呈现先增大后减小的变化过程,且正负位移对应的阻尼比的差值也具有先增大后减小的演化规律.阻尼比变化率大的位置,损伤程度大,可以利用阻尼比变化率实现基本损伤定位.与频率和振型相比,阻尼比更丰富敏感,可以作为钢筋混凝土桥梁的损伤识别指标,其拐点可以作为结构加固及维修的预警阈值.
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