受损简支梁固有频率变化规律研究

   1,尚晓兵2,郭景莉2 ,尚  1

1.西安公路研究院,陕西 西安  7100602.山西运城路桥有限责任公司,山西 运城  044000

  以钢筋混凝土梁为研究对象,基于Euler-Bernoulli梁理论和结构动力学理论,通过数值模拟分析,计算得到了不同损伤位置和损伤程度时简支梁单损伤情况下的固有频率,引入损伤因子、频率变化率、频率变化率震荡幅度、频率变化率中值、频率变化率比值等概念,研究了简支梁的固有频率以及频率变化率、频率变化率比值对梁振动响应的变化规律。结果表明,梁的损伤对频率和频率变化率的敏感性与梁的损伤程度和损伤位置相关,而频率变化率比值与梁的损伤位置有关,损伤程度对固有频率的影响大于损伤位置对固有频率的影响,而当损伤位置和损伤程度固定时,梁固有频率的变化率随模态阶数的增加并不是单调变化的。

关键词简支梁固有频率频率变化率频率变化率比值

中图分类号U441          文献标识码A

Research on Natural Frequency Characteristics of

Damaged Simply Supported Beam

JIAO Ming1SHANG Xiao-bing2GUO Jing-li2 SHANG Xin1

1. Xi'an Highway Research InstituteXi'an 710060china

2. Shanxi Yuncheng Road & Bridge Co.Ltd.YunchengShanxi 044000China

AbstractTaking damaged reinforced concrete beam as the research objectbased on Euler-Bernoulli beam and structure dynamics theory and by means of dynamic finite element analysisthe natural frequencies are obtained through calculations in various kinds of damage states. With the concept of damage factorfrequency change ratefrequency change rate oscillation amplitudefrequency change rate mid-value and the ratio of frequency change ratethe paper researches natural frequencyfrequency change rate and the ratio of frequency change rate characteristics of the simply supported beam. The results show that the sensitivities of the damaged beam about natural frequency and frequency change rate relate to damage degree and damage locationand that the sensitivities of the damaged beam about the ratio of frequency change rate relates to damage location onlyand that the effect of damage degree on the natural frequency is greater than that of damage locationand that the frequency change rate of the beam is not a monotonic variation with the increase of modes order.

Key words: simply supported beamnatural frequency frequency change ratethe ratio of frequency change rate