Railway steel bridge belongs to large-scale weld structures suffered with cyclic dynamic stress generated by the train. In recent years, the section of bridge member becomes bigger, plate becomes thicker, connection f...Railway steel bridge belongs to large-scale weld structures suffered with cyclic dynamic stress generated by the train. In recent years, the section of bridge member becomes bigger, plate becomes thicker, connection form becomes more complicated and steel bridge is applied to wider districts even in the lower temperature environment. Thus, fatigue and fracture problems become more serious. On the basis of CTOD （crack tip open displacement） test data of 372 specimens tested in different temperatures, this paper discusses research work about fracture proof design that involves how to determine the criterion of CVN （Charpy V-notch） impact toughness by establishing the relationship between CTOD and CVN, how to prevent from brittle fracture by stress control in railway steel bridge design based on COD （crack open displacement） design curve through the test data and how to do the fatigue design for railway steel bridge at -50 ℃ of design temperature in an easy way. The method of fatigue design at -50 ℃ environment has been used for railway steel bridge structure of Qinghai-Tibet Railway in China.展开更多
A method of the fuzzy cross-correlation factor exponent in dynamics is researched and proposed to diagnose abnormality of cracks in the concrete dam. Moreover, the Logistic time series changing from period-doubling bi...A method of the fuzzy cross-correlation factor exponent in dynamics is researched and proposed to diagnose abnormality of cracks in the concrete dam. Moreover, the Logistic time series changing from period-doubling bifurcation to chaos is tested first using this method. Results indicate that it can distinguish inherent dynamics of time series and can detect mutations. Considering that cracks in the concrete dam constitute an open, dissipative and complex nonlinear dynamical system, a typical crack on the downstream face of a concrete gravity arch dam is analyzed with the proposed method. Two distinct mutations are discovered to indicate that the abnormality diagnosis of cracks in the concrete dam is achieved dynamically through this method. Furthermore, because it can be directly utilized in the measured crack opening displacement series to complete abnormality diagnosis, it has a good prospect for practical applications.展开更多
文摘Railway steel bridge belongs to large-scale weld structures suffered with cyclic dynamic stress generated by the train. In recent years, the section of bridge member becomes bigger, plate becomes thicker, connection form becomes more complicated and steel bridge is applied to wider districts even in the lower temperature environment. Thus, fatigue and fracture problems become more serious. On the basis of CTOD （crack tip open displacement） test data of 372 specimens tested in different temperatures, this paper discusses research work about fracture proof design that involves how to determine the criterion of CVN （Charpy V-notch） impact toughness by establishing the relationship between CTOD and CVN, how to prevent from brittle fracture by stress control in railway steel bridge design based on COD （crack open displacement） design curve through the test data and how to do the fatigue design for railway steel bridge at -50 ℃ of design temperature in an easy way. The method of fatigue design at -50 ℃ environment has been used for railway steel bridge structure of Qinghai-Tibet Railway in China.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51079046, 50909041, 50809025, 50879024)the National Science and Technology Support Plan (Grant Nos. 2008BAB29B03, 2008BAB29B06)+7 种基金the Special Fund of State Key Laboratory of China (Grant Nos. 2009586012, 2010585212)the Fundamental Research Funds for the Central Universities (Grant Nos. 2009B08514, 2010B20414, 2010B14114)China Hydropower Engineering Consulting Group Co. Science and Technology Support Project (Grant No. CHC-KJ-2007-02)Jiangsu Province "333 High-Level Personnel Training Project" (Grant No. 2017-B08037)the Natural Science Foundation of Hohai University (Grant No. 2008426811)Graduate Innovation Program of Universities in Jiangsu Province (Grant No. CX09B_163Z)the Science Foundation for The Excellent Youth Scholars of Ministry of Education of China (Grant No. 20070294023)Dominant Discipline Construction Program Funded Projects of Universities in Jiangsu Province
文摘A method of the fuzzy cross-correlation factor exponent in dynamics is researched and proposed to diagnose abnormality of cracks in the concrete dam. Moreover, the Logistic time series changing from period-doubling bifurcation to chaos is tested first using this method. Results indicate that it can distinguish inherent dynamics of time series and can detect mutations. Considering that cracks in the concrete dam constitute an open, dissipative and complex nonlinear dynamical system, a typical crack on the downstream face of a concrete gravity arch dam is analyzed with the proposed method. Two distinct mutations are discovered to indicate that the abnormality diagnosis of cracks in the concrete dam is achieved dynamically through this method. Furthermore, because it can be directly utilized in the measured crack opening displacement series to complete abnormality diagnosis, it has a good prospect for practical applications.
