基于神经网络技术的南京长江大桥桥墩船舶撞击力识别

主要研究基于神经网络技术的南京长江大桥桥墩船撞力识别。在建立了南京桥4#桥墩的空间有限元分析模型后,对4#桥墩进行了动力特性分析;基于MATLAB平台建立了“船撞力-响应”神经网络,由沃辛试验船撞力曲线计算得到了船对桥墩的撞击响应并作为神经网络训练的样本。仿真计算结果表明,由桥墩墩顶的响应可有效识别船舶撞击力的大小、方向和撞击位置,该神经网络可用于有、无噪声干扰的船撞力识别,并且具有良好的容错性和鲁棒性。     

动力时程分析在桥梁安全监测中的应用

根据南京长江大桥的结构特点，建立了考虑横向联结系的空间有限元分析模型，将南京桥安全监测系统测得的列车活载作为激振力，采用ANSYS有限元分析程序对大桥进行动力时程分析，得出了动力时程分析结果能反映大桥的实际工作状态，可有效指导桥梁的检测和维护的结论。     

Structural safety monitoring for Nanjing Yangtze River Bridge

In order to evaluate objectively and accurately the integrity, safety and operating conditions in real time for the Nanjing Yangtze River Bridge, a large structural safety monitoring system was described. The monitoring system is composed of three parts: sensor system, signal sampling and processing system, and safety monitoring and assessment system. Combining theoretical analysis with measured data analysis, main monitoring contents and layout of measuring points were determined. The vibration response monitoring was significantly investigated. The main contents of safety monitoring on vibration response monitoring are vibration of the main body of the Nanjing Yangtze river bridge, collision avoidance of the bridge piers, vibration of girders on high piers for the bridge approach and earthquake. As a field laboratory, the safety monitorying system also provides information to investigate the unknown and indeterminate problems on bridge structures and specific environment around bridges.     

基于信号能量分析的结构阻尼比识别方法

本文提出一种基于信号能量分析计算结构阻尼比的新方法。推导出自由振动响应信号能量与阻尼比关系的理论表达式后，求出阻尼比。与传统的对数衰减率法相比，此法精度、抗噪声干扰能力强、稳定性好。振动系统信号的能量之所以会衰减，是因为阻尼的存在。本文提出的这种识别阻尼比的方法物理概念清晰，易于理解。仿真计算和洞庭桥实测试验结果表明所提出的方法有效、可行。