【作者】 刘光万；

【导师】 黄培彦；

【作者基本信息】 华南理工大学 ， 固体力学， 2012， 博士

【摘要】 在桥梁结构使用性能检测及评价方面，我国仍主要依靠人工外观检测以及现场荷载实验等传统的方法。此类检测评定存在如下缺点：工作量大、费用高、获得结构的信息不全面，检查结果的准确程度往往依赖于检查人员的工程经验和主观判断，难以对结构的安全储备及退化程度作出系统的评定。而且，对于预应力混凝土（PC）梁桥，即使结构在受到偶然的超设计荷载作用下产生了裂缝等损伤，但由于其预应力的作用，在偶然超设计荷载作用并卸载后，裂缝会闭合，常规检测方法根本无法满足桥梁结构状态评估的要求。因此，发展快速、便捷、经济的，并能够应用于复杂结构的定性、定量的桥梁整体状况检测评定方法己经成为迫切的任务和要求。本文分析了频域法和时域法在结构损伤识别中的各自特点，指出综合利用该两种参数识别方法是实际结构损伤识别的主要发展方向。在此基础上，对一种基于动态响应灵敏度的探伤法进行较全面和深入的探讨，并通过对简支PC小箱梁以及三跨连续PC箱型刚构桥进行静载实验和动态测试，对该方法的可行性进行验证。主要研究内容和结论如下：1、对于桥梁结构的动态测试，提出了基于不完备信息的时域动态响应灵敏度的探伤法，通过对结构动态位移、速度和加速度的灵敏度矩阵运算得到单元刚度参数，并通过反复迭代以获取结构较准确的探伤结果。研究结果表明，当采用多个响应量度时，探伤可以得到更好的结果；当没有测量噪音时，比起量度位移，量度加速度可以得到更好的探伤结果；当辅助以优化调整技术时，本方法甚至可以在量度数据被噪音污染的情况下仍然得到令人满意的结果。2、以初始位移激励作用下的简支足尺单片PC箱梁为对象进行了系统的探伤研究，采用本文所示的损伤识别方法，通过比较实验梁未损伤状态和损伤状态的有限元模型中的单元刚度系数，并与现场实测裂缝进行比较，则可以有效地识别箱梁结构的损伤区域及其损伤程度。识别结果表明，此方法可以用于箱梁结构在不同工况下的损伤定位及损伤程度识别。如果利用传感器的不同布置方案而得到多次的实验数据，并对此进行多次迭代计算，则可以进一步提高识别结果的精度。3、在采用预应力碳纤维薄板（CFL）对受损的PC箱梁进行加固后，箱梁的承载能力、结构刚度都可以由本文的损伤识别方法进行推算，而且理论分析结果与实测数据吻合得较好。研究结果表明，加固后箱梁的承载能力和结构刚度都稍有提高，这表明采用预应力CFL对受损的PC小箱梁进行加固，可以恢复箱梁的承载能力及结构刚度。4、对损伤前、损伤后、CFL加固后PC箱梁结构第一阶与第二阶的模态分析结果表明，预应力箱梁在受压损伤后，结构振型及频率发生了明显变化，基本频率有所减小、振型幅值有所增加；但是，采用CFL加固受损箱梁后，与加固前的损伤状态相比，结构振型及频率均未发生明显变化。这是由于CFL的厚度很小，它对结构刚度的贡献很小之故。5、以移动行车荷载激励作用下的三跨连续PC箱型刚构桥为对象进行了系统的探伤研究，探讨了移动荷载状态下桥--车系统结构的动态响应，并进行多个行车状态下的振动参数测量。通过对实验数据的分析，验证了移动行车荷载激励作用下桥梁动态测试及利用本文方法进行结构损伤评估工作的可行性，并指出了存在的问题。更多还原

【Abstract】 The methods of visual inspection or field test are mainly used to conduct the bridgestructural condition assessment. There are some limitations of these methods due to timeconsuming labor work and high cost. These methods cannot get the complete information ofthe structure and the accuracy depends on the subjective experience. Therefore, thesystematic evaluation cannot fulfill the structural safety. The extreme large load may inducesome cracks in the reinforced prestressed concrete (PC) bridge which would be close withoutthe large load. In this case, the traditional evaluation methods cannot detect the crack andfulfill the meet of structural condition assessment. Therefore, the rapid convenient andeconomical structural condition assessment for the bridge system is very necessary.In this thesis, the structural condition assessment methods in frequency and timedomain are studied, which have their own characteristics. A sensitivity method in this thesisare investigated and discussed. The static and dynamic tests of simply support box-sectiongirder bridge and three-span continuous box-section girder are studied to verify theproposed method. The main content includes that:1. Dynamic experiments are conducted to investigate the sensitivity of dynamic timedomain response. The structural stiffness is obtained with the sensitivity of structuraldisplacement, velocity and acceleration. The calculation iteration is used in the process ofstructural stiffness identification. The results of investigation demonstrate that the damagedetection results are more accurate with more structural response. The damage detectionresults are more accurate with the measurements of structural acceleration thandisplacement without measurement noise. The optimization method will be applied toobtain acceptable result in the structural stiffness identification for the case withmeasurement noise.2. Experimental studies with a box-section girder bridge are conduct with the proposeddamage detection method in this thesis. With the comparison of the response ofacceleration excited by the free falling of a mass from the structure the damage location andseverity could be obtained. The investigation illustrates that the proposed method can beapplied for structural damage detection. The identification result can be improved from thedifferent set of installment of the sensors with more iterative step. 3. CFL was used for the damage PC girder maintenance. The bearing capacity andstructural stiffness can be calculated with the proposed method in this thesis. The theoreticanalysis and the experimental result coincide very well. It is illustrated that the maintenanceof the box-section could improve the bearing capacity and the stiffness of the structure isreinforced. It is demonstrated that the damaged prestressed reinforce concrete can beimproved with carbon fiber laminate (CFL).4. The condition of the structure before and after structural damage was investigatedwith the first and second mode. It is demonstrated that the frequencies of first two modesdecrease apparently and the first and second mode shape become larger after the damage.While the box-section girder is reinforced, the frequencies and modal shape were nearly thesame with the damage structure. This is because the thickness of CFL is small whichcontribute to the stiffness limitedly.5. With the excitation of moving vehicle load a three continuous PC concrete reinforcebox-girder bridge was investigated for damage detection. Moving vehicle and bridgeinteraction was studied with parallel vehicles excitation. The proposed damage detection andstructural condition assessment method was validated with the above evaluation methodand the excitation and dynamic test.更多还原