【作者】 李海；

【导师】 张哲；

【作者基本信息】 大连理工大学 ， 桥梁与隧道工程， 2003， 硕士

【摘要】 荷载试验是一种重要的检测手段，可以为决策者对桥梁的承载能力做出科学地评估，提供有利、直观的依据，可以为新的结构、新的设计理论和新的施工工艺的发展与应用积累实践资料。公和斜拉桥采用单塔单索面双层结构，利用下悬臂来设置非机动车道，充分利用了下层空间，这是一种大胆的尝试，这种新的设计思想需要在实践当中检验。本文以现代桥梁设计理论、有限元法、随机振动、振动测试与分析技术为理论基础，在总结有关桥梁的荷载试验方法的基础上，对公和斜拉桥的荷载试验方法进行了研究和设计，具体开展了以下几方面的工作： 通过对公和斜拉桥的理论分析，在保证荷载试验效果的前提下，确定试验的控制荷载和加载工况，将各种工况下结构控制截面的实际变形或者应力同理论计算值进行了比较，计算出结构的校验系数。根据计算得到的结构的校验系数，确定了该桥的实际承载能力，证明了这种双悬臂结构是可行的。 桥梁结构的振动问题影响因素复杂，仅靠理论分析还不能满足工程应用的要求。为了测定该桥在动荷载作用下的真实情况，分别进行了跑车试验、刹车试验和跳车试验。根据控制断面在上述工况下的时程曲线图，分析确定了该桥的实际的冲击系数，并同理论设计时根据规范所取的冲击系数进行了比较。根据实测结果为公路管理、养护部门提出了有利的建议。 利用ANSYS软件建立了公和斜拉桥的空间有限元模型，并进行了理论上的模态分析，得到了该桥理论上的自振频率与振型。通过对公和桥实桥的脉动测试，分析确定了公和斜拉桥实测的模态参数(包括振型、频率以及阻尼比)。实测结果与理论计算结果的对比表明：该桥具有良好的动力性能。根据公和桥的结构特点，分析了产生这些振型的原因。 桥梁结构的阻尼因素十分复杂，本文通过脉动测试利用半功率点法得到了实测的阻尼比。实测结果表明：前5阶频率所对应的阻尼比的平均值在2.4％～5.9％之间，具有一定的离散性，而且随着自振频率的增加，阻尼比有减少的趋势。更多还原

【Abstract】 Load test is an important testing method, which can provide advantageous and direct bases for administrators to evaluate carrying capacity of bridge. Especially for the new structure ,bridge design theory and working technics it can provide valid actual datum. Gonghe bridge is a double deck structure with single tower and single cable plane ,which regrads the nether cantalever as non-mobile roadway. This idea fully using the lower space is a new experiment and it need verifying in practice. Based on the method of modern bridge design, infinite element, random vibration ,vibration testing and analysis technology this paper studies and designs the load test plan of Gonghe Cable-stayed bridge by summarizing the load test plans of some concerned bridges.Through the theoretical analysis of Gonghe bridge, this paper makes sure the controlling load and loading case under the condition of ensuring the load test efficiency. According to the results of comparison between the actual value and the theoretical value of the controlling section this paper makes clear the actual carrying capacity of bridge and verifies that this double-cantalever structure is viable.The problem of bridge vibration is very complicated and the analysis in theory still can not meet the requirement of the engineering application. In order to test the actual condition when the bridge is forced by dynamical load, running test, braking test and jumping test are carried out respectively. According to the time-travel curve under the cases above-mentioned, the actual figure of impact coefficient comes out .At the same time this paper compares it with that in theory and brings forward beneficial advices for the road managing and maintaining department.Theoretical mode analysis is made by establishing the dimensional infinite element model of Gonghe bridge with ANSYS software, thus natural vibration frequency and mode shape of Gonghe bridge theoretically are concluded. With pulsation measurement method this paper tests the actual mode parameters (including mode shape, natural vibration frequency and damping ratio). The comparison between actual results and those in theory indicates that this bridge is qualified with satisfactory dynamical peculiarity. Furthermore this paper analyses the causes that these mode shape lie in according to the structure characteristic of Gonghe bridge.The damping factor of bridge structure is very complicated. By pulsation measurement with half power point method this paper gets the actual figures of damping ratio of 5 steps, which are between 2.4% ~5.9%. These figures are scattered and they have the descending tendency with the increment of natural vibration frequency.更多还原