【作者】 钱景峰；

【导师】 张亚辉；

【作者基本信息】 大连理工大学 ， 动力学与控制， 2010， 硕士

【摘要】 随着我国经济建设的迅猛发展,很多海洋工程结构不断涌现。例如,近期已建成东海大桥、杭州湾大桥、青岛海湾大桥等多座跨海大桥。另外,琼州海峡大桥、渤海海峡大桥和台湾海峡大桥也正在酝酿规划之中。这些跨海峡桥梁不但跨径大,而且桥位处水深,浪高,气候、水文、地质、地震等海洋环境因素异常复杂。台风以及台风掀起的巨浪破坏力极大,而且两者之间在强度、方向以及频谱等方面具有复杂的相关关系,对跨海峡桥梁的作用具有强烈的动态特性、随机性和耦合性。在许多情况下,通常将瞬态的强风和波浪激励看作等效静力作用。但对于跨海峡桥梁,台风以及台风掀起的巨浪动态特性显著且具有强烈的耦合效应。因此,考虑台风以及台风掀起巨浪这种破坏性环境荷载的实际动力特征、随机性和耦合性,发展风和波浪作用下结构的随机响应分析方法,对跨海峡桥梁的设计和建造来说有着重要的意义。本文以上述海洋工程结构为背景,研究了结构在随机风浪作用下动力响应的理论与数值计算方法。主要研究内容包括：1)基于设计波法,利用ANSYS软件中的PIPE59单元模拟桥墩桥塔结构,用Airy波理论和Stokes五阶波理论分别计算了规则波下的响应时间历程。2)根据圆柱波浪力谱的计算方法,利用FORTRAN语言编写了计算波浪力谱的程序,并与ANSYS的随机振动响应分析方法结合来计算结构的动力响应。通过与文献中的算例的比较,验证了该方法的可靠性。利用该方法计算了桥墩桥塔结构在两种波浪力谱JONSWAP谱与P-M谱的作用下响应的功率谱,并且积分得到响应的方差。基于虚拟激励法,以大连理工大学自主开发的结构分析软件DDJ-W为基础,开发随机波浪响应分析功能,计算了相同波浪荷载条件下桥墩桥塔随机响应,并与ANSYS程序的计算结果进行比较。3)按照随机振动虚拟激励法的基本思想,通过构造虚拟激励,发展了风和波浪作用下结构的随机响应分析方法。应用Morison方程计算构件的波浪力,构件波浪力采用投影面积法转化为节点荷载,按Borgman假定处理非线性动水阻尼,然后进行迭代修正,并精确地处理非正交阻尼阵。该方法可以考虑风沿任意作用方向作用以及波浪沿任意方向的传播。以大连理工大学结构分析软件DDJ-W为基础,开发了结构在随机风浪作用下动力响应分析程序系统。最后以桥墩和桥塔结构为算例,对该方法进行了初步验证。更多还原

【Abstract】 With the rapid development of China’s economy, more and more ocean engineering structures are built. For example, many cross-sea bridges such as the East Sea Bridge, the Hangzhou Bay Bridge and the Qingdao Bay Bridge have been built recently. In addition, the Qiongzhou Strait Bridge, the Bohai Strait Bridge and the Taiwan Strait Bridge are also in planning. The over-strait bridge not only has a long span, but also locates in deep water. Its environment factors such as wave, climatic, hydrology, geology and earthquake are exceedingly complicated. The wind and wave have great power. Moreover, they have complicated relationship in intensity, direction, frequency spectrum and so on. The action on the over-strait bridge has intensive dynamic characteristic, randomness and coupling. Under many circumstances, the transient strong wind and wave excitation are regarded as equivalent static loads. But for the over-strait bridge, wind and wave have distinctive dynamic characteristic and coupling effect. It’s significant to considering the actual dynamic characteristic of wind and wave for the design and construction of the over-strait bridge. Therefore, it is important to develop an appropriate method for the random response of structures under wind and wave loads.A numerical method for the dynamic response analysis of the structures mentioned above subjected to wind and wave loads is developed in this article, and it includes:First, based on the designing wave method, the dynamic response analysis of a pier and a bridge tower is fulfilled by using ANSYS. The pier and tower are modeled by the PIPE59 element. Two different wave theories, i.e., the Airy wave theory and the fifth Stokes wave theory are used for comparison.Second, a Fortran Program is developed for obtaining the wave load spectrum of a cylinder from the wave spectrum. The wave load spectrum is then used in ANSYS for random vibration analysis of structures. This method is verified through a simple example. Moreover, it is used to obtain the response spectrum and mean square deviation of a pier and a bridge tower under JONSWAP wave spectrum and P-M wave spectrum. A random vibration method is developed for the response of structures under wave loads based on pseudo-excitation method. The corresponding program is developed in the structural analysis program DDJ-W of Dalian University of Technology. The random responses of a pier and a tower are implemented and compared with those obtained by ANSYS. Third, a random vibration method for analyzing the random responses of structures under wind and wave loads is developed. The wind and wave are taken as random loads while their spectra are regarded as basic inputs. This method is based on the pseudo-excitation method. The wave loads which are computed by Morison equation is translated to node loads by the projection area method. The nonlinear dynamic water damping is handled iteratively based on Borgman assumption. The non-orthogonal damping matrix can be dealt with precisely. This method can consider wind and wave which spread along arbitrary directions. Based on the structural analysis software DDJ-W of Dalian University of Technology, a program is developed to analyze dynamic responses of structures under random wind and wave loads. Finally, a pier and a bridge tower are analyzed to make a preliminary verification of the proposed method.更多还原