近场竖向地震作用下桥梁多次碰撞响应和特性研究

发布时间：2018-06-29 07:03

本文选题：近场竖向地震 + V/H谱　；参考：《南京理工大学》2014年博士论文

【摘要】：随着地震监测网的加密和监测手段的更新,越来越多的近场地震的监测数据表明,竖向地震加速度幅值往往超出了预期值。近年来坂神、集-集和汶川等近场地震造成的严重桥梁震害不能全部用传统的水平地震震因解释,如环形裂缝,支座断裂和桥墩局部破坏等,而用竖向地震震因解释被认为更合理。高幅值的竖向地震动被认为可以抛起主梁,分离桥梁与支座,导致桥梁再次落下时与支座产生重碰撞(pounding)。由此产生的桥梁动力学响应涉及变接触约束拓扑构形、桥梁结构内部的碰撞波动效应、局部结构破坏和非线性动力效应等复杂力学问题,理论和数值研究困难大。由于直接到现场实地观察几无可能,目前有关竖向地震引发桥梁震害的解释,仅是根据震后桥梁损坏状态所作的字面上的判断和猜测,没有理论依据和数值计算依据,存在相当的争议,并且也有一些其它不同的解释。缺乏必要的可靠理论方法的分析结果,甚至尚缺乏桥梁竖向地震响应的基础性研究。与桥梁的水平地震响应相比,竖向地震响应的研究缺乏,缺乏对桥梁竖向地震的基本认识,甚至缺乏基本的理论研究方法。本文运用瞬态波特征函数展开法,建立了带橡胶支座桥梁在近场竖向地震作用下碰撞响应分析的理论方法,研究了桥梁竖向碰撞响应的若干基本特征。本文的主要研究工作包括：(1)针对近场竖向地震动引起的桥梁多次碰撞响应问题,建立了“梁-弹簧-杆”连续体模型,采用瞬态波特征函数展开法,考虑主梁与支座碰撞接触与分离状态的切换,以及碰撞波在桥梁内的传播效应,建立了既可以分析桥梁碰撞瞬态响应,又可以完成全地震周期内桥梁地震响应分析的理论研究方法。(2)针对人工简谐竖向地震动作用,研究了带橡胶支座双跨连续梁桥的地震响应。运用瞬态波特征函数展开法,推导了桥梁多次碰撞响应的理论解。数值研究了理论解对计算时间步长和波模态截断数的收敛性,计算了地震波和碰撞激发瞬态波在桥梁结构内的传播,观察了多次碰撞现象,研究了竖向地震激励周期和幅值的影响,探讨了碰撞响应与竖向地震激励的关系,以及碰撞响应对桥梁结构安全的影响。发现的桥梁若干异常损坏形式与桥梁竖向地震下的碰撞响应存在密切的联系。(3)针对人工简谐竖向地震动作用,通过改变地震激励周期、桥梁结构固有周期和地震激励幅值,大量计算了竖向碰撞次数和最大碰撞力,详细研究了竖向地震激励周期、竖向地震激励幅值和桥梁结构固有周期对竖向碰撞的影响。研究发现随着竖向地震激励周期的变化,桥梁间断出现了3个竖向碰撞区,3个竖向碰撞区分别处在桥梁的前3阶竖向固有振动周期附近,碰撞区的出现与竖向地震激励幅值有关。另外,近场竖向地震激励,容易引发处在桥梁的第2阶和第3阶竖向固有振动周期附近的竖向碰撞,与远场地震响应明显不同。(4)对比分析了“梁-弹簧-杆”连续体模型和“梁-杆”连续体模型,研究表明“梁-弹簧-杆”连续体模型更为合理。系统研究了桥梁结构和材料参数桥梁竖向地震下的碰撞特性和响应的影响,研究表明桥梁支座刚度、主梁跨度和抗弯刚度的影响明显,桥墩高度和桥墩弹性模量的影响不大,但是,在高墩桥下出现了第4个碰撞区。因此,合理设计的桥梁结构有可能降低竖向地震下桥梁碰撞的烈度和出现频次,提高桥梁抵抗竖向地震的能力。(5)对实际近场竖向地震动记录的离散数据进行快速傅里叶变换(FFT)分析,将其展开成各频率成份简谐波的叠加,考虑桥梁支座的作用,采用瞬态波特征函数法,推导了实际近场竖向地震动作用下带支座桥梁结构多次碰撞响应的理论解。并且,建立桥梁结构三维弹性有限元模型,用于对比理论解和有限元方法计算的结果,验证理论方法的可靠性和精度。通过数值算例,计算了实际近场竖向地震动作用下带支座桥梁结构碰撞响应,研究了实际近场竖向地震动作用下多次竖向碰撞特性。研究表明本文建立的理论方法可以用来指导有限元模型的建立,判断有限元数值结果的正确性。在实际近场竖向地震作用下,桥梁结构可能发生竖向碰撞现象和多次竖向碰撞现象。竖向碰撞现象出现近场竖向地震的主要激励周期与桥梁整体结构的前2阶固有振动周期逼近时,并且在桥梁第2阶固有振动周期附近的碰撞,其作用效果接近甚至超过在桥梁第1阶固有振动周期附近的碰撞。在强近场竖向地震动激励作用下,在桥梁弯矩会出现反转,桥墩会出现高幅值波动的轴向压应力,甚至出现轴向拉应力,这些现象与观察到的桥梁结构的异常破坏现象相吻合。在实际近场竖向地震动激励作用下的计算分析结果,验证了通过单个主简谐竖向地震波作用下得到的竖向碰撞特性。
[Abstract]:With the encryption of seismic monitoring network and the updating of monitoring methods, more and more monitoring data of near field earthquakes show that the amplitude of vertical seismic acceleration is often beyond the expected value. In recent years, the serious bridge damage caused by the near field earthquake of Sakamoto, set set and Wenchuan can not be explained entirely by the horizontal seismic seismic cause, such as ring cracks and branches. It is considered more reasonable to explain the partial fracture of the seat and the pier of the pier, and it is considered more reasonable to use the vertical seismic seismic explanation. The vertical ground motion of the high amplitude is considered to be able to throw up the main beam and separate the bridge and support, causing the bridge to have a heavy collision with the support (pounding) when the bridge falls down again. The collision wave effect, the local structural failure and the nonlinear dynamic effect in the structure are difficult. The theoretical and numerical research is difficult. The explanation of the bridge earthquake damage caused by the vertical earthquake is only the literal judgment and guessing based on the damage state of the bridge after the earthquake. There is no theoretical basis and numerical basis, there are considerable disputes, and there are some other different interpretations. Lack of the necessary analytical results of reliable theoretical methods, and even the lack of basic research on bridge vertical seismic response. Compared with the horizontal seismic response of the bridge, the study of vertical seismic response is lack and the bridge erection is lacking. The basic understanding of the earthquake and even the lack of basic theoretical research methods. This paper uses the transient wave characteristic function expansion method to establish the theoretical method of the impact response analysis of the bridge with rubber bearing under the near field vertical earthquake, and studies some basic characteristics of the bridge vertical impact response. The main research work of this paper includes: (1) needle The "beam spring rod" continuum model is established for the multiple impact response of the bridge caused by the near field vertical ground motion. The transient wave characteristic function expansion method is adopted to consider the switch between the collision contact and separation state of the main beam and the bearing and the propagation effect of the collision wave in the bridge. The theoretical research method of seismic response analysis of bridge in the whole earthquake cycle can be completed. (2) in view of the artificial simple harmonic vertical ground motion, the seismic response of the double span continuous beam bridge with rubber bearing is studied. The theoretical solution of the multiple impact response of the bridge is derived by using the transient wave characteristic function expansion method. The numerical study on the calculation time of the theoretical solution is studied. The convergence of step length and wave mode truncation number, the propagation of seismic wave and collision excited transient wave in bridge structure is calculated, multiple collisions are observed, the influence of the period and amplitude of the vertical earthquake excitation is studied. The relationship between the impact response and the vertical earthquake excitation is discussed, and the impact of the collision response on the safety of the bridge structure is found. There is a close relationship between the abnormal damage forms of the bridge and the impact response of the bridge under the vertical earthquake. (3) in view of the vertical earthquake action of the artificial simple harmonic, the number of vertical collisions and the maximum impact force are calculated by changing the earthquake excitation period, the inherent period of the bridge structure and the amplitude of the earthquake excitation, and the vertical seismic excitation is studied in detail. The effect of periodic, vertical earthquake excitation amplitude and the inherent cycle of the bridge structure on the vertical collision is found. It is found that with the change of the vertical earthquake excitation period, 3 vertical collision zones are discontinuous, and the 3 vertical collision regions are located near the first 3 vertical natural vibration cycles of the bridge, and the occurrence of the collision area and the amplitude of the vertical earthquake excitation are found. In addition, the vertical seismic excitation in the near field is easy to cause the vertical collision near the second and third order vertical natural vibration cycles of the bridge, which is obviously different from the far field seismic response. (4) the "beam spring rod" continuum model and the "beam rod" continuum model are compared and analyzed, and the study shows that the "beam spring rod" continuum model is more important. The impact of bridge structure and material parameter bridge on the impact characteristics and response of bridge under vertical earthquake is studied systematically. The study shows that the influence of bridge support stiffness, girder span and flexural rigidity is obvious, the influence of pier height and pier modulus of elasticity is not significant, but fourth collision zones appear under the high pier bridge. Therefore, reasonable design The bridge structure may reduce the intensity and frequency of the bridge collision in the vertical earthquake, and improve the ability of the bridge to resist the vertical earthquake. (5) the fast Fourier transform (FFT) analysis of the discrete data of the actual near field vertical ground motion records is carried out to form the superposition of the harmonic waves of each frequency, and the effect of the bridge support is taken into consideration. The transient wave characteristic function method is used to derive the theoretical solution of multiple impact responses of the bridge structure with a supporting bridge under the action of the actual near field vertical ground motion. And a three-dimensional elastic finite element model of the bridge structure is established to verify the reliability and accuracy of the theoretical square method by comparing the results of the theoretical solution and the finite element method. Under the actual near field vertical ground motion, the impact response of the bearing bridge structure is studied. The multiple vertical impact characteristics of the actual near field vertical ground motion are studied. The study shows that the theoretical method established in this paper can be used to guide the establishment of the finite element model and judge the correctness of the finite element numerical results. Under the actual near field vertical earthquake, The vertical impact and multiple vertical collisions may occur in the bridge structure. The main excitation period of the vertical impact of the vertical impact and the first 2 natural vibration cycles of the bridge overall structure are approaching, and the impact near the second order inherent vibration period of the bridge is close to even more than the first order of the bridge. There will be a reversal in the bending moment of the bridge under the excitation of the strong near field vertical ground motion. The axial compressive stress of the bridge pier will appear with high amplitude fluctuation, and even the axial tensile stress appears. These phenomena coincide with the abnormal failure phenomenon of the observed bridge structure. The excitation effect of the vertical ground motion in the actual near field. The results of calculation and analysis verify the vertical collision characteristics under the action of a single principal harmonic vertical seismic wave.
【学位授予单位】：南京理工大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：U442.55

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