近断层竖向地震动的特征及对连续梁桥的影响研究

发布时间：2019-04-12 12:06

【摘要】：近断层地震竖向与水平向加速度峰值比通常是取为1/2-2/3。而近年来的研究发现,这一比值和震级、震中距、周期等因素的关系非常密切,竖向与水平向加速度谱比值的曲线在短周期段的峰值随断层距的减小而增大,很多近断层地震动记录的竖向与水平向加速度峰值比超过2/3。部分竖向峰值加速度竟然超过了水平向峰值加速度,因此这一比值取值明显偏小。在铁路桥梁的抗震设计中,小于9度地震竖向地震动的影响一般是不考虑的,但随着对强震中结构破坏现象的调查和研究,以及越来越多的地震记录显示,特别是近断层区域及震中区域,竖向地震动的作用相当显著,造成了许多结构的破坏。因此,研究竖向地震动的规律特点及对连续梁桥的影响显得尤为重要。论文以四座跨径不同的铁路连续梁桥为研究对象,建立四组有限元模型,研究竖向地震动对桥梁结构的影响,研究内容主要包括以下内容：(1).通过对大量地震动数据的处理,具体阐述了近断层竖向地震动加速度峰值比和PGV/PG4与震级、断层距、断层类型和剪切波速的关系。(2).通过有限元软件MIDAS建立四组连续梁模型,输入不同峰值的竖向加速度,研究竖向地震动作用下连续梁桥上部结构的反应；通过输入同等峰值的竖向加速度,研究竖向地震动对不同跨径连续梁桥的影响及规律。(3).研究了竖向地震动对不同高度桥墩的影响及规律特点,分析了不同高度桥墩在竖向地震动作用下可能发生的破坏形式。
[Abstract]:The peak ratio of vertical to horizontal acceleration of near fault earthquakes is usually taken as 1 ~ 2 ~ 2 ~ 2 ~ 3. In recent years, it has been found that this ratio is closely related to magnitude, epicenter distance, period and other factors, and the peak value of the ratio of vertical to horizontal acceleration spectrum increases with the decrease of fault distance in the short period. The ratio of vertical to horizontal peak acceleration of many near-fault ground motion records is more than 2. 3. Part of the vertical peak acceleration actually exceeds the horizontal peak acceleration, so the value of this ratio is obviously smaller than that of the horizontal peak acceleration. In the seismic design of railway bridges, the influence of vertical ground motion of earthquake less than 9 degrees is generally not considered. However, with the investigation and research of structural failure phenomenon in strong earthquakes, and more seismic records show that, Especially in the near fault area and epicenter area, the vertical ground motion is very significant, which results in the destruction of many structures. Therefore, it is very important to study the characteristics of vertical ground motion and its influence on continuous beam bridges. In this paper, four groups of finite element models are established to study the influence of vertical seismic ground motion on the structure of four continuous railway girder bridges with different spans. The main contents of the study are as follows: (1) the main contents of this paper are as follows: (1) the main contents of this paper are as follows: (1). By processing a large number of ground motion data, the relationship between the peak acceleration ratio of vertical ground motion near fault and PGV/PG4 and magnitude, fault distance, fault type and shear wave velocity is described in detail. (2) the relationship between the acceleration peak ratio and earthquake magnitude, fault distance, fault type and shear wave velocity is discussed in detail. Four groups of continuous beam models were established by finite element software MIDAS, and the vertical acceleration with different peak values was inputted to study the response of the superstructure of continuous beam bridge under vertical ground motion. The influence of vertical seismic ground motion on continuous beam bridges with different spans is studied by inputting the vertical acceleration of the same peak value. (3). In this paper, the influence of vertical seismic ground motion on different height piers and its regularity are studied, and the possible failure forms of bridge piers with different heights under vertical ground motion are analyzed.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U448.215;U442.55

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