近断层地震动输入方向对刚构桥地震反应影响

发布时间：2018-03-26 11:24

本文选题：连续刚构桥　切入点：近断层地震动　出处：《大连海事大学》2017年硕士论文

【摘要】：我国西部断层和地震带广泛分布,地下构造活动较为活跃,地震危险性较高。地震断层绵延百公里甚至上千公里,西部交通建设中桥梁无法避免临近(或穿越)地震断层,近断层地震动下桥梁抗震问题突出。由于近断层地震动具有明显的向前方向性效应,一般在垂直断层方向会存在明显的大脉冲,结构地震破坏效应显著。连续刚构桥是西部山区采用较多的桥型,桥梁走向与断层走向并不总是平行或垂直,在目前桥梁抗震分析中对该问题考虑较少。由此,本文研究了连续刚构桥走向与断层走向之间夹角对桥梁地震反应的影响问题。主要工作进展如下:(1)介绍了近断层地震动及其特点,分别从桥梁易损性分析、减隔震设计和地震动输入方向效应等方面阐述了近断层地震动下桥梁反应的研究现状。(2)利用Midas Civil软件建立3座墩高分别126m、58m和22m的大跨度连续刚构桥计算模型,分析了各自结构的自振特性。(3)利用美国PEER交通抗震波中的近断层地震动及适当旋转为输入,对比了桥梁纵桥向与断层走向之间不同夹角时,近断层双向水平地震激励下连续刚构桥的地震响应。分析表明:桥梁纵桥向最大反应容易发生在夹角为60°至120°之间,而桥梁横桥向的最大反应容易发生在夹角为0°至30°或者150°至180°之间。就算例桥梁结果,认为上述结论受桥梁墩高的影响并且横桥向的影响要大于纵桥向。(4)研究了近断层竖向地震动对连续刚构桥地震反应的影响,与仅考虑双向水平地震输入对比表明:竖向地震动对桥墩纵向地震反应影响很小,增加不足10%;但竖向地震动会增加主梁的竖向弯矩反应,其放大系数可能达到2-3倍及以上,特别是边跨与主墩的交界处。
[Abstract]:In western China, faults and seismic belts are widely distributed, underground structures are active and seismic risk is high. The seismic faults extend for 100 kilometers or even thousands of kilometers. Bridges in traffic construction in western China cannot avoid approaching (or crossing) seismic faults. The seismic problem of bridges under near-fault earthquake is serious. Due to the obvious forward directional effect of near-fault seismic action, there are usually large pulses in the vertical fault direction. The continuous rigid frame bridge is a bridge type in the western mountainous area. The strike of the bridge is not always parallel or vertical to the strike of the fault, so the problem is seldom considered in the seismic analysis of the bridge at present. In this paper, the influence of the angle between strike and fault strike of continuous rigid frame bridge on the seismic response of the bridge is studied. The main work progress is as follows: 1) the near fault ground motion and its characteristics are introduced, and the vulnerability of the bridge is analyzed respectively. In this paper, the research status of bridge response under near-fault ground earthquake is described in the aspects of isolation design and directional effect of ground motion input. The calculation models of three long-span continuous rigid frame bridges with the height of 126mt 58m and 22m, respectively, are established by using Midas Civil software. The natural vibration characteristics of each structure are analyzed. (3) using the near fault ground earthquake and proper rotation in the seismic wave of PEER traffic in the United States as the input, the different angles between the longitudinal bridge and the fault strike are compared. The seismic response of a continuous rigid frame bridge subjected to horizontal seismic excitation in the near fault direction is analyzed. The results show that the maximum response of the bridge in the longitudinal direction occurs easily between 60 掳and 120 掳in the angle of the bridge. The maximum response of the transverse direction of the bridge is between 0 掳and 30 掳or 150 掳to 180 掳. It is considered that the above conclusions are influenced by the height of bridge piers and the influence of transverse bridge direction is greater than that of longitudinal bridge direction.) the influence of vertical ground motion near fault on seismic response of continuous rigid frame bridge is studied. The comparison with only considering the bidirectional horizontal seismic input shows that the vertical ground motion has little effect on the longitudinal seismic response of the pier and increases less than 100.But the vertical ground motion will increase the vertical moment response of the main beam, and its magnification factor may reach 2-3 times or more. In particular, the border between the side span and the main pier.
【学位授予单位】：大连海事大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U442.55;U448.23

【参考文献】