多跨曲线连续刚构桥地震反应分析

发布时间：2018-08-05 18:55

【摘要】：随着我国公路交通事业在西部地区的快速发展,山区高等级公路上修建了大量控制性工程——桥梁。曲线桥梁能够很好的克服山区地形限制,服从路线整体设计要求,从而推动了曲线刚构桥的迅速发展。自1971年美国圣费尔南多(San Fernando)地震后曲线梁桥的抗震研究起步至2008年汶川地震,曲线桥梁仍遭到不同程度的震害,表明国内外学者就曲线桥梁的地震反应分析与抗震性能的研究难度大,认识规律不足,亟待深入探讨。本文以某高速公路上一座多跨预应力混凝土曲线连续刚构桥为工程背景,采用Midas Civil软件建立了考虑桩-土相互作用的结构模型进行动力特性分析、反应谱分析和动力时程分析,具体研究内容与所得结论如下:(1)运用Midas Civil有限元软件建立了该连续刚构桥的两种模型——墩底固结模型与考虑桩-土效应的模型,对其进行模态分析并比较两种模型的自振频率及相应振型特点等动力特性,结果表明:考虑桩土相互作用后,一阶振型周期增大69.03%,而随着振型阶次的增加,高阶振型的周期与墩底固结模型对应的周期逐渐接近,十阶自振周期仅增大6.43%。说明在软土地基中,桩基础增大了结构的自振周期,但对高阶振型周期的影响不大。(2)对曲线刚构桥进行E1地震作用下的水平双向反应谱分析,得到结构最大的地震响应以确定最不利地震动水平输入方向,然后对墩底固结模型与考虑桩-土效应的模型进行反应谱分析与动力时程分析,得出:考虑桩-土效应后桥梁结构横桥向的地震响应比顺桥向大;对该曲线连续刚构桥进行抗震性能分析时,可以忽略竖向地震动的影响;地震作用下,动力时程法的计算结果不小于反应谱法计算结果的80%,符合最新颁布的《公路桥梁抗震设计细则》规定要求。(3)设计三种桥墩形式,即原桥矩形实心墩、双肢薄壁实心墩和内八角形空心墩进行时程分析,结果表明:采用双肢薄壁空心墩,顺桥向除1#墩内力增加外,其他桥墩均明显减少,而横桥向所有桥墩的内力变化不大,位移大幅增加;采用内八角形空心墩,其弯矩和剪力均小于矩形实心墩,只是墩顶位移略有增大而已;由墩顶、墩底的最大应力比较可知,双肢薄壁实心墩最大,矩形实心墩次之,内八角形空心墩最小。因此建议将原矩形实心墩改为内八角形空心墩,该桥的抗震性能更好。
[Abstract]:With the rapid development of highway traffic in the western region of China, a large number of control projects - bridges have been built on high grade highways in mountain areas. The curved bridges can overcome the terrain constraints of the mountain areas well, comply with the overall design requirements of the route, and thus promote the rapid development of the curved rigid frame bridge. Since 1971, San Fernando (San Fernan, USA) Do) after the earthquake, the seismic study of the curved beam bridge started to the Wenchuan earthquake in 2008, and the curve bridges were still subjected to different degrees of earthquake damage. It shows that the scholars at home and abroad are difficult to study the seismic response analysis and seismic performance of the curved bridges, and the law of understanding is insufficient. The curved continuous rigid frame bridge is the engineering background. The dynamic characteristic analysis, the response spectrum analysis and the dynamic time history analysis of the pile soil interaction are established by Midas Civil software. The specific research contents and the conclusions are as follows: (1) the two models of the continuous rigid frame bridge are established by using Midas Civil finite element soft parts. The modal analysis of the bottom consolidation model and the pile soil effect model is carried out and the dynamic characteristics of the two models are compared and the results show that the first order mode period increases by 69.03% after considering the interaction of pile and soil, and the period of the high order mode is corresponding to the consolidation model of the bottom of the pier with the increase of the order of vibration. The cycle gradually approaches, and the ten order self vibration period increases only 6.43%., which indicates that in the soft soil foundation, the pile foundation increases the self vibration period of the structure, but has little effect on the high order mode period. (2) the horizontal bi-directional response spectrum analysis of the curved rigid frame bridge is carried out under the E1 earthquake, and the maximum seismic response is obtained to determine the most unfavorable ground motion level. In the direction of input, the response spectrum analysis and dynamic time history analysis of the pier bottom consolidation model and the pile soil effect model are carried out. It is concluded that the seismic response of the bridge structure is larger than that of the clockwise bridge after the pile soil effect is considered, and the effect of the vertical ground motion can be ignored when the seismic performance of the continuous rigid frame bridge is analyzed; the seismic action can be ignored. The calculation results of the dynamic time history method are not less than 80% of the calculation results of the response spectrum method, which conforms to the newly promulgated regulations for the seismic design of highway bridges. (3) the design of three kinds of bridge piers, namely the original bridge rectangular solid piers, the two limb thin-walled solid piers and the inner octagonal hollow piers, is analyzed. The results show that the two limb thin-walled hollow piers are adopted. In addition to the increase of the internal force of the bridge to the 1# pier, the other piers are obviously reduced, while the internal forces of the transverse bridge to all the piers have little change, and the displacement is greatly increased. The bending moment and shear force of the inner octagonal hollow piers are smaller than the rectangular solid piers, but the displacement of the pier top is only slightly increased; the two limb thin wall solid piers are compared to the pier top and the bottom of the pier. It is suggested that the original rectangular solid pier should be replaced by the inner octagonal hollow pier, which has better seismic performance.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U442.55;U448.23

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