【作者】 贾红梅；

【导师】 阎贵平； 钟铁毅；

【作者基本信息】 北京交通大学 ， 防灾减灾及防护工程， 2008， 博士

【摘要】 客运专线以高速、安全、准时、方便、舒适的综合优势在世界得到了广泛发展,我国铁路也掀起了建设客运专线的新高潮。现行铁路抗震设计规范在桥梁抗震的设防标准、地震作用计算方法、抗震设计方法及抗震构造措施等方面,都比旧规范大大提高,但是该规范是针对普通铁路桥梁研究制定的,并不能直接适用于客运专线桥梁的抗震设计,这是由客运专线桥梁的质量大、刚度大、采用延性设计及高耐久性等设计特点所决定的。我国虽对客运专线设计进行了多年的前期研究,并已具有建成秦沈客运专线的成功经验,但对客运专线桥梁的抗震设防标准、性能目标、设计方法以及抗震性能等关键问题仍缺乏系统的理论和试验研究。因此,本文结合目前我国客运专线抗震设计中存在的不足,就客运专线低矮桥墩的墩顶反应系数、桥墩的弹塑性分析、桥墩实用简化延性抗震设计方法、桥墩抗震设防标准等问题进行了系统研究。主要研究工作如下:(1)介绍了本课题的选题背景和意义,从国内外高速铁路的发展状况、国内外高速铁路的结构形式,以及我国客运专线设计中存在的问题等方面,综合性地进行了论述,提出了客运专线桥梁抗震设计中存在的主要问题,并就某些亟需解决的问题进行课题研究。(2)对客运专线的桥梁来说,由于基础均为群桩基础,客运专线的桥梁基础不能按刚性地基来计算,必须考虑结构与地基的相互作用对结构地震反应的影响。对于剪跨比较小的低矮桥墩,建立了桩-土-结构的实体单元计算模型;对于中等高度桥墩,通过对实体单元计算模型与梁单元计算模型的计算比较,认为梁单元能满足计算精度,且能大大降低工作量,所以建立了桩-土-结构的二维梁单元计算简化模型。选用了地基弹簧模拟土对桩基的实际约束功能;模型中考虑了土的附加质量、阻尼系数、地基系数等影响因素。(3)提出适合客运专线桥梁的静力法抗震设计判定标准。本文以高度在4m以下剪跨比较小的圆端形低矮墩为研究对象,梁跨度为20m、24m、32m,选取Ⅰ、Ⅱ、Ⅲ、Ⅳ类场地各40条典型的地震波作为激励,考虑了不同的地基系数的影响,通过大量的弹塑性时程计算及数理统计分析,当频率在4.7～9.8Hz时,墩顶反应系数在1.0～1.2之间,变化不大,可以视为刚体考虑,直接按静力法进行计算。建立了客运专线刚性桥墩的计算简化模型,并通过算例证明了该方法的精确性。(4)以4～20m中等高度的圆端形桥墩为研究对象,对地基条件、地震波及跨度等影响桥梁弹塑性地震反应特性的主要因素进行了比较分析,给出了这些因素对桥梁反应特性、屈服和破坏情况的影响规律;当基础先于桥墩屈服时,在满足运营要求条件下,选择空心截面以降低桥墩的屈服强度。经过对空心桥墩大量的分析研究,当0.3≤D_i/D≤0.7时,能够使桥墩的屈服强度降低,保证塑性铰出现在桥墩底部,桩基不屈服,解决了墩身和基础设计的不协调问题;对于桥墩先于基础屈服的情况,提出了延性设计原则及构造措施。(5)针对桥墩先于基础屈服的情况,建立了这类桥墩的简化延性抗震计算模型,用简化计算方法来求出结构地震反应特征参数,并与时程分析方法计算结果进行比较,证明该模型在墩高15m以下时具有足够的工程抗震计算精度。(6)给出了客运专线桥梁抗震设计的地震设防水准、性能目标,以及适用于客运专线桥梁抗震设计的分析方法及设计流程。设计过程分为四个基本步骤:概念设计、常遇地震下强度设计、罕遇地震下的位移设计和抗震构造措施设计。通过一座桥梁的抗震设计实例,给出了本文方法的具体操作过程和可行性。更多还原

【Abstract】 Because of the synthesis advantages in high speed,safety,punctuality, convenience,comfortability,passenger railway has been widely developed all over the world,and a new peak to built passenger railway is being formed.Current executed Seismic Design Code for Railway in fortification criteria,earthquake action calculated method,earthquake design method and seismic constructional measures of bridge seismic has been updated on the basis of old code,but the new code is made for common railway bridge and can not be directly used in passenger railway bridge design, which is determined by the factors characterizing the design of passenger railway bridge of big mass,big rigidity,ductile design and high durability.Although passenger railway design had been researched for many years,as well as we had gained lots of successful experience,systemic theory and test research on the key problems of passenger railway seismic fortification criteria,performance aims,design method,analysis method and seismic performance is still deficient.As to the current shortages in the seismic design for passenger railway in china,some important problems are systematically studied in present paper,including response factor at top of low pier,elastic-plastic analysis of pier, simply ductile seismic design method of pier,pier seismic fortification criterion.The principal contents are as follows:(1)Fist of all,the background and significance of the present subject are introduced. Comprehensive discuss proceed from development of domestic and overseas high railway and structure types to current problem of passenger railway in china.Main questions in the seismic design of passenger railway are put forward,and problems to be solved urgently are researched.(2)The foundation of passenger railway can’t be regarded as rigidity foundation because of the pile group,so the interaction between structure and foundation for influences of earthquake reaction must be taken into account.An analytical solid model of pile-soil-pier is established for short bridge piers of ratio of shear span.A simplified analytical model of pile-soil-pier of beam unit is established for middle bridge because beam units can satisfy calculated accuracy and decrease work time by comparing solid unit model with beam unit model.Real restraint function is simulated by subgrade spring in model.Influent factors,such as soil additional mass,damp coefficient and base factor, are considered in models. (3)Judge criterion that is suitable for static seismic design of passenger railway is presented.The research subjects in this paper are low shear-span round-ended pier, which height is below four meters and spans are twenty meters,twenty-four meters,and thirty-two meters,respectively.The results by elastic-plastic time history analysis are counted and analyzed,which the influence of different base coefficient and every forty earthquake waves of four types of site as excitation have been taken into consideration. When frequency is from 4.7Hz to 9.8Hz,structural response factor at top of pier range from 1.0 to 1.2 and change very small,structure may be taken as rigidity and direct analyze as static method.A computed simplified model of rigidity pier of passenger railway is established,and the method is more accuracy by the example proof.(4)The research subjects in this paper are round-ended pier whose height is four meters to twenty meters.Main factors of base condition,earthquake wave and span for influencing elastic-plastic earthquake response characteristic are analyze,influence laws of bridge response characteristic,yield and damage from are obtained.As foundation yield prior to bridge pier,yield intensity of bridge pier is reduced by selected hollow section under meet operational requirements.When D_i/D is greater than equal 0.3 and less than equal 0.7,yield intensity of bridge pier is reduced,plastic hinge appear in pier bottom and pile group do not yield,which solved inconsistent design problem between piers and foundation.When bridge pier yield prior to foundation,the ductile design principle and construct measures are presented.(5)Simply ductile seismic model that solved the earthquake response parameters of the structure in simply way was established,and calculated results between in the simply way and in history time analysis way were compared.The model is enough calculated accuracy under 15 meters high in engineering seismic.(6)Seismic hazard level,performance objectives,seismic analysis,and design method of passenger railway bridges are given.Four main steps are:conceptual design, force/strength based design under occasional earthquake,displacement-based design under rare earthquake and detailing constructional measures design.A design example is given also.更多还原