变宽连续钢箱梁桥计算模型比较分析

厦门第二东通道互通主线桥为4×90m大悬臂变宽度宽幅连续钢箱梁桥.主梁采用单箱多室斜腹板箱形截面,箱室从单箱七室变至单箱五室.变宽度钢箱梁桥作为异型桥的空间结构体系,结构复杂且受力状态上具有明显的空间效应.通过对比梁格法和板壳模型的计算结果,探究基于梁格法计算分析变宽度钢箱梁桥受力状态和结构变形的可靠性和合理性.结果表...     

氯盐锈蚀钢筋的屈服强度退化分析及其概率模型

对混凝土内氯盐锈蚀HRB335级钢筋的坑蚀现象及其对钢筋力学性能的影响进行了研究;分析了现有拉伸试验中屈服强度判断方法的局限性,提出了锈蚀HRB335级钢筋名义屈服强度的判断方法(YPPCR法);将YPPCR法与数值分析相结合,建立了坑蚀钢筋数值拉伸试验方法;探讨了蚀坑三维尺寸对钢筋名义屈服强度退化的影响规律,建立了与蚀坑三维尺寸相关的单坑钢筋屈服强度退化的计算模型;最后对不同锈蚀率下由单个蚀坑引起的钢筋屈服强度的退化进行计算和概率分析,建立了与锈蚀率相关的钢筋屈服强度退化概率模型.     

预应力混凝土弯桥的极限承载力及其分析

针对传统的平面线弹性理论无法客观分析预应力混凝土桥梁中预应力效应和极限承载力的问题,采用三维实体退化单元模拟混凝土,用荷载等效移置模拟预应力,同时引入材料非线性,对一座典型的曲线梁桥的极限承载力和影响参数进行了分析研究。结果表明,提高结构预应力度,结构的开裂荷载将有所提高,但结构的延性显著降低,极限位移有所减小;采用部分预应力混凝土,结构开裂荷载有所下降,但结构的延性有所增加,对提高抗震性能有利;布置腹板束的弯桥极限承载力要好于仅布置平板预应力束的弯桥。     

锈蚀H型钢压弯构件强度分析

钢结构在长期使用过程中,由于周围环境的影响,钢构件表面发生不同程度的锈蚀,当锈蚀达到一定量时,将对钢结构造成安全隐患。利用钢的大气腐蚀的发展规律,以H型钢为例,对大气均匀腐蚀环境下偏心受压构件的强度进行分析。建立压弯构件的强度随锈蚀变化的关系,为耐久性设计提供一定的基础。     

变宽箱梁桥支座计算分析

变宽箱梁的构造、力学特点与等截面箱梁有很大区别,在运用程序建模分析中选择合适的方法对结构分析的精确度有较大的影响,因此,通过对某变宽箱梁桥进行梁格法和单梁法的建模分析对比,得出了对实际工程有指导意义的结论。     

基于粘结强度变化的锈蚀无腹筋梁承载能力的研究

基于锈蚀钢筋混凝土梁内钢筋与混凝土间粘结强度随锈蚀量的变化,对锈蚀梁承载能力和破坏模式进行了研究。首先,基于梁内粘结强度的变化,计算锈蚀梁的抗弯承载力。其次,基于“拉、剪临界破坏”的概念和“梁-拱”共同作用的混凝土抗剪抵抗机制,计算锈蚀无腹筋梁的抗剪承载力。较小钢筋锈蚀量时,与粘结强度有关的“梁作用”因粘结强度的增加而增加;随锈蚀量的增加和粘结强度的退化,与粘结强度有关的“梁作用”不断降低,“拱作用”则有所增加。再次,对锈蚀梁随钢筋锈蚀量变化破坏模式的变化进行了分析。最后,对文中提出的模型进行了试验验证。     

锈蚀箱梁极限强度试验中板变形量的分析

根据垂直弯曲荷载下3个锈蚀箱梁板的压应力试验结果,分析初始和倒塌后的板变形量。研究初始缺陷和腐蚀对倒塌后最终变形的影响,得出不同的荷载响应、初始缺陷和板高厚比之间的关系。分析初始缺陷、板高厚比和倒塌后最终变形,建立高厚比准则以计算倒塌后变形。     

钢结构桥的试验模态分析

军用钢结构便桥是保障作战部队快速克服江河、沟渠障碍的工兵装备.其动态特性影响着不同载荷在桥上的通行方式,关系到部队的机动性和可靠性.阐述对某一便桥桥跨所进行的试验模态分析及其试验所采用的激振方式、激振点的选择、支撑方式的设定以及响应点的选择.对随机锤击连续采样,加海宁窗与重叠处理进行分析.并用ME'scopt软件对其进行模态分析.最终得出该桥跨前5阶的频率、阻尼及阻尼比,并得出其振型.     

Ultimate strength reliability analysis of corroded steel-box girder bridges

Structural reliability theory is a useful tool for estimating the risks associated with deteriorating structures. The aim of this study is to develop and demonstrate a procedure for the assessment of box girder bridge ultimate strength reliability with the degradation of plate members due to general corrosion taken into account. A probabilistic model for ultimate steel-box girder strength is established on the basis of an analytic formula that considers corrosion-related, time-dependent strength degradation. The study involves the selection of representative structures, formulation of limit state functions, development of resistance models for corroded steel-box girders, development of load models, development of a reliability analysis method, reliability analysis of the selected bridges and development of the time-dependant reliability profiles, including deterioration due to corrosion. The results of this study can be used for the better prediction of the service life of deteriorating steel-box girder bridges and the development of optimal reliability-based maintenance strategies.     

大跨度斜拉桥扁平钢箱梁的多尺度可靠度分析研究

以润扬大桥斜拉桥为分析对象,提出了扁平钢箱梁结构的多尺度可靠度分析方法。采用子结构方法将扁平钢箱梁整体结构尺度模型和局部构件尺度模型相互衔接,在此基础上采用改进响应面法分析了扁平钢箱梁结构的静力可靠度。分析结果表明：①采用改进响应面法能有效地解决传统响应面法存在的收敛失败和计算误差大的缺点;②采用钢箱梁多尺度模型可以较准确地计算斜拉桥在活荷载作用下的静力可靠指标;③钢箱梁活荷载的分布方式和斜拉桥的几何非线性对斜拉桥静力可靠度具有较大的影响;④采用钢箱梁多尺度模型,可以较真实地研究钢箱梁局部构件损伤对斜拉桥静力可靠度的影响。钢箱梁局部构件损伤对斜拉桥静力可靠指标的影响程度要明显大于对斜拉桥静力特性的影响。因此,在斜拉桥钢箱梁的可靠度设计与状态评估中需要计入结构多尺度效应的影响。     

Reliability of maintained ship hull girders subjected to corrosion and fatigue

A formulation is presented to account for the effect of corrosion and fatigue on the reliability of ship hulls. A time variant formulation is presented in which the effect of these degradation phenomena on the hull section modulus is quantified. The effect of maintenance actions is accounted for by considering that the repaired elements are restored to a state as new. Different repair policies can be studied and the approach can be used as a tool to plan the maintenance actions based on reliability results.     

Reliability analysis in building physics design

The idea of reliability analysis in building physics design is presented. Reliability of building performance is described in terms of the probability of exceeding the critical values by the physical measures as a result of the changes of physical state of a building due to variations of climatic, structural or serviceability parameters.     

Comparative Analysis of Bridges with AASHTO and Florida I-Beam Girders

A comparative study of two pre-stressed girder bridges, one with AASHTO （American Association of State Highway and Transportation Officials） Type III girders and the other with new FIB （Florida l-beam） girders, is presented. FIB girders are expected to provide increased lateral stiffness, higher load carrying capacity, cost-efficiency and better reliability. In this paper, the first bridge that is analyzed is a 3-span bridge designed with six AASHTO Type III girders, and the second bridge has four FIB girders with the same span length, width and girder depth. The bridges are analyzed for Florida state legal loads SU4 and C5. Both bridges are analyzed using a sophisticated finite element method. The deflections, moment envelopes, section capacity and live load rating of the two bridges are obtained and compared. FIB girders have higher vertical stiffness, higher section capacity providing higher load rating than the AASHTO girders.     

基于非线性静态分析和软件的公路桥抗震评估

受地震扰动时,可以通过一系列方法对桥的响应进行评估。传统的方法是采用线性静态或动态分析结合适当的修正来说明非弹性响应,而现行的实践着重强调非线性静态分析方法。本研究采用线性动态分析程序,对两跨公路桥的初步地震响应进行分析以确定潜在的非弹性响应。按照两个非线性静态分析方法对桥进行分析,评估了两种方法所预测的全部响应的差别以及采用各种软件进行非线性静态分析的效率。结果显示:所采用的两种不同非线性响应预测的非线性静态分析方法,由于存在大量的简化,都不能获得正确的结果。此外,研究还揭示在综合分析和提供破坏过程图方面,一些软件更适合进行非线性静态分析(如塑性铰的性能)。     

Probabilistic function evaluation system (ProFES) for reliability-based design

ProFES is a probabilistic analysis and design software that allows users to perform a wide range of probabilistic function evaluations including finite element analysis in a graphical environment. This paper summarizes the ProFES Version 2.0 capabilities with a focus on recent ProFES enhancements in three major areas related to probabilistic design: design optimization, damage tolerance, and possibilistic-probabilistic analysis. Several efficient computational probabilistic methods developed for the recent enhancements are highlighted and demonstrated using structural application problems.     

X型圆管相贯节点极限承载力分析

根据X型圆管相贯节点的几种典型破坏模式，在研究两种分析模型的基础上，得出了此类节点极限承载力的解析解．并将分析结果和钢结构GB50017—2003进行了比较，验证了分析结果的正确性。     

既有铁路钢筋混凝土梁桥动态可靠性评估

介绍了既有桥梁结构的动态可靠性分析方法,提出了桥梁的恒载概率模型、活载概率模型及抗力概率模型,并对可靠度计算方法中的验算点法进行了介绍。以一座既有铁路钢筋混凝土梁桥为工程背景,计算了该桥的活载效应统计参数、恒载效应统计参数及抗力统计参数等,利用验算点法计算了桥梁结构构件的可靠度指标,又采用PNET方法分析了整个桥梁体系的可靠性,最后给出了桥梁的可靠性评估结果。结果显示动态可靠性评估应用于铁路钢筋混凝土梁桥可以得到较好的评估结果。