山区中小跨径桥梁设计原则及要点

山区桥梁工程建设难度系数较高,且受地形条件的影响较大,所以主要设计成中小跨径桥梁。本文根据山区中小跨径桥梁工程,简要介绍了设计基本原则,然后从上部结构、下部结构以及结构基础等方面研究了中小跨径桥梁设计要点,从而为类似桥梁工程设计提供指导与参考。     

中小跨径桥梁的经济性分析

中小跨径桥梁是桥梁设计是中占比最大、应用最广的桥型结构,如何选择最经济的中小跨径桥梁,是每位建设者都关心的问题。本文通过对空心板、小箱梁、T梁、钢混组合结构四种最常见的上部结构形式以及在联长相同情况下不同跨径和墩高组合的T梁方案的经济性分析对比,得到相比较而言较经济的结构形式和跨径墩高组合,以为建设者选择上下部结构提供参考。     

二次预应力梁的徐变和承载力试验研究

在中小跨径的预应力梁式桥中,经常出现张拉过程中直梁反拱过大,弯梁横移,刚构桥立柱开裂等问题,这些都是由于预应力附加内力过大引起的。为了解决此类问题,提出二次预应力新型桥梁结构的概念。通过对这种结构与常规预应力结构的比较分析和10 m跨径的二次预应力梁和常规预应力梁的对比试验,证明二次预应力技术在低高度梁中的应用,可以大大改善低高度梁在施工和长期使用过程中的受力和变形性能。同时推导了二次预应力结构任意时刻的徐变内力计算公式,并验证了二次预应力结构的承载能力。指出二次预应力技术在中小跨径预应力梁式桥中有着广阔的应用前景。     

碳纤维布在中小跨径桥梁上部结构加固中应用

结合具体工程实例,介绍了碳纤维布加固中小跨径桥梁上部结构的处治方案和加固机理,分别阐述了该工艺的计算方法、设计要点、材料及施工方法等,对于同类桥梁的加固具有指导作用和推广价值。     

密肋式T梁在城市中小跨径桥梁设计中的应用

在城市中小跨径桥梁上采用密肋式T梁可以避免常规装配式空心板梁的一些先天缺陷,减少桥梁上部结构的长期病害。而且施工简单,安装方便,易于快速化施工,在城市桥梁设计中非常具有推广价值。通过对密肋式T梁内力分析计算和结构设计优化,为密肋式T梁在城市桥梁中应用提供借鉴。     

钢构桥结构新体系及其施工技术(一)

1 概况 钢构桥是桥的一种型式,是指一座桥的上部结构的主要承重受力部分主要是由钢材制成的。 钢构桥由于采用高强度的材料,匀质性好,易于加工,故而构件轻、运输架设方便,为大跨度桥梁理想材料。目前,世界上桥梁结构体系中大跨度桥梁多为钢桥。例如世界上最大跨径的悬索桥明石桥为1990m,最大跨径的斜拉桥为890m的多多罗桥,最大跨径的拱桥为主跨550m的上海卢浦大桥,均比预应力混凝土斜拉桥及预应力混凝土拱桥跨越能力大,而梁式桥也是如此。     

中小跨径梁桥检测与常见病害调查研究

我国桥梁建设步入了大规模发展阶段,由于众多大桥及特大桥的存在,产生了对中小跨径桥梁的养护重视度不够等问题。在总结某市桥检报告与病害研究的基础上,对中小跨径梁桥的常见病害进行了整理与分析。研究发现,病害主要集中在梁桥的主要部件及上部一般构件上,以裂缝和钢筋锈蚀为主。针对中小跨径空心板梁和T梁的典型病害,从设计与施工的角度分析病害的成因,并对桥检评定工作及公路桥梁技术状况评定标准中存在的问题做一个总结。     

简支T梁桥拓宽连接后新建基础沉降的作用分析

以某中小跨径简支T梁桥拓宽工程为背景,采用ANSYS 10.0建立空间实体有限元模型,结合现场实测沉降值数据,分析了新建基础沉降对上部结构受力的影响,并据此探讨了新旧桥连接时机的选取,对类似桥梁有重要的指导意义。     

《城市首桥与防洪》01/2009京津高速公路钢－混凝土组合箱梁的新设计理念

对于跨越现况主要道路（高等级公路）的跨径为30－40m的桥梁结构，从设计及拖工的便捷性考虑，采用钢－混凝土组合粱结构是适宜的。此类跨径的弯桥，采用体外预应力结构，改善了钢－混凝土连续弯桥的受力状态。同时减小了结构顶、底板钢材的用量，降低了工程造价。体外预应力在钢－混凝土组合粱结构中无论大跨径或中小跨径挢梁都应大力推广使用，其设计与施工技术日趋成熟。     

浅谈40mT梁预制施工过程

简单阐述了40 m T梁的施工顺序、模板的制作和安装、钢筋的加工和绑扎、混凝土的浇筑和养护、预应力张拉等施工过程,总结了T型桥梁的优点,以利于在中小跨径的连续桥梁中推广使用。     

Fragility analysis of track-on steel-plate-girder railway bridges in Korea

More than 40% of the bridges in conventional Korean railway lines are track-on steel-plate-girder (TOSPG) bridges. They are characterized by a superstructure consisting of railway tracks sitting directly on steel plate girders without any ballast system. Most of these bridges have been designed with little or no consideration given to seismic loading. In this paper, seismic fragility curves of TOSPG bridges in Korea are developed. Fragility curves are developed first for the components, by using the probabilistic seismic demand model. The developed component fragility curves show that the bearings are the most vulnerable components of the TOSPG bridges against seismic loading. On the other hand, the piers are much less vulnerable, although they contain no reinforcing bars. This is because the superstructure mass is very light, and therefore horizontal loading transferred from the superstructure to the piers is minimal. A generic damage measure is introduced for measuring the system-level damage of structures out of the component-level damages. The system fragility curves are then developed, using the generic damage measure. Finally, representation of seismic risk in terms of expected seismic losses is demonstrated. This demonstration shows how the fragility analysis is utilized for risk assessment and support in decision-making.     

Seismic vulnerability assessment of wall pier supported highway bridges using nonlinear pushover analyses

Pushover analyses were conducted to assess the seismic vulnerability of wall pier supported highway bridges on southern Illinois priority emergency routes. Three-dimensional finite element models were developed to reflect typical hammerhead and regular wall pier bridges from a random sample of the bridge inventory. The models incorporated expected nonlinear structural and material behavior of all the bridge components—superstructure, expansion joints, approach embankments and/or abutments, bearings, wall piers, footings and/or pile caps, and pile and/or mat foundations (plus soil effects)—as well as defining failure measures for each component. Both transverse and longitudinal pushover analyses were conducted on ninety wall pier bridge models reflecting the sample population variation in bridge characteristics such as wall pier type, number of piers, skew, type of foundation, concrete reinforcement ratio, bearing type, and wall height. It was found that the population of wall pier bridges studied was generally vulnerable to wall bearing and abutment bearing failures, wall pier ductility failures, and footing shear and/or bending failures, with bridge skew leading to a coupling of the failure mechanisms from the two pushover directions.     

公路桥梁病害分析及检查方法

对桥梁的常见病害进行归纳和分析总结,并介绍了桥面铺装、伸缩缝装置、桥梁上部结构、桥梁墩台、基础的检查方法,通过对现有桥梁进行检查,了解其各部位损坏的程序,为桥梁的维修加固提供必要的依据。     

谈两种设计理念在桥梁加固中的运用

桥梁加固设计是比新建桥梁设计更为复杂的系统工程,结合两种不同加固设计理念,综合阐述了桥梁加固设计的特点和加固工艺,对目前国内普遍存在的常规桥梁的加固具有一定的借鉴意义。     

Messtechnische Überwachung extern vorgespannter Betonbrücken

Monitoring of reinforced concrete bridges retrofitted by external tendons An established retrofitting method for bridges with deficits in their load bearing capacity is the installation of external tendons to increase the lifespan of the structure. A critical detail of the retrofitting is the anchorage block, where significant forces have to be introduced into the existing superstructure. Therefore, the anchorage blocks of three bridges in Hessen were monitored. They were fitted with extensometers, strain gauges were installed on prestressing rods and the temperature was recorded. Furthermore alert protocols were established, to detect potentially critical situations. The effects of different construction stages were tracked. The influence of short‐ and long‐term temperature changes on the readings was assessed. In summary, the monitoring provided valuable insights into the structural interaction between the existing superstructure and the elements of the retrofitting.     

浅谈桥梁的加固施工

根据公路旧桥加固方面的实践经验，按桥梁的组成介绍了旧桥上部及下部结构的加固技术措施，并总结了桥梁的常见加固方法，通过加固方法的实施，从而达到提高桥梁承载能力的目的。     

A design method for seismically isolated bridges with abutment restraint

Seismic isolation is a commonly used technique for protecting new and existing bridges. It usually consists of introducing isolation bearings between the superstructure and the substructures in order to decouple their motion and reduce the force demand due to the earthquake action. This paper deals with partially restrained seismically isolated continuous bridges, which are a particular class of isolated bridges whose transverse motion is restrained at the abutments.In this study a method is proposed for the preliminary design of these systems, which can be applied to both new and existing bridges. The dynamic problem is described in a variational form in order to obtain a simplified solution based on a pre-fixed transverse deformed shape of the deck. The objective of the design procedure is to control the internal actions on the piers by means of an appropriate configuration of the isolation bearings. Simple formulas for estimating the forces transmitted to the abutments and the superstructure transverse curvature demand are also derived, which account for the contribution of higher modes of vibration.Validation studies are undertaken for different bridge configurations, in order to assess the ability of the simplified method to control the force demand at the piers.     

整体式桥台无缝桥梁技术

整体式桥台无缝桥梁是将桥梁的上部结构与桥台结为整体,避免了伸缩缝桥梁常见的水侵蚀和冻害。分析了桥梁伸缩缝装置存在的问题;介绍了国内外无伸缩缝桥梁的工程实践;提出了整体式桥台无缝桥梁应用中存在的问题。     

风暴潮、浪作用下中小型跨海桥梁破坏形式与数值模拟研究

强台风形成的巨浪、风暴潮对跨海桥梁的安全造成了严重威胁,为探讨台风风暴潮、浪共同作用下中小型跨海桥梁上部结构和下部结构的破坏机理及台风风暴潮期间不同水位下的波浪对下部结构的作用规律,开展了台风风暴潮、浪共同作用下中小型跨海桥梁破坏形式调研,发现风暴潮、浪作用下中小型跨海桥梁上部结构的破坏形式主要有梁体离位、梁体脱落和梁体断裂,主要原因为梁体被迫发生无约束运动;下部结构破坏主要表现为结构偏移、倒塌以及盖梁连接失效破坏,主要原因为水动力作用较强及上部结构撞击。通过CFD三维数值模拟研究了桥梁下部结构波浪荷载,给出了考虑风暴潮水位下波浪冲击桥墩的经验公式。根据调研及数值模拟,提出了设计及施工建议。     

中小跨径板式橡胶支座梁桥横向抗震设计研究

为提高中小跨径板式橡胶支座梁桥在强震作用下的横向抗震性能,在总结汶川震区该类梁桥震害特点和国内外桥梁抗震设计规范中相关抗震设计策略规定的基础上,归纳当前我国板式橡胶支座梁桥横向抗震体系存在的问题,提出适合我国中小跨径板式橡胶支座梁桥的横向抗震设计方法,即允许上、下部结构连接构件牺牲的准隔震设计方法,介绍该抗震设计方法设计思想,给出在两设防水准下结构各部件的性能目标要求。选择一座典型板式橡胶支座简支梁桥为研究对象,基于文中抗震设计方法的设计思想,提出采用新型隔震系统对计算桥例进行准隔震设计。结果表明：通过对横向限位装置力学性能参数的合理设计,通过桥梁结构在强震作用下板式橡胶支座的滑移、横向限位装置的损伤或牺牲,控制上、下部结构间传递的梁体惯性力,保护墩柱和基础等下部结构免遭严重损害,同时能有效控制墩梁相对位移,防止过大的梁体移位导致的交通阻断、甚至落梁。