矮塔斜拉桥结构参数分析

探讨了矮塔斜拉桥塔根无索区长度及边支座无索区长度对活载作用下主梁变形、内力以及斜拉索的索力等的影响,得出了合理无索区长度的取值范围;提出了斜拉索荷载效应影响率的计算公式,定量分析了矮塔斜拉桥斜拉索作用的实质,对进一步认识矮塔斜拉桥的结构性能提供了新的判断指标。     

单索面矮塔斜拉桥长度参数的影响分析

以广东省佛山市石湾特大桥为项目背景,参照国内外其他矮塔斜拉桥的设计参数,研究矮塔斜拉桥长度参数特性,通过改变边中跨比、塔高、梁上无索区长度、塔上无索区长度等设计参数,分别分析这些长度参数对主梁内力和位移、塔的内力和位移、拉索应力幅和拉索活载系数的影响,确定其比较合理的取值范围。     

无索区布置对独塔斜拉桥静力特性影响分析

独塔斜拉桥的静力特性主要包括主梁内力、主梁挠度及塔顶偏位等,通过改变塔梁固结处及主跨边支座附近的无索区长度,分析其对桥梁静力特性的影响。分析结果表明,在塔梁固结处设置无索区能减小主梁正弯矩、主梁下挠及塔顶偏位,但会增大主梁负弯矩;在主跨边支座附近设置适当的无索区能够显著提高独塔斜拉桥的受力性能。     

矮塔斜拉桥无索区优化

针对矮塔斜拉桥的结构特性,以主梁弯矩为目标,对斜拉索的布置方式进行了优化处理,研究了无索区的长度变化对主梁弯矩产生的影响,得到了经济、合理的结构形式,从而证实了对矮塔斜拉桥无索区长度进行优化的必要性。     

矮塔斜拉桥斜拉索无索区长度研究

以矮塔斜拉桥为工程实例建立了有限元计算模型,通过对比分析塔根与跨中的无索区长度比值结构参数的变化对矮塔斜拉桥结构性能的影响,得出无索区长度变化对主梁内力和塔顶位移影响较大,而对拉索内力影响较小等规律。从而为今后矮塔斜拉桥的设计提供了参考和借鉴。     

斜拉桥下中跨无索区合理长度分析

以佛山某83m+150m+83m三跨单索面矮塔斜拉桥工程实例为研究背景,通过采用大型有限元分析软件Midas/civil分别建立4种不同中跨无索区长度的斜拉桥计算模型,对比分析不同的中跨无索区长度对主梁的弯矩、应力和挠度等结果的影响。通过对比分析表明:中跨无索区长度与主跨径比值为:La/L=0.20~0.25,给出了该桥合理的主梁无索区长度范围,按该比值布置拉索所用斜拉索的平均索力降低,配索量减少,更经济适用,为类似工程设计提供参考建议。     

设计参数对独塔协作体系斜拉桥的影响研究

对于工程中常见的独塔不对称协作体系斜拉桥,从主跨无索区长度、主梁的高跨比、边跨与主跨比、塔高与主跨的比值等设计参数着手,分析了协作体系斜拉桥合理的布置形式,提出合理的取值范围,拟供今后的工程设计参考.     

无索区长度对多塔斜拉桥力学行为的影响研究

为探讨多塔斜拉桥无索区长度对受力特性的影响，以某多塔斜拉桥为基础，通过改变单一参数的方法，分析了无索区的长度和内力、位移、桥塔位移等指标之间的关系。结果表明在跨中无索区的长度比例为0.14～0.22，塔根无索段的长度之比在0.15～0.19范围内，结构受力较为理想。     

多跨连续梁独塔斜拉协作体系桥梁结构参数分析

从协作体系的结构状态和一些重要的设计参数着手,研究多跨连续独塔斜拉协作体系桥梁的塔、梁、索受力特征及位移形态,分析主跨无索区长度、主梁高跨比、主边跨比及塔的高跨比等设计参数变化对结构所产生的影响,并提出合理的取值范围。     

矮塔斜拉桥结构参数敏感性分析

文章以某矮塔斜拉桥为研究对象,利用Midas/Civil建立有限元模型进行参数敏感性分析,研究主梁混凝土容重、主梁弹性模量、斜拉索弹性模量、主梁预应力荷载等结构参数变化对成桥状态主梁线形、斜拉索索力、主梁应力等静力响应的影响。结果表明:主梁混凝土容重、预应力荷载为主要敏感性参数,主梁弹性模量、斜拉索弹性模量为次要敏感性参数,分析结果可为施工控制提供参考。     

Influence of Stabilizing Cables on Seismic Response of a Multispan Cable-Stayed Bridge

Abstract:   A recent trend in the design of long-span bridges is multispan cable-stayed bridges with three or more towers. A critical problem of multispan cable-stayed bridges is the stabilization of the central tower(s), which has resulted in increasing application of stabilizing cables. The Ting Kau Bridge in Hong Kong is one of a few multispan cable-stayed bridges adopting stabilizing cables ever built. In this article, the dynamic properties of multispan cable-stayed bridges with stabilizing cables and the effect of stabilizing cables on bridge seismic response are studied by referring to the Ting Kau Bridge. Based on a validated 3D finite-element model, modal analysis is conducted which shows that the longitudinal stabilizing cables bring about a number of global modes with strong modal interaction among the deck, towers, and cables. The seismic response and internal force in the central tower are found to be much larger than those in the side towers. The longitudinal stabilizing cables are very effective in reducing the internal force in the central tower generated by longitudinal earthquake excitation, but insignificantly affect the seismic response in the bridge deck and side towers. As a whole, the stabilizing cables act favorably in the reduction of seismic response of the bridge.     

Shrinkage cracking at interior supports of continuous pre-cast pre-stressed concrete girder bridges

This study deals with the control of cracking at interior supports of continuous pre-cast pre-stressed concrete (PCS) girder bridges. Since PCS-girder bridges are constructed by placing in-situ concrete decks on the PCS-girders at time intervals, the differences in material properties and age at loading between the deck and girder lead to time-dependent material behaviors. In addition, the continuous deck by providing a negative moment connection at interior supports, also causes the transverse cracking of the concrete deck at interior supports. In that way, cracking at interior supports is predicted with the analytical model introduced in the companion paper. Based on the ACI model, the ultimate shrinkage strain is expressed as a function of concrete slump and the relative humidity while the other remaining factors such as unit weight of cement and air content are assumed, in accordance with the typical values in mixed concrete. Finally, field recommendations in terms of concrete slump and relative humidity are suggested to minimize early transverse cracking of concrete decks at interior supports.     

Life-cycle cost analysis of a TPSM applied continuous composite girder bridge

Transverse cracks in composite girder bridges are repeatedly reported because the tensile stresses in the concrete deck induced by the negative bending moment at the intermediate supports of continuous composite girder bridges. The occurred transverse cracks rapidly deteriorate the concrete deck, giving rise to frequent need for maintenance work. Prestressing methods are usually utilized in this kind of situation for the concrete structures, however no effective and feasible method has yet been proposed for steel-concrete composite structures. A new type of prestressing method entitled Thermal prestressing method (TPSM) has been proposed for innovative construction of continuous composite girder bridges, as effective prestressing method to prevent the occurrence of the tensile transverse crack of the concrete deck at the negative bending moment regions. In this study, the methodology for the economic analysis of TPSM applied bridges and case studies are introduced based on the life-cycle cost, considering initial construction cost and maintenance cost, to demonstrate the financial viability of the TPSM applied bridges compared to conventional continuous composite girder bridges.     

Instandsetzung einer “müden” Straßenbrücke mit orthotroper Fahrbahn

Repair of a “tired” road bridge with orthotropic deck. The proneness to fatigue of steel bridges with an orthotropic deck appears in many damages because of the increasing traffic of heavy vehicles. On the example of an aggrieved highway‐bridge the specific weak points and the executed damage analysis will be shown. The gained knowledge leaded to the development of different alternatives of repair and to the presented repair concept. To improve the global characteristics of the structure additional supports will be built, for the local strengthening a reinforced concrete slab will be built as composite structure with the existing steel deck.     

高速铁路下承式系杆拱桥桥面形式的研究

通过有限元分析,对采用结合梁桥面和整体钢桥面两种桥面形式的下承式钢系杆拱桥的竖向刚度、系梁和拱肋的内力、桥面系统的内力和自振特性进行对比分析。计算结果表明:两种形式的竖向刚度基本上相等;系梁和拱肋的内力后者略优于前者,并且不均匀降温对前者更不利;端部横梁都存在较严重的应力集中,方案一对温度荷载很敏感;日照引起的局部温差能较大的增加方案一混凝土桥面板的拉应力值;方案二的纵梁、加劲横梁和桥面板的组合应力都较低。提出整体钢桥面为适合于我国新建高速铁路下承式钢系杆拱桥的合理桥面形式。     

大跨径钢桥面铺装设计理论与方法研究

结合南京长江第二大桥、舟山桃夭门大桥、润扬长江公路大桥和杭州湾大桥等大型桥梁桥面铺装的研究与设计 ,对大跨径钢桥面铺装设计理论与方法 ,包括铺装材料与结构、钢桥面铺装体系受力特性、疲劳特性、热塑性沥青混合料铺装车辙、设计指标、轴载换算方法、设计方法等关键技术进行系统的分析与研究 ,研究成果已在多座大跨径钢箱梁桥面铺装设计和铺装工程中应用     

Efficient combination of a TCUD method and an initial force method for determining initial shapes of cable-supported bridges

The TCUD method (Kim and Lee, 2001) can provides the reasonable initial shape of cable-supported bridges under full dead load by including the unstrained lengths of the cable members as unknowns and introducing additional constraint conditions equal to the total number of the cable members. However, the axial deformations in the girder and main tower members are not avoidable which result in some difference from a target configuration when long-span cable-supported bridges are considered. In this study, an effective method to be able to eliminate those axial deformations as well as to preserve merits of the TCUD method is newly proposed. For this purpose, the TCUD method and the initial force method with successive substitution are reviewed based on an elastic catenary cable element, respectively, and a new algorithm combining two methods efficiently is presented. In addition, a truss-cable element for modeling hangers and a beam-column element for the girder and main tower members are supplementarily developed, respectively. The proposed method is applied for two suspension bridges and a cable-stayed bridge to demonstrate its accuracy and effectiveness.     

独塔单索面宽斜拉桥空间动力行为研究

以西宁通海路跨越湟水河斜拉桥为研究对象,分别采用鱼刺梁模型和梁格法计算了动力特征值,考察了结构的刚度和边界条件设置合适与否,并比较了两种建模理论计算结果的异同,在动力特性计算的基础上,采用第一类线弹性稳定方法,分别研究了桥塔的屈曲稳定性和全桥的屈曲稳定性,考察了结构的整体稳定安全性,为较宽独塔单索面斜拉桥提供了动力分析的工程实践经验及有效的分析方法。     

斜拉索的参数振动

对斜拉桥拉索的参数振动问题建立了非线性力学模型 ,并进行了数值计算分析。指出了拉索参数振动的可能性 ,并对其特征进行了研究。对桥面振动而导致的拉索振动提出了一种新的抑振装置 ,计算结果表明具有较好的减振效果     

Improved methods for determining the 3 dimensional initial shapes of cable-supported bridges

The TCUD method (Kim and Lee, 2001) can minimize undesirable lateral displacements in cable bridge structures by including the unstrained lengths of the cable members as unknowns and introducing additional constraint conditions. The axial deformations in the girder and the main tower deviating from the target configuration are, however, unavoidable when self-anchored cable bridges are considered. On the other hand, the IFM (initial force method) can be used to adjust the axial deformations to conform to the initial shape but it is critical that the unstrained lengths of the cables are accurately evaluated. In this study, improved schemes for the TCUD method and the IFM for finding the initial shape of 3 dimensional cable-supported bridges under dead load, are presented. For this purpose, the TCUD method and the initial force method are firstly reviewed. Two improved algorithms, which can overcome shortcomings of the previous initial-shaping analysis methods, are developed based on an elastic catenary cable element and a nonlinear space frame element. Finally, the accuracy and effectiveness of the proposed analysis algorithms are demonstrated through the numerical application to 3 dimensional initial shape problems for self-anchored suspension and cable-stayed bridges.