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Bronx-Whitestone Bridge: Vertical median barrier extension enhances aerodynamics 布朗克斯-白石大桥:垂直中间护栏扩展增强了空气动力学性能
IF 0.6 Q4 CONSTRUCTION & BUILDING TECHNOLOGY Pub Date : 2023-12-21 DOI: 10.3233/brs-230216
Gavin Daly, Ted Zoli, S. Stoyanoff
The Bronx-Whitestone Bridge was designed during the 1930s in an era of suspension bridges with decks stiffened by shallow plate girders, many of which were subsequently found to be vulnerable to aerodynamic instabilities such as vortex shedding and flutter. Following the occurrence of mild and benign wind-induced oscillations in the first several years after opening in 1939, the bridge has undergone a series of retrofits, from structural solutions such as stay cables, stiffening trusses, and a steel orthotropic deck, to aerodynamic enhancements such as a tuned mass damper and wind fairings. Wind tunnel studies in 2015 confirmed the improved aerodynamic performance due to the recently installed wind fairing system and stiffer orthotropic deck. A subsequent rehabilitation project gave the opportunity to assess measures to further improve the aerodynamic performance of the bridge. A 3 ft (0.91 m) tall solid screen added on top of the median barrier was found to act as an above-deck vertical baffle plate, disrupting the alternating pattern of vortices, reducing the susceptibility of the bridge to instabilities. This led to the conceptual design of a Median Barrier Extension (MBE) comprised of 3 ft (0.91 m) solid transparent acrylic panels fixed to the top of the existing median barrier posts, supported by a tubular steel frame. To ensure this unique barrier modification met current industry safety standards, the MBE design was iterated through a crash analysis study using non-linear finite element models before the final design proceeded to a full-scale physical crash testing program to MASH Test Level 4. This paper presents the full timeline of this innovative retrofit project, from conception during wind tunnel testing, through to design, crashworthiness studies and final construction in 2020. This project has demonstrated that a vertical extension to a median barrier can act as a simple and cost-effective enhancement to the aerodynamic performance of existing bridges.
布朗克斯-白石大桥设计于 20 世纪 30 年代,当时的悬索桥桥面都是由浅板梁加固的,后来发现其中许多都容易受到空气动力不稳定性的影响,如涡流脱落和飘移。在 1939 年通车后的最初几年里,该桥曾出现过轻微、良性的风致振荡,之后又进行了一系列改造,包括留索、加劲桁架和正交异性钢桥面等结构解决方案,以及调谐质量阻尼器和风整流罩等空气动力学改进措施。2015 年的风洞研究证实,最近安装的风整流罩系统和更坚固的正交甲板改善了空气动力性能。随后的修复项目为评估进一步改善桥梁空气动力性能的措施提供了机会。研究发现,在中间护栏顶部加装 3 英尺(0.91 米)高的实心屏风可作为桥面上方的垂直挡板,扰乱涡流的交替模式,降低桥梁的不稳定性。这就促成了中间分隔带扩展装置 (MBE) 的概念设计,该装置由 3 英尺(0.91 米)的实心透明丙烯酸面板组成,固定在现有中间分隔带立柱的顶部,并由管状钢架支撑。为确保这种独特的护栏改装符合当前的行业安全标准,在最终设计进入全面的物理碰撞测试程序(MASH 测试等级 4)之前,使用非线性有限元模型对 MBE 的设计进行了反复碰撞分析研究。本文介绍了这一创新改装项目从风洞试验期间的构思,到设计、耐撞性研究和 2020 年最终施工的全部过程。该项目证明,对中间护栏进行垂直延伸,可以简单而经济地提高现有桥梁的空气动力性能。
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引用次数: 0
Applicability of available NDT methods for damage detection in concrete elements reinforced or strengthened with FRP 现有无损检测方法在检测用玻璃纤维增强材料加固或强化的混凝土构件的损伤方面的适用性
IF 0.6 Q4 CONSTRUCTION & BUILDING TECHNOLOGY Pub Date : 2023-12-19 DOI: 10.3233/brs-230217
P. Malla, S. S. Khedmatgozar Dolati, A. Mehrabi, J. Ortiz Polanco, A. Nanni, K. Dinh
The application of Fiber Reinforced Polymer (FRP) materials in concrete structures has been rising due to their several advantages, including lightweight, high tensile strength, ease of installation, and corrosion resistance. They have been mostly implemented for strengthening and repairing existing structures in the form of an externally bonded system, i.e., sheet, jacket, near surface mounted. Furthermore, they have been recently utilized as internal reinforcement of concrete elements in the form of strands, bars, tendons, etc. Although higher durability and performance are associated with the FRP material in some aspects compared to steel, concerns remain regarding damages and defects in this material, many of which are related to their unique features. Importantly, debonding of FRP materials from a concrete surface or within a concrete element has always been an issue resulting in the premature failure of the structure. To this end, concrete elements strengthened or reinforced with FRP materials has to be inspected periodically to detect potential issues and hence prevent any premature failures. This study first determines all possible or potential damages and anomalies attributed to FRP reinforced/strengthened concrete (FRP-RSC) elements. It then investigates Non-Destructive Testing (NDT) methods that can be applicable to the inspection of FRP-RSC elements from a literature survey of past studies, applications, and research projects. Furthermore, this study evaluates the ability of two of the most commonly used NDT methods, Ground Penetrating Radar (GPR) and Phased Array Ultrasonic (PAU), in detecting FRP bars/strands embedded in concrete elements. GPR and PAU tests were performed on two slab specimens reinforced with GFRP (Glass-FRP) bars, the most commonly used FRP bar, with variations in their depth, size and configuration, and a slab specimen with different types of available FRP reinforcements. The results of this study propose the most applicable methods for detecting FRP and their damage/defects in FRP-RSC elements. This study further investigates the feasibility of two new methods for improving the detectability of embedded FRP bars. By providing the inspection community with more clarity in the application of NDT to FRP, this study offers means for verifying the performance and, therefore, help the proliferation of FRP materials in concrete structures.
纤维增强聚合物(FRP)材料具有重量轻、抗拉强度高、易于安装和耐腐蚀等优点,因此在混凝土结构中的应用日益增多。玻璃纤维增强聚合物材料主要用于加固和修复现有结构,采用外部粘接系统的形式,如板材、护套、近表面安装等。此外,最近还以钢绞线、钢筋、钢筋等形式用作混凝土构件的内部加固。虽然与钢材相比,玻璃钢材料在某些方面具有更高的耐久性和性能,但这种材料的损坏和缺陷仍然令人担忧,其中许多都与其独特的特性有关。重要的是,玻璃钢材料与混凝土表面或混凝土构件内部的脱粘一直是一个问题,会导致结构过早失效。为此,必须定期检查使用玻璃钢材料加固或增强的混凝土构件,以发现潜在问题,从而防止任何过早失效。本研究首先确定了玻璃纤维增强/加固混凝土(FRP-RSC)构件所有可能或潜在的损坏和异常情况。然后,通过对以往研究、应用和研究项目的文献调查,研究可用于检测 FRP-RSC 构件的无损检测 (NDT) 方法。此外,本研究还评估了两种最常用的无损检测方法--地面穿透雷达(GPR)和相控阵超声波(PAU)--在检测嵌入混凝土构件中的玻璃钢条/带方面的能力。研究人员对两种板试样进行了 GPR 和 PAU 测试,一种是使用最常用的玻璃纤维增强塑料(FRP)钢筋(玻璃纤维增强塑料)进行加固的板试样,其深度、尺寸和配置各不相同;另一种是使用不同类型的玻璃纤维增强塑料进行加固的板试样。研究结果提出了检测 FRP-RSC 构件中 FRP 及其损坏/缺陷的最适用方法。本研究进一步探讨了两种新方法的可行性,以提高嵌入式 FRP 钢筋的可检测性。通过为检测界提供更清晰的玻璃钢无损检测应用,本研究提供了验证性能的方法,从而有助于玻璃钢材料在混凝土结构中的推广。
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引用次数: 0
Evaluation of minimum flexural reinforcement for precast prestressed concrete NEXT beam bridges 预制预应力混凝土 NEXT 梁桥最小抗弯配筋评估
IF 0.6 Q4 CONSTRUCTION & BUILDING TECHNOLOGY Pub Date : 2023-12-18 DOI: 10.3233/brs-230218
Jianwei Huang
The minimum flexural reinforcement requirement has been used in the current bridge design specifications to protect the member from brittle failure after the formation of the first flexural cracks. Several variables have been reported to affect this requirement, such as concrete strength, amount of prestressing in the member, and type of cross section. Recently, the Precast/Prestressed Concrete Institute (PCI) developed a new type of beam section (NEXT beam) to accelerate bridge construction and enhance the sustainability of bridges. As a newly developed beam section, no research on the minimum flexural reinforcement has been reported for NEXT beam bridges. This paper aimed to examine the minimum flexural reinforcement requirements in the current AASHTO LRFD Bridge Design Specifications for NEXT beam bridges. A comprehensive parametric study was analytically conducted with various parameters, including bridge section, beam section, concrete strength, and span length. The results from this study showed that the current minimum flexural reinforcement requirements were met for all bridges examined herein; the concrete strength, beam cross section, and span length could affect the levels of safety against brittle failure after first flexural cracks for NEXT beam bridges.
在现行的桥梁设计规范中,最小抗弯配筋要求用于保护构件在形成第一条抗弯裂缝后不会发生脆性破坏。据报道,有几个变量会影响这一要求,如混凝土强度、构件中的预应力量和横截面类型。最近,预制/预应力混凝土协会(PCI)开发了一种新型梁截面(NEXT 梁),以加快桥梁建设速度并提高桥梁的可持续性。作为一种新开发的梁截面,目前还没有关于 NEXT 梁桥最小抗弯配筋的研究报告。本文旨在研究现行 AASHTO LRFD 桥梁设计规范中对 NEXT 梁桥的最小抗弯配筋要求。通过分析各种参数,包括桥梁截面、梁截面、混凝土强度和跨度长度,进行了全面的参数研究。研究结果表明,本文研究的所有桥梁均满足现行的最低抗弯配筋要求;混凝土强度、梁截面和跨度长度会影响 NEXT 梁桥在首次出现抗弯裂缝后的脆性破坏安全等级。
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引用次数: 0
Quantification of the effects of the spatial variation of ground motions on the seismic response of highway bridges 地震动空间变化对公路桥梁地震反应影响的量化
IF 0.6 Q4 CONSTRUCTION & BUILDING TECHNOLOGY Pub Date : 2023-07-11 DOI: 10.3233/brs-230205
Nassira Belkheiri, B. Tiliouine
The stochastic responses of highway bridges to spatial variation of ground motions (SVGM) are analysed in this paper. A model of spatially varying ground motions is used to investigate the relative importance of the incoherency effect, the wave passage effect and the site effects on the stochastic dynamic response of an asymmetrical R.C box girder highway bridge with variable inertia. In this study, the incoherency effect is investigated using two widely used models while the wave-passage effect is incorporated using various wave velocities. Then, the random vibration theory is applied to study the effect of the non-uniform seismic excitations on the bridge structure. The bridge response is evaluated in terms of the mean values of the maximum displacements and the bending moments. Analyses of both stationary and transient response are performed. The results show that the stochastic dynamic responses related to site effects are mostly much greater than those calculated using uniform, delayed and incoherent seismic excitation assumptions. As a result, analytical models used for the stochastic dynamic analysis of long span highway bridges should take into account all the SVGM components, particularly the site-response effects.
本文分析了公路桥梁对地震动空间变化的随机响应。采用空间变化地震动模型,研究了非相干效应、通道效应和场地效应对变惯性非对称钢筋混凝土箱梁公路桥梁随机动力响应的相对重要性。在本研究中,使用两种广泛使用的模型来研究非相干效应,同时使用不同的波速来考虑波通过效应。然后,应用随机振动理论研究了非均匀地震激励对桥梁结构的影响。桥梁响应是根据最大位移和弯矩的平均值来评估的。进行了平稳响应和瞬态响应分析。结果表明,与场地效应相关的随机动力响应大多远大于采用均匀、延迟和非相干地震激励假设计算的随机动力响应。因此,用于大跨度公路桥随机动力分析的分析模型应考虑所有SVGM分量,特别是场地响应效应。
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引用次数: 0
Influence of pier-water interaction on natural vibration characteristics of bridge with complex piers in water 墩水相互作用对水中复杂桥墩桥梁自振特性的影响
IF 0.6 Q4 CONSTRUCTION & BUILDING TECHNOLOGY Pub Date : 2023-07-11 DOI: 10.3233/brs-230204
Jie Li, Sida Li, Junfeng Zhang, Yupeng Geng, Da-Yong Yang
In order to clarify the influence of water on the natural vibration of bridge with complex piers, based on a continuous beam with 4-column pier, the numerical analysis model is established. Single column circular pier is taken to discuss the range of waters. Then the influences of water on the natural vibration are analyzed. The research shows that waters reduce the natural frequency. When waters area width is less than 10 m, the natural frequency of the pier decreases. And the first-order longitudinal bending frequency is reduced by 3.36%. When waters area width is more than 10 m, the vibration frequencies tend to be stable gradually. Therefore, the waters 10 m can be regarded as an infinite boundary. The natural frequencies of single column pier and 4-column pier decrease with the increase of water depth. When the water depth is less than 10 m, the changes of natural frequency of the first four orders of single column pier are relatively small, and the changes of 5–10 order natural frequency are large. The maximum effect of the first ten orders is 14.84%. The natural vibration frequency of the bridge decreases gradually with the increase of water depth. The maximum effect of the first five orders is 3.33%.
为了弄清水对复杂桥墩桥梁自振的影响,以4柱桥墩连续梁为例,建立了数值分析模型。采用单柱圆形墩来讨论水域范围。然后分析了水对结构固有振动的影响。研究表明,水降低了固有频率。当水域宽度小于10 m时,桥墩固有频率减小。一阶纵向弯曲频率降低了3.36%。当水域宽度大于10 m时,振动频率逐渐趋于稳定。因此,10米的水域可视为无限边界。随着水深的增加,单柱墩和四柱墩的固有频率逐渐减小。当水深小于10 m时,单柱墩前4阶固有频率变化较小,5-10阶固有频率变化较大。前十个订单的最大效果为14.84%。随着水深的增加,桥梁的自振频率逐渐降低。前五个订单的最大效果为3.33%。
{"title":"Influence of pier-water interaction on natural vibration characteristics of bridge with complex piers in water","authors":"Jie Li, Sida Li, Junfeng Zhang, Yupeng Geng, Da-Yong Yang","doi":"10.3233/brs-230204","DOIUrl":"https://doi.org/10.3233/brs-230204","url":null,"abstract":"In order to clarify the influence of water on the natural vibration of bridge with complex piers, based on a continuous beam with 4-column pier, the numerical analysis model is established. Single column circular pier is taken to discuss the range of waters. Then the influences of water on the natural vibration are analyzed. The research shows that waters reduce the natural frequency. When waters area width is less than 10 m, the natural frequency of the pier decreases. And the first-order longitudinal bending frequency is reduced by 3.36%. When waters area width is more than 10 m, the vibration frequencies tend to be stable gradually. Therefore, the waters 10 m can be regarded as an infinite boundary. The natural frequencies of single column pier and 4-column pier decrease with the increase of water depth. When the water depth is less than 10 m, the changes of natural frequency of the first four orders of single column pier are relatively small, and the changes of 5–10 order natural frequency are large. The maximum effect of the first ten orders is 14.84%. The natural vibration frequency of the bridge decreases gradually with the increase of water depth. The maximum effect of the first five orders is 3.33%.","PeriodicalId":43279,"journal":{"name":"Bridge Structures","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2023-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47696604","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Safety BIM intelligent modeling analysis of prestressed concrete continuous girder bridge construction scene 预应力混凝土连续梁桥施工现场安全BIM智能建模分析
IF 0.6 Q4 CONSTRUCTION & BUILDING TECHNOLOGY Pub Date : 2023-07-11 DOI: 10.3233/brs-230203
Tao Li, Bori Cong, Maowang Yan, Qingying Li, Xinyuan Zhu
BIM intelligent modeling is used to analyze the safety of the construction scene of prestressed concrete continuous girder bridge, so as to realize the safety management of the bridge construction scene and improve the construction efficiency. The construction safety analysis system is used to analyze the binding data of construction safety, and the data is combined with the self-applicable equilibrium control and the game equilibrium control to build the construction scene safety objective function model. On this basis, combined with the control constraints of the whole life cycle, the statistical analysis regression model is used to build the scene safety analysis model based on BIM. The whole life cycle safety intelligent analysis of the construction scene is realized, and the improved particle swarm optimization algorithm is used to solve the model by adaptive differential evolution, so as to shorten the calculation time of the model. The experimental results show that the safety management performance of the proposed method is high, and the safety management evaluation grade is 285. The identification accuracy of main beam stress change is high. Under the conditions of unbalanced load, combination of unbalanced load and prestress, combination of wind load and prestress and unbalanced load, the safety analysis of upper edge stress and lower edge stress of main beam can be effectively completed, and the construction safety of prestressed concrete continuous beam bridge can be realized.
利用BIM智能建模对预应力混凝土连续梁桥施工现场安全性进行分析,实现桥梁施工现场安全管理,提高施工效率。利用施工安全分析系统对施工安全绑定数据进行分析,并将该数据与自适用均衡控制和博弈均衡控制相结合,构建施工现场安全目标函数模型。在此基础上,结合全生命周期的控制约束,运用统计分析回归模型构建基于BIM的现场安全分析模型。实现了建筑场景全生命周期安全智能分析,采用改进的粒子群优化算法,通过自适应差分进化对模型进行求解,从而缩短了模型的计算时间。实验结果表明,该方法具有较高的安全管理性能,安全管理评价等级为285。主梁应力变化识别精度高。在非平衡荷载、非平衡荷载与预应力相结合、风荷载与预应力与非平衡荷载相结合的条件下,可以有效地完成主梁上缘应力和下缘应力的安全性分析,实现预应力混凝土连续梁桥的施工安全。
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引用次数: 0
Evaluation and retrofit of steel girder Shiplap connections 钢梁船扣连接评价与改造
IF 0.6 Q4 CONSTRUCTION & BUILDING TECHNOLOGY Pub Date : 2023-07-06 DOI: 10.3233/brs-230212
B. Kozy, Jonathan Beckstrom, Tim Armbrecht
Over time, owners may face challenges with management of bridges with outdated details. One such detail that is no longer used today is the steel girder shiplap connection. These were originally employed to simplify analysis of continuous girders while also moving joints away from the piers, improving longevity of bridge bearings and substructures. Unfortunately, fatigue issues have appeared in these connections resulting in cracking at critical load-carrying locations. In this project, analysis was performed to investigate connection fatigue and strength and retrofit design verification. Results utilizing non-linear analysis showed that while stresses from ultimate loading could adequately redistribute throughout the web, high stress concentrations were created, exacerbating fatigue. Stress calculations for shiplap web details are not well codified or easily assessed with simple hand calculations, so finite element analysis was utilized. Results showed web fatigue life had been exhausted with more cracking expected at other locations, convincing the owner retrofit was necessary even though the bridge was programmed for replacement.
随着时间的推移,业主可能会在管理细节过时的桥梁方面面临挑战。如今不再使用的一个细节是钢梁搭接连接。这些最初用于简化连续梁的分析,同时也将接头从桥墩上移开,从而提高桥梁支座和下部结构的使用寿命。不幸的是,这些连接中出现了疲劳问题,导致关键承载位置出现裂纹。在该项目中,对连接疲劳和强度进行了分析,并对改造设计进行了验证。利用非线性分析的结果表明,虽然极限载荷产生的应力可以在整个腹板上充分重新分布,但会产生高应力集中,加剧疲劳。搭接腹板细节的应力计算没有很好的编码,也不容易用简单的手工计算进行评估,因此采用了有限元分析。结果显示,腹板疲劳寿命已经耗尽,预计其他位置会出现更多裂缝,这让业主相信,即使桥梁已被计划更换,也有必要进行改造。
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引用次数: 0
Correlation between corrosion level and fatigue strength of high-strength galvanized steel wires used for suspension bridge cables 悬索桥用高强度镀锌钢丝腐蚀程度与疲劳强度的关系
IF 0.6 Q4 CONSTRUCTION & BUILDING TECHNOLOGY Pub Date : 2023-07-06 DOI: 10.3233/brs-230214
K. Miyachi, Shoya Saimoto, Yusuke Oki
This study investigated the relationship between “rust color distribution ratio,” “corrosion surface shape,” and “fatigue strength” of high-strength galvanized steel wires used in cable supported bridges. The study utilized a digital image color analysis system to classify the rust color distribution rate and categorize corrosion levels based on the distribution ratio. The relationship between cross-sectional loss rate and corrosion depth tendency was visually and quantitatively comprehended from the categorized corrosion levels. The study found that fatigue and tensile strengths of the specimens from the corrosion levels set in this study were equivalent to or higher than those of new wires. However, the possibility of variations due to the small number of specimens or insufficient corrosion progress cannot be ruled out.
本研究调查了缆索支撑桥梁中使用的高强度镀锌钢丝的“锈色分布率”、“腐蚀表面形状”和“疲劳强度”之间的关系。该研究利用数字图像颜色分析系统对铁锈颜色分布率进行分类,并根据分布率对腐蚀程度进行分类。从分类的腐蚀水平可以直观、定量地理解横截面损失率与腐蚀深度趋势之间的关系。研究发现,在本研究中设定的腐蚀水平下,试样的疲劳和拉伸强度等于或高于新线材的疲劳和抗拉强度。然而,不能排除由于试样数量少或腐蚀进度不足而产生变化的可能性。
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引用次数: 0
Renovation of the Van Brienenoord Bridge, The Netherlands 荷兰Van Brienenoord大桥改造
IF 0.6 Q4 CONSTRUCTION & BUILDING TECHNOLOGY Pub Date : 2023-07-06 DOI: 10.3233/brs-230211
Kevin Acosta, Daan Tjepkema, Felix de Meijier
Part of the Netherlands’ busiest highway, the Van Brienenoord Bridge comprises 12 lanes of traffic split across the eastbound bridge built in the 1960 s and the western bridge built in the 1990 s. The Van Brienenoord Bridge complex consisting of two parallel 300 m span steel arch bridges, approach structures and three parallel bascule bridges over the New Meuse. The bridges carry about 230,000 vehicles daily. A strengthening and replacement strategy was developed to reduce road closures to one of the two bridges at a time and reducing this time to weeks instead of months. The strengthening consists of plate stiffeners to the main girders and arches and a new deck. Construction begins in 2025 and will extend the bridge’s useful life to another 100 years. The strengthening instead of replacing is in line with RWS’ commitment to adopting circular economy principles for their infrastructure network.
作为荷兰最繁忙的高速公路的一部分,Van Brienenoord大桥由12条车道组成,横跨建于1960年的东行大桥 s与1990年代建造的西部大桥 s.Van Brienenoord大桥由两个平行的300 m跨度的钢拱桥、引桥结构和三座横跨新默兹的平行基架桥。这些桥梁每天可运载约23万辆汽车。制定了一项加固和更换战略,将道路封闭时间一次减少到两座桥梁中的一座,并将这一时间减少到几周而不是几个月。加固包括主梁和拱的板加劲肋以及一个新的甲板。工程将于2025年开始施工,并将把大桥的使用寿命再延长100年。强化而非取代符合RWS对其基础设施网络采用循环经济原则的承诺。
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引用次数: 0
Rail-structure interaction and vehicle-track-structure interaction level 1 and 2 analyses 轨道-结构相互作用和车辆-轨道-结构相互作用的一级和二级分析
IF 0.6 Q4 CONSTRUCTION & BUILDING TECHNOLOGY Pub Date : 2023-07-06 DOI: 10.3233/brs-230213
M. Fedorova, M. Sivaselvan, O. Kurc, A. Karakaplan
Rail-structure interaction (RSI) analysis and vehicle-track-structure-interaction (VTSI) analysis are often required during bridge design. For example, the California High-Speed Train Project requires RSI analysis for final design of all structures, as well as VTSI analysis, with the level of interaction to be modeled determined by the complexity of a structure. The goal of RSI analysis is to ensure that superstructure deformations and rail stresses are within acceptable limits. VTSI analysis is a dynamic analysis that takes into account influence of actual trainsets. VTSI Level 1 analysis includes train loads as a series of moving loads. This analysis allows evaluation of dynamic impact effects from trainsets and vertical accelerations of the deck. For complex high-speed railway bridges, VTSI Level 2 might be required, accounting for full dynamic interaction between the trainset and the bridge. To represent this interaction, the trainset is modeled as a multibody system consisting of rigid bodies, springs, and dashpots. The interaction between wheels and rails is accounted for through kinematic constraints and Lagrange multipliers. This paper presents modeling, RSI, and VTSI analyses of a railway bridge in the LARSA 4D software package. The track and superstructure are modeled in an expedited way using a macro that generates the track, approach, and bridge geometries. Fasteners are modeled as hysteretic springs and automatically positioned along the curved geometry of the track using a LARSA 4D’s bridge path coordinate system definition. RSI analysis is performed accounting for temperature differentials between rails and the deck, vertical train loads, acceleration and braking forces. Break in the rail is introduced using stage construction analysis, followed by progressive collapse analysis (with adapting increments and arc-length control) or nonlinear dynamic analysis. Finally, VTSI Level 1 and 2 analyses are performed and the results are compared. Car body accelerations are compared to limit values to ensure passenger comfort.
桥梁设计中经常需要进行轨道-结构相互作用(RSI)分析和车辆-轨道-结构交互作用(VTSI)分析。例如,加州高速列车项目要求对所有结构的最终设计进行RSI分析,以及VTSI分析,相互作用的水平由结构的复杂性决定。RSI分析的目标是确保上部结构变形和轨道应力在可接受的范围内。VTSI分析是一种考虑实际列车组影响的动态分析。VTSI 1级分析包括作为一系列移动荷载的列车荷载。该分析允许评估列车组和甲板垂直加速度的动态冲击效应。对于复杂的高速铁路桥梁,可能需要VTSI 2级,以考虑列车组和桥梁之间的全动态相互作用。为了表示这种相互作用,列车集被建模为一个由刚体、弹簧和阻尼器组成的多体系统。车轮和轨道之间的相互作用是通过运动学约束和拉格朗日乘子来解释的。本文在LARSA 4D软件包中介绍了铁路桥梁的建模、RSI和VTSI分析。使用生成轨道、引道和桥梁几何形状的宏,以快速的方式对轨道和上部结构进行建模。紧固件被建模为滞后弹簧,并使用LARSA 4D的桥梁路径坐标系定义沿着轨道的弯曲几何形状自动定位。RSI分析考虑了轨道和甲板之间的温差、垂直列车荷载、加速度和制动力。钢轨断裂采用阶段施工分析,然后采用渐进坍塌分析(采用自适应增量和弧长控制)或非线性动力学分析。最后,进行VTSI 1级和2级分析,并对结果进行比较。将车身加速度与极限值进行比较,以确保乘客的舒适性。
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引用次数: 0
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Bridge Structures
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