Finite element model updating of existing steel bridge based on structural health monitoring

Based on the physical meaning of sensitivity,a new finite element(FE) model updating method was proposed. In this method,a three-dimensional FE model of the Nanjing Yangtze River Bridge(NYRB) with ANSYS program was established and updated by modifying some design parameters. To further validate the updated FE model,the analytical stress-time histories responses of main members induced by a moving train were compared with the measured ones. The results show that the relative error of maximum stress is 2.49% and the minimum relative coefficient of analytical stress-time histories responses is 0.793. The updated model has a good agreement between the calculated data and the tested data,and provides a current baseline FE model for long-term health monitoring and condition assessment of the NYRB. At the same time,the model is validated by stress-time histories responses to be feasible and practical for railway steel bridge model updating.

Health Monitoring-Based Assessment of Reinforcement with Prestressed Steel Strand for Cable-Stayed Bridge

This paper presents the method of reinforcing main girder of reinforced concrete cable-stayed bridge with prestressed steel strands.To verify the effectiveness of external prestressed strand reinforcement method.Static load tests and health monitoring-based assessment were carried out before and after reinforcement.Field load test shows that the deflection and stress values of the main girder are reduced by 10%~20%after reinforcement,and the flexural strength and stiffness of the strengthened beam are improved.The deflection and strain data of health monitoring of the specified section are collected.The deflection of the second span is 4 mm~10 mm,the strain range of the upper edge of the second span is-10με~-40με,and the strain range of the lower edge is 30με~75με.These values show the deflection and strain values fluctuate within a prescribed range,verifying the safety of the bridge.The reinforcement method of prestressed steel strand is feasible and effective.It can provide reference basis for the application of external prestressed strand reinforcement technology in similar projects.

Fatigue damage reliability analysis for Nanjing Yangtze river bridge using structural health monitoring data

To evaluate the fatigue damage reliability of critical members of the Nanjing Yangtze river bridge, according to the stress-number curve and Miner’s rule, the corresponding expressions for calculating the structural fatigue damage reliability were derived. Fatigue damage reliability analysis of some critical members of the Nanjing Yangtze river bridge was carried out by using the strain-time histories measured by the structural health monitoring system of the bridge. The corresponding stress spectra were obtained by the real-time rain-flow counting method. Results of fatigue damage were calculated respectively by the reliability method at different reliability and compared with Miner’s rule. The results show that the fatigue damage of critical members of the Nanjing Yangtze river bridge is very small due to its low live-load stress level.

Application of Wireless Monitoring System to Structural Health Monitoring of Long-Spanned Cable-Stayed Bridge

The remote monitoring system applied to the construction control and health monitoring of the Nanjing Third Yangtze River Bridge is introduced. The System makes it possible to get the structure capabilities and environmental parameters of the bridge at the predetermined moment. It sends the collected data over a long distance to an assigned position for display and analysis. The related methods and working condition of the wireless monitoring system are discussed. The measured data during 48 h are employed to determine the feasibility for the closure of the bridge.

Analysis on Deflection Characteristics of Steel Cable-Stayed Bridge

Various kinds of deflection characteristics on the steel cable-stayed bridge(Nanjing No.3 Yangtze River Bridge)are investigated by different mathematical statistical methods.Firstly,via Pearson correlation coefficient calculation,it shows good consistency between the adjacent measuring point of side span or middle span.Secondly,taking mid-span deflection as an example,the correlation analysis of deflection and temperature is conducted.They are synchronous via cross correlation coefficient calculation but not completely linear and a"hysteresis loop"phenomenon of three stages is formed.The fitting result on the monitoring data at day time is consistent with the numerical value through the application of unit temperature difference between the cable and girder and the positive temperature gradient of girder in the finite element model.And the temperature effect is considerable.Vehicle loads effect is obtained from wavelet analysis.The extracted curve can indirectly reflect the change of traffic loads.Finally,the structural damage is analyzed through the trend fusion on the deflection,cable force and visual inspection from 2006 to 2015.Relevant conclusions can provide a basis for management departments to carry out special detection.

基于模糊理论的桥梁监测设备评估方法研究

针对桥梁监测设备运行状态难以量化评估的问题,提出一种基于模糊理论的综合评估方法,构建监测设备运行状态自诊断服务系统。基于现行规范建立监测设备运行状态评估指标体系,采用正态分布隶属度函数,并引入Pearson相关系数和信息熵确定各评估指标权重;采用基于混合算子的模糊评估模型,实现监测设备运行状态量化评估;通过自诊断服务系统,实时监测设备运行状态并进行报警。将该方法应用于某悬索桥监测设备评估,工程应用结果表明:该方法与规范方法和概率分析法评估结果相同,但该方法基于模糊理论“自下而上”逐级综合加权分析,全面量化评估桥梁监测设备体系各等级运行状态隶属度,评估结果简单直观,所构建的自诊断服务系统有助于科学指导桥梁健康监测系统运维。

桥梁传感器优化布置的研究现状与发展趋势

桥梁在交通网络中充当着极其重要的角色,其正常运行与否关系到人民生活幸福指数的高低。所以,为其建立结构健康监测系统以实时监测其安全状态、预警其异常行为及预测其工作性能走向的方法极为必要。桥梁结构传感器的优化布置,简单来说就是通过正确合理地布置所需传感器来获取桥梁的各项信息。传感器的优化布置研究的关键则在于其布置方法与评价准则,国内外的学者经过多年的研究,在该领域取得一定的突破与创新,但是仍然存在很多不完善的地方,如何通过改进各种算法来确定传感器优化布置最优解成为研究的主要方向。该文重点阐述传感器优化布置准则和传感器优化布置的方法在目前研究方向中发挥的重要作用,并对桥梁健康监测的后续发展表达看法和展望。

大跨度变截面钢箱梁托管桥安全监测设计与成果分析

针对目前国内单跨跨度最大的变截面连续钢箱梁桥面上铺设的输水管道直径最大的托管桥桥体应力应变、竖向挠度以及桥上输水管道应力应变监测成果进行分析。结果表明,钢箱梁上下表面的钢板应力均与环境温度呈负相关,与过水荷载大小呈正相关;桥体竖向挠度与过水荷载呈正相关,运行期变形量较首次通水时小;输水管道钢板应力分布上基本呈底部最大、左右管腰次之、顶部最小。

桥梁结构安全AI检测平台研究

桥梁作为城市交通系统的重要组成部分,对其安全和健康的监测尤为重要。传统的监测方法往往耗时、费力,且无法准确预测潜在问题。文中探索和开发了基于人工智能(AI)的桥梁结构安全与健康监测平台,以提高桥梁监测的效率和准确性,希望能为工程师和维护人员提供及时的预警和决策支持。

健康监测系统在桥梁运营中的应用

为了探讨健康监测系统在桥梁运营中应用的精确性,以石河子市军垦一桥(独塔双索面预应力混凝土斜拉桥)为例,介绍了该桥健康监测系统的设计与实施,迄今已完成了对结构的6次定期监测,以第6次的监测数据为基础,结合前5次的监测结果对比分析可知:各斜拉索索力与设计值相比基本不超过±3%,吻合度较好;主梁及桥塔应力监测值远小于截面控制应力;桥面两侧高程监测值与设计值相比较为接近,且均高于设计值。结果表明健康监测系统在该桥具有良好的应用效果,能够确保桥梁结构状况预警的准确性,可为准确判断桥梁在运营中的健康状态提供数据支撑。

大跨屋架结构健康监测系统数据处理方法研究

以南京某文化中心项目为基础,针对大跨屋架结构的健康监测系统数据处理方法,进行了深入的研究与应用。分析了结构监测点的布置原则,并结合项目实际情况,合理地布置了温度、位移、应变传感器。基于健康监测系统,进行了数据的传输和获取,并设定了数据预警阈值。最后对采集的数据进行分析,发现数据变化平稳,结构处于安全状态。

基于健康监测系统的斜拉桥快速评定方法研究

荷载试验是评估桥梁承载能力的最主要手段,但传统荷载试验加载时间久,加载成本高,且需要封闭交通。本文在某斜拉桥上进行快速荷载试验,基于健康监测系统实测值与实际检测值对比发现,单车道车辆加载时实测值与理论值吻合性较好,可一定程度上代替常规静态荷载试验。多车道同时加载时,跨中变形较大处吻合较好。结果表明基于健康监测系统的快速荷载试验评估方法快捷,对交通影响小,测试效率高,可实现随时对桥梁进行快速评估,为定期养护和日常维护管理提供依据和参考。

下穿铁路框架桥的基坑设计及安全分析

基坑在工程建设中较为常见,基坑开挖安全分析在每一个特定工程中都具有其重要意义,以杭州市萧山区彩虹快速路下穿沪昆铁路的建设工程为研究对象,介绍了下穿铁路线的框架桥及其深基坑的设计、施工方案,并基于现场监控和数值模拟的手段分析了基坑施工过程中围护结构的变形情况及周边地表的沉降情况。结果表明,相较于预制框架顶进施工法,明挖基坑现浇框架法更易保证其施工安全性,且对既有铁路线的运营影响更小;该基坑施工过程中,围护结构最大水平变形22 mm、最大沉降3.0 mm,立柱桩最大沉降15 mm,基坑结构具有很好的安全稳定性;然而,基坑周边地表沉降最大可达18 mm,且影响范围处于距离基坑边缘2 m~25 m范围内,应尤其注意该距离范围内既有铁路线的维护与检修,并适当降低铁路运营速度。

钢-混组合梁桥健康监测系统设计与应用

为研究健康监测技术在钢-混组合梁桥中的应用,文章以山东枣木高速东延段某简支钢-混组合梁桥为背景,重点探讨了结构健康监测系统布设方案、监测传感器和系统平台构建等,提出了钢-混组合梁桥健康监测关键指标。结果表明,该桥健康监测系统布设方案合理,监测数据能有效反映结构运营工作状态,研究成果可为中小跨径钢-混组合梁桥的健康监测提供参考。

长大连续钢构桥梁健康监测系统平台的研究及应用

目前,我国尚没有完全面向桥梁施工期和运维期的仿真分析系统,同时存在传统桥梁结构监测系统大数据处理自适应能力较差、状态评价分析片面及预警模式不完备等问题,通过对普通国省道长大连续钢构桥梁智慧健康安全监测集群式平台研究、长大连续钢构桥梁结构仿真分析、CAE+AI结构反演监测与可视化预测预警,采用力学仿真分析、机器学习、双向长短期记忆神经网络等方法,实现了可视化结构模型,为该类桥梁在运营期养护决策提供数据依据,提高养护精准性。

Estimating extreme temperature differences in steel box girder using long-term measurement data

The extreme temperature differences in flat steel box girder of a cable-stayed bridge were studied.Firstly,by using the long-term measurement data collected by the structural health monitoring system installed on the Runyang Cable-stayed Bridge,the daily variations as well as seasonal ones of measured temperature differences in the box girder cross-section area were summarized.The probability distribution models of temperature differences were further established and the extreme temperature differences were estimated with a return period of 100 years.Finally,the temperature difference models in cross-section area were proposed for bridge thermal design.The results show that horizontal temperature differences in top plate and vertical temperature differences between top plate and bottom plate are considerable.All the positive and negative temperature differences can be described by the weighted sum of two Weibull distributions.The maximum positive and negative horizontal temperature differences in top plate are 10.30°C and13.80°C,respectively.And the maximum positive and negative vertical temperature differences between top plate and bottom plate are 17.30°C and 3.70°C,respectively.For bridge thermal design,there are two vertical temperature difference models between top plate and bottom plate,and six horizontal temperature difference models in top plate.

运营期盾构隧道结构健康安全评估方法研究

对隧道的健康状态进行安全评估,是确保隧道运营期安全平稳运行的关键。传统人工巡检记录的数据多以定性为主,且较为浅显,使得传统评价模型无法准确实时地评估隧道的健康状态,结合盾构隧道结构健康监测系统的实时数据对隧道进行安全评估则可克服这一问题。针对盾构隧道结构健康监测中常见传感器的布设形式,提出一种适用于盾构隧道安全评估的模糊综合评价模型,将该模型录入济南黄河隧道健康监测系统,实现对隧道西线后半段整体、各监测断面、不同监测部位的实时安全评估,通过对各级健康评价值的分析,确定控制盾构隧道健康状态的区域位于隧道最深覆土区域的拱顶处,在隧道运营过程中需对该区域加以重视。

基于物联网技术的大型桥梁安全监测系统设计

万物互联是智慧城市未来发展的形式,基于物联网技术的飞速发展,为获取重要城市的基础设施实时状态信息提供优越的机会。文章针对传统人工桥梁监测方法存在监测效率差、不灵活、检测结果有误差等问题,在物联网技术的基础上提出一种新型的桥梁监测系统,对桥梁安全状况进行实时监控、预判及评估分析。该系统对我国大型桥梁安全工程具有建设性意义。

钢-UHPC组合桥面疲劳评估方法中外规范对比

为分析中外规范对钢-UHPC组合桥面疲劳评估的适用性,以武汉军山长江大桥加固改造工程为背景,分别利用美国规范AASHTO LRFD Bridge Design Specifications、欧洲规范Eurocode 3:Design of Steel Structures(BS EN 1993-1-9:2005)、日本规范《道路桥示方书·同解说(钢桥篇)》和中国规范《公路钢结构桥梁设计规范》(JTG D64—2015)评估该桥正交异性钢桥面板经UHPC铺装层加固后的疲劳性能和剩余寿命。采用Abaqus软件建立钢-UHPC组合桥面节段模型,采用中外规范的标准疲劳车加载,计算各疲劳细节处的应力幅值,并对比分析各疲劳细节处的应力水平;同时对运营状态下各疲劳细节处开展连续动应变监测,获取各疲劳细节处实测应力时程,对钢桥面板进行疲劳寿命评估。结果表明:美国规范更适用于重车比例较高的桥梁,欧洲规范更适用于桥面板较厚的桥梁,日本规范更适用于桥面宽度较小的桥梁,中国规范均可适用。当横隔板弧形切口应力水平较高时,美国规范疲劳评估结果的安全性不佳;在桥面板纵肋对接焊缝处,美国规范和日本规范的常幅疲劳极限值较欧洲规范分别低19.0%和22.2%,较中国规范分别低18.8%和22.0%;当桥面板纵肋对接焊缝应力幅为46~59 MPa时,采用美国规范和日本规范进行评估的结果更安全。除横隔板弧形切口和纵肋对接焊缝外的其余疲劳细节,中外规范给出的常幅疲劳极限值比较接近,评估结果均为无限寿命。

城市轨道桥梁群健康监测系统设计及应用

为防范检测或维养不及时导致的城市轨道交通桥梁运营安全风险,以武汉轨道交通1号线为背景,采用五层次功能架构,设计和建设武汉市轨道交通桥梁健康监测系统管理平台,将1号线30座不同结构形式桥梁纳入平台进行统一的监测和数字化管养。结合桥梁现场环境、设计图纸、相关规范及计算成果,针对性设计了轨道交通桥梁健康监测方案;采用基于早班空载编组列车的快速荷载试验获取校验系数,以评估结构状态。数据分析结果表明:结构静态响应参数主要表现为日周期和长周期温度效应,结构恒载状态未发生明显变化;桥梁的应变、挠度校验系数计算结果验证了桥梁结构状态的长期稳定性。平台可实现桥梁环境特征分析、桥梁结构状态评估、系统可靠性自证等功能,充分发挥了桥梁健康监测系统的应用价值。