Application of engineered compressible inclusions to mitigating soilstructure interaction issues in integral bridge abutments

The thermally induced cyclic loading on integral bridge abutments causes soil deformation and lateral stress ratcheting behind the abutment wall due to the expansion and contraction of the bridge deck.The forward and backward movements of the abutment in response to the expansion/contraction of the bridge deck lead to the formation of settlement trough and surface heaving,frequently creating a bump at the bridge approach and increasing the lateral earth pressure behind the abutment.Measures to reduce the bump at the bridge approach,including several treatment methods,such as compaction of selected backfill materials,grout injection,installation of approach slab,and using a layer of compressible inclusion material behind the abutment were proposed.However,these guidelines still lack sufficient design details and there are limited experimental findings to validate design assumptions.In this paper,the use of engineered compressible materials to alleviate the lateral earth pressure ratcheting and settlement at the bridge approach is investigated.The comparative study is presented for the soil-inclusion,material-structure and soil-structure interactions for an integral bridge under three different backfill conditions,i.e.(a)sand,(b)sand and EPS geofoam,and(c)sand and Infinergy®.The study was conducted in a special large-scale test chamber with a semi-scale abutment to gain better insights into the soil-structure interaction(SSI).The kinematics and rearrangement of the soil during the cyclic loading have been investigated to identify the mitigating effects of compressible inclusions.The comparative study indicates that both compressible inclusions perform comparatively well,however,Infinergy®is a better alternative than the medium-density EPS geofoam,as it works more effectively to reduce the backfill settlement and heaving as well as soil ratcheting effects under cyclic translational movement.

Application Strategy of Digital Comprehensive Management and Maintenance System for Bridges

Effective application of digital integrated management and maintenance systems is essential for successful operation and maintenance management of bridge projects.This article analyzes the application strategy of such systems.It provides an overview of comprehensive digital management and maintenance of bridges,an analysis of the basic components of the integrated management and maintenance system,and its application strategies.This study aims to offer guidance for the application of the system and to improve the quality of modern bridge engineering management and maintenance work.

A Novel Topology of Single-Phase AC-DC Integrated Boost-SEPIC (IBS) Converter Using Common Part Sharing Method (CPSM) for High Step-Up Applications

A novel topology of Integrated Boost-SEPIC (IBS) AC-DC converter using common part sharing method (CPSM) has been proposed in this paper. Conventional boost converters with bridge rectifier configuration are inefficient due to limited voltage step-up ratio which may not be applicable for high step-up applications as in the case of micro generators. The proposed IBS topology is based on the common part sharing method capable of operating both for positive and negative half cycle of the input signal. Result and simulation were conducted using PSIM environment. The proposed AC-DC IBS topology eliminates the requirement of bridge rectifier achieving high efficiency (about 99%), improved power factor (0.75, leading) and lower THD (about 38.8%) which is within IEEE standard.

Evaluation of vertical impact factor coefficients for continuous and integral railway bridges under high-speed moving loads

In the railway bridge analysis and design method,dynamic train loads are regarded as static loads enhanced by an impact factor(IF).The IF coefficients for various railway bridges have been reported as a function of span length or frequency of the bridges in Eurocode(2003).However,these IF coefficient values neglect the effects of very high speeds(>200 km/h)and soil-structure interaction(SSI).In this work,a comprehensive study to assess the impact factor coefficients of mid-span vertical displacements for continuous and integral railway bridges subjected to high-speed moving loads is reported.Three different configurations,each for the three-dimensional(3D)continuous and integral bridge,are considered.Also,single-track(1-T)and two-track(2-T)“real train”loading cases for both these bridge types are considered.Subsequently,finite element analysis of the full-scale 3D bridge models,to identify their IF values,considering the effects of SSI for three different soil conditions,is conducted.The IF values obtained from the study for both bridge types are comparable and are greater than the values recommended by Eurocode(2003).The results reveal that with a loss of soil stiffness,the IF value reduces;thus,it confirms the importance of SSI analysis.

MIBS分组密码的改进积分攻击

MIBS算法是由Izadi等人在CANS 2009上提出的一个轻量级分组密码算法,整体采用Feistel结构,轮函数使用SP结构,分组长度为64 b,包含MIBS-64和MIBS-80这2个版本,适用于资源受限的环境,例如RFID(radio frequency identification)标签.研究MIBS算法针对积分攻击的安全性.首先,针对该算法的密钥编排算法,利用密钥搭桥技术,分别得到了MIBS-64和MIBS-80的轮密钥的相关性质.其次,利用基于MILP(mixed integer linear programming)的比特可分性的自动化建模搜索方法,构造了MIBS的8轮和9轮积分区分器.然后,基于8轮积分区分器,给出了12轮MIBS-64的密钥恢复攻击,数据复杂度为2^(60),时间复杂度为2^(63.42);最后,基于9轮积分区分器,给出了14轮MIBS-64的密钥恢复攻击,数据复杂度为2^(63),时间复杂度为2^(66).这是目前对MIBS-64和MIBS-80轮数最长的积分攻击.

Integrity Design Strategy in Steel Structure Bridge Design

Nowadays,the scope of bridge construction projects in China is becoming wider,which promotes China's economic development to a large extent and also improves China's transportation system.Meanwhile,people also put forward new requirements for the quality of steel structure bridges.However,in actual design,due to the influence of many fectors,some problems are inevitable,which will affect the integrity of the design.Therefore,the designer needs to fully grasp the possible design problems,and then take efiective measures to improve the integrity of the design scheme,so as to ensure the quality of the steel structure bridge and improves the safety of the steel structure bridge from the fundamentals.This paper mainly focuses on steel structure bridges,analyzed the current status of steel structure bridge types and their selection,and proposes the integrity design strategy of steel structure bridges.

IB物理课程对普通高中物理教学的启示——以跨学科部分为例

现代社会的高速发展加深了各学科的交叉融合,IB物理课程特别是它的跨学科部分对普通高中物理课程的教学有一定的启示。文章比较了普通高中物理课程与IB课程在理念上的异同,从课程实施、课程评价等维度评价学生的学习效果,能够有效地促进物理学科核心素养和课堂教学的深度融合,培养学生解决真问题的能力。

Preservation Strategies of Timber-framed Arch Bridges as Cultural Landscape Heritage

Theoretical study on and safeguarding of cultural landscape heritage has been put on the agenda of heritage protection in Zhejiang and Fujian provinces.The safeguarding of timber-framed arch bridge heritage in the past 5 decades could be classified into 3 stages,and heritage protection in all 3 stages was closely related to original meaning of "landscape",which proved that timber-framed arch bridge heritage had profound inside information,and the safeguarding of timber-framed arch bridge from the perspective of cultural landscape heritage was worth further study.Safeguarding of timber-framed arch bridge cultural landscape heritage focused on integrated conservation,but not protection of individual bridges.Integrated conservation of world heritage is to maintain and restore the integrated environment landscape of the heritage,thus protection of timber-framed arch bridge heritage is not only to explore its architectural craftsmanship,but also to lay a foundation for the dynamic succession of such craftsmanship as intangible cultural heritage.Value of the existing timber-framed arch bridges as historic building heritage was discussed,and it was proposed that ultimate objectives of the safeguarding could be realized step by step from 3 layers.

Developments and Prospects of Long-Span High-Speed Railway Bridge Technologies in China

With the rapid developments of the high-speed railway in China, a great number of long-span bridges have been constructed in order to cross rivers and gorges. At present, the longest main span of a constructed high-speed railway bridge is only 630 m. The main span of Hutong Yangtze River Bridge and of Wufengshan Yangtze River Bridge, which are under construction, will be much longer, at 1092 m each. In order to overcome the technical issues that originate from the extremely large dead loading and the relatively small structural stiffness of long-span high-speed railway bridges, many new technologies in bridge construction, design, materials, and so forth have been developed. This paper carefully reviews progress in the construction technologies of multi-function combined bridges in China, including com- bined highway and railway bridges and multi-track railway bridges. Innovations and practices regarding new types of bridge and composite bridge structures, such as bridges with three cable planes and three main trusses, inclined main trusses, slab-truss composite sections, and steel-concrete composite sections, are introduced. In addition, investigations into high-performance materials and integral fabrication and erection techniques for long-span railway bridges are summarized. At the end of the paper, prospects for the future development of long-span high-speed railwav bridges are provided.

Density Functional Approach Based on Numerically Obtained Bridge Functional

The Ornstein Zernike equation is solved with the Rogers Young approximation for bulk hard sphere fluidand Lennard-Jones fluid for several state points. Then the resulted bulk fluid radial distribution function combinedwith the test particle method is employed to determine numerically the function relationship of bridge functional as afunction of indirect correlation function. It is found that all of the calculated points from different phase space statepoints for a same type of fluid collapse onto a same smooth curve. Then the numerically obtained curve is used tosubstitute the analytic expression of the bridge functional as a function of indirect correlation function required in themethodology [J. Chem. Phys. 112 (2000) 8079] to deterrnine the density distribution of non-uniform hard spherefluid and Lennard Jones fluid. The good agreement of theoretical predictions with the computer simulation data isobtained. The present numerical procedure incorporates the knowledge of bulk fluid radial distribution function intothe constructing of the density functional approximation and makes the original methodology more accurate and moreflexible for various interaction potential fluid.

基于FMEA方法的船舶IBS航行安全分析

以某型船为例,介绍故障模式和影响分析(Failure Mode and Effect Analysis,FMEA)的基本方法和分析步骤。采用该方法对船舶综合桥楼系统(Integrated Bridge System,IBS)的航行安全性进行深入分析,验证某型船IBS的航行安全性,为今后类似船舶IBS的设计提供参考。

Density Functional Approach Based on Numerically Obtained Bridge Functional

The Ornstein-Zernike equation is solved with the Rogers-Young approximation for bull, hard sphere fluid and Lennard-Jones fluid for several state points. Then the resulted bulk fluid radial distribution function combined with the test particle method is employed to determine numerically the function relationship of bridge functional as a function of indirect correlation function. It is found that all of the calculated points from different phase space state points for a same type of fluid collapse onto a same smooth curve. Then the numerically obtained curve is used to substitute the analytic expression of the bridge functional as a function of indirect correlation function required in the methodology [J. Chem. Phys. 112 (2000) 8079] to determine the density distribution of non-uniform hard sphere fluid and Lennard-Jones fluid. The good agreement of theoretical predictions with the computer simulation data is obtained. The present numerical procedure incorporates the knowledge of bulk fluid radial distribution function into the constructing of the density functional approximation and makes the original methodology more accurate and more flexible for various interaction potential fluid.

新工科下基于科教融合的“桥梁工程”教学改革

如何立足新工科思维,开展针对“桥梁工程”的探索性教学改革成为道桥专业人才亟须解决的关键问题。在结合学科特点和当代大学生特征的基础上,深入分析当前桥梁课程教学方式的不足。基于科教融合理念,以“创新工程教育模式”为指引,提出了将工程实践引入教学内容、将科研成果引入教学过程、将科研思维引入教学组织的教改实施路径,并给出“课堂教学催生问题提出”“实践教学推动科研进展”“学科竞赛提升科研质量”等创新理念。成果可为同类课程教学改革提供借鉴。

Exploration of the Mining of Ideological and Political Elements and Teaching Integration of Bridge Engineering Courses in Applied Undergraduate Programs

The questions of what kind of individuals university education should cultivate,how to cultivate them,and for whom they are being trained are pressing issues that require immediate solutions.Implementing ideological and political education is a fundamental way to address these challenges.Integrating political education into professional courses is just as important as imparting knowledge,fostering interest,transmitting values,and shaping students’character and spirit.The excavation of ideological and political elements in bridge engineering courses should comprehensively consider the dependent subject of ideological and political elements,the source of cases,the depth of excavation,the trade-offs between courses,the commonality and multifaceted nature of ideological and political elements,as well as the two ways of ideological and political elements integration.Ideological and political elements should be integrated into all stages of classroom lectures,course assignments,final examinations,course design,discipline competitions,school-enterprise cooperation,etc.,so as to achieve the effect of educating people in the whole process.

组织桥接整合因子1、Ⅰ型胶原蛋白基因、核转运蛋白基因2与三阴性乳腺癌术后复发关系

目的探究组织桥接整合因子1(BIN1)、Ⅰ型胶原蛋白基因(COL1A1)、核转运蛋白基因2(KPNA2)表达与三阴性乳腺癌(TNBC)术后复发关系及联合检测意义。方法选取2019年5月至2020年5月上海市第八人民医院行手术治疗的TNBC病人80例,根据术后2年是否复发分为复发组、未复发组,比较两组临床资料、组织BIN1、COL1A1、KPNA2基因表达,复发的相关影响因素采用单因素与多因素logistic回归分析,组织BIN1、COL1A1、KPNA2基因表达预测术后复发的价值采用受试者操作特征曲线(ROC曲线)分析,组织BIN1、COL1A1、KPNA2基因表达与复发时间关系采用Pearson分析,比较不同组织BIN1、COL1A1、KPNA2基因表达病人无复发生存期(RFS)。结果复发组T分期、N分期与未复发组比较,差异有统计学意义(P<0.05);复发组组织BIN1mRNA表达为0.24±0.07,低于未复发组的0.35±0.10(P<0.05),复发组组织COL1A1mRNA、KPNA2mRNA表达分别为2.07±0.62、2.91±0.84,高于未复发组的1.48±0.43、1.85±0.60(P<0.05);T分期、N分期、COL1A1 mRNA、KPNA2 mRNA均是复发相关独立危险因素,BIN1 mRNA是复发相关独立保护因素(P<0.05);BIN1 mRNA、COL1A1 mRNA、KPNA2 mRNA的AUC分别为0.76、0.80、0.78,三者联合的AUC为0.94;BIN1mRNA与复发时间呈负相关(r=-0.79,P<0.001),COL1A1mRNA、KPNA2mRNA与复发时间呈正相关(r=0.77、0.78,均P<0.001);BIN1mRNA高水平病人RFS长于低水平病人,COL1A1mRNA、KPNA2mRNA高水平病人RFS短于低水平病人(P<0.05)。结论BIN1mRNA、COL1A1mRNA、KPNA2mRNA与TNBC术后复发风险、复发时间有关,联合检测可作为早期预测术后复发的一个可靠方案,为临床治疗提供重要的参考信息。

横向贯通式中低速磁浮一体轨道梁钢-混结合部试验研究

为解决中低速磁浮分离式轨道梁存在的养护难、构件多,以及无法考虑F轨刚度贡献等问题,提出一种横向贯通式梁轨一体轨道梁结构,针对其钢-混结合部的静力性能开展有限元分析和足尺模型试验研究,并对关键设计参数进行参数分析。结果表明,在5倍设计荷载内,钢-混结合部基本处于弹性状态,承载力满足设计要求,且具备较高富裕量;竖向荷载主要通过钢板承压作用传递至混凝土梁体,焊钉对竖向荷载的传递作用较小;设计参数分析表明,适量提高钢连接件钢板厚度有利于竖向荷载的平顺传递。研究结果可以为梁轨一体轨道梁设计提供参考。

地铁连续刚构桥上无砟轨道无缝线路纵向力分析

【目的】为研究地铁连续刚构桥上无砟轨道无缝线路纵向受力与变形规律,对地铁连续刚构桥上无砟轨道无缝线路设计改进、运营养护维修提供理论指导。【方法】根据梁-板-轨相互作用原理,建立地铁连续刚构桥上整体道床式无砟轨道无缝线路空间耦合模型,计算伸缩、挠曲、制动、断轨工况下轨道结构和桥梁纵向力及位移,并对轨道结构静力特性进行对比分析,为地铁连续刚构桥上无缝线路轨道结构设计提供参考。【结果】结果表明:双线列车荷载中点与中部梁端处重合时为列车垂向荷载最不利工况,此时钢轨纵向力与钢轨、桥梁纵向位移均为最大,均出现在中部梁端附近,数值分别为70.3 kN与0.6,0.8 mm;双线制动荷载列车尾部位于两侧梁端时为列车制动荷载最不利工况,此时钢轨纵向力与钢轨、桥梁纵向位移均为最大,数值分别为107.8 kN与1.6,1.7 mm。【结论】伸缩力作用下各个端部桥缝处为薄弱部位,在平时养护中应特别注意梁端部桥缝处轨道结构,防止因伸缩力过大而产生断轨;钢轨发生断轨时,在断缝处纵向力、纵向位移均发生突变,严重影响线路行车安全。

“桥建合一”型高架车站实测分析及结构减振优化

针对“桥建合一”型高架车站振动舒适度问题,以某一典型“桥建合一”型高架车站为研究对象,对列车运行引起的楼板振动进行现场实测分析,并基于车桥耦合分析理论,建立高架车站精细化有限元模型,从振源、传递路径和受振体对高架车站进行结构减振优化分析。研究表明:“桥建合一”型高架车站所受车致振动影响严重,站厅层振动敏感区为跨中楼板中心;通过提升轨道梁弹性模量、适度增加层高、在站厅层区域楼板中心布置次梁以及铺设浮筑楼板的方法均可减小楼板振动响应,但单独采取某一结构减振优化措施效果较差;同时采取以上4种结构减振优化组合措施时减振效果良好,减振后楼板中心的最大Z振级为73.15dB,减振量达13.54dB,满足振动舒适度要求。

考虑高阶振型效应的大跨度钢桁拱桥瑞利阻尼参数取值研究

为了解高阶振型效应对大跨度钢桁拱桥地震反应的影响机制,以及在采用直接积分法时构建合适的瑞利阻尼矩阵,以某490 m跨径钢桁拱桥为背景,采用SAP 2000软件建立全桥弹性动力计算模型。针对主拱圈上(下)弦杆轴力、弯矩,研究振型参与质量最大的7阶(第1、4、8、11、13、23、49阶)振型反应与总反应的占比关系,并对构建瑞利阻尼矩阵的特征频率选取方法展开研究。结果表明:主拱圈上、下弦杆拱脚区域的轴力主要由1阶振型(第1阶)控制,由拱脚向拱顶过渡,逐渐转变为由2~4阶振型控制,高阶振型效应显著;同一阶振型对主拱圈上、下弦杆轴力贡献率及分布规律的影响不同;对于复杂钢桁拱桥,采用振动方向上振型参与质量较大的2阶振型特征频率构建瑞利阻尼矩阵可能因高估了高阶振型阻尼比,导致除拱脚区域以外的拱圈弦杆杆件轴力计算结果偏小,结构偏于不安全;采用直接积分法对复杂钢桁拱桥进行地震反应分析时,建议选取多阶控制振型构建相应的瑞利阻尼工况,并对其计算结果取包络用于抗震设计。

基于三相桥光储一体系统的建模与控制

为解决光伏发电具有波动性且伴有“弃光”现象的问题,提出了一种基于三相桥的光储一体转换器拓扑结构及相关控制策略。该结构能够实现光伏电源、蓄电池、负载之间的功率流动,并具有LLC谐振变换器的软开关性质、高效率、输入电压范围适应性更宽、高功率密度等优点。在控制策略方面,采用带有复合反馈的电导增量法来实现最大功率点跟踪;为实现双向DC-DC变换器共用电感和直流母线电压稳定,采用双频率控制方法确定电感,并实现电压外环电流内环双闭环控制;为保证输出负载电压稳定,LLC谐振转换器采用电压闭环的调频控制。最后,搭建了光储一体系统仿真模型与实验平台,仿真与实验结果表明:提出的新型光储一体系统结构简单,可以稳定运行且易于实现。