Grand Bridge Research Articles

Life-cycle CO2 emissions and influential factors for asphalt highway construction and maintenance activities in China

ABSTRACTThis study tried to clarify the magnitude of CO2 emissions from highway construction and maintenance in China through life cycle assessment (LCA) method. For this, 227 real highway projects constructed from the year 2000 to 2011 in Zhejiang Province, China are classified into six types by two categories of N road (62 projects without grand bridge, great bridge and tunnel) and Y road (165 projects with the same road structures) and three sub-categories of (i) newly constructed road, (ii) replacing pavement road and (iii) full rehabilitated road. Significant influential factors of LCA results were revealed through multivariate linear regression models, combined with data quality assessment and sensitivity analysis. Numerical interval of assessment results indicate that the construction emissions of N highway project are more centralized to no more than 2900 t/lane-km, while Y project have a normal upper boundary of construction CO2 emissions, about 5000 t/lane-km. The contribution of maintenance to CO2 emissions probably could exceed that of newly construction both for Y project and N project. In addition, the pavement replacing and rehabilitation could bring about large amount of CO2 emissions which even match with the CO2 emissions from cumulative traffic volume during highway's life cycle. There are common factors for six categories. Cement and steel are the top largest CO2 emissions contributors and sensitive factors for N road and Y road. The LCA results are not sensitive to the local construction materials but sensitive to the emission factor of diesel used in transportation and on-site construction.

Development of a High Precision Displacement Measurement System by Fusing a Low Cost RTK-GPS Sensor and a Force Feedback Accelerometer for Infrastructure Monitoring.

A displacement measurement system fusing a low cost real-time kinematic global positioning system (RTK-GPS) receiver and a force feedback accelerometer is proposed for infrastructure monitoring. The proposed system is composed of a sensor module, a base module and a computation module. The sensor module consists of a RTK-GPS rover and a force feedback accelerometer, and is installed on a target structure like conventional RTK-GPS sensors. The base module is placed on a rigid ground away from the target structure similar to conventional RTK-GPS bases, and transmits observation messages to the sensor module. Then, the initial acceleration, velocity and displacement responses measured by the sensor module are transmitted to the computation module located at a central monitoring facility. Finally, high precision and high sampling rate displacement, velocity, and acceleration are estimated by fusing the acceleration from the accelerometer, the velocity from the GPS rover, and the displacement from RTK-GPS. Note that the proposed displacement measurement system can measure 3-axis acceleration, velocity as well as displacement in real time. In terms of displacement, the proposed measurement system can estimate dynamic and pseudo-static displacement with a root-mean-square error of 2 mm and a sampling rate of up to 100 Hz. The performance of the proposed system is validated under sinusoidal, random and steady-state vibrations. Field tests were performed on the Yeongjong Grand Bridge and Yi Sun-sin Bridge in Korea, and the Xihoumen Bridge in China to compare the performance of the proposed system with a commercial RTK-GPS sensor and other data fusion techniques.

Multifunctional Robotic Crawler for Inspection of Suspension Bridge Hanger Cables: Mechanism Design and Performance Validation

This paper presents a robotic system, called multifunctional robotic crawler for cable INspection II, which is developed for inspection of hanger cables of suspension bridges. The robot can move over hanger cables and perform inspections with instruments such as cameras, nondestructive testing tools, etc. The novel mechanisms for the robotic system are proposed under the consideration of the environmental conditions of suspension bridges. Its driving mechanism adopts a crawler type one driven by brushless direct current motors, and the detachable adhesion tool ensures simple and quick installation procedures. The safe-landing mechanism for emergency situations guarantees the retrieval of the robot while preserving the safety of operators. This paper presents the robot system and its field test results under a super long-span suspension bridge, called Yeong-Jong Grand Bridge in South Korea. For practical applications, the real environmental conditions of a suspension bridge and the other fields where the robot can be applied are discussed.

Mammalian Status of Mt. Cheomchalsan in Jindo, Korea

In order to analyze a status of animal in an area where has been became a land cause of Jindo Grand Bridge established on Jindo island area, mammal status in the biggest mountain in Jindo province, Mt. Cheomchalsan has been investigated for four times from May to October of 2016. According to the investigation, 5 orders, 9 families and 15 species of inhabitation was confirmed, and water deer (Hydropotes inermis), raccoon (Nyctereutes procyonoides), cat (Felis catus), and etcetera were dominant. Biodiversity and evenness index were likely to be high as 2.24 and 0.83, respectively and it is considered that favorable condition of natural ecosystem for inhabitation of mammalian is established. Meanwhile, since the cat designated as control species is confirmed as a dominant species, it is supposed that continuous management is necessary.

Optimized Prestressed Continuous Composite Girder Bridges with Corrugated Steel Webs

AbstractThis paper proposes different optimization schemes for enhancing the performance of conventional continuous composite girder bridges with corrugated steel webs. In particular, for the positive moment region, the substitution of a ribbed steel plate for the reinforced concrete bottom flange is proposed for optimizing such bridges. Three-dimensional finite-element analysis was used to preliminarily validate this optimization scheme based on the background project, Dongbaohe Xinan Grand Bridge. An experimental study revealed that the optimization scheme can afford advantages, such as reduced self-weight, avoidance of cracking in the bottom flange, and convenient construction. If the steel plate with proper thickness is used, higher flexural stiffness and load capacity can be achieved as additional advantages due to the enhanced steel ratio of the cross section. For the negative moment region of the bridge, the optimization scheme was implemented in two parts identified as Optimization Schemes I and I...

Development of a “stick-and-detect” wireless sensor node for fatigue crack detection

A fatigue crack and its precursor often serves as a source of nonlinear mechanism for ultrasonic waves, and nonlinear ultrasonic techniques have been widely studied to detect fatigue crack at its very early stage. In this study, a wireless sensor node based on nonlinear ultrasonics is developed specifically for fatigue crack detection: (1) through packaged piezoelectric transducers, ultrasonic waves at two distinctive frequencies are generated, and their modulation due to a microcrack (less than 0.1 mm in width) is detected; (2) an autonomous reference-free crack detection algorithm is developed and embedded into the sensor node, so that users can simply “stick” the sensor to a target structure and automatically “detect” a fatigue crack without relying on any history data of the target structure; and (3) the whole design of the sensor node is fulfilled in a low-power working strategy. The performance of the sensor node is experimentally validated using aluminum plates with real fatigue cracks and compared with that of a conventional wired system. Furthermore, a field test in Yeongjong Grand Bridge in South Korea has been conducted with the developed sensor nodes.

Development and field application of a nonlinear ultrasonic modulation technique for fatigue crack detection without reference data from an intact condition

In this study, a fatigue crack detection technique, which detects a fatigue crack without relying on any reference data obtained from the intact condition of a target structure, is developed using nonlinear ultrasonic modulation and applied to a real bridge structure. Using two wafer-type lead zirconate titanate (PZT) transducers, ultrasonic excitations at two distinctive frequencies are applied to a target inspection spot and the corresponding ultrasonic response is measured by another PZT transducer. Then, the nonlinear modulation components produced by a breathing-crack are extracted from the measured ultrasonic response, and a statistical classifier, which can determine if the nonlinear modulation components are statistically significant in comparison with the background noise level, is proposed. The effectiveness of the proposed fatigue crack detection technique is experimentally validated using the data obtained from aluminum plates and aircraft fitting-lug specimens under varying temperature and loading conditions, and through a field testing of Yeongjong Grand Bridge in South Korea. The uniqueness of this study lies in that (1) detection of a micro fatigue crack with less than 1 μm width and fatigue cracks in the range of 10–20 μm in width using nonlinear ultrasonic modulation, (2) automated detection of fatigue crack formation without using reference data obtained from an intact condition, (3) reliable and robust diagnosis under varying temperature and loading conditions, (4) application of a local fatigue crack detection technique to online monitoring of a real bridge.

Estimation of Extreme Wind Speeds in Korean Peninsula using Typhoon Monte Carlo Simulation

국내 서해대교, 인천대교와 같은 장대교량은 대부분 빈번하게 태풍에 의해 영향을 받는 해안에 위치하였으며, 교량의 길이가 긴 만큼 풍하중에 의한 영향이 다른 하중에 비해 상대적으로 크기 때문에 내풍 안정성을 확보하기 위해 정확한 설계풍속을 산정하는 것이 매우 중요하다. 본 연구에서는 태풍의 기후학적 특성 인자로 중심기압깊이, 태풍이동속도, 태풍이동방향, 최단접근거리를 결정하였으며, 태풍의 기후학적 특성들의 확률 분포를 추정하고, 바람장 모형과 중심기압상승 모형을 적용하여 몬테카를로 시뮬레이션을 실시하였다. 분석결과, 대체적으로 제주도와 남해안 지역의 재현기간 풍속이 크게 나오며 고위도로 갈수록 작아지는 특징을 나타냈다. 이와 같은 특징이 나타난 가장 큰 원인은 고위도 분석지점 표본 태풍의 중심기압이 저위도 분석지점 표본 태풍의 중심기압보다 높기 때문으로 판단되며, 또한 우리나라에 해상에서 육지로 이동하면서 쇠퇴기를 겪어 점차 약해지기 때문인 것으로 분석되었다. 또한, 시뮬레이션 결과를 도로교 설계기준 100년 재현기간 풍속(10분 평균, 지상 10m, 지표조도 II)과 비교한 결과, 태풍시뮬레이션의 결과가 낮게 나타났으며, 이러한 점을 볼 때 도로교 설계기준의 기본 풍속이 높게 산정되어 있다고 판단되며, 기상자료 분석과 같은 추가적인 연구를 통해 기본풍속 조정에 대한 연구가 수행 되어야 할 것으로 사료된다. The long-span bridges such as Incheon Bridge and Seohae Grand Bridge are located on the coastal region effected frequently by strong wind of typhoons. In order to ensure the wind-resistant performance of the structure, estimation of the proper design wind speed is very important. In this study, stochastic estimation of design wind speed incurred by typhoons is carried out. For this purpose, we first established probability distribution of climatological parameters such as central pressure depth, distance of closest approach, translation speed and heading to build statistical model of typhoons, which are employed in Monte Carlo simulation for hypothetical typhoons. Once a typhoon is generated with statistically justified parameters, wind speeds are estimated along its path using wind field model. Thousands of typhoons are generated and their peak wind speeds are utilized to establish the extreme wind speeds for different return period. The results are compared with design basic wind speeds in Korean Highway Bridge Design Code, showing that the present results agree well with similar studies while the existing code suggests higher design wind speed.

Real-time Semi-active Vibration Control in Cable-stayed Bridges by Shear-type MR damper and Clipped-optimal Control Algorithm

This paper is concerned with an experimental research to control of random vibration caused by external loads specially in cable-stayed bridges which tend to be structurally flexible. For the vibration control, we produced a model structure modelled on Seohae Grand Bridge, and we designed a shear type MR damper. On the center of its middle span, we placed a shear type MR damper which was to control its vibration and also acquire its structural responses such as displacement and acceleration at the same site. The experiments concerning controlling vibration were performed according to a variety of theories including un-control, passive on/off control, and clipped-optimal control. Its control performance was evaluated in terms of the absolute maximum displacements, RMS displacements, the absolute maximum accelerations, RMS accelerations, and the total power required to control the bridge which differ from each different experiment method. Among all the methods applied in this paper, clipped-optimal control method turned out to be the most effective to reduces of displacements, accelerations, and external power. Finally, It is proven that the clipped-optimal control method was effective and useful in the vibration control employing a semi-active devices such MR damper.

Mathematical Modelling Of The Bridges Structural Monitoring II

Abstract We have seen in the previous paper that in the case of resistance elements made of steel, at least in this case study, the structure’s response to strains, in this case sunshine, is uncertain, may or may not be linear. The analysis continues for the four characteristic months of 2013, respectively the second month (February), the fifth (May), the eighth (August) and the event (November), covering the four seasons and approximately the entire range of temperatures to which the resistance elements of the bridge are subject to along a calendar year - case study Incheon Grand Bridge, Seoul, South Korea. The number of data pairs recorded, as we have noted, every 15 minutes, is initially 11,616, being difficult to process. Some software (e.g. Table Curve 2D) can work with a maximum of 3000 data pairs. In what follows we will examine the behaviour of a reinforced concrete element of the North Bridge Gap front line and we will build a mathematical model of its behaviour to sunshine, from the input data, one recording every hours, thus reducing the number of measurements to 2904. The aim is to obtain a mathematical model with a correlation coefficient above 0.9, which is also verified and validated. This model will allow us to calculate the expected position of the sensor mounted on the resistance element for a certain temperature, the degree of confidence of the result, the interval of residual values. Because the history of the evolution of temperatures for each moment analyzed is different it produces different results, but ones that fit the specified regressive mathematical model.

Mathematical Modelling Of The Bridges Structural Monitoring I

Abstract Structural Health Monitoring is an extremely complex and relatively expensive activity, and the current offer of tools, methods and technologies is varied, which can lead to a virtually high number of structural monitoring systems that can be customized for each case. In time, the monitoring of bridges became the engine for the development of SHM tools, methods and technologies, or manager monitoring systems. The case study, in continuous quasi-static condition, was performed on Incheon Grand Bridge South Korea. Tracking the behaviour of an objective under the influence of sunshine is performed by VCE Vienna Consulting Engineers ZT GmbH. This paper presents the effect of sunshine on a steel structural element, the first lamella front North line, by comparing data pairs that reflect the cause: steel temperature and the effect: the movement of a sensor mounted on the structural element. The analysis was performed using several software dedicated to mathematical modelling, trying to establish different mathematical models that can be tested and validated.

The Key Measures on Safety and Linear Control in Catwalk Erection

Multiple factors affect internal force and linear of catwalk, meanwhile, there are many safety and quality risks caused by these factors during its erection. So the control of the catwalks during its erection is very important. Based on the Puli grand bridge, the key control technology of catwalks erection is studied in this paper . The unstressed length of track cable in catwalks and the ultimate unbalance horizontal force on top of bridge tower during erection are calculated, which are part of precondition for safety control. The effects of temperature and tower deviation, which are main factors influenced the linear of catwalk track rop, are analyzed in this paper. Then the safety and linear control measures are put forward. The construction result shows that the safety control methods and linear adjustment measures are effective.

Evaluation on Risk for Ship Collision with Archbridge and Crash Capability of Anti-Collision

The development of the highway traffic has promoted the construction of increasing numbers of river-crossing bridges, but at the same time, large-size ship causes serious threat to structural safety of the bridge. The probability of bridge-ship collision increases, water safety accidents have happened frequently in the recent years. Arch bridge is easier to be subjected to the threat of ship collision because of small navigation clearance on both sides. However, study on the destructive consequences by ship impact on arch bridge is seldom. This paper takes reinforced concrete arch bridge as an example, on the basis of the forecast of the water-level frequency, flow velocity and long-term navigation density of the ship, the ship collision probability on different parts of the arch ring at different water levels are analyzed to deduce the annual collapse frequency of the grand bridge. The risk matrix evaluation result shows that there is medium risk in long-term. The establishment of finite element numerical model concludes the energy absorption and the change process when the arch ring suffers from collision from the ship under different working conditions as well as the relationship among the impact force, crown displacement and collision depth along with time change. According to the result of simulated analysis, the maximum collision force of the main arch ring suffered from the ship is 25.9MN, and the resistance of the main arch ring is 33.6 MN, so the existing structure basically meets the requirement for fortification against the ship collision. The numerical simulation results are qualitatively consistent with the risk of evaluation. The results of the analysis can provide scientific foundation to the maintenance and management of the arch bridge.

Reliability Assessment of Tie-Down Cables for Cable-Stayed Bridges Subject to Negative Reactions: Case Study

Abstract This paper presents a reliability assessment for tie-down cables of cable-stayed bridges subject to negative reactions. The advanced first-order second-moment reliability method (AFOSM) is used to evaluate the reliability indexes. The strength of a tie-down cable and load parameters are selected as random variables. A Newton-type solution scheme with double iteration loops is used to solve the minimization problem defined in the AFOSM. Reactions at supports are calculated through the stiffness equation formed by a finite-element model, and the sensitivities of the reactions with respect to the random variables are obtained by the direct differentiation of the stiffness equation. The reliability indexes of the tie-down cables are evaluated for two cable-stayed bridges in service in Korea: the Second Jindo Grand Bridge and Incheon Grand Bridge. Three limit states on the pretension, required strength, and design strength are considered for the load combination of the Strength I limit state in LRFD b...

Study on Cable Forces in Cable-Stayed Bridges Based on Forward Simulation Method

According to cable tension calculation of cable-stayed bridge on construction, and combining with the example of Xinzao Pearl River Grand Bridge, this work proposes forward-calculation method to analyze cable tension force on construction and establishes geometric calculation simulation model to compare measured cable tension with theoretical cable tension. This paper introduces some kinds of methods calculating cable tension force on construction. It importantly discusses the principle and method of forward-calculation and the practical application in the actual project. Spacial finite element model is established for analysis based on finite element software MIDAS and the application of forward-analysis iterative method is considered to analyze the cable tension on construction , then the method of determining cable force on construction is explored. Finally the result shows that the cable tension based on forward-calculation method is usually accurate, the measured value is approximately equal to the theoretical value and the error is in the extent permitted. The correctness and reliability of the frequency method is effectively confirmed and the cable tension calculation of the similar bridge on construction is compatibly applied.

Discussion on the Measurements in Cantilever Construction with Guyed Hanging Basket

Guyed hanging basket is qualified with reasonable structure , great carrying ability and clear construction process, and also can provide a good operating space for beam segment construction. Applying cantilever pouring construction with guyed hanging basket should be the development direction of the construction of large-span reinforced concrete cable-stayed bridge. By taking the girder construction of the grand bridge over Beijing-Hangzhou Canal as an example, this paper introduces the measurements in cantilever construction with guyed hanging basket, aiming at providing reference for other similar projects.

제주 팽림월대(彭林月臺)의 경관특성 및 관리방안

제주 팽림월대(彭林月臺)의 경관특성 및 관리방안

비선형 FEM 해석을 이용한 기존 강재 주탑기부 설계의 개선방안 연구

본 연구에서는 강주탑 기부와 기초콘크리트 연결 구조에 대해서 국내에서 특수교량의 강주탑 기부 설계에 보편적으로 적용하고 있는 명석해협대교(明石海峽大橋) 시방기준과 비선형 FEM 해석결과를 비교하였다. 명석해협대교(明石海峽大橋) 시방기준은 1970년도에 만들어진 일본 기준으로 주탑 기부와 PS 강봉 및 기초콘크리트를 스프링으로 선형 모델링하여 설계하는 방법으로서 43년이 지난 지금까지도 간편성을 이유로 이 기준을 적용하고 있다. 그러나 비선형 FEM 해석결과의 비교를 통해 특수 장대교의 강주탑 기부의 해석 및 설계에 이 기준을 적용하는 것은 여러 가지 문제점이 있음을 알 수 있었으며, 풍하중, 지진하중에 주요하게 저항하면서도 다양한 부재들로 복잡하게 연결된 강주탑 기부에 대해서는 한계상태설계법으로 발전하려는 현 시대에 맞추어 실제 거동을 반영하는 비선형 FEM해석을 적용해야 할 것이다. In this study nonlinear FEM analysis for steel pylon base of a cable supported bridge is performed in order to compare the results of Akashi-Kaikyo bridge's design specification established in 1970. Due to convenience of its application, the Akashi grand bridge's design specification has been applied to the base design of cable stayed bridges. It has been using linear spring in order to model prestressed high tensioned bars between steel pylon bottom plates and the base concrete. However, the results of nonlinear FEM analysis revealed that the Akashi-Kaikyo bridge's design specification has various problems in the analysis of the steel pylon base. And the steel pylon base has various complex members connecting with each other, and it is main member to resist against the wind load or the earthquake load. Therefore, the nonlinear FEM analysis has to be conducted in order to predict the behavior of steel pylon base exactly. Also, the nonlinear FEM analysis is more reasonable for the load and resistant factor design.

Wireless health monitoring of stay cable using piezoelectric strain response and smart skin technique

In this paper, wireless health monitoring of stay cables using piezoelectric strain sensors and a smart skin technique is presented. For the cables, tension forces are estimated to examine their health status from vibration features with consideration of temperature effects. The following approaches are implemented to achieve the objective. Firstly, the tension force estimation utilizing the piezoelectric sensor-embedded smart skin is presented. A temperature correlation model to recalculate the tension force at a temperature of interest is designed by correlating the change in cable's dynamic features and temperature variation. Secondly, the wireless health monitoring system for stay cables is described. A piezoelectric strain sensor node and a tension force monitoring software which is embedded in the sensor are designed. Finally, the feasibility of the proposed monitoring technique is evaluated on stay cables of the Hwamyung Grand Bridge in Busan, Korea.

장경간 강바닥판 교량용 에폭시 아스팔트 혼합물의 적용성 평가

The main objective of the research is to evaluate the laboratory performances of epoxy asphalt mixtures for long-span steel bridge decks. The aggregate gradations were recommended for field applications. The laboratory performance test results showed that the durability of epoxy asphalt mixtures was more noticeable than that of conventional ones. The structural analysis was conducted using resilient modulus and bond-shear test results. The analysis results revealed that just 9% out of total bond-shear stress was enough for the entire required bond-shear stress in the pavement system. The tensile stresses in the bridge decks were within limits compared to the laboratory test results from the Nanjing Grand Bridge in China. As a result, the laboratory performances of the epoxy asphalt mixtures for long-span steel bridge decks were better than those of conventional asphalt mixtures. However, the laboratory performance tests of epoxy asphalt mixtures for long-span steel bridge decks should be conducted precisely since the strengths of the mixtures are sensitive to the temperatures and curing times.