• Journal of the Korea institute for structural maintenance and inspection
• /
• v.18 no.6
• /
• pp.147-154
• /
• 2014

The cable damages of the bridge structures induce very important impact on the structural safety, which implies the close monitoring of the cable damage is required to secure sustained safety of the bridges. Most usual available maintenance techniques are based on the monitoring the change of the natural frequency of the structures by damages. However, existing method are based on vibration method to calculate lateral vibration and system identification can calculate the axial stiffness using sensitivity equation by trial error method. But the frequency study by the longitudinal movement need because of the sag effect in system identification. This study proposes a new method to investigate the damage magnitudes and status. The method improves the accuracies in the magnitudes and status of damages by adopting the natural frequency of longitudinal movement. The study results have been validated by comparing them with the approximate solution of FEM. Thus, the relationship of cable damage and frequency appear with relation that the severe damage has the little frequency. If we know the real frequency we can estimate the cable damage severity using this relationship. This method can be possible the efficient management of the cable damage.

• Journal of Korean Society of Steel Construction
• /
• v.19 no.3
• /
• pp.313-321
• /
• 2007

The study discussed in this paper presents a method of estimating sources of geometric errors in suspension bridges in use, based on geometric survey data. A geometric error is defined as the difference between the survey data and the design geometry of a main cable. It is assumed that the geometric error in a suspension bridge is caused by the variations in the weight of the stiffening girder and the deformation of the anchorage foundations due to the creep of soil. The variations in the girder weight and the deformation of the foundation were estimated by constructing a matrix of factors that affect suspension bridges due to the variations. To check the validity of the proposed method, it was applied to the Kwang-An Bridge, and the sources of geometric errors in the bridge were estimated using the survey data.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2009.09a
• /
• pp.545-553
• /
• 2009

A lot of long-span marine bridge, which connects land to island or island to island, are being designed and constructed lately in south-west coast in South Korea. In the past, caisson foundations in marine were mainly adopted in construction and stability aspect, however, nowadays with development of pile construction technology, drilled shaft foundations are mainly adopted. As the long span cable stayed bridge and suspension bridge applied with lots of loads are being designed, the scale of pile foundations are getting larger. As the construction cost of substructure including foundation in marine bridges is too high, the appropriate evaluation of the axial bearing capacity of pile becomes a core factor to decide the construction cost of foundation if the drilled shaft is adopted as foundation type of bridge. The evaluation values of skin friction and end bearing capacity of drilled shaft in weathered rock suggested in south Korea are only to introduce the foreign specifications, and most of them are designed in a kind of hard soil layer. Also the allowable load of pile section is less than the expected bearing capacity of pile in the soil condition since the allowable capacity of pile is undervalued. Recently in order to improve this factor the bi-axial hydraulic load test of pile was taken, the data of load transfer analysis of pile, unit of skin friction and end bearing capacity are accumulated. In our country, the design of piles are made with ASD, however, LRFD considering service, strength and extreme state was adopted in Incheon Grand Bridge implemented with BTL, and the research to systematize the resistance coefficient appropriate at home country are being progressed.

• Journal of Korean Society of Steel Construction
• /
• v.20 no.1
• /
• pp.93-104
• /
• 2008

study deals with the reliability assesment for the 5-year phases of a suspension bridge construction in Korea. The main objectives of this study are; (1) the evaluation of the reliability of a suspension bridge by considering an ultimate limit state for the fracture of main cable wires, (2) the determination of the critical phases among 28 construction stages for the deck erection, and (3) the evaluation of the reliability of the limit state for the erection control during construction stages. The research and the design of the suspension bridge have been focused on the state of construction mainly based on empirical data. Based on the recent survey of the distribution of accidents in Korean railways, over 80% of the accidents related to the uncertainties in human error, planning, design, materials and loads during construction have ben reported before the completion of construction. While many researches have evaluated the safety of bridges, the uncertainties in the construction phases have not been well treated in a guidelines or a specifications. An improved adaptive response surface method is used for the risk assessment in the construction phases of the target suspension bridge.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.36 no.1
• /
• pp.49-56
• /
• 2023

With the development of technology worldwide, bridges are becoming larger, and the number of old bridges is also rapidly increasing. Monitoring the structural health of large, aging bridges is essential to preventing large-scale accidents. In this study, the application of a LoRa low-power wide-area network (LPWAN)-based wireless measurement system was investigated, and a LoRa wireless measurement system was established in the cable-stayed bridge section of Cheonsa Bridge, located in Shinan-gun, Jeollanam-do, Korea. The applicability of the LoRa LPWAN-based wireless monitoring system to large marine bridges was reviewed by comparing the performance and economic feasibility with wire-based monitoring systems that were built and operated by establishing a measurement system for the pylons, cables, and reinforcing girders of the bridge.

• Journal of Korean Society of Disaster and Security
• /
• v.16 no.4
• /
• pp.129-136
• /
• 2023

A special offshore bridge with a high pylon has special structural features.Special offshore bridges have inspection blind spots that are difficult to visually inspect. To solve this problem, safety inspection methods using drones are being studied. In this study, image data of the pylon of a special offshore bridge was acquired using a drone. In addition, an artificial intelligence algorithm was developed to detect damage to the pylon surface. The AI algorithm utilized a deep learning network with different structures. The algorithm applied the stacking ensemble learning method to build a model that formed the ensemble and collect the results.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.12 no.1
• /
• pp.117-126
• /
• 2008

In this paper, it is presented a digital image processing method and the program (Visual C++) to determine the shape of the suspension bridge. To investigate the precision of this method, a suspension bridge is divided into 5, 13 and 19 images, respectively, by using the 6.3M pixels digital camera with 300mm zoom lens. Obtained results of the Kwang-Ahn Grand Bridge by using this method are fairly close to the real precision surveyed data. The accuracy is more improved by increasing the number of divided images of the structure. The total cost, man power and time of field survey by this method presented in this study could be much more reduced and the developed program could be applied with little modification for other structures like cable-stayed bridges, if lens compensation algorithms and program access capabilities are improved.

• Journal of the Korea Concrete Institute
• /
• v.24 no.4
• /
• pp.453-463
• /
• 2012

Steel-concrete composite rigid-frame bridge is a type of integral bridge having advantages in bridge maintenance and structural efficiency from eliminating expansion joints and bridge supports, the main problems in bridge maintenance. The typical steel-concrete composite rigid-frame bridge has the girder-abutment connection where a part of its steel girder is embedded in abutment for integrity. However, the detail of typical girder-abutment connection is complex and increases the construction cost, especially when a part of steel girder is embedded. Recently, a new type of bridge was proposed to compensate for the disadvantages of complex details and cost increase. The compensation are expected to improve efficiency of construction by simplifying the construction detail of the girder-abutment connection. In this study, a static load test has been carried out to examine the behavior of the girder-abutment connection using real-scale specimens. The results of the test showed that the girder-abutment connection of proposed girder bridge has sufficient flexural capacity and rebars to control concrete crack should be placed on the top of abutment.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.15 no.2
• /
• pp.153-160
• /
• 2011

Recently there are many long span cable supported bridges like Cable Stayed Bridge and Suspension Bridge already constructed or planned. Reconsidering of proper design wind load of long span bridge is required since the meteorological value based on the data only from 1960s to 1995 has been used when we estimate the wind load for designing long span bridges. In this paper, the research area was confined to western and southern coasts where many long span bridges have constructed. The method of moment and the least-squares method were used to estimate the expected wind speeds of 100 year's return period for girder bridges and for 200 year's return period for long span bridges based on the Gumbel's distribution. As the return-period wind speed on the land face was revised because of recent high speed velocity, the revised return-period wind speed is increased by 17%. Compatibility of return-period wind speed was also evaluated using RMS (Root Mean Square) error method. Aa a result of this paper, the least-squares method is more compatible than the method of moment in the case of western and southern coasts in Korea.

• Journal of Korean Society of Steel Construction
• /
• v.10 no.3 s.36
• /
• pp.369-381
• /
• 1998

This paper is intended to show some new approaches and concepts for the development of system model and prototype software for computer-aided Monitoring and Assessment(M&A) of grand bridges. The system model that incorporates optimal strategies for M&A of grand bridges is suggested. Reliability models are developed and a reliability-based capacity rating method is established for the evaluation of the bridge safety and reliability based on the real responses measured from a series of field load tests. Based on the proposed models, an integrated prototype software is then developed for computer-aided M&A of grand bridges under the environment of the graphic user interface, which is successfully applied to the M&A of an existing cable-stayed bridge. It may be stated that the system model and prototype software developed in this paper can be utilized and implemented in the development of the computer-aided M&A system for cable-stayed and suspension bridges.