• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.15 no.3
• /
• pp.409-420
• /
• 2002

This paper proposed a technique of structural re-analysis for the evaluation of dynamic responses of bridge structure under moving loads using experimental modal results. For successful structural re-analysis, it is required to have accurate estimation techniques of the modal characteristics of bridge structures. The natural frequencies and mode shapes were identified by direct fourier analysis techniques and damping ratios by the random decrement method, respectively. An interpolation method was also proposed for the extension of mode shape measured on limited DOFs. Second, the structural reanalysis was performed using moving mass model and identified modal parameters. The results from the reanalysis show that the proposed technique is very reasonable to evaluate the actual behavior of bridge structures under moving loads.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.11 no.2
• /
• pp.93-102
• /
• 2007

A large number of FRP decks are already in service worldwide because the lighter FRP-based bridge decks are ideal for rapid construction to reduce the dead load of superstructures. And the proper design process is demanded for the effective FRP deck application. In this paper, to get the basic prototype of FRP bridge decks, the ratio of individual parameters, which compose the specification of FRP bridge decks, are determined by a finite element analysis. In addition, optimum FRP deck shapes are determined considering complex constraints and material properties of bi-directional characteristics. Upon these results, the prototype of FRP bridge decks is validated.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.10 no.4 s.50
• /
• pp.77-84
• /
• 2006

Recently, as large structures such as high-rise building and long span bridge become lighter and more flexible, the necessity of structural control for reducing excessive dynamic response due to seismic excitation is increased. In this study, a semi-active base isolation system using Magneto-Sensitive (MS) rubbers is proposed to effectively protect structures against earthquakes. MS Rubber is a class of smart controllable materials whose mechanical properties change instantly by the application of a magnetic field. To demonstrate the performance of this device, the MS Rubber isolation system is compared to Lead-Rubber Bearing (LRB) isolation systems and judged based on computed responses to several historical earthquakes. The MS Rubber isolation system is shown to achieve notable decreases in base drifts over comparable passive systems with no accompanying increase in base shears or in accelerations imparted to the superstructure. The proposed MS Rubber system is shown to perform better than the passive isolation system.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.04a
• /
• pp.221-224
• /
• 2008

Recently various types of prefabricated pier has been developed. In this paper, prefabricated composite columns with core steel elements embedded in concrete were proposed, which has no prestressing. Based on the previous research on composite columns with low steel ratio, the column were designed. A simple bolt connection detail between a footing and a pier element were also suggested. In order to investigate the seismic performance of the composite columns, several tests on concrete encased composite columns, which are prefabricated, were performed. Quasi-static tests were carried out and their performance was evaluated and compared with the results from the tests on CIP composite piers. In the case of precast piers, the end part of the pier needs to be carefully reinforced and related recommendations on details were derived.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.13 no.2
• /
• pp.51-59
• /
• 1993

This paper develops practical and realistic reliability models and methods for the evaluation of system-reliability and system reliability-based rating of various types of box-girder bridge superstructures. The strength limit state model for box-girder bridges suggested in the paper are based on not only the basic flexural strength but also the strength interaction equations which simultaneously take into account flexure, shear and torsion. And the system reliability problem of box-girder superstructure is formulated as parallel-series models obtained from the FMA(Failure Mode Approach) based on major failure mechanisms or critical failure states of each girder. In the paper, an improved IST(Importance Sampling Technique) simulation algorithm is used for the system reliability analysis of the proposed models. This paper proposes a practical but rational approach for the evaluation of capacity rating in terms of the equivalent system-capacity rating corresponding to the estimated system-reliability index which is derived based on the concept of the equivalent FOSM(First Order Second Moment) form of system reliability index. The results of the reliability evaluation and rating of existing bridges indicate that the reserved reliability and capacity rating at system level are significantly different from those of element reliability or conventional methods especially in the case of highly redundant box-girder bridges.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.3C
• /
• pp.149-158
• /
• 2008

This study is concerned with the characteristics of the behavior of drilled shafts with steel casing, a material that is used for large bridge foundations in Korea, and especially for weak submerged ground conditions. The effect of steel casing on bearing capacity of drilled shafts was also verified in this study. Three large drilled shafts with 1.8, 2.4, 3.0m diameter respectively were selected, and 3-D finite element analysis has been undertaken on the following three models: 1) drilled shafts without steel casing, 2) drilled shafts with steel casing, 3) steel-concrete composite drilled shafts. Interface element between concrete core and steel casing was taken into account, and ground conditions and load combinations were applied which had been considered in the fields. Detailed characteristics of the stress and displacement distributions were evaluated to understand the characteristics of the behavior of the drilled shafts. Based on the study performed, the steel casing used as load-carrying materials in the drilled shafts can reduce the horizontal and vertical displacement of drilled shafts by 32~37% and 15~19% respectively compared with drilled shafts without steel casing.

• Journal of Korean Society of Steel Construction
• /
• v.27 no.2
• /
• pp.195-205
• /
• 2015

The rahmen bridge is well known common type of bridge in which all members are connected rigidly. The rahmen bridge is built for several situations because it has many advantages such as no need of bridge bearing system, easy of maintenance, reduction of the cross-sectional area of superstructure, and relatively low construction cost compared with other bridge types. Recently, to lengthen the span of rahmen bridge system, steel-concrete composite beam is used for superstructure of rahmen bridge instead of normal concrete girder with slab. However, member forces are increased because of extension of span length of superstructure and substructure is designed and constructed inefficiently when steel-concrete composite rahmen bridge is designed. In this study, new-type steel-concrete composite bridge is suggested. New-type steel-concrete composite rahmen bridge is adopted hinge connection between abutment and foundation for the reduction of the bending momemt at the foundation. In this study, we present the results of experiment conducted to estimate the load carrying capacity of new-type steel-concrete composite rahmen bridge and the structural characteristics of hinge connection.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.5
• /
• pp.502-509
• /
• 2019

Studies have been made on performance evaluation of expansion joint systems for an ordinary highway or road bridge. However little study has been made for runway connection bridges at airports. A study on performance evaluated from computer code analysis and shrinkage, extension, and compression repetition tests based on KS F 4425 is conducted to a newly developed expansion joint system which has been installed in a runway connection bridge at Incheon Airport Extension 2 Construction Site. The MIDAS computer code is used to analyze the performance before the manufacture of the mock-up of expansion joint system on the basis of design requirements. Tests based on the KS F 4425 of 2001 year-version are conducted for the mock-up. Domestic codes and standards to validate the performance of the expansion joint system in a connection bridge have been developed for a vehicle. However the expansion joint system tested in this study is installed in a runway connection bridge for an aircraft. Conservatively the heaviest one among airplanes departing and landing at Incheon Airport is assumed level-F $468.4kN/m^2$ and adopted for the tests and analyses in this study. KS F 4425 method is selected for the shrinkage, extension, and compression repetition tests. No remarkable problem was observed for the 2,500-cycle shrinkage and extension and two million-cycle repeatition load tests. The results of this study are expected to contribute to establishment of code and standard for the performance validation of an expansion joint system installed in a runway connection bridge for an aircraft by providing performance test results and computer analysis results based on finite element methods.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.12 no.2
• /
• pp.33-44
• /
• 2008

Most of the civil structure - bridges, offshore structures, plant, etc. - have been designed by the classical approaches which deal with all the design parameters as deterministic variables. However, some more advanced techniques are required to evaluate the inherent randomness and uncertainty of each design variable. In this research, a seismic safety assessment algorithm based on the structural reliability analysis has been formulated and computerized for more reasonable seismic design of turbine-generator foundations. The formulation takes the design parameters of the system and loading properties as random variables. Using the proposed method, various kinds of parametric studies have been performed and probabilistic characteristics of the resulted structural responses have been evaluated. Afterwards, the probabilistic safety of the system has been quantitatively evaluated and finally presented as the reliability indexes and failure probabilities. The proposed procedure is expected to be used as a fundamental tool to improve the existing design techniques of turbine-generator foundations.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.11
• /
• pp.716-723
• /
• 2016

A computerized information management system of road bridges as a national key infrastructure is needed to effectively collect data of the current status, improve the reliability of data, and use the results from the analysis of the accumulated data as fundamental resources for supporting the establishment of policies. The Internet-based Bridge Information System (BIS), including a database and geographic information systems (GIS), was designed, and the data items were comprised of essential information, such as GIS-based location coordinates, bridge condition grade information and so on. The BIS was developed to be connected with a related information system, and it is possible to make the current information of traffic volume, address and so on by adopting the GIS. To enhance the reliability of the information of current bridge status, it is also possible to improve the accuracy of data through an information verifying function to prevent entry errors. In addition, the BIS can easily support the establishment of policies offering various types of knowledge information that were available in the past based on an analysis of the accumulated data. The intuitive identification and analysis of the current status is to be feasible through a GIS screen. Improvement of the business efficiency and data accuracy and time-series information analysis are available by managing the information of current status through BIS. In the future, it is expected that BIS can be used effectively for the establishment of reasonable maintenance policies of the nation.