Dong-Jun Lee

Dynamic Analysis of PSC Bridge for a High-Speed Railway Vehicle Using Improved 38-Degree of Freedom Model

A dynamic analysis procedure is developed to provide a better estimation of the dynamic responses of pre-stressed concrete (PSC) box girder bridges on the Korea high speed railway. Particularly, a three dimensional numerical model including the structural interaction between high speed vehicles, bridges and railway endures to analyze accurately and evaluate with in-depth parametric studies for dynamic responses of bridge due to the high speed railway vehicles. Three dimensional frame element is used to model the PSC box girder bridges, simply supported span lengths 40 m. The high-speed railway vehicles (K-TGV) including a locomotive are used as 38-degree of freedom system. Three displacements (vertical, lateral, and longitudinal) as well as three rotational components (pitching, rolling, and yawing) are considered in the 38-degree of freedom model. The dynamic analysis by Runge-Kutta method which are able to analyze considering the dynamic impact factors are compared and contrasted. It is proposed as an empirical formula that the impact factors damaged the bridge load-carrying capacities occurs to the bride due to high-speed vehicle.

Dynamic Analysis of Wheel Forces of KTX Vehicle Running with High-Speed on the PSC Bridge

Dynamic analysis of wheel forces of KTX vehicle was carried out to compare the differences of wheel force (D.W.F.) and wheel force ratios (W.F.R.) on the road and bridge up to 450 km/h running speed, considering the interactions among vehicle/rail/bridge. An evaluation method of running safety of vehicles, lateral wheel force, derail factor, and offload factor are adopted for traffic safety of bridges.

A Long-Term Friction Test of Bridge Bearings Considering Running Speed of Next Generation Train

Structural behaviour of PSC box bridge, on which KTX train runs, is analysed up to 500 km/h speed considering 12 stages track irregularity and interaction between bridge and vehicle. To evaluate wheel forces and rotations of vehicle, lateral wheel forces, derail factor and offload factor calculated on the track combining the bridge and 170 m normal track are compared with existing allowed limits. Maximum longitudinal displacement and accumulated sliding distance of the brige bearings for simply supported and 2 span continuous PSC bridges are presented by each running speeds. Long-term friction tests based on EN-1337-2 are conducted between PTFE and DP-mate plates. Finally, the long-term friction tests are proposed to consider the increasing speed of next generation high-speed train.

An optimal mix design of sound absorbing block on concrete ballast in urban train tunnel

ABSTRACT: As spreading of train concrete ballast leads to the increase resounding friction noise, an porous sound absorbing block is applied in urban train tunnel as a counterparts against the friction noise. Three steps of major variables tests for a n optimal mix design of the block are conducted to pursue the light weight of the block. Pilot property tests of the block for the cases of the fly-ash only as lightweight aggregates are carried satisfying KRT(Korean Rail Transit) and new KRS(Korean Railway Standards). Based on the results of pilot tests, required structural strength and admixture effects are evaluated. Additionally, typical lightweight aggregates are replaced so that lightweight and strength are improved for serviceability of poor working conditions and proper maintenance in urban train tunnel.Keywords: Light sound absorbing block, Concrete ballast, Lightweight aggregate, Optimal mix design, Urban train tunnel 초 록: 최근 도시철도 터널내부에서 콘크리트 도상의 확대로 유발된 반사마찰소음에 대한 저감대책으로 다공성 흡음블럭이 적용되고 있다. 운영 중인 도시철도용 품질시험기준과 제정 중인 철도표준규격을 만족하는 흡음블럭의 개발을 위하여 3 단계의 최적 배합설계를 위한 주요 변수시험을 수행하였다. 순환 골재인 플라이애쉬를 혼합하여 건비빔 발포 시료를 개발하여 요구되는 구조성능을 시험하고 혼화재의 영향성을 평가하였다. 또한 도시철도 터널 내부에 시공할 경우 열악한 작업환경과 원활한 유지관리에 대한 대책으로 대표적인 경량골재들을 혼합하여 경량화와 구조성능을 평가하였다.주요어: 경량 흡음블럭, 콘크리트 도상, 경량골재, 최적배합설계, 도시철도 터널구간Copyright ⓒ2016, Korean Tunnelling and Underground Space Association

Dynamic Analysis of a Wheel force for a Running High-Speed Vehicle on Railway PSC Box Girder Bridge

A dynamic analysis procedure is developed to provide a comprehensive estimation of the dynamic responses of locomotive`s wheels running over a Pre-Stressed Concrete (PSC) box girder bridge on the Korea high speed railway. Particularly, a three dimensional numerical model including the structural interaction between high speed vehicles, bridges and railway endures to analyze accurately and evaluate with in-depth parametric studies of the bridge lengths (25, 30, 35, 40 m) for dynamic responses of railway vehicle wheel forces due to the critical crossing speeds (300~315 km/h) on the bridges. The high-speed railway locomotive (KTX) is used as 38-degree of freedom system. Three displacements (vertical, lateral and longitudinal) as well as three rotational components (pitching, rolling and yawing) are considered in the 38-degree of freedom model. Three dimensional frame element is used to model the PSC box girder bridge, simply supported span length of 40m. The irregulation of rail-way is derived using the exponential spectrum density function under assumption of normal probability procedure. The results of dynamic analysis by Runge-Kutta method which are able to analyze considering the dynamic wheel forces between bridges and normal rail-ways are compared and contrasted. It is presented as an wheel forces spectrum that is varying either the bridge lengths or the critical crossing speeds.