Nonlinear Analysis of Reinforced Concrete Structure Using an Eight-Node Solid Shell Element

송삭(Suthasupradit Songsak),김영회(Kim Young-Hoe),사차락 (Pornpeerakeat Sacharuck),김기두(Kim Ki-Du) 대한토목학회 2007 대한토목학회 학술대회 Vol.2007 No.10

Application of Multibody Dynamics Simulation in Approximation of Rail Vehicle Dynamic Envelope

Songsak Suthasupradit,Thitiwut Petcharat,김기두,Rattapoohm Parichatprecha 한국철도학회 2023 한국철도학회논문집 Vol.26 No.12

The master plan for Thailand’s Eastern High-Speed Rail Project calls for the Airport Rail Link to be shared with high-speed trains. To ensure the safety of mixed operations, it is imperative to assess loading and structural gauges. This study determined the dynamic envelopes of rail vehicles using multibody dynamics modeling, focusing on three rolling stock models—Siemens Desiro UK Class 360/2 EMU, CRH2C EMU, and Shinkansen Series 300 High-Speed EMU— across a spectrum of operating conditions. Factors such as train mass, suspension characteristics, running speed, wheel wear, track geometry, and track irregularities were incorporated as dynamic simulation parameters. The greatest vehicle movement occurred along the westbound curve path, particularly at the transition between the 996-meter-radius curve to the 180-meter-radius curve. The Shinkansen Series 300 exhibited the greatest lateral and vertical maneuverability. Both the CRH2C EMU and Shinkansen 300 Series trains exceeded the structural envelope limitations of the Airport Rail Link.

Application of Indicial Function for the Flutter Analysis of Long Span Suspension Bridge During Erection

Panot Chobsilprakob,김기두,Songsak Suthasupradit,Anaphat Manovachirasan 한국강구조학회 2014 International Journal of Steel Structures Vol.14 No.1

The design of cable supported bridge with long span is challenging due to the sensitivity of the dynamic excitation. Theaerodynamic instability caused by fluttering can severely affect the safe operation. An application of indicial function to the flutteranalysis in time domain is applied to the Great belt East Bridge for both completed and erection stage. The nonlinear least squaremethod was used to extract the aerodynamic indicial parameters for flutter analysis in time domain. The geometric nonlinearityis considered through the nonlinear dynamic analysis. The results showed the good agreement with the wind tunnel test and thevalidity of the indicial function as well as the important role of the geometrically nonlinear analysis during deck erection.

Aeroelastic Analysis of Long Span Bridges Via Indicial Functions Considering Geometric and Material Nonlinearity

Panot Chobsilprakob,Songsak Suthasupradit,김기두 한국강구조학회 2011 International Journal of Steel Structures Vol.11 No.2

A time domain approach for predicting the flutter response of long-span bridges was presented. The unsteady aerodynamic forces were presented by the indicial functions through a convolution integral, whereas the nonlinear least square method was used to calculate the aerodynamic indicial parameters. The nonlinear dynamic analysis which includes both the geometric and material nonlinearities due to the unsteady self excited aerodynamics force was considered. Numerical analyses were then performed using three dimensional finite element model of the suspension bridge. The results show that the geometric and material nonlinearities have a significant influence on the critical velocity and the response of long-span bridges.

The Evaluation of Axial Stress in Continuous Welded Rails via Three-Dimensional Bridge–Track Interaction

Anaphat Manovachirasan,Songsak Suthasupradit,최준혁,김범준,김기두 한국강구조학회 2018 International Journal of Steel Structures Vol.18 No.5

The crucial diff erences between conventional rail with split-type connectors and continuous welded rails are axial stress in the longitudinal direction and stability, as well as other issues generated under the infl uence of loading eff ects. Longitudinal stresses generated in continuously welded rails on railway bridges are strongly infl uenced by the nonlinear behavior of the supporting system comprising sleepers and ballasts. Thus, the track structure interaction cannot be neglected. The rail-support system mentioned above has properties of non-uniform material distribution and uncertainty of construction quality. The linear elastic hypothesis therefore cannot correctly evaluate the stress distribution within the rails. The aim of this study is to apply the nonlinear fi nite element method using the nonlinear coupling interface between the track and structural model and to illustrate the welded rail behavior under the loading eff ect and uncertain factors of the ballast. Numerical results of nonlinear fi nite analysis with a three-dimensional solid and frame element model are presented for a typical track–bridge system. A composite plate girder, modeled by solid and shell elements, is also analyzed to consider the behavior of the welded rail. The analysis result showed buckling under the independent calculations of load cases, including ‘temperature change’, ‘bending of the supporting structure’, and ‘braking’ of the railway vehicle. A parametric study of the load combination method and the loading sequence is also included in this analysis.

보강변형률 8절점 솔리드-쉘요소의 선형 해석에 관한 연구

차재윤(Cha Jae Yoon),송삭(Songsak Suthasupradit),김범준(Kim Bum Jun),김기두(Kim Ki Du) 대한토목학회 2010 대한토목학회 학술대회 Vol.2010 No.10

XFINAS 계면요소와 고체요소를 이용한 콘크리트-강재 합성구조물의 비선형 거동해석

김기두,수타스트라디트 송삭,박종화,박재균,Kim, Ki-Du,Suthasupradit, Songsak,Park, Jong-Hwa,Park, Jae-Gyun 한국전산구조공학회 2010 한국전산구조공학회논문집 Vol.23 No.3

합성구조는 전체가 동일한 재료 특성을 가지는 구조와는 달리 서로 다른 특성 즉 강재와 콘크리트의 구조로 결합되어 있다. 따라서 실제 모델링 시 이러한 재료 특성을 반영하지 않으면 실제 거동을 예측할 수 없으므로 콘크리트와 강재 사이에 인터페이스 요소를 연결하여 강재와 콘크리트의 슬립을 예측할 수 있게 한다. 인터페이스 요소는 일반적으로 사용되는 구성방정식은 적합하지 않고 실제 부착 및 슬립을 고려한 비선형 구성 방정식을 사용하여야만 적절히 사용할 수 있다. 이 계면요소를 이용하여 판형 강재 박스와 콘크리트의 접촉면을 묘사하였다. 그리고 강재 박스의 휨-좌굴 거동을 묘사하기 위해서는 일반적인 8절점 적합 요소의 사용은 부적절하므로 판형 강재 박스는 보강 변형도(Enhanced Assumed Strain) 고체요소를 사용하여 휨거동을 묘사할 수 있게 하였다. Unlike the structure which has a homogeneous material property, a composite structure is coupled with materials which have different properties, namely, steel and concrete. At actual modeling, the real behavior cannot be predicted without consideration of those material characteristics. Therefore, by putting the interface element between concrete and steel, a slip of steel and concrete is made predictable. Interface element can be used properly not by an ordinary constitutive relation, but by a non-linear constitutive relation considering actual adhesion and slip. A contact surface between plate-shape steel box and concrete is described by using this interface element. Furthermore, because the general 8 node conforming element is inappropriate for describing a bending buckling behavior of steel box, the EAS(Enhanced Assumed Strain) solid-shell element is used to describe a bending behavior of plate-shape steel box.

PSC 교량의 3차원 시공 중 해석기법을 위한 준적합 쉘 요소 개발

김기두,변윤주,김현기,롬보이,송삭,김영회,Kim, Ki-Du,Byun, Yun-Joo,Kim, Hyun-Ky,Lomboy, Gilson R.,Suthasupradit, Songsak,Kim, Young-Hoe 한국전산구조공학회 2007 한국전산구조공학회논문집 Vol.20 No.3

PSC 박스 교량은 콘크리트, 철근과 텐던으로 구성된 구조물로서 콘크리트의 인장 균열, 철근의 비선형 거동 등 재료의 비선형성 거동 특성 및 콘크리트의 시간 의존적 특성을 가지고 있는 복합 구조물이다. PSC 박스 교량의 시공 중 거동 특성을 고려하기 위하여 뼈대 요소(프레임 요소)를 이용한 시공단계의 설계가 수행되고 있다. 그러나 PSC 박스 교량 중 곡선램프교 등의 경우는 교량의 외측 및 내측의 변위 및 응력 값이 현저히 다르다. 따라서 PSC 박스 교량의 텐던량 및 시공 중 긴장력이 외측 및 내측에서 다르게 산정되어야 함에도 불구하고 현실적으로는 계산이 불가능하여 같은 양의 텐던과 부적절한 긴장력을 사용하고 있어 시공 중 항상 안전사고에 노출되고 있다. 이러한 단점을 해결하기 위하여 3차원 해석이 필수적으로 요구되고 있으며 본 연구에서는 PSC 박스 교량의 해석 기법에 필요한 준 적합 쉘 요소를 제안하고자 한다. The PSC box bridge constructed of concrete, reinforcing bar and tendon is a complex structure that exhibits tension cracks, nonlinear behaviour of steel and time dependent behaviour of concrete. The frame element is commonly used for construction stage analysis PSC bridges. However, the frame element does not show sufficient information when in the curved PSC box bridges. For the case of curved PSC bridges, the deformations in the inner and outer web are different. In this case, different jacking forces are required in the inner and outer webs. However, it is impossible to calculate different jacking forces if we use the frame element for construction stage analysis. In order to overcome this problem, the use of the shell element is essential for a three-dimensional construction stage analysis of PSC bridges. In the following, the formulation of a Quasi-conforming shell element and its application of PSC box girder bridge analysis are presented.

철도 차량 - 교량 상호작용에 의한 3차원 동적 해석 모델 개발

딘반위엔,김기두,심재수,최은수,송삭,Dinh, Van Nguyen,Kim, Ki Du,Shim, Jae Soo,Choi, Eun Soo,Songsak, Suthasupradit 한국강구조학회 2008 韓國鋼構造學會 論文集 Vol.20 No.1

본 논문에는 KTX (Korean eXpres Train)을 위한 3차원 관절대차의 차량-교량 동적 상호작용의 해석모델의 공식이 제안되었다. 궤도틀림의 반주기적 파형이 FRA의 레일틀림 최대허용기준을 사용하여 제안되었고, 레일 이음매와 침목의 간격 또한 포함되었다. 궤도틀림은 수준, 구배, 수평 및 궤간틀림을 포함하고 있다. 결과적으로 나타나는 차량-교량 시스템 행렬은 매우 적은 요소를 포함하기 때문에 1차원의 배열에 저장할 수 있으며, 시간절약적인 해법을 창출한다. 반복기법을 포함하는 차량-교량 작용 계산의 수치적 알고리즘 또한 공식화하였으며, 차량-교량 상호작용을 모사하고 새로운 알고리즘에 의해서 이 문제를 풀기 위한 프로그램이 'XFINAS'라고 불리는 프로그램에 모듈로서 내포되었다. 새로운 프로그램에 의해서 계산된 결과가 검증된 2차원의 차량-교량 상호작용 모델의 결과에 의해서 검증되었다. 본 연구에서 제시한 3차원 해석은 차량의 보다 상세한 응답을 제공한다. 예를 들면, 회전운동-롤링, 요잉 및 피칭- 및 수평 및 수직운동에 대한 가속도를 제공할 수 있으며, 이러한 응답은 승객의 승차감 평가에 유용한 자료로 활용될 수 있다. 차량의 안정성과 차륜의 탈선 또한 본 프로그램에서 계산되는 차륜의 상대변위를 이용하여 직접적으로 계산이 가능하다. A formulation of three-dimensional model of articulated train-b ridge dynamic interaction has been made for the Korean eXpress Train (KTX). Semi-periodic profiles of rail irregularities consisting of elevation, alignment, cross and gauge irregularities have also been proposed using FRA maximum tolerable rail deviations. The effects of rail joints and sleeper step were also included. The resulting system matrices of train and bridge are very spare, and thus, are stored in one-dimensional arrays, yielding a time-efficient solution. A numerical algorithm for computing bridge-train response including an iterative scheme is also formulated. A program simulating train-bridge interaction and solving this problem using the new algorithm is implemented as new modules for the f inite element analysis software named XFINAS. Computed results using the new program are then checked by that of the validated 2-D bridge-train interaction model. This new 3D analysis provides more detailed train responses such as swaying, bouncing, rolling, pitching and yawing accelerations, which are useful inevaluating passenger riding comfort. Train operation safety and derailment could also be directly investigated by relative wheel displacements computed from this program.