수치해석을 통한 고성능 격자지보재의 성능 평가

김동규,안성율 사단법인 한국터널지하공간학회 2019 한국터널지하공간학회논문집 Vol.21 No.6

The objective of this study is to evaluate the field support performance of highperformance lattice girder (BK-Lattice Girder) by using numerical analysis. Three types (50, 70, 95-type) of existing and high performance lattice girders were applied to the cross section of highway 2, 3, and 4 lane tunnels to compare the supporting performance. The numerical analysis was the finite element method and the lattice girder was modeled in three dimensions with an elasto-plastic frame. The ground was modeled as a spring receiving only compression. The load was applied as a concentrated load on the central ceiling of the tunnel section. The yield strengths of the lattice girders were determined from the numerical results to compare the supporting performance of lattice girder. In case of 50-type, the yield strengths of high-performance lattice girders were increased by 6.7~10.0% compared with those of the existing lattice girders. In the case of 70-type, the high-performance lattice girders increased yield strengths by 12.1~14.9% than the existing lattice girder. In the case of 95-type, the high-performance lattice girders increased yield strengths by 13.3~20.0% than the existing lattice girder. As a result of numerical analysis, it was considered that the high-performance lattice girder supported better than the existing lattice girder when only the lattice girders were constructed. 본 연구의 목적은 수치해석을 수행하여 고성능 격자지보재(BK-Lattice Girder)의 현장 지지성능을 평가하기 위한 것이다. 고속도로 2차로, 3차로와 4차로 터널 단면에 3가지 형태(50, 70, 95 타입)의 기존 및 고성능 격자지보재를 적용하여 지지성능을 비교하였다. 수치해석은 유한요소방법을 사용하였고 격자지보재는 탄소성 프레임으로 3차원으로 모델링하였다. 지반은 압축만을 받는 스프링으로 모델링하였다. 하중은 터널 단면의 중앙 천정부에 집중하중으로 적용하였다. 수치해석 결과로부터 격자지보재의 항복강도를 결정하여 지지성능을 비교하였다. 50타입의 경우, 고성능 격자지보재는 기존 격자지보재보다 항복강도가 6.7~10.0% 증가하였다. 70타입의 경우, 고성능 격자지보재는 기존 격자지보재보다 항복강도가 12.1~14.9% 증가하였다. 95타입의 경우에도, 고성능 격자지보재는 기존 격자지보재보다 항복강도가 13.3~20.0% 증가하였다. 수치해석을 수행한 결과, 격자지보재만 시공된 경우에 고성능 격자지보재는 기존 격자지보재보다 지지성능이 우수한 것으로 판단되었다.

Analysis of Spiral Lattice Girder Shape in preparation for HSR Speed Increase

Ki-Young Eum,Jee-Ha Lee,Young-Kon Park,Jangho Yun,Seongwoon Jeong 한국철도학회 2013 International Journal of Railway Vol.6 No.4

Analysis of Spiral Lattice Girder Shape in preparation for HSR Speed Increase

Eum, Ki-Young,Lee, Jee-Ha,Park, Young-Kon,Yun, Jangho,Jeong, Seongwoon The Korean Society for Railway 2013 International Journal of Railway Vol.6 No.4

A spiral lattice girder-reinforced Bi-block sleeper which has enhanced durability against increasingly growing impact force and vibration by wheel load and improved structural performance while train runs at 350km/h high speed is hereby proposed. The section of a spiral lattice girder has stable and superior structural performance thanks to its confinement effect. To compare and analyze the structural performance of spiral lattice girder-reinforced bi-block sleeper, strain and stress distribution were evaluated after applying same load condition as existing triangular lattice girder-reinforced biblock sleeper, and to compare the structural performance of triangular lattice girder and spiral lattice girder, structural analysis of lattice girder was performed separately. As a result, a spiral lattice girder proved to have had superior structural characteristics to bi-block sleeper, and furthermore as a result of evaluating the fastener interface and constructibility with shape-improved lattice girder, no interference with existing railroad structure was found and in terms of cost efficiency, a spiral lattice girder appeared to be superior to existing lattice girder.

Performance evaluation of lattice girder and significance of quality control

Kim, H.J.,Song, K.I.,Jung, H.S.,Shin, Y.W.,Shin, J.H. Elsevier 2018 Tunnelling and underground space technology Vol.82 No.-

<P><B>Abstract</B></P> <P>It has been reported that lattice girders fail due to inadequate steel members. An experimental analysis is herein conducted using material and structural tests to determine the behavior of lattice girders made of B500B and SS400, two representative steel materials. A numerical analysis is also carried out to evaluate the performance of lattice girder in a tunnel. Both the experimental and numerical study indicated that the use of inadequate steel members results in a significant reduction in the working load and can also affect the overall structural stability of the tunnel. Therefore, quality control for lattice girders is of great importance. A review of the quality control systems for lattice girders reveals it to be desirable to introduce an on-site testing method to identify the adequacy of a steel member in the field. Thus, the portable indentation test is suggested as an on-site quality control test for a lattice girder.</P>

로드셀 실내시험을 통한 터널 격자지보 계측 기법

김학준 ( Hak Joon Kim ),박시현 ( Si Hyun Park ),이기세 ( Ki Se Lee ) 대한지질공학회 2009 지질공학 Vol.19 No.3

최근 국내 터널현장에서는 기존 H형 강지보를 대체하는 격자지보의 사용이 증가하고 있다. 그러나 터널 현장에서 격자지보 계측은 거의 수행되지 않고 있으며 적절한 계측 방법도 확립 되지 못한 상태이다. 기존 연구결과에 의하면 H형강 계측에 사용되는 진동현식 변형률 게이지는 격자지보 계측에는 부적합하다. 본 연구에서는 격자지보용 로드셀을 개발하여 격자지보 시료에 부착한 후 압축시험기를 이용하여 로드셀에 대한 신뢰성을 검증하였다. 압축시험 결과분석을 통하여, 터널 계측시 격자지보에 로드셀을 사용할 경우의 계측 방법을 제시하였다. The use of lattice girder is increased at the tunnel site in Korea recently for the substitute of H-steel rib. However, field measurements at the lattice girder are rarely performed at the tunnel site and the method of the measurement is not well established. The use of the vibrating wire strain gauges used for the H-steel rib was proven to be not suitable for the strain measurements of the lattice girder according to the previous research. The credibility of the load cell was investigated using laboratory compression tests for load cells, specially manufactured for the lattice girder for this study, installed at the specimen of the lattice girder. The method of the tunnel instrumentation for the lattice girder using the load cell is given from the interpretation of the compression test results.

Evaluation of the Structural Performance of Tetragonal Lattice Girders

김승준,한택희,백정식,강영종 한국강구조학회 2013 International Journal of Steel Structures Vol.13 No.1

This paper presents an evaluation of the structural performance of tetragonal lattice girders for NATM tunnel construction. H-shaped steel ribs and triangular lattice girders have been widely used as a temporary support for NATM tunneling. H steel ribs have high flexural stiffness and strength, but they may induce unexpected internal gaps after shotcreting, because of their geometric characteristics. To overcome the problem, triangular lattice girders were developed. However, the lattice girder revealed frequent local failure at the joints of each bar. Moreover, those two supports show the quite low connection strength of members. Recently, a new type support, the tetragonal lattice girder, was developed to overcome the weaknesses of former supports. In this study, the structural performance of the new type support was studied by analytical and experimental methods. For the evaluation, 4-point flexural analysis, the conventional evaluation method, and arch analysis including stability analysis were performed. In addition, a 4-point flexural experiment was performed to evaluate the ultimate load carrying capacity, and observe whether local failure occurs or not. In the experimental study, a connected model was also considered as well as a unit model, in order to check the rationality of the connection method of the girder. All analytical and experimental results were compared with the structural performance of former supports.

A comparative study of multi-objective evolutionary metaheuristics for lattice girder design optimization

Tugrul Talaslioglu 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.77 No.3

The geometric nonlinearity has been successfully integrated with the design of steel structural system. Thus, the tubular lattice girder, one application of steel structural systems have already been optimized to obtain an economic design following the completion of computationally expensive design procedure. In order to decrease its computing cost, this study proposes to employ five multi-objective metaheuristics for the design optimization of geometrically nonlinear tubular lattice girder. Then, the employed multi-objective optimization algorithms (MOAs), NSGAII, PESAII, SPEAII, AbYSS and MoCell are evaluated considering their computing performances. For an unbiased evaluation of their computing performance, a tubular lattice girder with varying size-shape-topology and a benchmark truss design with 17 members are not only optimized considering the geometrically nonlinear behavior, but three benchmark mathematical functions along with the four benchmark linear design problems are also included for the comparison purpose. The proposed experimental study is carried out by use of an intelligent optimization tool named JMetal v5.10. According to the quantitative results of employed quality indicators with respect to a statistical analysis test, MoCell is resulted with an achievement of showing better computing performance compared to other four MOAs. Consequently, MoCell is suggested as an optimization tool for the design of geometrically nonlinear tubular lattice girder than the other employed MOAs.

Modelling and classification of tubular joint rigidity and its effect on the global response of CHS lattice girders

Wang, Wei,Chen, Yiyi Techno-Press 2005 Structural Engineering and Mechanics, An Int'l Jou Vol.21 No.6

In engineering practice, tubular connections are usually assumed pinned or rigid. Recent research showed that tubular joints may exhibit non-rigid behavior under axial or bending loads. This paper is concerned with establishing a new classification for tubular joints and investigating the effect of joint rigidity on the global behavior of CHS (Circular Hollow Section) lattice girders. Parametric formulae for predicting tubular joint rigidities are proposed, which are based on the finite element analyses through systematic variation of the main geometric parameters. Comparison with test results proves the reliability of these formulae. By considering the deformation patterns of respective parts of Vierendeel lattice girders, the boundary between rigid and semirigid tubular connections is built in terms of joint bending rigidity. In order to include characteristics of joint rigidity in the global structural analysis, a type of semirigid element which can effectively reflect the interaction of two braces in K joints is introduced and validated. The numerical example of a Warren lattice girder with different joint models shows the great effect of tubular joint rigidities on the internal forces, deformation and secondary stresses.

현장계측에 의한 터널 지보재에 작용하는 지반하중 평가 연구

문홍득 진주산업대학교 1998 論文集 Vol.37 No.-

NATN(New Austrian Tunnelling Method) uses a support system of shotcrete, rockbolt, and steel support, which are installed after tunnel excavation. Among these support system, a steel support is used for reinforcement of a unsupported ground, redistribution of the rock load applied to shotcrete, and resistance of the earth pressure until the strength of shotcrete and rockbolt is fully developed. Recently, a H-shaped steel set is reported to have some problems in installation. So, a Lattice girder was developed to replace a problematic H-shaped steel set in Switzerland and German. Lattice girder is a triangular shape welded with steel rods. Lattice girder is a light-weight support system which enables fast installation. The major advantage of lattice girder is the good bonding with shotcrete. To evaluate the applicability of a lattice girder to tunnelling in Korea, field test was performed at a high speed railway tunnelling site with a large section and was compared with the feature of a H-shaped steel set. This paper especially presents the evaluation of the percentage of the rock load distributed to shotcrete and a steel support system(lattice girder and H-shaped steel set) which were investigated in this study. Field tests proved that a lattice girder fully supported the initial earth pressure developed right after tunnelling and therefore limited ground deformation effectively.

터널지보용 격자지보의 시공성 평가 연구

문홍득 진주산업대학교 건설기술연구소 1998 건설기술연구소보 Vol.1 No.-

Recently, a lattice girder is used in tunnelling as a tunnel support. A lattice girder is a new steel support developed in Europe for the replacement of an existing H-shaped steel set, which is reported to have some problems in installation. In this study, to evaluate the workability of a lattice girder in tunnelling in Korea, field observations were performed at a subway tunnel construction site with a small section. Also, features of lattice girder in field observations were compared with those of a H-shaped steel set respectively.