• Title/Summary/Keyword: steel structures

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Determination of displacement distributions in welded steel tension elements using digital image techniques

  • Sozen, Sahin
    • Steel and Composite Structures
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    • v.18 no.5
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    • pp.1103-1117
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    • 2015
  • It is known that material properties, connection quality and manufacturing methods are among the important factors directly affecting the behavior of steel connections and hence steel structures. The possible performance differences between a fabricated connection and its computer model may cause critical design problems for steel structures. Achieving a reliable design depends, however, on how accurately the material properties and relevant constitutive models are considered to characterize the behavior of structures. Conventionally, the stress and strain fields in structural steel connections are calculated using the finite elements method with assumed material properties and constitutive models. Because the conventional strain gages allow the measurement of deformation only at one point and direction for specific time duration, it is not possible to determine the general characteristics of stress-strain distributions in connections after the laboratory performance tests. In this study, a new method is introduced to measure displacement distribution of simple steel welded connections under tension tests. The method is based on analyzing digital images of connection specimens taken periodically during the laboratory tension test. By using this method, displacement distribution of steel connections can be calculated with an acceptable precision for the tested connections. Calculated displacements based on the digital image correlation method are compared with those calculated using the finite elements method.

The Evaluation of Structural Stability of Corrugated Steel Plate Method applied in High-Speed Railway Vertical Tunnel Structures (고속철도 수직구 터널구조물에 적용된 파형강판공법의 구조적 안정성 검토)

  • Chung, Jee-Seung;Shin, Hwa-Cheol;Kim, Jin-Gu
    • Journal of the Korean Society of Safety
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    • v.31 no.2
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    • pp.64-69
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    • 2016
  • In this paper, structural analysis of High-Speed railway vertical tunnel structures was performed to verify the structural stability. The corrugated steel plate method was applied to the vertical tunnel structures for its simple construction method and low cost. The structural stability of Wall, Connection and Storage section was performed with LRFD and ASD design method at joint part, buckling, stress and plastic hinge. From the results, all of vertical tunnel structures shown the structural stability regardless of design method and structure types. So, the application of corrugated steel plate in vertical tunnel structures instead of cast-in-placed concrete was quite enough.

Seismic Fragility Analysis for Steel Fiber Applicability Assessment for Containment Structure of Nuclear Power Plant (원전 격납건물의 Steel Fiber 적용성 평가를 위한 지진취약도 분석)

  • Kim, Min Kyu;Park, Junhee;Choun, Young-Sun;Choi, In-Kil
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.25 no.5
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    • pp.381-388
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    • 2012
  • In this study, a seismic risk analysis performed for an applicability assessment of steel fiber in containment structures. Steel fiber can increase tensile properties of concrete structures moreover compressive and shear capacity. But many of researches about steel fiber reinforced concrete structures are now only focused in axial load condition. Also it is very difficult to find an effort for application to containment structures in NPP. Therefore, in this study, seismic fragility assessment for a steel fiber reinforced concrete containment structure. As a result, a seismic fragility capacity improved according to increase of shear and ductile capacity of concrete. In the case of 1.0% of steel fiber volume fraction, seismic capacity increases as 10%. But very limited previous experimental results were used in this study, so various element tests were needed for more accurate investigation.

Current practices and future directions of steel design in Japan

  • Yamaguchi, Eiki
    • Steel and Composite Structures
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    • v.5 no.2_3
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    • pp.159-168
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    • 2005
  • Four design codes/regulations for steel structures in Japan are briefly reviewed. Some of them employ the limit state design concept while the others are still based on the allowable stress design concept. The process for revision is now in action. The directions in the development of structural design codes are also reported herein. It is noted that a current trend in this development is to employ the performance-based design concept that has been successfully implemented in some seismic design codes.

Connections of the Corrugated Steel Plate Culvert with the Concrete Box (신설 파형강판 지중암거의 기존 콘크리트 박스 접합부 해석)

  • 조성민;변순주
    • Proceedings of the Korean Geotechical Society Conference
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    • 2000.03b
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    • pp.373-378
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    • 2000
  • Zinc galvanized steel plates(sections) of annular corrugations have been used in buried steel culverts. These structures are referred to by a variety of names such as flexible pipes, buried pipes, soil-steel bridges, corrugated steel culverts, and etc. Buried corrugated steel structures show flexible behaviour under the soil load. compared with concrete box structures. Finite element analysis was performed to suggest the reasonable connecting method between the flexible steel culverts and the rigid concrete box. It was predicted that perfectly constrained connections could induce the excessive stress in steel plates. Therefore elastic bearing connections that allow vertical displacement at the connecting point were applied.

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Numerical Analysis of Engineering Plastics Slit Damper (엔지니어링 플라스틱 슬릿댐퍼의 수치해석적 연구)

  • Kim, Yu-Seong;Kim, Gee-Cheol
    • Journal of Korean Association for Spatial Structures
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    • v.24 no.3
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    • pp.79-86
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    • 2024
  • Recently, steel dampers are widely used as seismic reinforcement devices. Steel dampers have the advantage of being easy to manufacture and being able to absorb a lot of energy through stable hysteresis behavior. However, there is a possibility that the steel damper may be damaged due to fatigue caused by repeated seismic loads. In this study, the seismic performance of steel dampers and engineering plastic dampers with different physical characteristics were compared and analyzed. In addition, numerical analysis was performed on a hybrid damper that combines a steel damper and an engineering plastic damper. It is more effective to apply engineering plastic dampers to structures that experience significant displacement due to seismic loads. The behavior of hybrid dampers combining steel dampers and engineering plastic dampers is dominated by steel dampers. A hybrid damper in which an engineering plastic damper yields after a steel damper yields can effectively respond to various seismic loads and secure high ductility and excellent seismic performance.

Non-linear performance analysis of existing and concentric braced steel structures

  • Erdem, R. Tugrul
    • Steel and Composite Structures
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    • v.19 no.1
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    • pp.59-74
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    • 2015
  • Since there are several places located in active seismic zones in the world, serious damages and losses have happened due to major scaled earthquakes. Especially, structures having different irregularities have been severely damaged or collapsed during these seismic events. Behavior of existing structures under several loading conditions is not completely determined due to some uncertainties. This situation reveals the importance of design and analysis of structures under seismic effects. Several non-linear static procedures have been developed in recent years. Determination of the seismic safety of the existing structures and strengthening techniques are significant civil engineering problems Non-linear methods are defined in codes to determine the performance levels of structures more accurately. However, displacement based ones give more realistic results. These methods provide more reliable evaluation possibilities for existing structures with developing computer technology. In this study, non-linear performance analysis of existing and strengthened steel structures by X shaped bracing members with 3, 5 and 7 stories which have soft story irregularity is performed according to FEMA-356 and Turkish Earthquake Code-2007. Damage ratios of the structural members and global performance levels are determined as well as modal properties and story drift ratios after non-linear finite elements analysis for each structure.

Analytical Studies on the Steel Plate-Concrete Structures under Compressive Load (압축력을 받는 강판-콘크리트 구조의 해석적 고찰)

  • Choi, Byong Jeong;Han, Hong Soo
    • Journal of Korean Society of Steel Construction
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    • v.20 no.2
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    • pp.269-278
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    • 2008
  • The primary object of the paper is to understand the compressive buckling characteristics of steel-concrete structures through the finite element analysis. The buckling pattern, compressive strength and stiffness of the steel plate concrete structures were investigated by the FEM analysis using the variations of B/t ratios and stud pitches. The investigation was focused on steel plate concrete structures with and without ribs placed on the surface of steel plates. The results of the FEM analysis were compared with the previous results from the theoretical equations. Conclusively, the buckling of the steel plate concrete structures occurred in the transverse direction of the loading direction. The stiffness of the steel plate concrete structure with ribs is greater than the one without the stiffened rib. The compressive strength in the FEM analysis is similar to that of JEAG 4681 and it showed 20% greater value than that of the proposed equations.

Numerical investigation of SHS steel beam-columns strengthened using CFRP composite

  • Keykha, Amir Hamzeh
    • Steel and Composite Structures
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    • v.25 no.5
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    • pp.593-601
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    • 2017
  • Carbon Fiber Reinforced Polymer (CFRP) is one of the materials used to strengthen steel structures. Most studies on strengthening steel structures have been done on steel beams and steel columns. No independent study, to the researcher's knowledge, has studied the effect of CFRP strengthening on steel beam-columns, and it seems that there is a lack of understanding on behavior of CFRP strengthening on steel beam-columns. However, this study explored the use of adhesively bonded CFRP flexible sheets on retrofitting square hollow section (SHS) steel beam-columns, using numerical investigations. Finite Element Method (FEM) was employed for modeling. To determine the ultimate load of SHS steel beam-columns, ten specimens, eight of which were strengthened with the different coverage length and with one and two CFRP layers, with two types of section (Type A and B) were analyzed. ANSYS was used to analyze the SHS steel beam-columns. The results showed that the CFRP composite had no similar effect on the slender and stocky SHS steel beam-columns. The results also showed that the coverage length, the number of layers, and the location of CFRP composites were effective in increasing the ultimate load of the SHS steel beam-columns.

Incremental dynamic analyses of concrete buildings reinforced with shape memory alloy

  • Mirtaheri, Masoud;Amini, Mehrshad;Khorshidi, Hossein
    • Steel and Composite Structures
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    • v.23 no.1
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    • pp.95-105
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    • 2017
  • The use of superelastic shape memory alloys (SMAs) as reinforcements in concrete structures is gradually gaining interest among researchers. Because of different mechanical properties of SMAs compared to the regular steel bars, the use of SMAs as reinforcement in the concrete may change the response of structures under seismic loads. In this study, the effect of SMAs as reinforcement in concrete structures is analytically investigated for 3-, 6- and 8-story reinforced concrete (RC) buildings. For each concrete building, three different reinforcement details are considered: (1) steel reinforcement (Steel) only, (2) SMA bar used in the plastic hinge region of the beams and steel bar in other regions (Steel-SMA), and (3), beams fully reinforced with SMA bar (SMA) and steel bar in other regions. For each case, columns are reinforced with steel bar. Incremental Dynamic Analyses (IDA) are performed using ten different ground motion records to determine the seismic performance of Steel, Steel-SMA and SMA RC buildings. Then fragility curves for each type of RC building by using IDA results for IO, LS and CP performance levels are calculated. Results obtained from the analyses indicate that 3-story frames have approximately the same spectral acceleration corresponding with failure of frames, but in the cases of 6 and 8-story frames, the spectral acceleration is higher in frames equipped with steel reinforcements. Furthermore, the probability of fragility in all frames increases by the building height for all performance levels. Finally, economic evaluation of the three systems are compared.