• Title/Summary/Keyword: box section

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Evaluation of Wind Force Coefficients of a Box-Type Girder Bridge with Noise Barriers (방음벽의 유무에 따른 박스형 거더교의 풍력계수 평가)

  • Jeong, Seung Hwan;Lee, Youngki
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.38 no.5
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    • pp.627-634
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    • 2018
  • In the study, computational fluid dynamics analysis was performed to estimate wind force coefficients for a box-type concrete girder bridge under the influence of wind. The drag, lift and pitching moment coefficients were obtained for the bridge section without noise barrier and compared with those of the bridge section with noise barriers of various heights. The shear stress transport $k-{\omega}$ turbulence model was employed to estimate the wind force coefficients, and the contribution of the friction drag force to the total drag force was investigated. It was found from the study that the drag force coefficients increased as the height of noise barrier increased when a wind blew horizontally, and that the contribution of the friction drag force was highest for the bridge section without noise barrier. It is concluded that the impact of the height of noise barriers should be considered in the design of bridges, and the friction force played an important role in evaluating wind forces on bridges.

Direct strength method for high strength steel welded section columns

  • Choi, Jong Yoon;Kwon, Young Bong
    • Steel and Composite Structures
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    • v.29 no.4
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    • pp.509-526
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    • 2018
  • The direct strength method adopted by the AISI Standard and AS/NZS 4600 is an advanced design method meant to substitute the effective width method for the design of cold-formed steel structural members accounting for local instability of thin plate elements. It was proven that the design strength formula for the direct strength method could predict the ultimate strength of medium strength steel welded section compressive and flexural members with local buckling reasonably. This paper focuses on the modification of the direct strength formula for the application to high strength and high performance steel welded section columns which have the nominal yield stress higher than 460 MPa and undergo local buckling, overall buckling or their interaction. The resistance of high strength steel welded H and Box section columns calculated by the proposed direct strength formulae were validated by comparison with various compression test results, FE results, and predictions by existing specifications.

Evaluation of Effective Temperature for Estimate Design Thermal Loads in Steel Deck of Steel Box Girder Bridges (강상자형교의 강바닥판에서 설계온도하중을 위한 유효온도 산정)

  • Shin, Dong-Wook;Kim, Kyoung-Nam;Choi, Chul-Ho;Lee, Seong-Haeng
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.17 no.6
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    • pp.77-87
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    • 2013
  • A present LSD (limited state design) code for temperature load in the domestic bridge design has applied a uniform standard for various bridge types. In this study, in order to calculate the effective temperature, a specimen of steel box girder bridge section with real size dimension was manufactured. For a year, the temperature data were measured at the 18 point in steel deck of steel box girder bridges specimen. Effective temperature within the cross section according to atmospheric temperature was calculated by this experiment data. The analyzed results were very similar correlation when compared with the effective temperature of the Euro Code. Therefore, the effective temperature which calculated based on the present data could be used as the basic data in order to present to the appropriate design criteria for the thermal loads on the domestic bridge design.

Non-linear analyses model for composite box-girders with corrugated steel webs under torsion

  • Ko, Hee-Jung;Moon, Jiho;Shin, Yong-Woo;Lee, Hak-Eun
    • Steel and Composite Structures
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    • v.14 no.5
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    • pp.409-429
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    • 2013
  • A composite box-girder with corrugated steel webs has been used in civil engineering practice as an alternative to the conventional pre-stressed concrete box-girder because of several advantages, such as high shear resistance without vertical stiffeners and an increase in the efficiency of pre-stressing due to the accordion effect. Many studies have been conducted on the shear buckling and flexural behavior of the composite box-girder with corrugated steel webs. However, the torsional behavior is not fully understood yet, and it needed to be investigated. Prior study of the torsion of the composite box-girder with corrugated steel webs has been developed by assuming that the concrete section is cracked prior to loading and doesn't have tensile resistance. This results in poor estimation of pre-cracking behaviors, such as initial stiffness. To overcome this disadvantage of the previous analytical model, an improved analytical model for torsion of the composite box-girder with corrugated steel webs was developed considering the concrete tension behavior in this study. Based on the proposed analytical model, a non-linear torsional analysis program for torsion of the composite box-girder with corrugated steel webs was developed and successfully verified by comparing with the results of the test. The proposed analytical model shows that the concrete tension behavior has significant effect on the initial torsional stiffness and cracking torsional moment. Finally, a simplified torsional moment-twist angle relationship of the composite box-girder with corrugated steel webs was proposed based on the proposed analytical model.

A Weight-reduction Design Method by Underframe Material Substitution in a Box-type Bodyshell with Cut-outs (Cut-out이 있는 Box형 차체의 하부구조 소재대체 경량화 설계 방법)

  • Cho, Jeonggil;Koo, Jeongseo;Jung, Hyunseung
    • Transactions of the Korean Society of Automotive Engineers
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    • v.21 no.2
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    • pp.45-54
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    • 2013
  • In this paper, a theoretical weight-reduction method was suggested to substitute an underframe material of a box-type bodyshell having cut-outs with an alternative light-weight material. To utilize the material substitution method previously developed for a box-type hybrid bodyshell not having cut-outs, we derived a box-type baseline model without cut-outs which is similar to the stiffness condition of a box-type bodyshell having cut-outs. To do this, the thicknesses of roof and walls of the baseline model were determined such that the deflection of the baseline model under a distributed vertical load condition is equal to the sum of the theoretical section deflections of the original box model with cut-outs. Next, to derive a hybrid bodyshell by under-frame material substitution, the material substitution method for a box-type hybrid bodyshell without cut-outs was applied to the box-type baseline model. Finally, we compared the FE simulation results of the derived hybrid bodyshells having cut-outs for various materials with the theoretical results of the suggested method, and we obtained their good correlations.

Effect of Vibration during Distribution Process on Compression Strength of Corrugated Fiberboard Boxes for Agricultural Products Packaging (농산물 포장용 골판지상자의 수송 중 진동에 의한 압축강도 변화)

  • Shin, Joon Sub;Kim, Jongkyoung
    • KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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    • v.27 no.2
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    • pp.91-100
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    • 2021
  • Agricultural corrugated fiberboard packaging boxes frequently experience damage due to loading and unloading, vibration during transport, and shock by dynamic distribution condition change. This study was carried out to estimate effect of vibration during distribution process on compression strength of corrugated fiberboard boxes for agricultural products. In order to identify the degradation caused by vibration, after box packaging the agricultural products(tangerine or cucumber), the natural frequencies of the packaging boxes were measured by varying the relative humidity(50, 70 and 90%) at 25℃ temperature. Various types of corrugated fiberboard boxes were packed with tangerines and cucumbers, and the PSD plot vibration tests were conducted by utilizing the actual vibration recording results of the Gyeongbu Expressway section between Seoul and Gimcheon. As a result of the experiment, the decrease in compression strength of the box was relatively low in DW-AB, and the decrease in compression strength of the SW-A 0201(RSC) type box was the highest at 20.49%. In particular, both SW-A and DW-AB showed low compression strength degradation rates for open folder type boxes. The moisture content varies depending on the type of the box or agricultural products, and the enclosed 0201(RSC) type box was generally higher than the open folder or bliss type box, which is believed to be the reason for the decrease in compression strength of RSC type box due to humidity. By the agricultural product, the percentage of decrease in compression strength of box packed with cucumbers was especially high.

Minimum cost design of overhead crane beam with box section strengthened by CFRP laminates

  • Kovacs, Gyorgy;Farkas, Jozsef
    • Structural Engineering and Mechanics
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    • v.61 no.4
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    • pp.475-481
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    • 2017
  • An overhead travelling crane structure of two doubly symmetric welded box beams is designed for minimum cost. The rails are placed over the inner webs of box beams. The following design constraints are considered: local buckling of web and flange plates, fatigue of the butt K weld under rail and fatigue of fillet welds joining the transverse diaphragms to the box beams, fatigue of CFRP (carbon fibre reinforced plastic) laminate, deflection constraint. For the formulation of constraints the relatively new standard for cranes EN 13001-3-1 (2010) is used. To fulfill the deflection constraint CFRP strengthening should be used. The application of CFRP materials in strengthening of steel and concrete structures are widely used in civil engineering applications due to their unique advantages. In our study, we wanted to show how the mechanical properties of traditional materials can be improved by the application of composite materials and how advanced materials and new production technologies can be applied. In the optimization the following cost parts are considered: material, assembly and welding of the steel structure, material and fabrication cost of CFRP strengthening. The optimization is performed by systematic search using a MathCAD program.

Analysis of Compressive Fracture Behavior of Filled FRP Composite Box Module (충전형 FRP 합성박스 모듈의 압축파괴 거동 분석)

  • Kim, Ho-Sun;Jang, Hwa-Sup;Lee, Ho-Hyun;Yun, Kuk-Hyun
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.25 no.1
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    • pp.1-8
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    • 2012
  • This study is a basic experimental research to apply FRP (Fiber Reinforced Polymer) box members to slabs and girders among various architectural structures, which receive bending stress. We prepared prefabricated FRP member and connected it to an FRP box member as a large cross section before we conducted an experiment in diverse conditions to analyze characteristics of compressive fracture behavior. In this study, we carried out a compressive fracture behavior test according to fillers on the upper part of the FRP box member, loading methods, and connective types and thereby performed a finite element analysis. The comparison of analysis results with test results revealed that rigidity was found to be slightly low, while stress was concentrated on the fracture point of the sample.

Studies on restoring force model of concrete filled steel tubular laced column to composite box-beam connections

  • Huang, Zhi;Jiang, Li-Zhong;Zhou, Wang-Bao;Chen, Shan
    • Steel and Composite Structures
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    • v.22 no.6
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    • pp.1217-1238
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    • 2016
  • Mega composite structure systems have been widely used in high rise buildings in China. Compared to other structures, this type of composite structure systems has a larger cross-section with less weight. Concrete filled steel tubular (CFST) laced column to box-beam connections are gaining popularity, in particular for the mega composite structure system in high rise buildings. To enable a better understanding of the destruction characteristics and aseismic performance of these connections, three different connection types of specimens including single-limb bracing, cross bracing and diaphragms for core area of connections were tested under low cyclic and reciprocating loading. Hysteresis curves and skeleton curves were obtained from cyclic loading tests under axial loading. Based on these tested curves, a new trilinear hysteretic restoring force model considering rigidity degradation is proposed for CFST laced column to box-beam connections in a mega composite structure system, including a trilinear skeleton model based on calculation, law of stiffness degradation and hysteresis rules. The trilinear hysteretic restoring force model is compared with the experimental results. The experimental data shows that the new hysteretic restoring force model tallies with the test curves well and can be referenced for elastic-plastic seismic analysis of CFST laced column to composite box-beam connection in a mega composite structure system.

Design methodology in transverse webs of the torsional box structure in an ultra large container ship

  • Silva-Campillo, Arturo;Suarez-Bermejo, J.C.;Herreros-Sierra, M.A.;de Vicente, M.
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.13 no.1
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    • pp.772-785
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    • 2021
  • Container ships has a transverse section in the form of an open profile, making it very sensitive to torsion phenomena. To minimize this effect, a structure known as a torsion box exists, which is subject to high stresses influenced by the fatigue phenomenon and the existence of cut-outs, for the passage of the longitudinal stiffeners, acting as stress concentrators. The aim of this study is to propose a two-stage design methodology to aid designers in satisfying the structural requirements and contribute with to a better understanding of the considered structure. The transverse webs of a torsional box structure are examined by comparing different cut-out geometries from numerical models with different regular load conditions to obtain the variables of the fatigue safety factor through linear regression models. The most appropriate geometry of the torsion box is established in terms of minimum weight, from nonlinear multivariable optimization models.