• Steel and Composite Structures
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• v.30 no.4
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• pp.393-403
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• 2019

Cold-formed steel (CFS) has a great potential to meet the global challenge of fast-track and durable construction. CFS members undergo large buckling instabilities due to their small wall thickness. CFS beams with corrugated webs have shown great resistance towards web buckling under flexure, when compared to the conventional I-sections. However, the magnitude of global imperfections significantly affects the performance of CFS members. This paper presents the first attempt made to experimentally study the effect of global imperfections on the structural efficiency of various strengthening schemes implemented in CFS beams with corrugated webs. Different strengthening schemes were adopted for two types of beams, one with large global imperfections and the other with small imperfections. Strength and stiffness characteristics of the beams were used to evaluate the structural efficiency of the various strengthening schemes adopted. Six tests were performed with simply supported end conditions, under four-point loading conditions. The load vs. mid-span displacement response, failure loads and modes of failure of the test specimens were investigated. The test results would compensate the lack of experimental data in this area of research and would help in developing numerical models for extensive studies for the development of necessary guidelines on the same. Strengthening schemes assisted in enhancing the member performance significantly, both in terms of strength and stiffness. Hence, providing an economic and time saving solution to such practical structural engineering problems.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.5
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• pp.1353-1362
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• 2014

In recent years, numerous environmental problems associated with the excessive use of fossil fuel are taking place. For an alternative energy resource, the importance of renewable energy and the demands of facilities to generate renewable energy are continuously rising. To satisfy such demands, a large number of photovoltaic energy generation structures are constructed and planned with large scale. However, because these facility zones are mostly constructed on land, some troubles are occurred such as rising of construction cost due to the cost of land use, environmental devastation, etc. To solve such problems, the floating type photovoltaic energy generation system using FRP members have been developed in Korea. FRP members are recently available in civil engineering applications due to many advantages such as high strength, corrosion resistance, light weight, etc. and they are suitable to fabricate the floating structures because of their material properties. In this study, the analytical and experimental investigations to evaluate the structural performance of floating PV generation structure and SMC FRP vertical member which is used to fabricate the structure were conducted. The static and dynamic performances of floating PV generation structure are evaluated through the FE analysis and the experiment, respectively. Moreover, the structural safety evaluation and buckling analysis of SMC FRP vertical compression member are also conducted by the FE analysis, and the structural behavior of SMC FRP member under compression and pullout is investigated by the experiments. From this study, it was found that the structural system composed of pultruded FRP and SMC FRP members are safe enough to resist externally applied loads.

• Journal of the Society of Naval Architects of Korea
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• v.54 no.3
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• pp.242-249
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• 2017

A design system for doubler reinforcement of the ship plate members subjected to in-plane shear and biaxial compressive loads was developed. This design system of doubler reinforcement on ship plate members established by design supporting system and this system was based on the buckling evaluation process of ship plate members for these in-plane loads. Each design parameters were suggested by equations as the form of influence coefficients for the doubler reinforcement subjected to the various in-plane loads including shear load. Strength of doubler plate member reinforced on the plate member could be suggested by the equivalent flat plate thickness after the consideration of corelation equations in the design system of doubler reinforcement. Level of strength recovery of ship plate members for these in-plane loads according to the local reinforcement by doubler could be suggested by use of this design system in the initial repair design stage of shipyards.

• Journal of Korean Association for Spatial Structures
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• v.19 no.4
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• pp.45-52
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• 2019

The purpose of the paper is to introduce a system that reduces the occurrence of weak-story in the event of earthquake. Weak-story concentrates deformation on the story and causes all member to collapse before the capacity of all member is reached. This paper introduces Strong-Back system (SB) to protect weak story. SB is a hybrid of zipper frame, tied eccentrically braced frame, and elastic truss system and it is divided into elastic and inelastic areas. Elastic areas prevent the generation of weak story by distributing energy, and inelastic areas dissipate energy through buckling or yielding. In this paper, the seismic performance is evaluated by comparing the four type braced frame with SB through push-over analysis. The four criteria are compared from the base shear, the ductility capacity, the column failure order, and the quantity of brace. As a result, SB proved to have sufficient performance to protect the weak-story.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.3
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• pp.78-85
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• 2008

Roll forming process is one of the most widely used processes in the world for forming metals. It can manufacture goods of the uniform cross section throughout the continuous processing. However, process analysis is very difficult because of the inherent complexity. Therefore, time is consuming and much money are needed for manufacturing goods. In order to overcome this difficulty, a new computational method based on the rigid-plastic finite element method is developed for the analysis of roll forming process. In this paper, the design of roll forming process and the simulation are performed to manufacture the upper member at under rail composed of three members. The cold rolled carbon steel sheet(SCP-1) is used in this simulation, and a flow stress equation is set up by conducting the tensile test. The upper member is designed using two types of design for a excellent design. Each types are simulated and compared with the strain distribution using SHAPE-RF software. In addition, the numerical magnitude of bow and camber which are the buckling phenomenon is estimated.

• Steel and Composite Structures
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• v.22 no.6
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• pp.1487-1505
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• 2016

This paper presents the results of an experimental study on the behavior of a new type of composite FRP-concrete-steel member subjected to bi-axial eccentric loading. This new type of composite member is in the form of concrete-filled square steel tube slender columns with inner CFRP (carbon fiber-reinforced polymer) circular tube, composed of an inner CFRP tube and an outer steel tube with concrete filled in the two tubes. Tests on twenty-six specimens of high strength concrete-filled square steel tube columns with inner CFRP circular tube columns (HCFST-CFRP) were carried out. The parameters changed in the experiments include the slenderness ratio, eccentric ratio, concrete strength, steel ratio and CFRP ratio. The experimental results showed that the failure mode of HCFST-CFRP was similar to that of HCFST, and the specimens failed by local buckling because of the increase of lateral deflection. The steel tube and the CFRP worked together well before failure under bi-axial eccentric loading. Ductility of HCFST-CFRP was better than that of HCFST. The ultimate bearing capacity of test specimen was calculated with simplified formula, which agreed well with test results, and the simplified formula can be used to calculate the bearing capacity of HCFSTF within the parameters of this test.

• Journal of the Society of Naval Architects of Korea
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• v.33 no.2
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• pp.111-118
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• 1996

Ship structure basically consists of plate members and it's overall strength depends an the stiffness and strength of each plate member. The buckling strength of plate is one of the most important design criteria when we investigate the structural intergraty. Therefore, it is necessary to surly reasonable buckling formula in order to carry out a more efficient and reliable design. In the present study, the buckling design formula of plate panels under combined loads(inplane compression, tension and shear) is obtained on the theoretical solution or reference paper. This formula is compared with the existing theoretical solution, other author's formula[1], design codes of LR and results which are obtained by numerical analysis. It has a good correlation with numerical analysis results or theoretical ones. When we evaluate buckling strength of plate panels, this formula can be presented with reasonable accuracy.

• Journal of Korean Society of Steel Construction
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• v.26 no.2
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• pp.105-118
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• 2014

The number of the deteriorated bridge has been sharply increased due to the increase in the bridge service period in Korea. Local corrosion problem of structural member can be occurred according to atmospheric corrosion environments based on the installation location of steel bridges. Especially, in case of the plate girder bridge, corrosion damage is concentrated on the web panel and stiffener at girder end. An asymmetrical shear resistant web section in the plate girder bridge can be caused from the local corrosion of the web panel, because local corrosion is not symmetrically occurred to the bridge. In this study, therefore, the shear buckling strength and behavior of a plate girder with asymmetrically corroded web panel was numerically evaluated using FE analysis, which was considering an aspect ratio and corrosion damage level of web panel. The shear buckling strength reduction of an asymmetrical shear resistant web panel was compared and evaluated according to corroded volume ratio for a web panel and for diagonal tension field of a web panel.

• Journal of Korean Society of Steel Construction
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• v.21 no.2
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• pp.193-201
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• 2009

Structural design of most nonprismatic Pre-Engineered Building Systems (PEBS) is performed using optimizing software developed in foreign countries. In this study, a structural optimizing software for the design of 3-D structures of nonprismatic PEBS is developed according to the allowable stress design method of AISC2005 and KBC. Optimizing structural design with nonprismatic members is carried out by repeating the process of structural analysis and member design to minimize the weight of a structure. According to the optimizing design results of 2-D and 3-D structures with nonprismatic members, there are considerable steel savings in designing structures with nonprismatic H-shaped built-up sections rather than with H-shaped rolled sections. When H-shaped built-up sections were used, the weight of the structural steel was reduced when AISC2005 specification rather than AISC1898 was used in the design. It is therefore concluded that utilizing the new AISC2005 specification is safer in preventingweb buckling because the height of a member is designed to be small despite some differences depending on the structural type.

• Journal of the Korean Society of Safety
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• v.32 no.3
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• pp.60-65
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• 2017

This study examined the effect of rotational stiffness of joints between vertical and horizontal members in system supports. In order to prevent repeated disasters of system supports, it is important to examine the accurate behavior of system supports. Among various factors affecting the complex behavior of system supports, this study focused on the stiffness of joints between vertical and horizontal members. The considered joint was modelled by a rotational spring, but the translational displacements were fixed. The stiffness of rotational spring was calculated by utilizing the usable experimental data. In addition, the hinge connection condition, which is generally considered in design and only restrict the translational displacements, was modelled to compare the results. The case with the rotational stiffness in joints showed 3.5 times buckling loads compared to the case without the rotational stiffness. Thus, the structural behavior of the vertical member in system supports was similar to the vertical member with the fixed condition. For the combined stresses of vertical members, the combined stress ratios were reduced 5~6% by considering the rotational stiffness of connecting parts. However, for the horizontal member where showed relatively small stress range, the stresses were increased 2.3~7.6 times by considering the rotational stiffness in connecting parts.