• Journal of the Korean Society of Safety
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• v.9 no.2
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• pp.18-25
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• 1994

In this thesis, the fatigue tests were performed on a series of reinforced concrete to Investigate the variation of strength and the safety of reinforced concrete structures under fatigue load. The specimens were of the same rectangular cross-section, of effective height 24cm and width 30cm and their span was 330cm. The three point loading system is used in the fatigue tests. In these tests, the fracture mode of reinforced concrete structures under fatigue load, relationship between the repeated loading cycles and the mid-span displacement of the specimens were observed. According to the test results, the following fatigue behavior of reinforced concrete specimens were observed. By increasing of the number of repeated loading cycles, the mid-span displacement became greater, however the Incremental amounts of the displacement were reduced. It could be also known that the inelastic strain energy of the doubly reinforced rectangular beams was larger than that of the singly reinforced rectangular beams as increasing the number of repeated loading cycles. Compliance of reinforced concrete structures tended to be reduced as increasing the repeated loading cycles, and the compliance of the doubly reinforced rectangular beams was generally smaller than that of the singly reinforced rectangular beams. Based on the above investigation, it could be concluded that the doubly reinforced rectangular beams under fatigue load were more efficient to resist the brittle fracture than the singly reinforced rectangular beams.

• Journal of Electrical Engineering and Technology
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• v.8 no.4
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• pp.872-878
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• 2013

In industrial control systems, flow measurement is a very important issue. It is frequently needed to calculate how much total fluid or gas flows through a cross-section. Flow volume measurement tools use simple sampling or rectangle methods. Actually, flow volume measurement process is an integration process. For this reason, measurement systems using instantaneous sampling technique cause considerably high errors. In order to make more accurate flow measurement, numerical integration methods should be used. Literally, for numerical integration method, Rectangular, Trapezoidal, Simpson, Romberg and Gaussian Quadrature methods are suggested. Among these methods, trapezoidal rule method is quite easy to calculate and is notably more accurate and contains no restrictive conditions. Therefore, it is especially convenient for the portable flow volume measurement systems. In this study, the volume measurement of air which is flowing through a cross-section is achieved by using PLC ladder diagram. The measurements are done using two different approaches. Trapezoidal rule method is proposed to measure the flow sensor signal to minimize measurement errors due to the classical sampling method as a different approach. It is concluded that the trapezoidal rule method is more effective than the classical sampling.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.3
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• pp.58-68
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• 2014

Transverse steel bars are used in the plastic hinge zone of columns to insure adequate confinement, prevention of longitudinal bar buckling and ductile behavior. Fabrication and placement of rectangular hoops and cross-ties in columns are difficult to construct and require larger amount of transverse steels. In this paper, to solve these problems, the new lateral confinement method using oblong hoop is proposed for the transverse confinement of columns of the oblong cross-section and flared column. The experimental study for octagonal oblong cross-section was carried out by the flared columns test in strong axis. The lateral confinement method using proposed oblong hoop detail showed satisfactory performance of lateral confinement. Therefore it can be the alternative for oblong cross-section and flared column with improved workability and cost-efficiency.

• Structural Engineering and Mechanics
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• v.74 no.1
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• pp.145-156
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• 2020

There are separate merits and demerits to wood and steel. The combination of wood and steel as a compound section is able to improve the properties of both and ultimately increase their final bearing capacity. The composite cross-section made of steel and wood has higher hardness while showing more ductility and the local buckling of steel is delayed or completely prevented. The purpose of this study is to investigate the behavior of composite columns enclosed in wooden logs and the hollow sections of steel that will be examined in a laboratory environment under the axial load to determine the final bearing capacity and sample deformation. In terms of methodology, steel sheet and carbon fiber reinforced polymer sheet (FRP) are tested to construct hollow rectangular sections and reinforce timber. Besides, the method of connecting hollow sections and timber including glue and screw has been also investigated. As a result, timber lumber enclosed with carbon fiber-reinforced polymer sheets in which fibers are horizontally located at 90° are more resistant with better ductility.

• Steel and Composite Structures
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• v.46 no.3
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• pp.353-366
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• 2023

This paper presents a finite-element analysis (FEA) of aluminum alloy rectangular hollow sections (RHSs) and square hollow sections (SHSs) with circular through-openings under three-point and four-point bending. First, a finite-element model (FEM) was developed and validated against the corresponding test results available in the literature. Next, using the validated FE models, a parametric study comprising 180 FE models was conducted. The cross-section width-to-thickness ratio (b/t) ranged from 2 to 5, the hole size ratio (d/h) ranged from 0.2 to 0.8 and the quantity of holes (n) ranged from 2 to 6, respectively. Third, results obtained from laboratory test and FEA were compared with current design strengths calculated in accordance with the North American Specifications (NAS), the modified direct strength method (DSM) and the modified Continuous strength method (CSM). The comparison shows that the modified CSM are conservative by 15% on average for aluminum alloy RHSs and SHSs with circular through-openings subject to bending. Finally, a new design equation is proposed based on the modified CSM after being validated with results obtained from laboratory test and FEA. The proposed design equation can provide accurate predictions of flexural capacities for aluminum alloy RHSs and SHSs with circular through-openings.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.05a
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• pp.85-88
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• 2001

Examination of the die design is carried out for a multi-stage rectangular cup drawing process with the large aspect ratio with the aid of the finite element analysis. The analysis considers the deep drawing process with the ironing process for the thickness control in the cup wall. Simulation is performed to investigate the deformation mechanism in the initial design and the modified design. The analysis clarifies that the irregular cross section and the irregular contact condition produces unfavorable deformation. The analysis results show that the modified design improves the quality of a deep-drawn product with the low possibility of failure. The analysis result also shows good agreement with the experimental one.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.943-948
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• 2003

The experimental study for oblong section was carried out by the column test in weak axis. The column specimens had 3 types of transverse steel configurations, such as interlocking spirals, interlocking circular hoop ties and rectangular ties. The oblong columns with interlocking spirals and with interlocking circular hoop ties showed better seismic performance than the rectangular columns with rectangular hoops and cross-ties. The objectives of this study were to provide experimental data on the behavior of interlocking spiral columns under cyclic loading, to compare the performance of columns with interlocking spirals to columns with various transverse steel configurations, to study the flexural detailing of interlocking spirals, interlocking circular hoops, and other transverse steel configurations as the transverse reinforcement, and to make recommendations for the design of bridge columns incorporating interlocking spirals, circular hoops as the transverse reinforcement.

• Journal of the Korea Concrete Institute
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• v.12 no.4
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• pp.3-14
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• 2000

Structural performance of the walls subjected to lateral load reversals depends on various parameters such as loading history, sectional shape, reinforcement, lateral confinement, aspect ratio, axial compression, etc. Thus, the performance of the shearwall for wall-type apartment should be evaluated properly considering above parameters. This study investigates the effect of sectional shape on the structural performance of the wall. Sectional shape of the specimen is rectangular, barbell and T. Based on this experimental results, all specimens behaved as ductile fashion and failed by concrete crushing of the compression zone. Deformation index of those specimens evaluated better than 3 of ductility ratio, and 1.5% of deformability specified by seismic provision. Moreover, the performance of the rectangular shaped specimen, whose compression zone was confined with U-bar and cross tie, was as good as the barbell shaped specimen. Therefore, if we considered construction practice such as workmanship and detailing, shearwall with rectangular section may be more economical lateral load resisting system.

• Steel and Composite Structures
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• v.10 no.2
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• pp.151-168
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• 2010

The subject of the paper is an isotropic metal foam rectangular plate. Mechanical properties of metal foam vary continuously through plate of the thickness. A nonlinear hypothesis of deformation of plane cross section is formulated. The system of partial differential equations of the plate motion is derived on the basis of the Hamilton's principle. The system of equations is analytically solved by the Bubnov-Galerkin method. Numerical investigations of dynamic stability for family rectangular plates with respect analytical solution are performed. Moreover, FEM analysis and theirs comparison with results of numerical-analytical calculations are presented in figures.

• Structural Engineering and Mechanics
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• v.16 no.5
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• pp.597-612
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• 2003

In this paper, multi-story buildings with shear-wall structures and with narrow rectangular plane configuration are modeled as a multi-step flexural-shear plate with varying cross-section for buckling analysis. The governing differential equation of such a plate is established. Using appropriate transformations, the equation is reduced to analytically solvable equations by selecting suitable expressions of the distribution of stiffness. The exact solutions for buckling of such a one-step flexural-shear plate with variable stiffness are derived for several cases. A new exact approach that combines the transfer matrix method and closed from solution of one-step flexural-shear plate with continuously varying stiffness is presented for stability analysis of multi-step non-uniform flexural-shear plate. A numerical example shows that the present methods are easy to implement and efficient.