• Journal of the Korean Society of Safety
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• v.37 no.5
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• pp.1-6
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• 2022

In this study, to confirm the effects of the mixed load of normal and shear forces acting on a fixing bolt, fatigue design criteria were developed by varying the loading angle and conducting tensile and fatigue tests. After evaluating and comparing the test results under different loading angles, the evaluation criteria were selected. These evaluation criteria were then applied to develop the design criteria. An Arcan fixture was designed and manufactured to simultaneously apply a mixed load of normal and shear forces to the fixing bolt of a turntable, and a fatigue test was conducted. S-N diagrams for various loading angles were obtained, and a 1% P-S-N diagram of failure probability was determined using statistical processing techniques. Our results show that failures of the fixing bolt can be prevented using these diagrams as a basis for developing fatigue design criteria.

• Journal of Korean Society of Steel Construction
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• v.17 no.2 s.75
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• pp.151-159
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• 2005

This study investigated the capacity evaluation of composite beam of the end-reinforced concrete, the center steel with attached main-bar of stud-bolt welting and flange with main parameter, such as shear span depth ratio (a/d=1.5, 2.5, 3.5), reinforcing method, reinforcing length, and steel main-bar ratio. The test results are summarized as follows: As the RC section becomes longer, the capacity ratio of Vsrc, test/Vsrc, the gradually decreased, with the tendency of decrease being remarkably more than a/d=3.5. The reinforcing method showed superior result both vertically and horizontally. And, capacity increase ratio displayed tendency that main-bar fixing length is obvious in 0.15L, and underestimate experimental value usually in Vsrc, Eq(3)~(5) equation. The capacity estimation was proposed equation by regression analysis with change of shear span depth ratio and main-bar fixing, steel main-bar ratio.

• Journal of Korean Association for Spatial Structures
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• v.19 no.1
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• pp.65-73
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• 2019

This paper assesses the structural performance (force-slip response, slip modulus, and failure modes) of a CLT-concrete composite by conducting fifteen push-out test specimens. In addition, non-linear 3D finite element analysis was also developed to simulate the load-slip behavior of the CLT-concrete specimens under shear load. All 15 test specimens simulating the effect of concrete thickness, connection angle and penetration depth with four different shear connector types were built and tested to evaluate the flexural performance. Experimental results show that the maximum shear capacity for the composite action is obtained when the fixing angle is $90^{\circ}$ and the penetration depth of 95mm for SC normal screw was used to achieve ductile failure compared to other shear connectors.

• Journal of the Korea Concrete Institute
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• v.27 no.6
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• pp.651-659
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• 2015

Currently, social demands for long span building structures are increasing due to architectural planning purposes and economic efficiency. As a result, lighter board-type voiding materials were suggested. With the use of board-type voiding materials, a slab is able to become light weight and convenient. This process efficiently eliminates concrete where it is not required; considerably diminishing dead weight while maintaining the flexural strength of the slab. The reduction in concrete also allows for overall cost reductions and design flexibility. Also it can be ease with fixing the voided material that is composed of one body form. Although board-type voiding materials are ideal, the top and bottom concrete plates lack integrity. Because of this, test results show horizontal cracking towards the tops and bottoms of the concrete columns, or webs, connecting the slabs. The key to correcting this problem is to increase the shear strength. In order to increase the shear strength of the structure, horizontal shear area must increase. R70(100)-D-F has the largest horizontal shear area as it also shows stronger strength. As a result, shear strength ($V_{nh}$) is dependent on the horizontal shear area (N). $V_{nh}={\alpha}{\times}0.16{\sqrt{f_{ck}}}{\frac{{\pi}D^2}{4}}{\times}N({\alpha}=1.8125)$. The web columns have a shear span to depth ratio (a/d) that is less than 2; which classifies it as a deep beam. In this case, however, the shear strength of the deep beams may be as much as 2 to 3 times greater than that predicated conventional equations developed for members of normal proportions. As a result, ${\alpha}$ is suggested as an extra coefficient in the equation for shear strength ($V_{nh}$).

• Composites Research
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• v.25 no.6
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• pp.211-216
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• 2012

FBG sensor peaks could be split due to polarization by shear strain, when the fiber optic sensors embedded or attached to the structure. For the fiber optic sensor packages, sensor grating has to be protected from shear strains. Also, pretension has to be applied to the sensor because compressive strain must be measured. Without pretension of sensor, the sensor does not show any change of signal until it is stretched. In order to mesure compressive and tensile strains, two fixing point and prestressed sensor need. In the fixing point, just holding the optical fiber cause slip between core and cladding in the fiber. A Fixation method of prestressed FBG sensors fixed with partially stripped fibers was developed. The sensor package has the prestress controllable fixtures at the fixing points. Prestress to the sensor imposed by controlling the two fixed points with bolts and nuts make it easy to measure compressive strain as well as tensile strain. The fiber optic sensor packages applied to the actual structure and the structural monitoring system using the package can be applied to safety through surveillance.

• The Journal of Engineering Geology
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• v.32 no.1
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• pp.143-155
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• 2022

In this study, the response acceleration amplification according to different conditions was analyzed by changing the boundary condition of the soil called LSB (Laminar Shear Box), which is placed on a 1 g shaking table for earthquake simulation experiments. Experiments were carried out with different boundary conditions by fixing both sides of the LSB, and two samples were tested by installing an accelerometer at the same location. In addition, using DEEPSOIL v7 program, a one-dimensional ground response analysis was performed to compare and analyze with the free field condition. As a result, it was confirmed that the acceleration was amplified as it went from the lower layer to the upper layer, and as a result of comparing it with the ground response analysis, it was confirmed that it appeared similar to the analysis under the free field condition. As a result of the SA (Spectrum acceleration) analysis, a result similar to that of the ground response analysis was obtained, and in the case of fixing, it was confirmed that the PSA (Peak Spectral Acceleration) was further amplified.

• Tunnel and Underground Space
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• v.21 no.3
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• pp.181-191
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• 2011

It is very difficult to prepare a lab. test specimen from weak rock masses affected by faults, highly fractured zone or weathered zone. In conventional method of in situ direct shear test a rock block is sheared inside galleries, where reactions for the hydraulic jacks are available. A new in situ direct shear test apparatus has been developed in this study to perform the test inside galleries as well as open pit conditions. The apparatus is composed of normal and shear reaction plates including load transfer plates, hydraulic cylinder systems, load cells, multistage shear boxes with fixing devices, and needle rollers. Maximum size of the test block is $400{\times}400{\times}460$ mm, and procedures of the test block preparation has been suggested. To explore the field applicability of in situ direct shear test apparatus, proper test block site was investigated by extensive geological field survey. In situ direct shear test has been successful in producing most of information related to strength and deformability of the weak rock.

• International Journal of High-Rise Buildings
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• v.11 no.4
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• pp.331-346
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• 2022

Reproducing the horizontally homogeneous atmospheric boundary layer in computational wind engineering is essential for predicting the wind loads on structures. One of the important issues is to use fully developed inflow conditions, which will lead to the consistence problem between inflow condition and internal roughness. Thus, by analyzing the previous results of computational fluid dynamic modeling turbulent horizontally homogeneous atmospheric boundary layer, we modify the past hypotheses, detailly derive a new type of inflow condition for standard k-ε turbulence model. A group of remedial approaches including formulation for wall shear stress and fixing the values of turbulent kinetic energy and turbulent dissipation rate in first wall adjacent layer cells, are also derived to realize the consistence of inflow condition and internal roughness. By combing the approaches with four different sets of inflow conditions, the well-maintained atmospheric boundary layer flow verifies the feasibility and capability of the proposed inflow conditions and remedial approaches.

• Journal of Welding and Joining
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• v.29 no.2
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• pp.72-79
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• 2011

The scope of this investigation is to evaluate the effect of joining parameters on the microstructural features and mechanical properties of dissimilar aluminum alloys, 1mm-thickness fixing AA6K31 at the top position and fixing AA5J32 at the bottom position. The friction stir lap welds were studied under various welding conditions, rotation speed of 1000, 1250, 1500rpm and welding speed of 100, 300, 500, 700mm/min, respectively. Mechanical test has been investigated in terms of tensile shear test and hardness test. The results showed that three type nugget shapes such as onion ring, zigzag type, hooking with the void, have been observed with revolutionary pitch. All welding conditions fractured at the HAZ of top plate, A6K31 and also the strength compare with base metal of lap joints were low efficiency, 52~63%. The thickness of fractured position was decreased with the lower heat input conditions. The relationships were excellent due to linear between the effective thickness of fractured position and peak load. The fractured position was the interface between joint area and not joint area. Also the strength efficiency compared with base metal was lower than decreasing rate of thickness because the hardness was decreased at fractured position due to softened material.

• Wind and Structures
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• v.18 no.5
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• pp.511-528
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• 2014

The characteristics of wake galloping phenomenon for two parallel/unparallel circular cylinders were investigated via wind tunnel tests. The two cylinders were initially deployed in parallel and wake galloping phenomena were observed by varying the center-to-center distance. The effect of an unparallel arrangement of two cylinders was next investigated by fixing the spacing ratio of one side of the cylinders at 5.0D and the other side at 3.0D, in which D represents the diameter of the cylinder. For the unparallel disposition, the 5.0D side showed a small, limited vibration while the 3.0D side produced much larger amplitude of vibration, resulting in a rolling motion. However, the overall amplitude appeared to decrease in unparallel disposition when compared with the amplitude of the 3.0D - 3.0D parallel case. This represents the mitigation effect of wake galloping due to the unparallel disposition between two cylinders. Flow visualization tests with particle image velocimetry were conducted to identify flow fields between two cylinders. The test results demonstrate the existence of a complex interaction of the downstream cylinder with the shear layer generated by the upstream cylinder. When the spacing ratio was large enough, the shear layer was not observed and the downstream cylinder showed only limited random vibration.