• Steel and Composite Structures
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• v.25 no.5
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• pp.603-615
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• 2017

This experimental research presents the seismic performance of steel reinforced high-strength concrete (SRHC) short columns. Eleven SRHC column specimens were tested under simulated earthquake loading conditions, including six short column specimens and five normal column specimens. The parameters studied included the axial load level, stirrup details and shear span ratio. The failure modes, critical region length, energy dissipation capacity and deformation capacity, stiffness and strength degradation and shear displacement of SRHC short columns were analyzed in detail. The effects of the parameters on seismic performance were discussed. The test results showed that SRHC short columns exhibited shear-flexure failure characteristics. The critical region length of SRHC short columns could be taken as the whole column height, regardless of axial load level. In comparison to SRHC normal columns, SRHC short columns had weaker energy dissipation capacity and deformation capacity, and experienced faster stiffness degradation and strength degradation. The decrease in energy dissipation and deformation capacity due to the decreasing shear span ratio was more serious when the axial load level was higher. However, SRHC short columns confined by multiple stirrups might possess good seismic behavior with enough deformation capacity (ultimate drift ratio ${\geq}2.5%$), even though a relative large axial load ratio (= 0.38) and relative small structural steel ratio (= 3.58%) were used, and were suitable to be used in tall buildings in earthquake regions.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.11a
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• pp.245-251
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• 2001

A fretting wear tester is developed for experimental study on the fuel fretting problem of light water reactor. The feature of the developed tester is it can simulate the existence of gap between spring and fuel rod as well as different contacting force including the just-contact condition (0 N on the contact). Used are a servo-motor, an eccentric cylinder and lever mechanism for driving system. A spacer grid cell is constituted with four strap segments (each segment has a spring). This fretting wear tester can also be used as a fatigue tester of a spacer grid spring with the frequency of more than 10 Hz. It is required to simulate the frequency of the vibrating fuel rod due to flow-induced vibration in a reactor. In fretting wear test, up to two span-length of a fuel cladding tube can be accommodated. A specimen of cladding tube of one span-length is specially designed, which can be extended for two-span test. For .fatigue test, a device for clamping the spring fixture is installed additionally, Presently, the tester is designed for the condition of air environment and room temperature. The variation of the reciprocal distance is measured to check the stability of input force, which will be exerted to the cladding (for fretting wear. test) and the spring (for fatigue test) specimen.

• Fisheries and Aquatic Sciences
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• v.7 no.1
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• pp.39-45
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• 2004

Six demographic parameters including life span (LS), maturation time (MT), net reproduction rate (Ro), mean generation length (G), innate capacity for increase $(r_m)$ and finite rate of increase $(\gamma)$ were estimated in the rotifer (Brachionus rotundiformis) cultured at three salinities of 5, 20 and 34 PSU and under a constant temperature of $28^{\circ}C$. The maximum life spans at salinities of 5, 20 and 34 PSU were 17, 12 and 13 days, respectively. The shortest maturation time (24 hr) was recorded at 5 PSU, and the rotifer at 20 PSU showed a most delayed maturation (192 hr). The maximum reproduction rate was 42 offspring per female in rotifer cultured at 5 PSU, while the longest generation length (8 days) was observed at 20 PSU. Maximum and minimum values of $r_m$ (1.56 and 0.46 individual per day) and $(\gamma)$ (6.67 and 1.70 individuals per day) were calculated at 5 and 34 PSU, respectively. Salinity also showed strong effect on correlation of the demographic traits examined. ANOVA revealed significant differences (P<0.05) between demographic parameters of the rotifer at the three salinity condition. Considering the higher values of life span, innate capacity and finite rate of increase, and shortest maturation time at 5 PSU, the rotifer we examined had a higher reproductive potential and longer life span at 5 PSU rather than at 20 or 34 PSU.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.5
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• pp.968-975
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• 1988

The maximum feedrate generated from the hardware DDA is closely related to its calculation efficiency. The smaller interpolation span results in the lower calculation efficiency. This paper presents the method to improve the calculation efficiency for the smaller interpolation span. For the linear interpolation the higher calculation efficiency can be achieved by putting biggest value that the interpolation DDA can hold. for the circular interpolation, however, the scheme used for linear interpolation does not work since arbitrary change of value in the interpolation DDA changes the radius of the circle. The bit length of the hardware DDA is adjusted instead of adjusting the value in DDA, which results in the every same effect on calculation efficiency for the circular interpolation. The hardware circuit and supporting software are designed, and tested by two axis step motor driven milling machine. The experimental results show that the proposed method drastically increases the maximum feedrate even for the smaller interpolation span.

• Computers and Concrete
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• v.29 no.3
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• pp.161-168
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• 2022

Bridges using double-tee (DT) girders from 12 m to 15 m are one of the good choices to improve accessibility in rural areas of the Mekong River Delta. In this study, nonlinear finite element method (FEM) analysis was conducted with different constitutive laws of materials. The FEM analysis results were compared to experimental results to confirm the applicability of the constitutive laws of materials for DT girders. A parametric study through FEM analysis was then conducted to investigate the effect of span lengths, top flange depths, and a number of prestressing tendons on the capacity of DT girders in order that propose DT girders for rural bridges. Parametric results showed that the top flange depth of a DT girder for rural bridges could be 120 mm. The DT girder with a span length of 12 m or 13 m could be used 16 tendons, while the DT girder with a span length of 14 m or 15 m could be set up with 20 tendons. The prestressed concrete DT girders based on FEM results can be suggested for the construction of rural bridges.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.165-168
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• 2005

Carbon Fiber Reinforced Polymer(CFRP) composites are widely applied to strengthen deteriorated concrete structures. This paper presents the experimental results of the performance of reinforced concrete(RC) decks strengthened with CFRP composites. Simple span decks with 2m span length were tested to investigate the effect of CFRP reinforcement types on the flexural behavior of strengthened RC beams. The test results were analyzed with the special emphasis on the failure mode and the maximum load.

• International Journal of High-Rise Buildings
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• v.11 no.1
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• pp.51-59
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• 2022

The 43 story, 178m tall Atlantis The Royal Resort and Residences tower nearing completion on the Palm in Dubai is a unique project in terms of its overall scale, geometry and form. The tower superstructure has a long narrow curved floor plan, measuring 400m in length above the podium with significant long span bridge structures forming voids and cantilevered blocks. This paper describes the innovative structural design solutions adopted and the construction solutions adopted by the Contractor to realize the Architectural vision.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.495-498
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• 2008

In this paper applicable range of U-Channel Bridge (UCB) that has recently been introduced as a new bridge type was studied. For structural analysis models used with the frame and plate elements was proposed, and verification of the models were performed. Using these structural models structural analysis of models with span length of 20m-45m and inner width of 5m-13m were performed. As a result for U-shape sections were applicable in the range of 20m span and 35m span, slab was applicable in the range of 5m inner width and 12m inner width. To increase applicable range of UCB H-shape sections and slab with rib were proposed. As a result UCB were applicable in the range of 20m span and 45m span, in the range of 5m inner width and 13m inner width.

• Journal of the Korean Society of Safety
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• v.31 no.4
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• pp.97-103
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• 2016

This study investigates effects of partially earth anchored cable system on the structural safety for a long-span cable-stayed bridge under dynamic loads such as seismic and wind load. For a three span cable-stayed bridge with a main span length of 810 m, two models are analyzed and compared; one is a bridge model with a self anchored cable system, the other is a bridge model with a partially earth anchored cable system. By performing multi-mode spectrum analysis for a prescribed seismic load and multi-mode buffeting analysis for a fluctuating wind component, the structural response of two models are compared. From results, the partially earth anchored cable system reduce the maximum pylon moment by 66% since earth anchored cables affect the natural frequencies of girder vertical modes and pylon longitudinal modes. In addition, the girder axial forces are decreased, specially the decrement of the axial force is large in seismic load, while girder moment is slightly increased. Thus, the partially earth anchored cable system is effective system not only on reduction of girder axial forces but also improvement of structural safety of a cable-stayed bridge under dynamic loads such as seismic and wind loads.

• Journal of the Korean Society of Safety
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• v.29 no.3
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• pp.72-78
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• 2014

The minimum thickness of long-span deck slab is proposed by checking the limit state according to the Korean highway bridge design code(limit state design). Both minimizing thickness and ensuring safety of deck slab are important design factors to increase a competitive price of the long span deck slabs. The required thicknesses for satisfying flexural capacity, preventing punching shear failure and limiting deflection were calculated by considering KL-510 load model which has increased total load compared to DB 24 from 432 kN to 510 kN. The results of the required thickness for various limit states were compared to propose the minimum thickness as a function of span length of deck slabs. The proposed minimum thickness is influenced by satisfying flexural capacity and limiting deflection. It turns out to be similar compared to the results of the previous study by ultimate strength design method even if the live load model was increased in total weights.