• Magazine of the Korean Society of Agricultural Engineers
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• v.45 no.2
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• pp.78-85
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• 2003

This study aims to investigate the effect of partially distributed loads on the static behavior of parabolic arches by using the elastic-plastic finite element model. For this purpose, the vertical, the radial, and the anti-symmetric load cases are considered, and the ratio of loading range and arch span is increased from 20% to 100%. Also, the elastic-visco-plastic analysis has been carried out to estimate the elapse time to reach the stable state of arches when the ultimate load obtained by the finite element analysis is applied. It is noted that the ultimate load carrying capacities of parabolic arches are 6.929 tf/$m^2$ for the radial load case, and 8.057 tf/$m^2$ for the vertical load case. On the other hand, the ultimate load is drastically reduced as 2.659 tf/$m^2$ for the anti-symmetric load case. It is also shown that the maximum ultimate load occurs at the full ranging distributed load, however, the minimum ultimate loads of the radial and vortical load cases are obtained by 2.336 tf/$m^2$, 2.256 tf/$m^2$, respectively, when the partially distributed load is applied at the 40% range of full arch span.

• Geomechanics and Engineering
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• v.29 no.5
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• pp.487-496
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• 2022

Most of the pile's vertical static load tests in construction sites are the proof load tests, which is difficult to accurately estimate the ultimate bearing capacity and analyze the reliability of piles. Therefore, a reliability analysis method based on the proof load-settlement (Q-s) data is proposed in this study. In this proposed method, a simple ultimate limit state function based on the hyperbolic model is established, where the random variables of reliability analysis include the model factor of the ultimate bearing capacity and the fitting parameters of the hyperbolic model. The model factor M = R_uR / R_uP is calculated based on the available destructive Q-s data, where the real value of the ultimate bearing capacity (R_uR) is obtained by the complete destructive Q-s data; the predicted value of the ultimate bearing capacity (R_uP) is obtained by the proof Q-s data, a part of the available destructive Q-s data, that before the predetermined load determined by the pile test report. The results demonstrate that the proposed method can easy and effectively perform the reliability analysis based on the proof Q-s data.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.10a
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• pp.284-292
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• 1995

This paper is on experimental study on the behavior of reinforced concrete columns subjected to longitudinal steel ratio To investigate the effects of concrete strength and longitedinal steel ratio on the behavior of reinforced concrete columns. a series of tests were carried out for thirty-six tied reinforced concrete columns with a 100mm square cross section and three slendemess ratio of 15, 30 and 50. And To study and illustrate the change of the ultimate loads and that of displacements, two different concrete strength of 180,26kfg/$\textrm{cm}^2$, 819,36kfg/$\textrm{cm}^2$ and five different longitudinal steel ratio of 0.5, 1.0, 4.0, 5.7 and 10.3% were used. The boundary conditions at the ends were both hinged and the end eccentricities (17mm) were equal and of the same sign. While the ultimate load capacity of high-strength concrete column was much increased when the columns were short, that was not when the columns were slender. The effect of longitudinal steel ratio on the increased of ultimate load of column was more evident for slender columns than for short ones and the ultimate of longitudinal steel ratio were more pronounced with increasing concrete strength. The more inserted the longitudinal steel, the more increased the ultimate load, but the superabundance of longitudinal steel ratio over the limitation of maximum steel ratio in ACI code was used, it was showed that the ultimate load was rather decreased.

• Bulletin of the Society of Naval Architects of Korea
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• v.20 no.4
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• pp.1-8
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• 1983

This paper describes the application of the finite element method to the large deflection elastic plastic analysis and ultimate load calculation of axisymmetric shell of revolution with initial imperfection subjected to external pressure. The nonlinear equilibrium equations are linearized by the successive incremental method and are solved by the combination of load increment and iteration scheme with considering plastic deformation theory. To get the more realistic effect of large deflection, corrected coordinats and directions of applied load ar every load increment steps are used. The effects of the plasticity, initial imperfection and the shape of shells on the ultimate load of clamped circular cap under external pressure are investigated. Consequently, the following conclusions are obtained; (1) At same geometric parameter $\lambda$, each shape of clamped circular caps yield same elastic ultimate loads in both cases, i.e. with and without initial imperfections, whereas, in the case of elastic-plastic state the shell becomes thicker, the ultimate loads are getting smaller. (2) The effects of initial imperfection to ultimate load are most significant in the elastic case and are more senstive in the elastic-plastic state with the thinner shells.

• Structural Engineering and Mechanics
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• v.59 no.6
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• pp.1095-1120
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• 2016

This paper investigates the change of structural characteristics of steel cable-stayed bridges after cable failure. Cables, considered as the intermediate supports of cable-stayed bridges, can break or fail for several reasons, such as fire, direct vehicle clash accident, extreme weather conditions, and fatigue of cable or anchorage. Also, the replacement of cables can cause temporary disconnection. Because of the structural characteristics with various geometric nonlinearities of cable-stayed bridges, cable failure may cause significant change to the structural state and ultimate behavior. Until now, the characteristics of structural behavior after cable failure have rarely been studied. In this study, rational cable failure analysis is suggested to trace the new equilibrium with structural configuration after the cable failure. Also, the sequence of ultimate analysis for the structure that suffers cable failure is suggested, to study the change of ultimate behavior and load carrying capacity under specific live load conditions. Using these analysis methods, the statical behavior after individual cable failure is studied based on the change of structural configuration, and distribution of internal forces. Also, the change of the ultimate behavior and load carrying capacity under specific live load conditions is investigated, using the proposed analysis method. According to the study, significant change of the statical behavior and ultimate capacity occurs although just one cable fails.

• Steel and Composite Structures
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• v.37 no.6
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• pp.741-759
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• 2020

Steel plate-concrete composite slabs provide attractive features, such as more effective loading transfer, and more cost-effective stay-in-place forms, thereby enabling engineers to design more high-performance light structures. Although significant studies in the literatures have been directed toward designing and implementing the steel plate-concrete composite beams, there are limited data available for understanding of the composite slabs. To fill this gap, nine the composite slabs with different variables in this study were tested to unveil the impacts of the critical factors on the ultimate strength behavior. The key information of the findings included sample failure modes, crack pattern, and ultimate strength behavior of the composite slabs under either four-point or three-point loading. Test results showed that the failure modes varied from delamination to shear failures under different design factors. Particularly, the shear stud spacing and thicknesses of the concrete slabs significantly affected their ultimate load-carrying capacities. Moreover, an analytical model of the composite slabs was derived for determining their ultimate load-carrying capacity and was well verified by the experimental data. Further extensive parametric study using the proposed analytical methods was conducted for a more comprehensive investigation of those critical factors in their performance. These findings are expected to help engineers to better understand the structural behavior of the steel plate-concrete composite slabs and to ensure reliability of design and performance throughout their service life.

• Structural Engineering and Mechanics
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• v.50 no.6
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• pp.709-722
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• 2014

Ultra-High Performance Concrete (UHPC) is an innovative new material that, in comparison to conventional concretes, has high compressive strength and excellent ductility properties achieved through the addition of randomly dispersed short fibers to the concrete mix. This study presents the results of an experimental investigation on the behavior of axially loaded UHPC short circular columns wrapped with Carbon-FRP (CFRP), Glass-FRP (GFRP), and Aramid-FRP (AFRP) sheets. Six plain and 36 different types of FRP-wrapped UHPC columns with a diameter of 100 mm and a length of 200 mm were tested under monotonic axial compression. To predict the ultimate strength of the FRP-wrapped UHPC columns, a simple confinement model is presented and compared with four selected confinement models from the literature that have been developed for low and normal strength concrete columns. The results show that the FRP sheets can significantly enhance the ultimate strength and strain capacity of the UHPC columns. The average greatest increase in the ultimate strength and strain for the CFRP- and GFRP-wrapped UHPC columns was 48% and 128%, respectively, compared to that of their unconfined counterparts. All the selected confinement models overestimated the ultimate strength of the FRP-wrapped UHPC columns.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.3
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• pp.447-456
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• 2021

Methods for predicting the ultimate/buckling strength of ship structures have been extensively improved in terms of design formulas and analytical solutions. In recent years, the design strategy of ships and offshore structures has tended to emphasize lighter builds and improve operational safety. Therefore, the corresponding geometrical changes in design necessitate the use of high-tensile steel and thin plates. However, the existing design formulas were mainly developed for thick plates and mild steels. Therefore, the calculation methods require appropriate modification for new designs beased on high-tensile steel and thin plates. In this study, a modified formula was developed to predict the ultimate strength of thin steel plates subjected to compressive and shear loads. Based on the numerical results, the effects of the yield stress, slenderness ratio, and loading condition on the buckling/ultimate strength of steel plates were examined, and a newly modified double-beta parameter formula was developed. The results were used to derive and modify existing closed-form expressions and empirical formulas to predict the ultimate strength of thin-walled steel structures.

• Computers and Concrete
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• v.21 no.2
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• pp.117-126
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• 2018

This research investigate the behavior of reinforced normal and lightweight aggregate concrete hollow core slabs with different core shapes, shear span to effective depth (a/d). The experimental work includes testing seven reinforced concrete slabs under two vertical line loads. The dimensions of slab specimens were (1.1 m) length, (0.6 m) width and (0.12 m) thickness. The maximum reduction in weight due to aggregate type was (19.28%) and due to cross section (square and circular) cores was (17.37 and 13.64%) respectively. The test results showed that the decrease of shear span to effective depth ratio from 2.9 to 1.9 for lightweight aggregate solid slab cause an increase in ultimate load by (29.06%) and increase in the deflection value at ultimate load or the ultimate deflection by (17.79%). The use of lightweight aggregate concrete in casting solid slabs give a reduction in weight by (19.28%) and in the first cracking and ultimate loads by (16.37%) and (5%) respectively for constant (a/d=2.9).The use of lightweight aggregate concrete in casting hollow circular core slabs with constant (a/d=2.9) (reduction in weight 32.92%) decrease the cracking and ultimate loads by (12%) and (5.18%) respectively with respect to the solid slab. These slab specimens were analyzed numerically by using the finite element computer program ANSYS. Good agreements in terms of behavior, cracking load (load at first visible crack) and ultimate load (maximum value of testing load) was obtained between finite element analysis and experimental test results.

• Journal of the Society of Naval Architects of Korea
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• v.52 no.4
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• pp.349-355
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• 2015

Through the recent accident, the checking of ultimate hull girder capacity for container ship should be needed. Smith’s method is well known as the only simplified method to access rapidly for ultimate hull girder capacity except very expensive nonlinear F.E approach. This simplified method, however, is admitted to apply only to bulker and tanker in accordance with Classification Rules up to now. The targets of this study are to verify effectiveness of the simplified method for container ship’s ultimate hull girder strength and to propose the safety factor considering the local bending in double bottom structures due to out of plane loads through the nonlinear F.E analyses. Two different sized ships and three loading conditions which are pure bending, homo-loading and one-bay empty condition were used for this study. Based on the F.E results, the present study showed that CSR’s simplified method is available for the ultimate hull girder strength of container ship and over 1.2 of safety factor should be applied to consider the local bending effect in double bottom structures due to out of plane loads such as sea pressure an cargo.