• Structural Engineering and Mechanics
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• v.23 no.5
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• pp.563-577
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• 2006

This study involves a series of experiments on the buckling strength of eccentrically compressed cold-formed stainless steel square hollow-section columns. The principal parameters in this study are slenderness ratios ($L_k/r$ = 30, 50, 70) and magnitude of eccentricity e (0, 25, 50, 75, 100 mm) on the symmetrical end-moment. The objectives of this paper are to obtain the buckling loads by conducting a series of experiments and to compare the behavior of the eccentrically compressed cold-formed stainless steel square hollow-section columns with the results of the analysis. The ultimate buckling strength of the square-section members were determined with the use of a numerical method in accordance with the bending moment-axial force (M-P) interaction curves. The behavior of each specimen was displayed in the form of a moment-radian (M-${\theta}$) relationship. The numerically obtained ultimate-buckling interaction curves of the beam columns coincided with the results of the experiments.

• Computers and Concrete
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• v.2 no.3
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• pp.177-188
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• 2005

This paper presents a numerical model developed to evaluate the load-deflection and moment-curvature relationship for concrete beams strengthened externally with four different Fiber Reinforced Polymer (FRP) composite systems. The developed model considers the inelastic behavior of concrete section subjected to a combined axial force and bending moment. The model accounts for tensile strength of concrete as defined by the modulus of rupture of concrete. Based on the adopted material constitutive relations, the model evaluates the sectional curvature as a function of the applied axial load and bending moment. Deflections along the beam are evaluated using a finite difference technique taking into account support conditions. The developed numerical technique has been tested on a cantilever beam with a transverse load applied at its end. A study of the behavior of the beam with tension reinforcement compared to that with FRP areas giving an equivalent ultimate moment has been carried out. Moreover, cracking of the section in the tensile region at ultimate load has also been considered. The results indicated that beams reinforced with FRP systems possess more ductility than those reinforced with steel. This ductility, however, can be tuned by increasing the area of FRP or by combining different FRP layers.

• Journal of the Society of Naval Architects of Korea
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• v.29 no.1
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• pp.93-102
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• 1992

In this paper presented is the reliability analysis of a double skinned hull structure against the ultimate bending moment and fatigue strength under longitudinal bending. The ultimate bending strength is obtained through the beam-column approach in which the load-end shortening curves(stress-strain curves) of stiffened plates under mini-axial compression are derived using the concept of plastic hinge collapse. The fatigue damage only is considered as fatigue failure for which the Miner's damage rule is employed. Assessed are fatigue reliability for the possible joint types found at deck structure. Also included is the reliability analysis of a series system of which elements are ultimate and fatigue failure.

• Journal of the Korea Concrete Institute
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• v.12 no.5
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• pp.101-110
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• 2000

A practical approach of calculating the ultimate strength of composite beams with unreinforced web opning is proposed through shear behavioral tests. In this method, the slab shear contribution at the opening is calculated as the smaller value of the pullout capacity of shear connector at the high moment end and the one way shear capacity of slab. A simple interaction equation is used to predict the ultimate strength under simultaneous bending moment and shear force. Strength prediction by the proposed method is compared with previous test results and the predictions by other analytical methods. The comparison shows that the proposed method predicts the ultimate capacity with resonable accuracy.

• Steel and Composite Structures
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• v.18 no.4
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• pp.873-887
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• 2015

The continuous composite I-girder should have a sufficient rotation capacity (or ductility) to redistribute the negative bending moment into an adjacent positive bending moment region. However, it is generally known that the ductility of the high strength steel is smaller than that of conventional steel, and application of high strength steel can cause ductility problems in a negative moment region of the I-girder. In this study, moment redistribution of the continuous composite I-girder with high strength steel was studied, where high strength steel with yield stress of 690 MPa was considered (the ultimate stress of the steel was 800 MPa). The available and required rotation capacity of the continuous composite I-girder with high strength steel was firstly derived based on the stress-strain curve of high strength steel and plastic analysis, respectively. A large scale test and a series of non-linear finite element analysis for the continuous composite I-girder with high strength steel were then conducted to examine the effectiveness of proposed models and to investigate the effect of high strength steel on the inelastic behavior of the negative bending moment region of the continuous composite I-girder with high strength steel. Finally, it can be found that the proposed equations provided good estimation of the requited and available rotation capacity of the continuous composite I-girder with high strength steel.

• Structural Engineering and Mechanics
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• v.43 no.2
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• pp.225-237
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• 2012

This paper presents an experimental investigation of the flexural behavior of square hollow steel section (HSS) beams subjected to pure bending. Totally six unfilled and nine ultra high performance concrete (UHPC)-filled HSS beams were tested under four-point bending until failure. The effects of the steel tube thickness, the yield strength of the steel tube and the strength of concrete on moment capacity, curvature, and ductility of UHPC-filled HSS beams were examined. The performance indices named relative ductility index (RDI) and strength increasing factor (SIF) were investigated with regard to different height-to-thickness ratio of the specimens. The flexural strengths obtained from the tests were compared with the values predicted by Eurocode 4, AISC-LRFD and CIDECT design codes. The results showed that the increase in the moment capacity and the corresponding curvature is much greater for thinner HSS beams than thicker ones. Eurocode 4 and AISC-LRFD predict the ultimate moment capacity of the all UHPC-filled HSS beams conservatively.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.357-360
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• 2008

This study was performed to estimate the workability and the static behavior for Bi Prestressed Concrete Girder(Bicon girder) which could introduce effectively prestressed forces into concrete girders. A bicon girder is manufactured by means of introducing pure bending moment that prestress simultaneously the compressive member(steel bar) and the tensile member(steel tendon). Static test was executed for 20m railway bridge girder specimen and evaluated whether pure bending moment was introduced or not, and the behaviors after cracking, and at the ultimate load. Test results showed that a bicon girder had the enough safety in the introduction of pure moment, the serviceability, and the ultimate behavior.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.04a
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• pp.45-52
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• 2003

A finite element procedure to estimate ultimate strength of space frames considering spread of plasticity is presented. The improved displacement field is introduced based on inclusion of second order terms of finite rotations. All the nonlinear terms due to bending and torsional moment as well as axial force are precisely considered. The concept of plastic hinge is introduced and the incremental load/displacement method is applied for the elasto-plastic analysis. The initial yield surface is defined based on the residual stress and the full plastification surface is considered under the combined action of axial force, bending and torsional moments. The elasto-plastic stiffness matrices are derived using the flow rule and the normality condition of the limit function. Finite element solutions for ultimate strength of space frames are compared with available solutions and experimental results.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.902-909
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• 2020

It is announced a new procedure for the real-time overall hull response monitoring system depends on inclinometer sensor data. The procedure requires a few inclinometer sensors' data, located on the deck. Sensor data is used to obtain curvature values; and curvature values are used to find out displacements or relevant moment values according to pre-calculated moment-curvature diagrams. Numerical studies are demonstrated with reasonable accuracy for the pre-ultimate and the post-ultimate nonlinear behaviors. Elastic, inelastic, and post-collapse structural bending moment capacity determination of the hull has been presented. The proposed inverse engineering technique will be able to see the response of the hull in real-time with high accuracy to manage the course and speed when cruising or control the loading and the unloading process at the port.

• Journal of Ocean Engineering and Technology
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• v.22 no.2
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• pp.85-90
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• 2008

Ships in bad weather conditions are likely to be subjected to accidental loads, such as high bending moment, collision, and grounding. Once she has damage to her hull, her ultimate strength will be reduced. This paper discusses an investigation of the effect of collision damage on the ultimate strength of a ship structure by performing a series of collapse tests. For the experiment, five box-girder models with stiffeners were prepared with a cross section of $720mm\;{\times}\;720mm$ and a length of 900mm. Of the five, one had no damage and four had an ellipse shaped damage area that represented the shape of the bulbous bow of a colliding ship. The amount of damage size was different between models. Among the damaged models, the damage in three of them was made by cutting the plate and stiffener, and in one by pressing to represent collision damage. Experiments were carried out under a pure bending load and the applied load and displacements were recorded. The ultimate strength was reduced as the damage size increased, as expected. The one with the largest amount of damage had damage to 30% of the depth, and its ultimate strength was reduced by 19% compared to the undamaged one. The pressed one has higher ultimate strength than those that were cut. This might be due to the fact that the plate around the pressed damage area contributes to the ultimate strength, whereas the cut one has no plate to contribute.