• Steel and Composite Structures
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• v.18 no.5
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• pp.1129-1144
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• 2015

Based on the experiment, this paper focuses on studying flexural behavior of splicing concrete-filled glass fiber reinforced polymer (GFRP) tubular composite members connected with steel bars. The test results indicated the confinement effects of GFRP tubes on the concrete core in compression zone began to produce, when the load reached about $50%P_u$ ($P_u$-ultimate load), but the confinement effects in tensile zone was unobvious. In addition, the failure modes of composite members were influenced by the steel ratio of the joint. For splicing unreinforced composite members, the steel ratio more than 1.96% could satisfy the splicing requirements and the steel ratio 2.94% was ideal comparatively. For splicing reinforced specimen, the bearing capacity of specimen with 3.92% steel ratio was higher 21.4% than specimen with 2.94% steel ratio and the latter was higher 21.2% than the contrast non-splicing specimen, which indicated that the steel ratio more than 2.94% could satisfy the splicing requirements and both splicing ways used in the experiment were feasible. So, the optimal steel ratio 2.94% was suggested economically. The experimental results also indicated that the carrying capacity and ductility of splicing concrete-filled GFRP tubular composite members could be improved by setting internal longitudinal rebars.

• Geotechnical Engineering
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• v.5 no.1
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• pp.19-26
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• 1989

In this study, the finite element method for nonlinear problems is developed theroretically to see the design loads of foundation, when the circular plate resting on elasto-viscoplastic soil medium is loaded axisymmetrically. The paper shows that the plastic zone of soil medium is displayed at the near the edge of plate at the first place; when the plastic zone of soil medium is linked around central axis, the external load is termed by allowable load or design load, and then the contact pressure changes abruptly, in this case it is approved to be the risk of shear failure. The results of numerical analysis using the Mohr-Coulomb yield criterion, and experimental analysis for a appropriate safety factor are approximative, but numerical results are smaller than the value based on Terzaghi's theory.

• Geotechnical Engineering
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• v.8 no.3
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• pp.37-50
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• 1992

Liquefaction leads to severe damage to earth structures after an earthquake. In this study, shaking table tests were performed on model waterfront structures as a countermeasure against liquefaction. The waterfront structure was reinforced by a compacted Bone, which was investigated for its effectiveness in protecting the structure from excessive deformation induced by the lateral pressure of liquefied ground. Through the tests . on embankment, double sheet pile wall, and anchor sheet pile wall, good quantitative information on the behavior of flow failure and the extent of reinforcement was obtained. The extent of a compacted zone for the protection of the structure depends on the magnitude of the acceleration during the shaking. The measured deformation was represented in terms of the extent of the compacted zone and the magnitude of the input acceleration.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.3
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• pp.507-512
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• 2017

Recently, more electric power facilities have been miniaturized and it is noted that the facilities maintenance will be essential through operation optimization. In this paper we applied and examined the operation optimization of electric power facilities by applying Matrix system which can improve reliability to minimize outage and recover failure rapidly when blackouts happen at 25.8kV Gas Insulated Switchgear(GIS). The fundamental problem for facilities maintenance of GIS can happen due to indeterminable internal state in real time. Matrix optimization organizes action states in all containers which contain pressurized $SF_6$ Gas such as circuit breaker, disconnector switch, bus for utilizing them each area. Then, we connect it with power system to monitor and control internal state remotely in real time, and we can minimize blackout zone or outage. Considering above process, we improved stability of overall facilities.

• Steel and Composite Structures
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• v.21 no.6
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• pp.1307-1325
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• 2016

Nonlinear behavior of two-span, continuous composite steel-concrete girders strengthened with Carbon Fiber Reinforced Polymers (CFRP) bonded to the top of concrete slab over the negative moment region was evaluated using a non-linear Finite Element (FE) model in this paper. A three-dimensional FE model of continuous composite girder using commercial software ABAQUS simulated and validated with experimental results. The interfacial regions of the composite girder components were modeled using suitable interface elements. Validation of the proposed numerical model with experimental data confirmed the applicability of this model to predict the loading history, strain level for the different components and concrete-steel relative slip. The FE model captured the different modes of failure for the continuous composite girder either in the concrete slab or at the interfacial region between CFRP sheet and concrete slab. Through a parametric study, the thickness of CFRP sheet and shear connection required to develop full capacity of the continuous composite girder at negative moment zone have been investigated. The FE results showed that the proper thickness of CFRP sheet at negative moment region is a function of the adhesive strength and the positive moment capacity of the composite section. The shear connection required at the negative moment zone depends on CFRP sheet's tensile stress level at ultimate load.

• Advances in Computational Design
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• v.4 no.3
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• pp.295-305
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• 2019

The sealing cement of total hip arthroplasty is the most widely used binder in orthopedic surgery for anchoring implants to their recipient bones. Nevertheless, this latter remains a fragile material with weak mechanical properties. Inside this material cracks initiate from cavities. These cracks propagate under the effect of fatigue and lead to the failure of this binder and consequently the loosening of the prosthesis. In this context, this work consists to predict the position of cracks initiation and their propagations path using the Extended Finite Element Method (XFEM). The results show that cracks can only be initiated from a sharp edges of an ellipsoidal cavity which the ratio of the minor axis over the major axis is equal to 0.1. A maximum crack length of 19 ?m found for a cavity situated in the proximal zone position under a static loading. All cracks propagate in same(almost) way regardless of the cavity(site of initiation) position and its inclination in the proximal zone.

• Structural Monitoring and Maintenance
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• v.6 no.2
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• pp.103-124
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• 2019

Present study concerns the safety evaluation of SefidRud dam's block No. 18 regarding probable crack propagation in the foundation gallery under a MCE record. Accordingly, a 3D finite element model of the block in companion with the reservoir and the foundation is modeled. All the associated thermal and structural parameters are derived via calibration with the records of thermometers and pendulums installed inside the dam body. The origination of the cracks and their whereabouts are determined by primary thermal and static analyses and through a linear dynamic analysis the potential failure zone and their extent and level are studied. The foundation gallery is the most probable zone among the other intensive tensile stress area to compromise the dam stability. Therefore, the nonlinear analysis of this risky region is inevitable. The results depict the permissible expansion of the cracks inside the gallery even under another future earthquake in MCE level. As a consequence, the general dam performance is assessed safe in spite of the seepage flow rate growth from the gallery fractures.

• Structural Engineering and Mechanics
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• v.83 no.4
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• pp.435-449
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• 2022

Constitutive modeling that could reasonably predict and effectively evaluate the post-peak structural behavior while eliminating the mesh-dependency in numerical simulation remains to be developed for general engineering applications. Based on the previous work, a simple one-dimensional modeling procedure is proposed to predict and evaluate the post-peak response, as characterized by the evolution of localized strain field, of a steel member to monotonically uniaxial tension. The proposed model extends the classic one-dimensional softening with localization model as introduced by (Schreyer and Chen 1986) to account for the localization length, and bifurcation and rupture points. The new findings of this research are as follows. Two types of strain-softening functions (bilinear and nonlinear) are proposed for comparison. The new failure criterion corresponding to the constitutive modeling is formulated based on the engineering strain inside the localization zone at rupture. Furthermore, a new mathematical expression is developed, based on the strain rate inside and outside the localization zone, to describe the displacement field at which bifurcation occurs. The model solutions are compared with the experimental data on four low-carbon cylindrical steel bars of different lengths. For engineering applications, the model solutions are also compared to the experimental data of a cylindrical steel bar system (three steel bars arranged in series). It is shown that the bilinear and nonlinear softening models can predict the energy dissipation in the post-peak regime with an average difference of only 4%.

• Journal of the Korean Geographical Society
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• v.47 no.3
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• pp.328-346
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• 2012

This study provides quantitative constraints on Neogene uplift in the Korean peninsula using onshore paleo-shoreline records and seismic data. The eastern margin of Northeast Asia including Korea sits in the back-arc system behind the Western Pacific Subduction Zone, a complex trench triple junction of the Philippine Sea, Pacific, and Eurasian (Amurian) plates. An analysis of seismic data in the subduction zone shows that the pattern of uplift in the peninsula mirrors the extent of deep seismicity in subducting Pacific plate beneath. Combined with previous tomographic studies it is proposed that uplift is partly driven by asthenospheric upwelling caused by a sinking slab during the Neogene. In addition, the SHmax orientations of E-W and N-S trends in the peninsula are consistent with the prevailing in-situ stress fields in the eastern Eurasian continent generated by various plate boundary forces. The uplift in Korea during the Late Neogene is attributed, in part, to lithospheric failure relating to faulting movements, thus providing a link between dynamic effects of mantle upwelling at sinking slab edge and lithospheric responses driven by plate boundary forces.

• Composites Research
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• v.29 no.2
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• pp.45-52
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• 2016

An understanding of the failure mechanisms of the adhesive layer is decisive in interpreting the performance of a particular adhesive joint because the delamination is one of the most common failure modes of the laminated composites such as the fiber metal laminates. The interface between different materials, which is the case between the metal and the composite layers in this study, can be loaded through a combination of fracture modes. All loads can be decomposed into peel stresses, perpendicular to the interface, and two in-plane shear stresses, leading to three basic fracture mode I, II and III. To determine the load causing the delamination growth, the energy release rate should be identified in corresponding criterion involving the critical energy release rate ($G_C$) of the material. The critical energy release rate based on these three modes will be $G_{IC}$, $G_{IIC}$ and $G_{IIIC}$. In this study, to evaluate the fracture behaviors in the fracture mode I and II of the adhesive layer in fiber metal laminates, the double cantilever beam and the end-notched flexure tests were performed using the reference adhesive joints. Furthermore, it is confirmed that the experimental results of the adhesive fracture toughness can be applied by the comparison with the finite element analysis using cohesive zone model.