• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.1113-1124
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• 2009

The limit equilibrium method and finite element method have been commonly used to assess the stability of anchored slope. However, the existing limit equilibrium methods do not consider the load transfer of anchor and, if the potential failure surface crosses the bonded zone of anchors, the anchor loads are not included in computing the factor of safety. In this paper, simplified bishop method, one among several methods based on the limit equilibrium is used to develope the Excel Sheet program and the working load of anchor along the failure surface is calculated by Flamant's formula, proposed by Morlier and Tenier(1982). Additionally, the finite element analysis of anchored slope considering the load transfer is performed in order to compare with the result from the limit equilibrium analysis and analyze the reinforced effect of anchor. From this study, new modelling method that limits the reinforcing range and considers the load transfer is proposed and Excel Sheet program is developed. The factor of safety for several cases between PC STABL and Excel Sheet program is also compared for verification of the program.

• Journal of Industrial Technology
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• v.23 no.A
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• pp.69-81
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• 2003

Numerical analysis is important for the design, construction and maintenance of large caverns. The rock mass contains generally discontinuities such as faults, joints and fissures. The mechanical behavior and geometric characteristics of these discontinuities would have a significant impact on the stability of the caverns. In this research the Distinct Element Method(DEM) was used to analyze the structural stability of the large cavern. The Barton-Bandis Joint Model (B-B J.M) was used as a constitutive model for the joint. In addition, two different cases 1) analysis with a support system and 2) analysis with no support system, were analyzed to optimize a support system and to investigate reinforcing effects of a support system. The most significant parameters of in-situ stress, JRC of in-situ natural joints, and spatial distribution characteristics of discontinuities were acquired through field investigation. Displacement (horizontal, joint shear), maximum joint opening, maximum and minimum principal stresses, range of relaxed zone, rockbolt axial forces and shotcrete stresses were calculated at each excavation stage. As a result of analysis the calculated values proved to be under the allowable value Rockbolts also proved to be an efficient support measure to control joint shear displacement which had significant effects on extending the relaxed zone. As a consequence, the structural stability of the cavern was assured with an appropriate support system.

• Journal of the Earthquake Engineering Society of Korea
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• v.15 no.1
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• pp.19-28
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• 2011

In this study, nonlinear finite element analysis procedures are presented for the structural performance assessment of damaged reinforced concrete structures. A computer program, named RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. This paper defines a damage index based on the predicted inelastic behavior of reinforced concrete structures. The proposed numerical method for the structural performance of damaged reinforced concrete structures is verified by comparison with reliable experimental results.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.2
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• pp.63-72
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• 2004

The purpose of this study is to evaluate seismic performance of reinforced concrete bridge piers supported by laminated rubber bearings. A computer program, named RCAHEST(Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. The smeared crack approach is incorporated. Seismic isolator element is developed to predict behaviors of laminated rubber bearings. The proposed numerical method for seismic performance evaluation of reinforced concrete bridge piers supported by laminated rubber bearings is verified by comparison with reliable experimental results.

• Structural Engineering and Mechanics
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• v.73 no.1
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• pp.17-25
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• 2020

A finite element (FE) model for analyzing slender reinforced high-strength concrete (HSC) columns under biaxial eccentric loading is formulated in terms of the Euler-Bernoulli theory. The cross section of columns is divided into discrete concrete and reinforcing steel fibers so as to account for varied material properties over the section. The interaction between axial and bending fields is introduced in the FE formulation so as to take the large-displacement or P-delta effects into consideration. The proposed model aims to be simple, user-friendly, and capable of simulating the full-range inelastic behavior of reinforced HSC slender columns. The nonlinear model is calibrated against the experimental data for slender column specimens available in the technical literature. By using the proposed model, a numerical study is carried out on pin-ended slender HSC square columns under axial compression and biaxial bending, with investigation variables including the load eccentricity and eccentricity angle. The calibrated model is expected to provide a valuable tool for more efficiently designing HSC columns.

• Steel and Composite Structures
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• v.33 no.1
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• pp.143-162
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• 2019

A number of desirable characteristics concerning excellent durability, aesthetics, recyclability, high ductility and fire resistance have made stainless steel a preferred option in engineering practice. However, the relatively high initial cost has greatly restricted the application of stainless steel as a major structural material in general construction. This drawback can be partially overcome by introducing composite stainless steel-concrete structures, which provides a cost-efficient and sustainable solution for future stainless steel construction. This paper presents a preliminary numerical study on stainless steel-concrete composite beam-to-column joints with bolted flush endplates. In order to ensure a consistent corrosion resistance within the whole structural system, all structural steel components were designed with austenitic stainless steel, including beams, columns, endplates, bolts, reinforcing bars and shear connectors. A finite element model was developed using ABAQUS software for composite beam-to-column joints under monotonic and symmetric hogging moments, while validation was performed based on independent test results. A parametric study was subsequently conducted to investigate the effects of several critical factors on the behaviour of composite stainless steel joints. Finally, comparisons were made between the numerical results and the predictions by current design codes regarding the plastic moment capacity and the rotational stiffness of the joints. It was concluded that the present codes of practice generally overestimate the rotational stiffness and underestimate the plastic moment resistance of stainless steel-concrete composite joints.

• Computers and Concrete
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• v.7 no.2
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• pp.159-167
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• 2010

This paper demonstrates numerical techniques for complex large-scale modeling with microplane constitutive theories for reinforced high strength concrete, which for these applications, is defined to be around the 7000 psi (48 MPa) strength as frequently found in protective structural design. Applications involve highly impulsive loads, such as an explosive detonation or impact-penetration event. These capabilities were implemented into the authors' finite element code, ParaAble and the PRONTO 3D code from Sandia National Laboratories. All materials are explicitly modeled with eight-noded hexahedral elements. The concrete is modeled with a microplane constitutive theory, the reinforcing steel is modeled with the Johnson-Cook model, and the high explosive material is modeled with a JWL equation of state and a programmed burn model. Damage evolution, which can be used for erosion of elements and/or for post-analysis examination of damage, is extracted from the microplane predictions and computed by a modified Holmquist-Johnson-Cook approach that relates damage to levels of inelastic strain increment and pressure. Computation is performed with MPI on parallel processors. Several practical analyses demonstrate that large-scale analyses of this type can be reasonably run on large parallel computing systems.

• Tribology and Lubricants
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• v.34 no.6
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• pp.307-312
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• 2018

Unlike a typical static seals, spring-energized static seals exhibit improvement in leak-tightness by reinforcing the spring inside the aluminum lining. Thus, spring-energized static seals are widely used in various industrial fields, such as aerospace, semiconductors, and petrochemical industries. The primary objective of this study is to develop design guidelines for spring-energized static seals in a wide range of temperatures, including that of cryogenic environments, by analyzing the required performance and influence of design variables through simulations. There are various parameters that can be controlled to design a leak-tight seal. In this study, the finite element analysis (FEA) is performed by controlling the parameters related to the spring and the thickness of the aluminum lining, and the result of the leakage between the seal and the casing is confirmed. Considering the influence of each parameters, all of them are found to be important. However, it is observed that the spring-related variables are more important than the aluminum lining or other variables when complexity is considered. We can identify the threshold value of spring stiffness that changes leak-tight performance of the seal by performing FEA. Simulation results, under the conditions that are considered in this study, show that spring stiffness should be at least 3.6 N/m to maintain leak-tightness caused by the sufficient contact force between the aluminum lining and the upper and lower casings.

• Geomechanics and Engineering
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• v.16 no.5
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• pp.495-501
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• 2018

Geogrid application that has proved to be an effective and economic method of reinforcing particles, is widely used in geotechnical engineering. The discrete element method (DEM) has been used to investigate the micro mechanics of the geogrid deformation and also the interlocking mechanism that cannot be easily studies in laboratory tests. Two types of realistically shaped geogrid models with square and triangle apertures were developed using parallel bonds in PFC3D. The calibration test simulations have demonstrated that the precisely shaped triangular geogrid model is also able to reproduce the deformation and strength characteristics of geogrids. Moreover, the square and triangular geogrid models were also used in DEM pull-out test simulations with idealized shape particle models for validation. The simulation results have been shown to provide good predictions of pullout force as a function of displacement especially for the initial 30 mm displacement. For the granular material of size 40 mm, both the experimental and DEM results demonstrate that the triangular geogrid of size 75 mm outperforms the square geogrid of size 65 mm. Besides, the simulations have given valuable insight into the interaction between particle and geogrid and also revealed similar deformation behavior of geogrids during pullout. Therefore, the DEM provides a tool which enable to model other possible prototype geogrid and investigate their performance before manufacture.

• Steel and Composite Structures
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• v.44 no.3
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• pp.407-421
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• 2022

Prefabricated hybrid wind turbine towers (WTTs) are promising due to height increase. This study proposes the use of ultra-high performance concrete (UHPC) to develop a new type of WTT without the need to use reinforcement. It is demonstrated that the UHPC WTT structure without reinforcing bars could achieve performance similar to that of reinforced concrete WTTs. To simplify the design of WTT, a design approach for the calculation of stresses at the horizontal joints of a WTT is proposed. The stress distribution near the region of the horizontal joint of the WTT structure under normal operating conditions and different load actions is studied using the proposed approach, which is validated by the finite element method. A further parametric study shows that the degree of prestressing and the bending moment both significantly affect the principal stress. The shear-to-torsion ratio also shows a significant influence on the principal tensile stress.