• Structural Engineering and Mechanics
• /
• v.91 no.3
• /
• pp.239-250
• /
• 2024

With the aim to provide better predication about fracture behavior, a numerical simulating strategy based on the rigid spring model is proposed for reinforced concrete (RC) structures in this study. According to the proposed strategy, concrete is partitioned into a series of irregular rigid blocks based on the Voronoi diagram, which are connected by interface springs. Steel bars are simulated by bar elements, and the bond slip element is defined at bar element nodes to describe the interaction between reinforcement and concrete. A concrete damage evolution model based on the separation criterion is adopted to describe the weakening process of interface spring between adjacent blocks, while a nonlinear bond slip model is introduced to simulate the synergy behaviour of reinforced steel bars and concrete. In the damage evolution model of concrete, the influence of compressive stress perpendicular to the interface on the shear strength is considered. To check the effectiveness and applicability of the proposed modelling, experimental and numerical studies about a simply-supported RC beam and the two-notched concrete plates in Nooru-Mohamed's experiment are conducted, and the grid sensitivity are investigated.

• Journal of the Korean Geotechnical Society
• /
• v.30 no.3
• /
• pp.29-46
• /
• 2014

For circular rigid footings with a rough base on sand, combined vertical - horizontal loading capacity was studied by three-dimensional numerical modelling. A numerical model was implemented to simulate the swipe loading and the probe loading methods and an interpretation procedure was devised in order to eliminate the numerical error from the restricted mesh density. Using the Mohr-Coulomb plasticity model, the effect of friction angle was studied under the associated flow-rule condition. The swipe loading method, which is efficient in that the interaction diagram can be drawn with smaller number of analyses, was confirmed to give similar results with the probe loading method, which follows closely the load-paths applied to real structures. For circular footings with a rough base, the interaction diagram for combined vertical (V) - horizontal (H) loading and the inclination factor were barely affected by the friction angle. It was found that the inclination factors for strip and rectangular footings are applicable to circular footings. For high H/V ratios, the results by numerical modelling of this study were smaller than the results of previous studies. Discussions are made on the factors affecting the numerical results and the areas for further researches.

• Steel and Composite Structures
• /
• v.4 no.5
• /
• pp.367-384
• /
• 2004

A numerical model based on the finite element technique is adopted to investigate the behavior and strength of thin-walled I-section beam-columns. The model considers both the material and geometric nonlinearities. The model results were first verified against some of the currently available experimental results. A parametric study was then performed using the numerical model and interaction diagrams for the investigated beam-columns have been presented. The effects of the web depth-to-thickness ratio, flange outstand-to-thickness ratio and bending moment-to-normal force ratio on the ultimate strength of thin-walled I-section beam-columns were scrutinized. The interaction equations adopted for beam columns design by the NAS (North American Specifications for the design of cold formed steel structural members) have been critically reviewed. An equation for the buckling coefficient which considers the interaction between local buckling of the flange and the web of a thin-walled I-section beam-column has been proposed.

• Korea-Australia Rheology Journal
• /
• v.18 no.2
• /
• pp.99-102
• /
• 2006

Primitive chain network model for block copolymers is used here to simulate molecular dynamics in the entangled state with acceptable computational cost. It was found that i) the hooking procedure rearranging the topology of the entangled network is critical for the equilibrium structure of the system, and ii) simulations accounting for the different chemistry, i.e., with a biased hooking probability based on interaction parameter ${\chi}$ for selection of the hooked partner, generates a reasonable phase diagram.

• Proceedings of the KSME Conference
• /
• 2007.05a
• /
• pp.718-723
• /
• 2007

A three dimensional multibody modeling of a launcher system was developed and dynamic characteristics of the system was carried out. All the components were modeled as rigid bodies, All the components of system, ie; chassis, turret, cage and suspension parts, are modeled as rigid. The force interaction between the ground and tire was modeled as a point contact model. The factors were selected as cause and effect diagram of the MINITAB. To see effect of the stiffness, damping, mass at the launcher system, several cases of suspension parameters were compared and optimal values were selected. The stiffness and the damping coefficient were selected as design variables to minimize the required time for the next fire. The dynamic simulation was carried out using the ADAMS, and the MINITAB was employed for data analysis.

• Structural Engineering and Mechanics
• /
• v.32 no.2
• /
• pp.301-320
• /
• 2009

Damage assessment for buried structures against an internal blast is conducted by considering the soil-structure interaction. The structural element under analysis is assumed to be rigid-plastic and simply-supported at both ends. Shear failure, bending failure and combined failure modes are included based on five possible transverse velocity profiles. The maximum deflections with respect to shear and bending failure are derived respectively by employing proper failure criteria of the structural element. Pressure-Impulse diagrams to assess damage of the buried structures are subsequently developed. Comparisons have been done to evaluate the influences of the soil-structure interaction and the shear-to-bending strength ratio of the structural element. A case study for a buried reinforced concrete structure has been conducted to show the applicability of the proposed damage assessment method.

• Journal of Environmental Science International
• /
• v.9 no.3
• /
• pp.241-252
• /
• 2000

Twenty-two water samples(fifteen groundwater and seven geothermal water samples) were collected to elucidate chemical characteristics of the ground and geothermal waters in the Haeundae hot spring area and its vicinity. Major and honor elements were analyzed for ground and geothermal water samples. The concentrations of $K^+$, Na+$, $Ca^{2+}$, $SO_4^{2-}$, $Cl^-$, ^F^-$ and $SiO_2$ were higher in the geothermal water samples than the groundwater samples except $HCO_3^- and Mg^{2+}$ ions. Based on the contents of Fe, Zn, Cu, Al, Mn and Pb, some of the ground and geothermal water samples are contaminated by anthropogenic sources. The ground waters shown on the Piper diagram belong to $Ca-HCO_3$ type, while the geothermal waters Na-Cl type. The graphs of $Cl^-$ versus $Na^+$, $Ca^{2+}, Mg^{2+}, K^+, SO_4^{2-} and HCO_3^-$ indicate that the groundwater is related partly with mineral-water reaction and partly with anthropogenic contamination, while the geothermal water is related with saline water. On the phase stability diagram, groundwater and thermal water mostly fall in the field of stability of kaolinite. This indicates that the ground and geothermal waters proceed with forming kaolinite. Factor and correlation analyses were carried out to simplify the physicochemical data into grouping some factors and to find interaction between them. Based on the Na-K, Na-K-Ca and Na-K-Ca-Mg geothermometers and silica geothermometers, the geothermal reservoir is estimated to have equilibrium temperature between 125${$\mid$circ}C$ and 160${$\mid$circ}C$.

• Resources Recycling
• /
• v.18 no.1
• /
• pp.30-37
• /
• 2009

Distribution diagram of Pt(IV), Pd(II), and Rh(III) in HCl solution was obtained as a function of HCl concentration from 0.001 to 10 M by considering complex formation reaction together with mass balance. When HCl concentration was higher than 0.1 M, most of Pt and Pd in HCl solution exist as $PtCl_6^{2-}$ and $PtCl_4^{2-}$. The concentration of HCl had a feat effect on the speciation of Rh(III). As HCl concentration increases from 0.1 to 10 M, the pedominant species changes from $PhCl_5^{2-}$ to $PhCl_6^{3-}$. Interaction parameters of $PtCl_6^{2-}$ and $PdCl_4^{2-}$ with hydrogen ion were evaluated from the solvent extraction data of Pt and Pd reported in the literature.

• Journal of the Korean Society of Systems Engineering
• /
• v.15 no.1
• /
• pp.1-8
• /
• 2019

Reverse engineering involves examining a system or component so as to comprehend its structure, functionality, and operation. Creation of a system model in reverse engineering can serve several purposes: test generation, change impact analysis, and the creation of a new or modified system. When attempting to reverse engineering a system, often the most readily accessible information is the system description, which does not readily lend itself to use in Model Based System Engineering (MBSE). Therefore, it is necessary to be able to transform this description into a diagram, which clearly depicts the behavior of the system as well as the interaction between components. This study demonstrates how sequence diagrams can be extracted from the systems description. Using MBSE software, the sequence diagrams for the Engineered Safety Features Component Control System (ESF-CCS) of the Nuclear Power Plant are created. Sequence diagrams are chosen because they are a means of representing the systems behavior and the interaction between components. In addition, from these diagrams, the system's functional requirements can be elicited. These diagrams then serve as the baseline of the reverse engineering process and multiple system views are subsequently be created from them, thus speeding up the development process. In addition, the use of MBSE ensures that any additional information obtained from auxiliary sources can then be input into the system model, ensuring data consistency.

• Advances in concrete construction
• /
• v.14 no.3
• /
• pp.153-167
• /
• 2022

The interaction between blast load and structures, as well as the interaction among structural members may well affect the structural response and damages. Therefore, it is necessary to analyse more realistic reinforced concrete structures in order to gain an extensive knowledge on the possible structural response under blast load effect. Among all the civilian structures, columns are considered to be the most vulnerable to terrorist threat and hence detailed investigation in the dynamic response of these structures is essential. Therefore, current research examines the effect of blast loads on the reinforced concrete columns via development of Pressure- Impulse (P-I) diagrams. In the finite element analysis, the level of damage on each of the aforementioned RC column will be assessed and the response of the RC columns when subjected to explosive loads will also be identified. Numerical models carried out using LS-DYNA were compared with experimental results. It was shown that the model yields a reliable prediction of damage on all RC columns. Validation study is conducted based on the experimental test to investigate the accuracy of finite element models to represent the behaviour of the models. The blast load application in the current research is determined based on the Lagrangian approach. To develop the designated P-I curves, damage assessment criteria are used based on the residual capacity of column. Intensive investigations are implemented to assess the effect of column dimension, concrete and steel properties and reinforcement ratio on the P-I diagram of RC columns. The produced P-I models can be applied by designers to predict the damage of new columns and to assess existing columns subjected to different blast load conditions.