• Structural Engineering and Mechanics
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• v.1 no.1
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• pp.1-16
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• 1993

The behavior of shear-wall dominant, low-rise, multistory reinforced concrete building structures is investigated. Because there are no beams or columns and the slab and wall thicknesses are approximately equal, available codes give little information relative to design for gravity and lateral loads. Items which effect the analysis of shear-wall dominant building structures, i.e., material nonlinearity including rotating crack capability, 3-D behavior, slab-wall interaction, floor flexibilities, stress concentrations around openings, the location and the amount of main discrete reinforcement are investigated. For this purpose 2 and 5 story building structures are modelled. To see the importance of 3-D modelling, the same structures are modelled by both 2-D and 3-D models. Loads are applied first the vertical then lateral loads which are static equivalent earthquake loads. The 3-D models of the structures are loaded in both in the longitudinal and transverse directions. A nonlinear isoparametric plate element with arbitrarily places edge nodes is adapted in order to consider the amount and location of the main reinforcement. Finally the importance of 3-D effects including the T-C coupling between walls are indicated.

• Transactions of Materials Processing
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• v.15 no.3 s.84
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• pp.206-212
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• 2006

Design programs of tube-sheet for heat exchanger based on the related engineering society codes have been widely used. But it is not easy fer beginners to use the design programs. So we need to develop an easy program for design of tube-sheet for heat exchanger. This paper describes a developed design-program of tube-sheet fur heat exchanger. The developed program was coded on boiler theory and pressure vessel codes, provided by TEMA(Tubular Exchanger Manufactures Association) and ASME(American Society of Mechanical Engineers). Visual Basic, which is convenient for beginners to deal with, was used in the programming. Also a finite element analysis of tube-sheet for heat exchanger was carried to verify this developed program by using a commercial software, ANSYS. In the finite element analysis, tube and tube-sheet of heat exchanger were substituted by solid plate having equivalent properties for convenience of calculation. The thickness of tube-sheet obtained by the developed design-program was in good agreement with that of tube-sheet by FEA.

• Composites Research
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• v.32 no.4
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• pp.185-190
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• 2019

This work investigates the elastic buckling characteristics of laminated composite trapezoidal corrugated plates with simply supported edges using the analytical method. In the analysis, three types of in-plane loading conditions: uniaxial, biaxial and shear loads are considered. Because it is very difficult to determine the mechanical behavior of 3-dimensional corrugated structures analytically, the equivalent homogenization model is adapted to investigate the overall mechanical behavior of corrugated plates. The corrugated element is homogenized as an orthotropic material. The previous formulae for bending rigidities of corrugated plate are adapted in this paper. The comparisons of the proposed analytical results with those of FEA based on the shell element are made to verify the proposed analytical method. In the comparison study both the critical buckling loads and the buckling mode shapes are presented. Some numerical results are presented to check the effect of the geometric properties.

• The Journal of the Acoustical Society of Korea
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• v.42 no.3
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• pp.227-232
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• 2023

Underwater noise pollution has a significant impact on the marine environment. This study proposed a simple approach to estimate the acoustic radiation efficiency of structures with air bubble layers. The method considered the insertion loss caused by the air bubble layer through post-processing of numerical results, assuming that insertion loss is equivalent to attenuation as demonstrated by previous studies. The proposed approach was validated by comparing it with a fully coupled analysis for plate structure models. The commercial finite element program COMSOL Multiphysics was used for the acoustic-structure interaction analysis, and the acoustic characteristics of air bubble layer for the fully coupled analysis was simulated by on the Commander and Prosperetti theory. The trends indicated good agreement between the simple approach and the fully coupled analysis in terms of radiation efficiency. It is confirmed that the proposed method is providing insight into the principal mechanism of underwater noise reduction for the bubble layer on the wedge-shaped structure.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.3
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• pp.576-585
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• 2002

A three-dimensional Lagrangian explicit time-integration finite element code for analyzing the dynamic impact phenomena was developed. It uses four node tetrahedral elements. In order to consider the effects of strain rate hardening, strain hardening and thermal softening, which are frequently observed in high-velocity deformation phenomena, Johnson-Cook model is used as constitutive model. For more accurate and robust contact force computation, the defense node contact algorithm was adopted and implemented. In order to evaluate the performance of the newly developed three-dimensional hydrocode NET3D, numerical simulations of the oblique impact of mild steel plate by mild steel sphere were carried out. Ballistic limit about various oblique angle between 0 degree and 80 degree was estimated through a series of simulations with different initial velocities of sphere. Element eroding by equivalent plastic strain was applied to mild steel spheres and targets. Ballistic limits and fracture characteristics obtained from simulation were compared with experimental results conducted by Finnegan et al. From numerical studies, the following conclusions were reached. (1) Simulations could successfully reproduce the key features observed in experiment such as tensile failure termed "disking"at normal impacts and outwards bending of partially formed plus segments termed "hinge-mode"at oblique impacts. (2) Simulation results fur 60 degrees oblique impact at 0.70 km/s and 0.91 km/s were compared with experimental results and Eulerian hydrocode CTH simulation results. The Lagrangian code NET3D is superior to Eulerian code CTH in the computational accuracy. Agreement with the experimentally obtained final deformed cross-sections of the projectile is excellent. (3) Agreement with the experimental ballistic limit data, particularly at the high-obliquity impacts, is reasonably good. (4) The simulation result is not very sensitive to eroding condition but slightly influenced by friction coefficient.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4A
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• pp.727-734
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• 2006

Although a limited number of experimental investigations and finite element analyses revealed that a curved web panel in practical design has a considerable reserve strength after the elastic buckling as a straight girder web panel, the current Guide Specifications for Horizontally Curved Steel Girder Highway Bridges (AASHTO, 2003) do not consider the postbuckling strength in the ultimate shear strength due to lack of a comprehensive study. In this study, the ultimate shear strength behavior of horizontally curved steel web panels was investigated through nonlinear finite element analysis and experimental test. It was found that curved web panels used in practical designs are able to develop the postbuckling strength that is equivalent to that of straight girder web panels having the same dimensional and material properties.

• Structural Monitoring and Maintenance
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• v.3 no.4
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• pp.349-375
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• 2016

The tension of an arch bridge hanger is estimated using a number of experimentally identified modal frequencies. The hanger is connected through metallic plates to the bridge deck and arch. Two different categories of model classes are considered to simulate the vibrations of the hanger: an analytical model based on the Euler-Bernoulli beam theory, and a high-fidelity finite element (FE) model. A Bayesian parameter estimation and model selection method is used to discriminate between models, select the best model, and estimate the hanger tension and its uncertainty. It is demonstrated that the end plate connections and boundary conditions of the hanger due to the flexibility of the deck/arch significantly affect the estimate of the axial load and its uncertainty. A fixed-end high fidelity FE model of the hanger underestimates the hanger tension by more than 20 compared to a baseline FE model with flexible supports. Simplified beam models can give fairly accurate results, close to the ones obtained from the high fidelity FE model with flexible support conditions, provided that the concept of equivalent length is introduced and/or end rotational springs are included to simulate the flexibility of the hanger ends. The effect of the number of experimentally identified modal frequencies on the estimates of the hanger tension and its uncertainty is investigated.

• Structural Engineering and Mechanics
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• v.64 no.2
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• pp.195-204
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• 2017

Analytical and experimental studies of the innovative pipe in pipe damper have been recently investigated by the authors. In this paper, by adding lead or zinc infill or slit diaphragm inside the inner pipe, it is tried to increase the equivalent viscous damping ratio improving the cyclic performance of the recently proposed multi-level control system. The damper consists of three main parts including the outer pipe, inner pipe and added complementary damping part. At first plastic deformations of the external pipe, then the internal pipe and particularly the added core and friction between them make the excellent multi-level damper act as an improved energy dissipation system. Several kinds of added lead or zinc infill and also different shapes of slit diaphragms are modeled inside the inner pipe and their effectiveness on hysteresis curves are investigated with nonlinear static analyses using finite element method by ABAQUS software. Results show that adding lead infill has no major effect on the damper stiffness while zinc infill and slit diaphragm increase damper stiffness sharply up to more than 10 times depending on the plate thickness and pipe diameter. Besides, metal infill increases the viscous damping ratio of dual damper ranging 6-9%. In addition, obtained hysteresis curves show that the multi-level control system as expected can reliably dissipate energy in different imposed energy levels.

• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.3
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• pp.452-465
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• 2015

This paper presents the simplified welding distortion analysis method to predict the welding deformation of both plate and stiffener in fillet welds. Currently, the methods based on equivalent thermal strain like Strain as Direct Boundary (SDB) has been widely used due to effective prediction of welding deformation. Regarding the fillet welding, however, those methods cannot represent deformation of both members at once since the temperature degree of freedom is shared at the intersection nodes in both members. In this paper, we propose new approach to simulate deformation of both members. The method can simulate fillet weld deformations by employing composite shell element and using different thermal expansion coefficients according to thickness direction with fixed temperature at intersection nodes. For verification purpose, we compare of result from experiments, 3D thermo elastic plastic analysis, SDB method and proposed method. Compared of experiments results, the proposed method can effectively predict welding deformation for fillet welds.

• Journal of the Korean Geosynthetics Society
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• v.17 no.4
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• pp.41-52
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• 2018

Since the composite ground design method is easy to apply for calculation or numerical analysis, it is applied to the design of cement mixing methods. However, the comparison studies between analysis and actual results such as a trial test and construction for the cement mixing method are few because the composite ground design method was developed for the compaction pile (SCP, GCP) methods. In this study, the results of various analysis methods, such as the composite ground analysis method (1 case) and the individual pile method (3 cases), were compared with actual measurements through a two-dimensional finite element numerical analysis. In case of the surface settlements, the results of study show that the individual plate method was larger than the actual measurements, while other methods are similar. The settlements at the under ground of the improved area is overestimated in all analysis methods. When comparing numerical analysis results for the horizontal displacement, and ground reaction forces, the individual pile method in equivalent wall concept was found to be the most similar to the measurements. The composite ground method was not able to predict the behavior of stress transfer (Arching effect) and it turned out that the prediction of horizontal displacement was too large.