• 국제강구조저널
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• 제18권5호
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• pp.1497-1507
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• 2018

Most of previous studies on fire resistance of restrained steel beams neglected creep effect due to lack of suitable creep model. This paper presents a finite element model (FEM) for accessing the fire resistance of restrained high strength Q460 steel beams by taking high temperature Norton creep model of steel into consideration. The validation of the established model is verified by comparing the axial force and deflection of restrained beams obtained by finite element analysis with test results. In order to explore the creep effect on fire response of restrained Q460 steel beams, the thermal axial force and deflection of the beams are also analyzed excluding creep effect. Results from comparison infer that creep plays a crucial role in fire response of restrained steel beam and neglecting the effect of creep may lead to unsafe design. A set of parametric studies are accomplished by using the calibrated FEM to evaluate the governed factors influencing fire response of restrained Q460 steel beams. The parametric studies indicate that load level, rotational restraint stiffness, span-depth ratio, heating rate and temperature distribution pattern are key factors in determining fire resistance of restrained Q460 steel beam. A simplified design approach to determine the moment capacity of restrained Q460 steel beams is proposed based on the parametric studies by considering creep effect.

• Structural Engineering and Mechanics
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• 제87권6호
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• pp.615-624
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• 2023

The focus of this study is on the structural behaviour of reinforced concrete beams in which basalt fiber and SBR latex were added and the cement was partially replaced with 10% of hypo sludge. Eight different mixes of reinforced beam specimens were tested under static loading behaviour. The experiments showed, the structural behaviour with features such as load-deflection relationships, crack pattern, crack propagation, number of crack, crack spacing and moment curvature. A stress-strain relationship to represent the overall behavior of reinforced concrete in tension, which includes the combined effects of cracking and mode of failure along the reinforcement, is proposed. The structural behaviour results of reinforced concrete beams with various types of mix were tested at the age of 28 days. The investigation revealed that the flexural behaviors of hypo sludge reinforced concrete beams with addition of basalt fiber and SBR latex was higher than that of control concrete reinforced beam. The specimen (LHSBFC) with 10% hypo sludge, 0.25% Basalt fiber and 10% SBR latex showed an increase of 5.08% load carrying capacity, 7.6% stiffness, 3.97% ductility, 31.29% energy dissipation when compared to the control concrete beam. The analytical investigation using FEM shows that it was in good agreement with the experimental investigation.

• Computers and Concrete
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• 제24권6호
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• pp.561-570
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• 2019

Understanding the realistic behavior of concrete up to failure under different loading conditions within the framework of damage mechanics and plasticity would lead to an enhanced design of concrete structures. In the present investigation, QR (Quick Response) code based random speckle pattern is used as a non-contact sensor, which is an innovative approach in the field of digital image correlation (DIC). A four-point bending test was performed on RC beams of size 1800 mm × 150 mm × 200 mm. Image processing was done using an open source Ncorr algorithm for the results obtained using random speckle pattern and QR code based random speckle pattern. Load-deflection curves of RC beams were plotted for the results obtained using both contact and non-contact (DIC) sensors, and further, Moment (M)-Curvature (κ) relationship of RC beams was developed. The loading curves obtained were used as input data for material model parameters in finite element analysis. In finite element method (FEM) based software, concrete damage plasticity (CDP) constitutive model is used to predict the realistic nonlinear quasi-static flexural behavior of RC beams for monotonic loading condition. The results obtained using QR code based DIC are observed to be on par with conventional results and FEM results.

• Advances in nano research
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• 제10권5호
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• pp.423-435
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• 2021

This paper examines the thermal post-buckling behaviors of graphene-reinforced metal matrix composite (GRMMC) laminated cylindrical panels which possess in-plane negative Poisson's ratio (NPR) and rest on an elastic foundation. A panel consists of GRMMC layers of piece-wise varying graphene volume fractions to obtain functionally graded (FG) patterns. Based on the MD simulation results, the GRMMCs exhibit in-plane NPR as well as temperature-dependent material properties. The governing equations for the thermal post-buckling of panels are based on the Reddy's third order shear deformation shell theory. The von Karman nonlinear strain-displacement relationship and the elastic foundation are also included. The nonlinear partial differential equations for GRMMC laminated cylindrical panels are solved by means of a singular perturbation technique in associate with a two-step perturbation approach and in the solution process the boundary layer effect is considered. The results of numerical investigations reveal that the thermal post-buckling strength for (0/90)_5T GRMMC laminated cylindrical panels can be enhanced with an FG-X pattern. The thermal post-buckling load-deflection curve of 6-layer (0/90/0)_S and (0/90)_3T panels of FG-X pattern are higher than those of 10-layer (0/90/0/90/0)_S and (0/90)_5T panels of FG-X pattern.

• 한국지역사회생활과학회지
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• 제24권1호
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• pp.85-97
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• 2013

The purpose of this study was to develop an appropriate jacket pattern for obese women in 20s and 30s, providing a good fit and appearance. The results were as follows: among 3 kinds of patterns collected in order to develop a jacket pattern to fit the average body of an obese woman in 20s and 30s, a business-type pattern(which was comparatively evaluated as a good fit) was worn and revised so as to design a final research pattern with proper fitness and a good shape. The biggest problem of the existing pattern was may overall spares, especially many spares of bust size, waist measurement, hip circumference, all of which makes a bad appearance. Considering the results of a survey which indicates that young obese women like tight-fitting clothes, bust size was decreased from 8 cm to 6 cm, and their waist measurements were bigger compared to other age groups, so a total of 1.1 cm(with 0.3 cm in the front, back side, and 0.5 cm in the back waist) was decreased. The hip circumference was decreased by 2 cm from H/2+4 to H/2+2 cm, the quantity of front deflection was established as 1.5 cm in order to compensate for the coming off of the front side caused by the fat on the stomach.

• Journal of Biosystems Engineering
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• 제20권1호
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• pp.3-12
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• 1995

This study was conducted to investigate the cutting mechanism of the reciprocating knife of combine harvester. The cutting operation of reciprocating knife was demonstrated through the cutting pattern diagram which was drawn by computer graphics. Various kinds and dimensions of standard-type reciprocating knives were analyzed by the developed program. The results are summarized as follows : (1) For the 50mm standard reciprocating knife, the bunching area and the maximum stalk-deflection were decreased rapidly according to the increase of cutting velocity ratio by 1.0 and decreased very slowly over this ratio. But, the secondary cut was occurred at ratio of 1.0 and increased rapidly over this ratio. (2) The 76mm standard knife showed better cutting mechanism than the 50mm, in two respects : the larger cutting area per one stroke and the lower revolutional speed of crank shaft for the same cutting velocity. (3) In respect to the bunching area and the secondary cutting length, the adequate height of 50mm standard reciprocating knife was 45~50mm. (4) In order to maintain the proper cutting mechanism, the adequate cutting velocity at forward speed of 0.5㎧ to 1.2m/s was from 0.4m/s to 1.2m/s for the standard knife.

• Coupled systems mechanics
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• 제2권3호
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• pp.289-302
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• 2013

The piled raft is a geotechnical construction, consisting of the three elements-piles, raft and the soil, that is applied for the foundation of a tall buildings in an increasing number. The piled rafts nowadays are preferred as the foundation to reduce the overall and differential settlements; and also, provides an economical foundation option for circumstances where the performance of the raft alone does not satisfy the design requirements. The finite element analysis of the piled raft foundation is presented in this paper. The numerical procedure is programmed into finite element based software SAFE in order to conduct the parametric study wherein soil modulus and raft thickness is varied for constant pile diameter. The problems of piled raft for three different load patterns as considered in the available literature (Sawant et al. 2012) are analyzed here using SAFE. The results obtained for load pattern-I using SAFE are compared with those obtained by Sawant et al. (2012). The fair agreement is observed in the results which demonstrate the accuracy of the procedure employed in the present investigation. Further, substantial reduction in maximum deflections and moments are found in piled raft as compared to that in raft. The reduction in deflections is observed with increase in raft thickness and soil modulus. The decrease in maximum moments with increase in soil modulus is seen in raft whereas increase in maximum moments is seen in piled raft. The raft thickness and soil modulus affects the response of the type of the foundation considered in the present investigation.

• Steel and Composite Structures
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• 제45권5호
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• pp.697-713
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• 2022

In the context of the finite elements method, the dynamic behavior of porous functionally graded double wishbone vehicle suspension structural system incorporating joints flexibility constraints under road bump excitation is studied and analyzed. The functionally graded material properties distribution through the thickness direction is simulated by the power law including the porosity effect. To explore the porosity effects, both classical and adopted porosity models are considered based on even porosity distribution pattern. The dynamic equations of motion are derived based on the Hamiltonian principle. Closed forms of the inertia and material stiffness components are derived. Based on the plane frame isoparametric Timoshenko beam element, the dynamic finite elements equations are developed incorporating joint flexibilities constraints. The Newmark's implicit direct integration methodology is utilized to obtain the transient vibration time response under road bump excitation. The presented procedure is validated by comparing the computational model results with the available numerical solutions and an excellent agreement is observed. Obtained results show that the decrease of porosity percentage and material graduation tends to decrease the deflection as well as the resulting stresses of the control arms thus improving the dynamic performance and increasing the service lifetime of the control arms.

• 한국공간구조학회논문집
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• 제3권4호
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• pp.69-76
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• 2003

In case of rectangular latticed pattern which shearing rigidity is very small, it has a concern to drop Buckling-strength considerably by external force. So, by means of system to increase buckling-strength, there is a method of construction that lattice of dome is reinforced by braced member. In a case like this, shearing rigidity of braced member increase buckling-strength of the whole of structure and can be designed economically from the viewpoint of practice. Therefore, this paper is aimed at investigating how much does rigidity of braced member united with latticed member bearing principal stress of dome increase buckling-strength of the whole of structure. the subject of study is rectangular latticed domes that are a set of 2-way lattice dome which grid is simple and number of member gathering at junction is small. Analysis method is based on FEM dealing with the geometrically nonlinear deflection problems.

• 대한치과보철학회지
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• 제34권1호
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• pp.85-99
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• 1996

Finite element models were constructed to analyze the mechanical behavior of a three unit fixed partial denture (FPD) with a 2nd premolar and 2nd molar abutment either employing a rigid and nonrigid connector. Gap elements were used to model the clearance space of the nonrigid connector. 1. High stress was generated in the FPD and supporting abutment around the rigid connector. 2. The pattern of stress and deflection is very similar between vertically and 20 degree mesially tilted nonrigid connector at the distal aspect of premolar abutment. 3. FPD with an inverted nonrigid connectors exhibited the worst undesirable mechanical stress states and deformations. 4. Nonrigid connector of normal orientation transmit the load to the abutment tooth, but inverted connector doesn't transmit the force.