• Structural Engineering and Mechanics
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• 제63권5호
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• pp.617-628
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• 2017

In order to study the failure mode and seismic behavior of the interior-joint in steel traditional-style buildings, a single beam-column joint and a double beam-column joint were produced according to the relevant building criterion of ancient architectural buildings and the engineering instances, and the dynamic horizontal loading test was conducted by controlling the displacement of the column top and the peak acceleration of the actuator. The failure process of the specimens was observed, the bearing capacity, ductility, energy dissipation capacity, strength and stiffness degradation of the specimens were analyzed by the load-displacement hysteresis curve and backbone curve. The results show that the beam end plastic hinge area deformed obviously during the loading process, and tearing fracture of the base metal at top and bottom flange of beam occurred. The hysteresis curves of the specimens are both spindle-shaped and plump. The ultimate loads of the single beam-column joint and double beam-column joint are 48.65 kN and 70.60 kN respectively, and the equivalent viscous damping coefficients are more than 0.2 when destroyed, which shows the two specimens have great energy dissipation capacity. In addition, the stiffness, bearing capacity and energy dissipation capacity of the double beam-column joint are significantly better than that of the single beam-column joint. The ductility coefficients of the single beam-column joint and double beam-column joint are 1.81 and 1.92, respectively. The cracks grow fast when subjected to dynamic loading, and the strength and stiffness degradation is also degenerated quickly.

• Advances in concrete construction
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• 제8권3호
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• pp.173-185
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• 2019

This article presents a comparative study of the effect of steel layouts on the seismic behavior of transition steel-concrete composite connections, both experimental and analytical investigations of concrete filled steel tube-reinforced concrete (CFST-RC) and steel reinforecd concrete-reinforced concrete (SRC-RC) structures were conducted. The steel-concrete composite connections were subjected to combined constant axial load and lateral cyclic displacements. Tests were carried out on four full-scale connections extracted from a real project engineering with different levels of axial force. The effect of steel layouts on the mechanical behavior of the transition connections was evaluated by failure modes, hysteretic behavior, backbone curves, displacement ductility, energy dissipation capacity and stiffness degradation. Test results showed that different steel layouts led to significantly different failure modes. For CFST-RC transition specimens, the circular cracks of the concrete at the RC column base was followed by steel yielding at the bottom of the CFST column. While uncoordinated deformation could be observed between SRC and RC columns in SRC-RC transition specimens, the crushing and peeling damage of unconfined concrete at the SRC column base was more serious. The existences of I-shape steel and steel tube avoided the pinching phenomenon on the hysteresis curve, which was different from the hysteresis curve of the general reinforced concrete column. The hysteresis loops were spindle-shaped, indicating excellent seismic performance for these transition composite connections. The average values of equivalent viscous damping coefficients of the four specimens are 0.123, 0.186 and 0.304 corresponding to the yielding point, peak point and ultimate point, respectively. Those values demonstrate that the transition steel-concrete composite connections have great energy dissipating capacity. Based on the experimental research, a high-fidelity ABAQUS model was established to further study the influence of concrete strength, steel grade and longitudinal reinforcement ratio on the mechanical behavior of transition composite connections.

• 한국지반공학회논문집
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• 제18권1호
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• pp.127-132
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• 2002

사질토 지반에 근입된 모형말뚝에 대한 진동대 실험을 수행하여 말뚝지반 동적 상호작용 현상을 분석하고 동적군말뚝 효과를 산정하였다. 실험은 단말뚝과 말뚝간격을 말뚝직경의 3~8배로 변화시킨 $3\times3$ 군말뚝에 대하여 수행하였다. 동적 군맡뚝 효과는 단말뚝과 군말뚝의 동적 p-y곡선의 중심 기울기를 비교하여 산정하였고, 실험에서 얻어진 p-y곡선은 API의 반복 p-y곡선과 비교하였다. 실험결과 말뚝 간격, 입력 지진파의 주파수와 진폭 변화에 따른 동적 군말뚝 효과를 산정할 수 있었다.

• 대한화학회지
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• 제26권3호
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• pp.179-187
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• 1982

N-acryloylpyrrolidone과 acrylonitrile을 혼성중합시켜 각 단위체의 반응성비를 구한 결과 생성되는 혼성중합체는 pyrrolidone이 음이온 중합에 매우 좋은 개시제임을 알 수 가 있었다. ($r_1$ = 0.43과 $r_2$ = 1.56) 그리고 그 혼성중합체를 개시제로 하여 그라프트된 nylon-4를 합성하여 중합속도 상수를 구했으며, 그에 따르는 여러 인자들의 효과를 관찰하였다. 그 결과 중합속도 상수로 40$^{\circ}$C에서 2.82${\times}10^3$(l/mole, min)와 50$^{\circ}$C에서 2.93${\times}10^3$(l/mole, min)을 얻었다.

• 한국지진공학회논문집
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• 제22권2호
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• pp.95-101
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• 2018

Diagonally reinforced concrete coupling beams (DRCB) play an important role in coupled shear wall systems since these elements dissipate most of seismic input energy under earthquake loading. For reliable seismic performance evaluation using nonlinear response history analysis, it is important to use an accurate analytical model for DRCBs. In this study, the Pinching4 model is used as a base model to simulate the cyclic behavior of DRCBs. For simulating the cyclic behavior of DRCBs using the Pinching4 model, the analytical parameters for backbone curve, pinching and cyclic deterioration in strength and stiffness should be computed. To determine the proper values of the constituent analytical parameters efficiently and accurately, this study proposes the empirical equations for the analytical parameters using regression analyses. It is shown that the hysteretic behavior of coupling beams can be simulated efficiently and accurately using the proposed numerical model with the proposed empirical equations of model parameters.

• 한국의류산업학회지
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• 제5권4호
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• pp.379-388
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• 2003

The purpose of this study was to compare the somatometric characteristics obtained from the factor scores of both upper and lower body by regional differences. The sample group was drawn from boys at the ages 7 to 12 living in Pusan and Kyungsangnam-do. Data from each boy comprised 57 anthropometric measurements and 11 photographic measurements. The study reached following conclusions. 1. According to the result of factor analysis, five indicative factor's were obtained from the upper body measurements and four indicative factors were obtained from the lower body measurements. 2. According to the comparision of factor scores on measurements of the upper body between Pusan and Kyungsangnam-do, there were differences in all five factors. Boys in Pusan had higher stature, bigger frame, more protruded chest and shoulder blades, more sloping curve along with the backbone, more protruded belly, narrower and sloping shoulders than boys in Kyungsangnam-do. 4. According to the comparision of factor scores on measurements of the lower body between Pusan and Kyungsangnam-do, there were differences in factor 1 and factor 4. Boys in Pusan had bigger frame and flatter hip than boys in Kyungsangnam-do.

• Current Applied Physics
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• 제18권11호
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• pp.1313-1319
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• 2018

The coil-to-globule behavior of poly{${\gamma}$-2-[2-(2methoxyethoxy)ethoxy]ethoxy-3-caprolactone} (PMEEECL) as a ${\gamma}$-substituted poly (${\varepsilon}$-caprolactone) was investigated via atomistic molecular dynamics (MD) simulation. For this purpose, radius of gyration, end-to-end distance and radial distribution function of the chain in the presence of water were calculated. Consequently, the lower critical solution temperature (LCST) of PMEEECL chain at which the coil-to-globule transition takes place, was determined in each calculated parameter curve. The simulation results indicated that the LCST of PMEEECL was occurred at close to 320 K, which is in a good agreement with previous experimental results. Additionally, the appearance of sudden change in both Flory-Huggins interaction parameter (${\chi}$) and interaction energy between the PMEEECL chain and water molecules at about 320 K confirmed the calculated LCST result. The radial distribution function (RDF) results showed that the affinity of the PMEEECL side chain to water molecules is lower than its backbone.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.188-197
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• 2010

This paper presents experimental results of a series of 1-g shaking table model tests performed on end-bearing single piles and pile groups to investigate the effect of particle size on the dynamic behavior of soil-pile systems. Two soil-pile models consisting of a single-pile and a $4{\times}2$-pile group were tested twice; first using Jumoonjin sand, and second using Australian Fine sand, which has a smaller particle size. In the case of single-pile models, the lateral displacement was almost within 1% of pile diameter which corresponds to the elastic range of the pile. The back-calculated p-y curves show that the subgrade reaction of the Jumoonjin-sand-model ground was larger than that of the Australian Fine-sand-model ground at the same displacement. This phenomenon means that the stress-strain behavior of Jumoonjin sand was initially stiffer than that of Australian Fine sand. This difference was also confirmed by resonant column tests and compression triaxial tests. And the single pile p-y backbone curves of the Australian fine sand were constructed and compared with those of the Jumoonjin sand. As a result, the stiffness of the p-y backbone curves of Jumunjin sand was larger than those of Australian fine sand. Therefore, using the same p-y curves regardless of particle size can lead to inaccurate results when evaluating dynamic behavior of soil-pile system. In the case of the group-pile models, the lateral displacement was much larger than the elastic range of pile movement at the same test conditions in the single-pile models. The back-calculated p-y curves in the case of group pile models were very similar in both sands because the stiffness difference between the Jumoonjin-sand-model ground and the Australian Fine-sand-model ground was not significantly large at a large strain level, where both sands showed non-linear behavior. According to a series of single pile and group pile test results, the evaluation group pile effect using the p-multiplier can lead to inaccurate results on dynamic behavior of soil-pile system.

• Bulletin of the Korean Chemical Society
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• 제23권2호
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• pp.330-336
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• 2002

A quantum-chemical investigation on the conformations and electronic properties of bis[2-{2-methoxy-4,6-di(t-butyl)phenyl}ethenyl]benzenes (MBPBs) as building block for ${\pi}$-conjugate polymer are performed in order to display the effects of t-butyl and methoxy group substitution and of kink(ortho and meta) linkage. The conjugation length of the polymers can be controlled by substituents and kink linkages of backbone. Structures for the molecules, o-, m-, and p-MBPBs as well as unsubstituted o-, m-, and p-DSBs were fully optimized by using semiempirical AM1, PM3 methods, and ab initio HF method with 3-21G(d) basis set. The potential energy curves with respect to the change of single torsion angle are obtained by using semiempirical methods and ab initio HF/3-21G(d) basis set. The curves are similar shape in the molecules with respect to the position of vinylene groups. It is shown that the conformations of the molecules are compromised between the steric repulsion interaction and the degree of the conjugation. Electronic properties of the molecules were obtained by applying the optimized structures and geometries to the ZINDO/S method. ZINDO/S analysis performed on the geometries obtained by AM1 method and HF/3-21G(d) level is reported. The absorption wavelength on the geometries obtained by AM1 method is much longer than that by HF/3-21G(d) level. The absorption wavelength of MBPBs are red shifted with comparison to that of corresponding DSBs in the same torsion angle because of electron donating substituents. The absorption wavelength of isomers with kink(orth and meta) linkage is shorter than that of para linkage.

• 콘크리트학회논문집
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• 제21권5호
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• pp.599-609
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• 2009

2층 규모의 철근콘트리트조 및 포스트텐션조 무량판구조를 1/3 스케일로 축소하여 제작한 실험체의 진동대 실험 결과를 바탕으로 무량판구조의 모델링 기법을 향상하고자 하는 연구를 수행하였다. 이 연구에서 적용한 모델링 방법은 슬래브의 휨모멘트에 의한 휨파괴, 불균형모멘트의 전달에 의한 휨파괴 및 펀칭전단파괴에 의한 슬래브-기둥 접합부의 모멘트 전달능력 상실등의 영향을 반영하는 매우 포괄적인 구조해석 방식이다. 펀칭전단파괴에 대해서는 중력비와 층간변위각에 기초한 한계상태 모델이 적용되었다. 이 논문에서 제안된 비선형 모델은 무량판구조의 진동대 실험 결과와 잘 부합하는 것으로 나타났다.