• Title, Summary, Keyword: P-${\Delta}$ 효과

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Seismic P-$\Delta$ Effects of Slender RC Columns in Earthquake Analysis (지진하중을 받는 철근콘크리트 장주의 P-$\Delta$ 효과)

  • Kwak, Hyo-Gyoung;Kim, Jin-Kook
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.19 no.4
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    • pp.375-387
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    • 2006
  • Different from the previous studies which investigated seismic P-$\Delta$ effect in slender columns though comparison of response spectra according to stability coefficients obtained from the analyses based on the assumed moment-curvature relationship, the axial force and P-$\Delta$ effect in RC columns are investigated on the basis of the layered section method which can effectively consider the changes of stiffness and yield strength due to the application of axial force in RC members. Practical ranges of slenderness and stability coefficient are assumed, and sixty sets of horizontal/vertical earthquake inputs are used in the analysis. From the parametric study, it is noted that the maximum deformation of the slender RC column is hardly affected by P-$\Delta$ effect or vortical earthquake but dominantly affected by the applied axial force. Therefore, it can be concluded that no additional consideration for the P-$\Delta$ effect and vortical earthquake is required in the seismic design of a slender RC column if the axial force effect is taken into account in the analysis and design procedures.

Seismic Performance Evaluation of Inverted V Braced Steel Frames with Considering P-Δ Effects: A Case Study (P-Δ 효과를 고려한 역 V형 철골 가새골조의 내진성능평가: 사례연구)

  • Lee, Cheol-Ho;Kim, Jeong-Jae
    • Journal of the Earthquake Engineering Society of Korea
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    • v.8 no.3
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    • pp.97-103
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    • 2004
  • Most of the columns in centrally braced steel frame buildings are usually designed as the gravity columns to reduce connection cost. For a rational seismic performance evaluation of centrally braced steel frame buildings, it is important to properly incorporate in the analysis  the P-${\Delta}$ effects arising from the gravity columns. An effective scheme for the P-${\Delta}$ effects modeling due to the gravity columns was illustrated based on the concept of fictitious leaning column. Seismic performance evaluation of inverted V braced steel frames with or without P-${\Delta}$ effects modeling was conducted by following the FEMA 273 NSP (Nonlinear Static Procedure). The problem in estimating dynamic P-${\Delta}$ modification factor (C3) in FEMA 273 was discussed. The results of this study indicated that the P-${\Delta}$ effects should be included in the seismic performance evaluation of centrally braced steel frames. This study also showed that the inverted V braced frames, retrofitted by applying the tie bars to redistribute the inelastic demand over the height of the building, exhibit significantly improved seismic performance.

Stability of Steel Frames with Weak Column-Strong Beam Considering P-Δ effect (P-Δ 효과를 고려한 기둥항복형 강구조 골조의 안정성)

  • Kim, Hee Dong;Lee, Myung Jae
    • Journal of Korean Society of Steel Construction
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    • v.15 no.4
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    • pp.457-466
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    • 2003
  • This study aimed to evaluate the stability of steel frames with weak column-strong beam and consider P-effect using the experimental approach. Towards this end, three specimens were tested under monotonic loading condition. Parameters of tests includes the stiffness of the column and the axial load ratio. Result showed that reduction in column stiffness promoted P- effect, which considerably influenced the frame's stability.

The Experimental Studu on the P-Δ Influence of Weak Beam Unbraced Frames (보항복형 비가새 골조의 PΔ 영향에 관한 실험적 연구)

  • Kim, Hee Dong;Park, Sang Chul;Lee, Myung Jae
    • Journal of Korean Society of Steel Construction
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    • v.13 no.4
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    • pp.363-372
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    • 2001
  • The objective of this study is to evaluate the $P-{\Delta}$ effect in the case of weak beam unbraced frames by experimental approach. To evaluate $P-{\Delta}$ effect, four specimens were tested under monotonic loading condition. The parameters of tests are the stiffness of column and the axial load ratio. The results show that the value of axial load affects frame stability because $P-{\Delta}$ effects promote the yielding of beam. The maximum lateral load increases in proportion to the increment of column stiffness and rotational stiffness of supports, The collapse mechanism of weak beam unbraced frames is stably formed in the condition of low axial load ratio. The $B_2$ factor of limit state design code does not properly consider the $P-{\Delta}$ effect in inelastic region.

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A Study on the Lateral Behavior of Pile-Bent Structures with $P-{\Delta}$ Effect ($P-{\Delta}$ 효과를 고려한 Pile-Bent 구조물의 수평거동 연구)

  • Jeong, Sang-Seom;Kwak, Dong-Ok;Ahn, Sang-Yong;Lee, Joon-Kyu
    • Journal of the Korean Geotechnical Society
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    • v.22 no.8
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    • pp.77-88
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    • 2006
  • In this study, the lateral behavior of Pile-Bent structures subjected to lateral loading was evaluated by a load-transfer approach. An analytical method based on the Beam-Column model and nonlinear load transfer curve method was proposed to consider material non-linearity (elastic and yielding) and $P-{\Delta}$ effect. Special attention was given to the lateral deflection of Pile-Bent structures depending on different soil properties, lateral load, slenderness ratio based on pier length and reinforcing effect of casing. From the results of the parametric study, it is shown that the increase of lateral displacement in a pile is much less favorable for an inelastic analysis than for an elastic analysis. It is found that for inelastic analysis, the maximum bending moment is located within a depth approximately 3.5D(D: pile diameter) below ground surface, but within 1.5D when $P-{\Delta}$ effect is considered. It is also found that the magnitude and distribution of the lateral deflections and bending moments on a pile are highly influenced by the inelastic analysis and $P-{\Delta}$ effect, let alone soil properties around an embedded pile.

Kinetics on the Reaction of Substituted Quinolines and p-Substituted Benzoylchlorides under Various Pressures (퀴놀린 유도체와 p-치환 염화벤조일류의 친핵성치환반응에 따른 반응속도의 압력효과)

  • Kim, Young Cheul;Lim, Jong Wan;Choi, Sung Yong;Kim, Se Kyong
    • Journal of the Korean Chemical Society
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    • v.43 no.1
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    • pp.15-22
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    • 1999
  • The reaction rates of substituted quinolines($6-CH_3C_9H_7N,\;C_9H_7N$) with p-substituted benzoylchlorides($p-CH_3,\;p-H,\;p-NO_2$) have been measured by conductometry in acetonitrile, and the rate constants are determined at various temperatures(10, 15, 20, 25$^{\circ}C$) and pressures(l, 200, 500, 1000bar). From the values of rate constants, the activation parameters($Ea,\;{\Delta}V^{\neq},\;{\Delta}H^{\neq},\;{\Delta}S^{\neq},\;{\Delta}G^{\neq}$) and the pressure dependence of Hammett p values were determined. The rate constants increase as a function of temperatures and pressures, and are further increase by introduction the electron donor substituents in nucleopbile($p-CH_3$) or electron acceptor($p-NO_2) substituents in substrate. The activation volume, and the activation entropy are all negative. Hammett p values are also negative for nucleophile (px) and positive for the substrate ($p_Y$) over the pressure range studied. The results of kinetic studies for pressure and substituent show that these reactions proceed in typical $S_N2$ reaction mechanism and "associative $S_N2$" in which bond formation favored with increasing pressures.

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Relationship between the Micellization of TTAB and the Solubilization of p-Bromophenol in TTAB Solution (TTAB 용액에서 p-브로모페놀의 가용화와 TTAB의 미셀화와의 상관관계에 대한 연구)

  • Lee, Byung-Hwan
    • Journal of the Korean Chemical Society
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    • v.57 no.6
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    • pp.665-671
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    • 2013
  • The solubilization of p-bromophenol by the micellar system of TTAB(tetradecyltrimethylammonium bromide) and the micellization of TTAB were studied by the UV-vis spectrophotometric method simultaneously. And the effects of temperature on these properties have been measured for the thermodynamic study. The results show that the ${\Delta}G_s{^o}$ and ${\Delta}H_s{^o}$ values are negative and the ${\Delta}S_s{^o}$ values are positive for the solubilization of p-bromophenol within the measured range. On the other hand, the ${\Delta}G_m{^o}$ values are negative and the ${\Delta}H_m{^o}$ and ${\Delta}S_m{^o}$ values are positive for the micellization of TTAB. The effects of additives such as n-butanol and NaCl have been studied also for both properties and the relationship between these two properties has been also studied. From the results, we can postulate the solubilization site of p-bromophenol in the micelle.

Pressure Transfer Analysis and Experimental Verification of Thin Plate Spring Type Check Valve Considering P-delta Effect (P-delta 효과를 고려한 박판 스프링 형 체크밸브의 압력전달 해석 및 실험적 검증)

  • Hwang, Yong-Ha;Nguyen, Anh Phuc;Hwang, Jai-Hyuk;Bae, Jae-Sung
    • Journal of Aerospace System Engineering
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    • v.12 no.5
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    • pp.32-39
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    • 2018
  • In this paper, the calculation of the theoretical pressure transfer ratio due to the deformation of the thin-plate spring type check valve applied to the small piezoelectric-hydraulic pump was carried out. A thin-plate check valve is a flexible body that is deformed by an external force. The deformation of the check valve affects the rate at which the chamber pressure is transferred to the load pressure. The theoretical pressure transfer ratio for each model was calculated to compare the difference between the assumption that the thin-plate check valve is a rigid body and that of the flexible body model. The P-delta effect was considered for the calculation of the pressure transfer ratio of the flexible check valve model. In addition, a verification test for the calculated pressure transfer ratio obtained by considering the deformation of the flexible check valve model was carried out. The load pressure was measured by applying a thin-plate and ball-thin plate spring type check valves, respectively. The experimental pressure transfer ratio was calculated using the respective load pressure obtained from the experiments. The validity of the pressure transfer analysis of the check valve, taking into consideration the P-delta effect, was verified by comparing it with the theoretically calculated pressure transfer ratio.

Kinetic Studies for the Reactions of Pyridine with Benzoylchlorides under High Pressure and High Vacuum (고압 및 고진공에서의 피리딘과 벤조일클로라이드류의 반응에 관한 속도론적 연구)

  • Kim, Se-Kyong
    • Journal of the Korean Chemical Society
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    • v.48 no.3
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    • pp.254-260
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    • 2004
  • The reaction rates of para-substituted benzoyl chlorides ($p-CH_3$, p-H, $p-NO_2$) with pyridine have been measured employing the conductometry method in acetonitrile. The pseudo first-order and second-order rate constants were determined at various pressures and temperatures. The activation parameters (${\Delta}V{\ddagger},\;{\Delta}{\beta}{\ddagger},\;{\Delta}H{\ddagger},\;{\Delta}S{\ddagger},\;{\Delta}G{\ddagger}$) and the Hammett ${\rho}$-values are determined from the values of rate constant. The values of ${\Delta}V{\ddagger},\;{\Delta}{\beta}{\ddagger}\;and\;{\Delta}S{\ddagger}$ are all negative. The Hammett ${\rho}$-values are positive for the substrate (${\rho}_Y$) over the given pressure range. The results of kinetic studies, for the pressure and substituent changes, show that these reactions are proceeded by a typical $SN_2$reaction mechanism and its bond formation is favored with elevating pressure.

Ultimate Resisting Capacity of RC Columns Considering P-$\Delta$ Effect (P-$\Delta$ 효과를 고려한 RC 기둥의 극한저항력 산정)

  • 곽효경;김진국;김한수
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.15 no.1
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    • pp.105-116
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    • 2002
  • In this paper, an analytical model to predict the resisting capacity of slender RC columns is introduced. Material and geometric nonlinearities are taken into account, and the layer approach is adopted to simulate the different material properties across the sectional depth. On the basis of the obtained numerical analysis results, an improved design equation as a function of concrete strength, slenderness ratio, steel ratio and eccentricity for slender RC columns, which can be used effectively in the preliminary design stage, is introduced. Finally, P-M interaction diagrams constructed by the introduced equation are compared with the ACI method with the objective of establishing the relative efficiencies of the introduced equation.