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Influences of Shrinkage,Creep,and Temperature on the Load Distributions in Reinforced Concrete Buildings During Construction

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Tsinghua Science and Technology 2009年第6期14卷 756-764页

作者：方东平席海峰王晓明张传敏 School of Civil Engineering Tsinghua University Urban Systems Program CSIRO Sustainable EcosystemsCommonwealth Scientific and Industrial Research Organisation(CSIRO) Henan Development and Reform commission

Site measurements have shown that slab loads re-distribute, between the slabs during the concrete curing, while the external Ioadings and structural geometry remain the same. Some have assumed that this is caused by concrete shrinkage and creep, but there have been no studies on how these factors exactly influence the load distributions and to what degree these influences exist. This paper analyzes the influences of concrete shrinkage, creep, and temperature on the load re-distributions among slabs. Although these factors may all lead to load re-distribution, the results show that the influence of concrete shrinkage can be neglected. Simulations indicate that shrinkage only reduces slab loads by a maximum of 1.1%. Creep, however, may reduce the maximum slab load by from 3% to 16% for common construction schemes. More importantly, temperature variations between day and night can cause load fluctuation as large as 31.6%. This analysis can, therefore, assist site engineers to more accurately estimate slab loads for construction planning.

关键词： reinforced concrete buildings construction load re-distribution structural characteristic parameter slab-shore interaction shrinkage creep and temperature

Mesoporous titanium-aluminosilicate as an efficient catalyst for selective oxidation of cyclohexene at mild reaction conditions

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Chinese Journal of Chemical Engineering 2023年第3期55卷 257-265页

作者： Jitendra Diwakar Selvamani Arumugam Bhavna Saini Anup Prakash Tathod Nagabhatla Viswanadham Academy of scientific and Innovative research(AcSIR) at CSIR-Indian Institute of PetroleumDehradun 248005India Light Stock Processing Division Council of Scientific&Industrial Research-Indian Institute of PetroleumCouncil of Scientific and Industrial ResearchDehradun 248005India

Mesoporous titanium containing alumino-silicate materials with various titanium/silicon(Ti/Si) ratio(AlSi-Ti(n);n = Ti/Si mole ratio) have been successfully synthesized by a novel single-step sodium(Na)-free method, for the first time. The obtained characterization results of the prepared materials reveal that in-situ addition of Ti into AlSi shows ordered mesoporous structure along with uniformly dispersed Ti species in +4 and +3 oxidation states suitable for selective oxidation of allylic C—H bond. The prepared mesoporouse Ti-AlSi(n) samples exhibited excellent activity in the oxidation of cyclohexene with 100%conversion and 100% selectivity to ketone-alcohol(KA) oil(cyclohex-2-en-1-ol and 2-cyclohexen-1-one) at low temperature and reaction time(35℃ and 30 min reaction time). This study suggests that AlSi-Ti(0.05) material can be a promising catalyst for the selective oxidation of cyclohexene under mild reaction conditions.

关键词： Cyclohexene Allylic oxidation KA oil Mesoporous AlSi Mild conditions

Anti-Crack Performance of Low-Heat Portland Cement Concrete

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Journal of Wuhan University of Technology(Materials Science) 2007年第3期22卷 555-559页

作者：杨华全 Changjiang River scientific research Institute

The properties of low-heat Portland cement concrete（LHC） were studied in detail. The experimental results show that the LHC concrete has characteristics of a higher physical mechanical behavior, deformation and durability. Compared with moderate-heat Portland cement（MHC）, the average hydration heat of LHC concrete is reduced by about 17.5%. Under same mixing proportion, the adiabatic temperature rise of LHC concrete was reduced by 2 ℃-3 ℃,and the limits tension of LHC concrete was increased by 10× 10^-6-15×10^-6 than that of MHC. Moreover, it is indicated that LHC concrete has a better anti-crack behavior than MHC concrete.

关键词： low-heat portland cement mass concrete high crack resistance moderate-heat portland cement

Sensitive Evaluation on Early Cracking Tendency of Concrete with Inclusion of Light-burnt MgO

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Journal of Wuhan University of Technology(Materials Science) 2011年第5期26卷 1018-1022页

作者：陈霞 Changjiang River scientific research Institute

The advanced temperature and stress test machine was introduced to determine the early cracking tendency of concrete with inclusion of light-burnt MgO under full restraint by tracking the development of thermal,physical and deformation *** showed that light-burnt MgO being incorporated ranging between 4 wt% and 6 wt% of cementitious materials was beneficial to increase the maximum compressive stress and cracking stress of concrete by 0.37 MPa and 0.2 MPa on average *** second zero stress temperature was reduced by 11.4 ℃ and the maximum temperature was slightly reduced while cracking thermal impact was significantly enhanced from 59.8 ℃ to 66.2 ℃.Sensitive anti-cracking coefficient F was forwarded to assess the early cracking tendency of concrete and the inclusion of 4 wt% light-burnt MgO with activity of 109 s ranked the best in crack resistance.

关键词： crack resistance cracking stress light-burnt MgO concrete sensitive evaluation

PREDICTION OF LOADING DISTRIBUTION AND HYDRODYNAMIC MEASUREMENTS FOR PROPELLER BLADES IN A RIM DRIVEN THRU-STER

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Journal of Hydrodynamics 2012年第1期24卷 50-57页

作者： CAO Qing-ming HONG Fang-wen TANG Deng-hai HU Fang-lin LU Lin-zhang China Ship scientific research Centre Wuxi 214082China

This article presents an approach which employs a commercial Reynolds-Averaged Navier-Stokes（RANS）solver to predict the steady wake field and loading distributions for a rim driven *** different cases of propeller blades are chosen to be calculated with the presented *** propeller blade radial circulation and chordwise circulation density distributions are *** maximum radial circulation is found at the blade tip,which is different from conventional shaft driven *** numerical results indicate that there is no tip leakage vortex in rim driven *** there exist the tip joint vortex and the root region *** characteristics are calculated by taking rim surface effect into *** the predicted results the second case in this paper is selected as the final one to perform hydrodynamic *** calculation results with empirical rim surface corrections are compared with the *** shows that the developed numerical method can well predict hydrodynamic performances of the rim driven thruster.

关键词： rim driven thruster Reynolds-Averaged Navier-Stokes(RANS)solver wake field radial circulation chordwise circulation density hydrodynamic experiment

Theory and applications of coupled fluid-structure interactions of ships in waves and ocean acoustic environment

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Journal of Hydrodynamics 2016年第6期28卷 923-936页

作者：吴有生邹明松田超司马灿祁立波丁军李志伟陆晔 China Ship scientific research Center Wuxi 214082 China

Wave induced motions and structural distortions, and machinery or propeller excited vibrations and acoustic radiations of a ship are two kinds of important fluid-structure interaction problems. The branch of ship science that describes the coupled wave induced dynamic behavior of fluid-structure interaction system is referred to as hydroelasticity. During the past three decades the development of three-dimensional hydroelasticity theories and applications gained great progress. Recently the 3-D hydroelasticity theory was further extended to account for the fluid compressibility and the effect of the ocean acoustic environment with finite water depth. A three-dimensional sono-elasticity theory was then produced. In this paper, the 3-D hydroelasticity theory and the 3-D sono-elasticity theory of ships are briefly described. To illustrate the applicability and feasibility of these theories and the corre- sponding numerical approaches, several examples are presented including the predictions of wave loads, rigid-body and flexible- body responses, springing and fatigue behaviors, machinery or propeller excited coupled structural vibrations and acoustic radiations, as well as design optimizations for improving safety and acoustic behaviors of ships.

关键词： hydroelasticity sono-elasticity wave load structural strength springing vibration acoustic radiation

Complex dynamical behaviors of compact solitary waves in the perturbed mKdV equation

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Chinese Physics B 2014年第8期23卷 205-210页

作者：殷久利邢倩倩田立新 Nonlinear scientific research Center Faculty of ScienceJiangsu University

In this paper, we give a detailed discussion about the dynamical behaviors of compact solitary waves subjected to the periodic perturbation. By using the phase portrait theory, we find one of the nonsmooth solitary waves of the mKdV equation, namely, a compact solitary wave, to be a weak solution, which can be proved. It is shown that the compact solitary wave easily turns chaotic from the Melnikov theory. We focus on the sufficient conditions by keeping the system stable through selecting a suitable controller. Furthermore, we discuss the chaotic threshold for a perturbed system. Numerical simulations including chaotic thresholds, bifurcation diagrams, the maximum Lyapunov exponents, and phase portraits demonstrate that there exists a special frequency which has a great influence on our system; with the increase of the controller strength, chaos disappears in the perturbed system. But if the controller strength is sufficiently large, the solitary wave vibrates violently.

关键词： Melnikov method compacted solitary waves control threshold

Efficient suction control of unsteadiness of turbulent wing-plate junction flows

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Journal of Hydrodynamics 2017年第2期29卷 353-360页

作者：刘建华宋长友 China Ship scientific research Center Wuxi 214082China

A wing-body junction flow of a navigating underwater vehicle is considered to be a crucial source of the flow radiating acoustic noise, which attracts much research interest. In this paper, wing-plate junction flows are experimentally investigated in a low-speed wind tunnel by smoke-wire flow visualizations and time-resolved PIV measurements. To reveal the physical behavior of such flows, smoke-wire flow visualizations are conducted for a laminar wing-plate junction. A novel control strategy is proposed, to accurately locate the suction openings where the streamline is about to roll up to form a vortex in the turbulent junction flows. The control effect is discussed in perspectives of both the time-averaged and instantaneous flow fields.

关键词： Wing-plate junction flow horseshoe vortex turbulence unsteadiness PIV

Effect of three dimensional stress state on unstable fracture condition and crack opening level in a new crack growth model

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Acta Metallurgica Sinica(English Letters) 2010年第1期23卷 41-49页

作者： Fang WANG Weicheng CUI China Ship scientific research Center Wuxi 214082 China

A new model for the analysis of fatigue crack growth in the metal structures was proposed. This model shows a promising capability of explaining various fatigue phenomena. The new crack growth model is further completed by a continuous empirical formula for estimating the value of variable fracture toughness during crack propagation and a modified continuous equation for the crack tip stress/strain constraint factor used to calculate the stress intensity factor at the opening level. The prediction results are proved to agree well with the observed phenomena in test.

关键词： Marine structures Crack growth rate Three dimensional stress state Fracture toughness Crack tip stress/strain constraint factor