预应力混凝土桥梁施工控制结构分析计算方法

结合某预应力混凝土桥梁施工预拱度的求解问题,阐述了分阶段施工法中立模标高的计算原理及正装计算与倒装计算二者之间的关系,分析了与施工控制预拱度相关的影响因素,并根据预应力混凝土桥梁分阶段施工时的施工过程及特点,综合考虑施工过程中各种因素(包括新梁段的浇筑、预应力筋的张拉、混凝土的收缩徐变等)的影响,建立计算模型,运用有限元软件Midas和桥梁博士,采用正装和倒装分析方法计算出各施工阶段的挠度,进而得出各悬浇段的预拱度,为施工控制提供依据。

连续刚构桥施工监控中的结构分析方法

连续刚构桥的施工必须通过合理的计算方法和理论分析来确定桥梁结构施工中在受力和变形方面的理想状态 ,使其最终的成桥线型和受力状态满足设计要求 ,本文通过对几种结构分析方法的比较 。

桥塔的结构振动响应分析及亟待解决的问题

本文对高耸结构顺风向响应计算理论的发展、研究方法进行了阐述与总结。在此基础上，对桥塔结构振动响应分析的必要性与方法进行了探讨与研究明，并提出了结构振动的控制措施。

Computation of Diffusion Activation Energies of C, N in γFe

A structure relaxation model based on the empirical electron theory of solids and molecules is developed to compute the diffusion active energies of C, N in γFe. First, adding a restriction, the lattice maintains rigidity when solute atom migrates to the saddle point. In this step, the hybridization classes of every atom do not change. Then, the restriction is loosed and the atoms are relaxed under the coulomb repulsive forces. It is supposed that the energy needed in the first step would be compensated partly by the second step. In this way, the diffusion active energies of C, N in γFe are computed. Compared with the experiment data, the relative errors are less than 5%, which are good results in the computation of activation energy of diffusion.

角闪石超族矿物的命名：挑战与机遇——以新矿物“钾绿钙闪石”的发现为例

IMA CNMNC认可和批准的角闪石矿物种成员数目已愈百个之多,而且还有上百个已命名的潜在矿物种尚待人们去发现和研究。这不但是挑战,更是发现新矿物的机遇。以新矿物“钾绿钙闪石”的发现与研究为例,解析“角闪石超族命名”的规则及其流程,提出了一种未测结构水情况下,有条件理论计算OH a pfu、结构水含量和矿物经验化学式的方法,供矿物学研究者参考。

The rough representation and measurement of quotient structure in algebraic quotient space model

Granular computing is a very hot research field in recent years. In our previous work an algebraic quotient space model was proposed,where the quotient structure could not be deduced if the granulation was based on an equivalence relation. In this paper,definitions were given and formulas of the lower quotient congruence and upper quotient congruence were calculated to roughly represent the quotient structure. Then the accuracy and roughness were defined to measure the quotient structure in quantification. Finally,a numerical example was given to demonstrate that the rough representation and measuring methods are efficient and applicable. The work has greatly enriched the algebraic quotient space model and granular computing theory.

Research on angle-dependent to mographic static correction

Reflection data in CMP has influenced seriously in static calculations,especially in some highly weathered and structurally altered circumstances. Because of static correction in the existed problems and requests,the authors studied the angle dependent tomographic static correction,and discussed its basic theory, including the establishment of forward model,the calculation theory of tomography and tomographic static correction. The usage of theoretical models and practical information on the method has been validated. The results show that using these methods to calculate static correction in a complex area,the quality of static correction is greatly improved.

Eight-body central configuration for conjugate-nested regular tetrahedrons

The sufficient and necessary conditions, the existence and uniqueness of a new class of central configuration in R^3, for the conjugate-nest consisting of two regular tetrahedrons, are proved. If the configuration is a central configuration, then all masses of outside layer are equivalent, and the masses of inside layer are also equivalent. At the same time p （the ratio of the sizes） and mass ratio τ=m^/m must be satisfied by some formulas. For any radius ratios ρ∈（0, 0.152996 918 2） or （0.715 223 148 7, 1.398 165 037）, there is only one central configuration. Otherwise, for any given mass ratio τ, there may exist more than one central configuration.

Insights into Syngas to Methanol Conversion on Cr_(2)O_(3) Oxide from First-Principles-based Microkinetic Simulations

Cr_(2)O_(3) has been recognized as a key oxide component in bifunctional catalysts to produce bridging intermediate,e.g.,methanol,from syngas.By combining density functional theory calculations and microkinetic modeling,we computationally studied the surface structures and catalytic activities of bare Cr_(2)O_(3)(001)and(012)surfaces,and two reduced(012)surfaces covered with dissociative hydrogens or oxygen vacancies.The reduction of(001)surface is much more difficult than that of(012)surface.The stepwise or the concerted reaction pathways were explored for the syngas to methanol conversion,and the hydrogenation of CO or CHO is identified as rate-determining step.Microkinetic modeling reveals that(001)surface is inactive for the reaction,and the rates of both reduced(012)surfaces(25−28 s^(-1))are about five times higher than bare(012)surface(4.3 s^(-1))at 673 K.These theoretical results highlight the importance of surface reducibility on the reaction and may provide some implications on the design of individual component in bifunctional catalysis.

Minimizing of the only-insertion insdel systems

A more recent branch of natural computing is DNA computing. At the theoretical level, DNA computing is powerful. This is due to the fact that DNA structure and processing suggest a series of new data structures and operations, and to the fact of the massive parallelism. The insertion-deletion system （insdel system） is a DNA computing model based on two genetic operations： insertion and deletion which, working together, are very powerful, leading to characterizations of recursively enumerable lan- guages. When designing an insdel computer, it is natural to try to keep the underlying model as simple as possible. One idea is to use either only insertion operations or only deletion operations. By helping with a weak coding and a morphism, the family INS4^7DEL0^0 is equal to the family of recursively enumerable languages. It is an open problem proposed by Martin-Vide et al. on whether or not the parameters 4 and 7 appearing here can be replaced by smaller numbers. In this paper, our positive answer to this question is that INS2^4DEL0^0 can also play the same role as insertion and deletion. We suppose that the INS2^4DEL0^0 may be the least only-insertion insdel system in this situation. We will give some reasons supporting this conjecture in our paper.

Conformations and Structures of Ethoxycarbonyl Isothiocyanate Revealed by Rotational Spectroscopy

The ethoxycarbonyl isothiocyanate has been investigated by using supersonic jet Fourier transform microwave spectroscopy.Two sets of rotational spectra belonging to conformers TCC(with the backbone of C-C-O-C,C-O-C=O,and O-C(=O)-NCS being trans,cis,and cis arranged,respectively)and GCC(gauche,cis,and cis arrangement of the C-C-O-C,C-O-C=O,and O-C(=O)-NCS)have been measured and assigned.The measurements of13C,15N and34S mono-substituted species of the two conformers have also been performed.The comprehensive rotational spectroscopic investigations provide accurate values of rotational constants and14N quadrupole coupling constants,which lead to structural determinations of the two conformers of ethoxycarbonyl isothiocyanate.For conformer TCC,the values of Pcckeep constant upon isotopic substitution,indicating that the heavy atoms of TCC are effectively located in the ab plane.

钢筋混凝土空心板梁静载试验研究

本文对上部结构为钢筋混凝土板梁的某桥在荷载作用下的实际工作状态进行了荷载试验和承载能力检算,综合分析判断了桥梁结构的承载能力和运营状态。

Substituent Effects on the Photocatalytic Properties of a Symmetric Covalent Organic Framework

Symmetric covalent organic framework(COF)photocatalysts generally suffer from inefficient charge separation and short-lived photoexcited states.By performing density functional theory(DFT)and time-dependent density functional theory(TDDFT)calculations,we find that partial substitution with one or two substituents(N or NH_(2))in the linkage of the representative symmetric COF(N_(0)-COF)gives rise to the separation of charge carriers in the resulting COFs(i.e.,N_(1)-COF,N_(2)-COF,(NH_(2))1-N_(0)-COF,and(NH_(2))2-N_(0)-COF).Moreover,we also find that the energy levels of the highest occupied crystal orbital(HOCO)and the lowest unoccupied crystal orbital(LUCO)of the N_(0)-COF can shift away from or toward the vacuum level,depending on the electron-withdrawing or electron-donating characters of the substituent.Therefore,we propose that partial substitution with carefully chosen electron-withdrawing or electron-donating substituents in the linkages of symmetric COFs can lead to efficient charge separation as well as appropriate HOCO and LUCO positions of the generated COFs for specific photocatalytic reactions.The proposed rule can be utilized to further boost the photocatalytic performance of many symmetric COFs.

Calculation of the Structural Parameters, and DOS of TaB2 with p6/mmm Space Group Using DFT

In this paper, the structural parameters, and density of the states of TaB2 compound have been calculated, and investigated in hexagonal phase with P6/mmm space group. The calculations have been performed with ultra-soft pseudo-potential in the frame work of Density Functional Theory （DFT） by using the Quantum Espresso package. With respect to high quantity of bulk modulus, and low quantity of the volume it is being understood that this compound has a very hard structure. The figure of density of states shows that this compound is a kind of metal. The obtained results from this research have good accord with experimental results, and with the same researches.

基于节段预制拼装施工阶段的PK箱梁剪力滞效应研究

为探究混凝土PK箱梁在节段预制拼装施工阶段的剪力滞效应,以石首长江公路大桥为工程背景,采用空间结构计算理论以及现场实测方法对模型计算结果进行验证,研究PK箱梁在自重作用,预应力张拉、提升与滑移不同阶段的剪力滞效应的变化规律,为类似工程提供理论支撑。研究结果表明:考虑空间预应力的PK箱梁结构模型计算结果与实测结果吻合较好,误差在6%~7%之间;自重作用时应力较小,但剪力滞效应最大,提升与滑移阶段的剪力滞效应相对较小,且沿箱梁截面呈非线性走势;张拉横向预应力越大,剪力滞系数曲线沿横桥向越趋于平缓,预应力对剪力滞的影响效果明显;预应力张拉量相等时,吊点与滑靴位置的改变是影响剪力滞效应的主要因素。建议在设计节段预制拼装施工方案时,对预应力张拉方法以及吊点与滑靴位置的设置予以充分考虑,控制箱梁剪力滞效应,保障施工阶段结构的安全性。

Risk-Identification-Based Hybrid Method for Estimating the System Reliability of Existing Jacket Platforms Under Fire

This paper proposes a risk-identification-based hybrid method for estimating the system reliability of steel jacket structures under fire.The proposed method starts with risk identification;according to the results of hazard identification and Dow’s fire and explosion index(F&EI) methodology,the most dangerous hazard sources are determined.In term of each equipment layout in steel jacket structures,fire load is imposed and elasto-plastic analysis is performed.According to the deformed state of steel jacket structures,the weakest failure mode of steel jacket structures is identified.In order to know the effect on ultimate bearing capacity of the offshore structural system,a series of elasto-plastic analyses are performed in which single failure element contained in the weakest failure mode is removed from the whole offshore platform structural system.Finally,the failure function of the steel jacket structure is generated and the failure probability of the steel jacket structure system is estimated under fire by genetic algorithm via MATLAB program.

New Unified Failure Model on Evenly Distributed Reinforced Concrete Members with Box Section

It is urgently needed to describe the structural collapse process under extreme conditions to survive people.For reinforced concrete structures it is still a difficulty to describe the failure of reinforced concrete members under complex internal force combination,such as under axial forces,bending moment,shear forces, and torsion working together.In this paper,based on the traditional Nielsen model,a new unified failure model on reinforcement evenly distributed concrete members with box section under combined forces is introduced.The advantages of the proposed new model are to consider the dowel actions of reinforcements and reasonably to consider of the shear carrying capacity of concrete,especially when compression stress of concrete is in a high value.Finally,the theoretical results of the new model are compared with a series of experimental results of box section members.The comparison has verified that the new model is more accurate and feasible for the design and calculation of box section members.

Application of Non-Detective Techniques Traditional Masonry Structures

Study on the non-destructive detection techniques and damage identification method is of great importance in protecting and rehabilitating the ancient architectural structure. In order to identify the location and the grade of structural damages, a multi-point microtremor measurement is performed on carved brick screen walls at Songjiang area in Shanghai, and the observed dynamic parameters （natural frequencies and natural modal） are obtained. On the other hand, the dynamic parameters of the original structure are calculated by finite-elementmethod （FEM）. Normalizing tile observed and calculated parameters on unified physical quantity, the damages are located by the variation on vibration modal, and the grade of structural damages is quantitatively evaluated by stiffness losses based on the variation on vibration modal.

Structural, electronic, and optical absorption properties of TiO_2 nanotube adsorbed with Cu_n clusters

The structural, electronic, and optical absorption properties of TiO2 nanotube （TiO2NT） with Cun clusters （n =1-4） adsorbed on its surface have been investigated based on density functional theory calculations. The TiO2NT is constructed by rolling up a （101） sheet of anatase TiO2 around the [ 1-01 ] direction; the ground states of Cun/TiOzNT systems are determined by analyzing the average adsorption energies. Calculation results show that odd-even oscillations occur for the average adsorption energy, the Cu-O bond length, and the amount of transferred electrons, with the increase in Cu. cluster size; and the Cun/TiO2NTs with odd n＇s demonstrate stronger interaction between the Cu. cluster and the TiO2NT. Also, the impurity states introduced by the Cun cluster to the band gap of TiOzNT cause an obvious redshift of the optical absorption spectrum toward the visible light region, especially for the even n cases.