毕业设计（论文）
外文翻译
设计（论文）题目：宁波新城艺术宾馆2#楼
结构设计与预算
学院名称：建筑工程
专业：土木工程
学生姓名：顾丽敏学号：06404010101 指导教师：袁坚敏
2010年01月10日
外文原文I：
A fundamental explanation of the behaviour of
reinforced concrete beams in flexure based
on the properties of concrete under multiaxial stress
M. D. Kotsovos
Department of Civil Engineering, Imperial College of Science and Technology, London (U. K.)
The paper questions the validity of the generally accepted view that for a reinforced concretestructure to exhibit "ductile" behaviour under increasing load it is necessary for the stressstrain relationships of concrete to have a gradually descending post-ultimate branch.Experimental data are presented for reinforced concrete beams in bending which indicate the presence of longitudinal compressive strains on the compressive face in excess of 0.0035. It is shown that these strains, which are essential for "ductile" behaviour, are caused by acomplex multiaxial compressive state of stress below ultimate strength rather than postultimate material characteristics. The presence of a complex stress system provides a fundamental explanation for beam behaviour which does not affect existing design procedures.
1. INTRODUCTION
The "plane sections" theory not, only is generally considered to describe realistically the deformation response of reinforced and prestressed concrete beams under flexure and axial load, but is also formulated so that it provides a design tool noted for both its effectiveness and simplicity [1]. The theory describes analytically the relationship between load-carrying capacity and geometric characteristics of a beam by considering the equilibrium conditions at critical cross-sections. Compatibility of deformation is satisfied by the "plane cross-sections remain plane" assumption and the longitudinal concrete and steel stresses are evaluated by the material stress-strain characteristics. Transverse stresses and strains are ignored for the purposes of simplicity.
The stress-strain characteristics of concrete in compression are considered to be adequately described by the deformational response of concrete specimens such as prisms or cylinders under uniaxial compression and the stress distribution in the compression zone of a cross-section at the ultimate limit state, as proposed by current codes of practice such as CP 110 [1], exhibits a shape similar to that shown in figure 1. The figure indicates that the longitudinal stress increases with the
distance from the neutral axis up to a maximum value and then remains constant. Such a shape of stress distribution has been arrived at on the basis of both safety considerations and the widely held view that the stress-strain relationship of concrete in compression consists of both an ascending and a gradually descending portion (seefig. 2). The portion beyond ultimate defines the post-ultimate stress capacity of
the material which, Typical stress-strain relationship for concrete in compression. as indicated in figure 1, is generally considered to make a major contribution to the maximum load-carrying capacity of the beam.
However, a recent analytical investigation of the behaviour of concrete under concentrations of load has indicated that the post-ultimate strength deformational response of concrete under compressive states of stress has no apparent effect on the overall behaviour of the structural forms investigated ( [2], [3]). If such behaviour is typical for any structure, then the large compressive
strains (in excess of 0.0035) measured on the top surface of a reinforced concrete beam at its ultimate limit state (see fig. 1), cannot be attributed to post-ultimate uniaxial stress-strain characteristics. Furthermore, since the compressive strain at the ultimate strength level of any concrete under uniaxial compression is of the order of 0.002 (see fig. 2), it would appear that a realistic prediction of the beam response under load cannot be based solely on the ascending portion of the uniaxial stress-strain relationship of concrete.
In view of the above, the work described in the following appraises the widely held view that a uniaxial stress-strain relationship consisting of an ascending and a gradually descending portion is essential for the realistic description of the behaviour of a reinforced concrete beam in flexure. Results obtained from beams subjected to flexure under two-point loading indicate that the large strains exhibited by concrete in the compression zone of the beams are due to a triaxial state of stress rather than the uniaxial post-ultimate stress-strain characteristics of concrete. It is shown that the assumption that the material itself suffers a completeand immediate loss of load-carrying capacity when ultimate strength is exceeded is compatible with the observed "ductile" structural behaviour as indicated by load-deflexion or moment-rotation relationships.
2. EXPERIMENTAL DETAILS
2.1. Specimens
Three rectangular reinforced concrete beams of 915 mm span and 102 mm height x 51 mm width cross-section were subjected to two-point load with shear spans of 305 mm (see fig. 3). The tension reinforcement consisted of two 6 mm diameter bars with a yield load of 11.8 kN. The bars were bent back at the ends of the beams so as to provide compression reinforcement along the whole length of the shear https://www.doczj.com/doc/d912702800.html,pression and tension reinforcement along each shear span were linked by seven 3.2 mm diameter stirrups. Neither compression reinforcement nor stirrups were
provided in the central portion of the beams. Due to the above reinforcement arrangement all beams failed in flexure rather than shear, although the shear span to effective depthratio was 3.
The beams, together with control specimens, were cured under damp hessian at 20~ for seven days and then stored in the laboratory atmosphere (20o C~and 40% R.H.) for about 2 months, until tested. Full details of the concrete mix used are given in table I.
2.2. Testing
Load was applied through a hydraulic ram and spreader beam in increments of approximately 0.5 kN. At each increment the load was maintained constant for approximately 2 minutes in order to measure the load and the deformation response of the specimens. Load was measured by using a load cell and deformation response by using both 20 mm long electrical resistance strain gauges and displacement transducers. The strain gauges were placed on the top and side surfaces of the beams in the longitud{nal and the transverse directions as shown in figure 4. The figure also indicates the position of the linear voltage displacement transducers (LVDT's) which were used to measure deflexion at mid-span and at the loaded cross-sections.
The measurements were recorded by an automatic computer-based data-logger (Solatron) capable of measuring strains and displacements to a sensitivity of ± 2 microstrain and ±0.002 ram, respectively.
3. EXPERIMENTAL RESULTS
The main results obtained from the experiments together with information essential for a better understanding of beam behaviour are shown in figures 5 to 14. Figure 5 shows the uniaxial compression stressstrain relationships of the concrete used in the investigation, whereas figures 6 and 7 show the relationships between longitudinal and transverse strains, measured on the top surface of the beams (a) at the cross-sections where the flexure cracks which eventually cause failure are situated (critical sections) and (b)at cross-sections within the shear span, respectively. Figures 6 and 7 also include the longitudinal straintransverse strain relationship corresponding to the stress-strain relationships of figure 5.
Figure 8 shows the typical change in shape of the transverse deformation profile of the top surface of the beams with load increasing to failure and figure 9 provides a schematic representation of the radial forces and stresses developing with increasing load due to the deflected shape of the beams. Typical load-deflexion relationships of the beams are shown in figure 10, whereas figure 11 depicts the variation on critical
sections of the average vertical strains measured on the side surfaces of the beams with the transverse strains measured on the top surface. Figure 12 indicates the strength and deformation response of a typical concrete under various states of triaxial stress and figure 13 presents the typical crack pattern of the beams at the moment of collapse. Finally, figure 14 shows the shape of the longitudinal stress distribution on the compressive zone of a critical section at failure predicted on the basis of the concepts discussed in the following section.
中文翻译I：
在多向应力作用下从混凝土的特性看受弯钢筋混凝土梁
变化的一个基本试验
M. D. Kotsovos 伦敦皇家科学与技术学院土木工程系
本文所探讨的问题是通常认为在荷载递增下钢筋混凝土结构呈现弹性状态，这必须是因为混凝土的应力-应变关系有一个逐渐递减的临界部分的真实性。试验数据显示受弯钢筋混凝土梁会在受压面的纵向压应变超出0.0035。这表明这些应变是钢筋混凝土结构的本质，它是由于一个比极限强度小的复杂多向的应力状态而不是塑性材料的特性引起的。一个复杂应力系统的存在为梁的状态提供了一个基本试验，而不是想象的一个现有设计过程。
1.引言
“剖面”理论不仅是通常认为能很真实地描述钢筋混凝土梁和预应力混凝土梁在弯矩和轴向荷载下的变形，而且能确切地阐述，所以它提供了一个设计工具，因为它的有效和简单而闻名[1]。假设在临界横截面伤是均衡的，这个理论分析地描述了一个梁的承载能力和几何特性之间的关系。变形协调必须满足“水平横截面荏苒水平”的假定和纵向混凝土和钢筋的应力是通过材料的应力-应变的特性来估算的。为了简化计算，忽略横向的应力和应变。
受压混凝土的应力-应变特性认为能够被混凝土试块的变形充分地描述，例如在极限的有限状态下，棱柱体或圆柱体在横截面的受压区受单轴压力和应力，就像现行规范所建议的CP110[1]，显示出一个与图1相似的形状。图1表明纵向应力随着与中和轴的距离增加而增加至最大值，然后保持不变。这个分布图已经达到安全性和受压混凝土的应力-应变关系的广泛观点，由上升和逐渐下降的两部分组成(如图2所示)。超出极限的部分，材料的塑性应力能力如图1所示，被认为对梁的最大承载能力有较大的作用。
图1.临界面破坏建议CP为110的应力和应变分布图2.受压混凝土结构的标准应力-应变关系然而，最近关于在集中力作用下的混凝土的变化的一个分析性调查表明，在压应力作用下混凝土的极限强度变形没有对所有被调查的结果形式的变化产生明显的影响([2],[3])。如果这个变化对任何结果都是典型的，那么在钢筋混凝土梁的顶面被测的很大的压应变(超出量0.0035)在它的极限有限状态下(如图1)，不能对极限单轴应力-应变特性产生作用。因此，因为压应变在单轴压力下的任何混凝土的极限强度等级下为ε=0.002(如图2所示)，在混凝土的单轴应力-应变关系下降部分，将出现一个在荷载作用下梁变化的现在可行的预测。
根据以上的观点，本文的描述都在以下的评价中，广泛的支持观点的一个单轴应力-应变关系由一个上升的和一个逐渐下降的部分组成，对受弯的根据混凝
土梁的变化的真实描述是非常必要的。这个结果是从梁在两点荷载作用下弯曲得到，表明很大的应变的通过梁受压的混凝土呈现的，由于三维应力而不是一味的混凝土极限应力-应变特性。这表明材料本身受到一个完整和直接的承载能力损失，当极限强度被超过的假定与弹性结构的变化并存的，通过偏心荷载或瞬间旋转关系表明的。
2.试验细节
2.1试块
三根矩形钢筋混凝土梁，跨度915mm，横截面为102mm 51mm，受剪区跨度为305mm(如图2所示)。受力筋由两个直径为6mm，屈服荷载为11.8kN的钢筋组成。在梁端部钢筋弯起，就能为整个受剪跨度提供抗力。整个受剪跨度内压缩张拉的加强筋布置了七个直径为3.2mm的箍筋。在梁的中间部分没有压缩加强筋和箍筋。根据上面所述的钢筋布置，所有的梁都是受弯破坏而不是受剪破坏，尽管剪跨比为3。
所有的梁与受控的试块一起放在20 o C的湿麻袋下七天，然后贮存在实验室条件下(20o C,40%湿度)2个月，直到试验结束。所有混凝土配料都在表格I中。
2.2试验过程
通过液压锤和分布梁加载，每次大约增加0.5kN。为了测量荷载和试块的形变，每次持荷约2分钟。荷载用一个荷载单元来测量，形变由20mm长的电阻应变片和位移转换器测得。应变片贴在梁纵向和横向的顶面和侧面(如图4所示)。图4也表明了直流电压位移转换器（LVDT’S）的位置，它是用来测量跨中和加载横截面的形变。
测量数据记录在计算机自动数据记录仪中，能够测量应变和形变的灵敏度分别为±2微应变和±0.002mm。
3.试验结果
主要的试验结果是从试验中得到的，能更好地了解梁的变化，所示图5 至图14的信息是必不可少的。图5表明结果的单轴压应力-应变关系应用于调查中，而图6 和图7表明纵向应变与横向应变的关系，分别位于(a)弯曲裂缝最终导致破坏横截面出和(b)受剪区跨内的横截面出。图6和图7也包含了纵向应变-横向应变与图5的应力-应变关系是一致的。
图8中标准的改变在梁顶面的横向形变轮廓图中和图9提供一个轴力和应力随着荷载的增加而增大，导致梁向下变形的图框表示方法。梁的标准偏心荷载关系如图10所示，而图11描述了测得平均竖向应变的梁侧面的临界截面变形和横向应变在顶面测得。图12中标准结果的强度和形变在各种状态的十三轴应力下河图13所呈现的梁标准裂缝图样在破坏的瞬间。最后图14表明在临界截面的受压区伤纵向应力的分布形状，可根据概念来预测破坏，在以下部分将被讨论。
图3.梁的细节
外文原文II:
Some questions on the corrosion of steel in concrete.
PartⅡ: Corrosion mechanism and monitoring, service
life prediction and protection methods
J.A. Gonzdlez , S. Felifd, P. Rodffguez , W. Lfpez , E. Ramlrez , C. Alonso , C. Andrade
ABSTRACT
This second part addresses some important issues that remain controversial despite the vast amounts of work devoted to investigating corrosion in concrete-embedded steel. Specifically,these refer to: 1) the relative significance of galvanic macrocouples and corrosion microcells in reinforced concrete structures; 2) the mechanism by which reinforcements corrode in an active state; 3) the best protective methods for preventing or stopping reinforcement corrosion; 4) the possibility of a reliable prediction of the service life of a reinforced concrete structure ; and 5) the best corrosion measurement and control methods. The responses provided are supported by experimental results, most of which were obtained by the authors themselves.
1. INTRODUCTION
Concrete-embedded steel is known to remain in apassive state under normal conditions as a result of the highly alkaline pH of concrete. The passivity of reinforcements ensures unlimited durability of reinforced concrete (1KC) structures. However, there are some exceptional conditions that disrupt steel passivity and cause reinforcements to be corroded in an active state. This has raised controversial interpretations, some of which were discussed in Part I of this series [1]. This Part II analyses though far from exhaustively, other - to the authors minds at least - equally interesting issues on which no general consensus has been reached.
2. MATERIALS AND METHODS
The reader is referred to Part I for a detailed description of the materials and methods used in this work. Most of the experimental results discussed herein were obtained with the same types of specimens and slabs.Galvanic couples were determined on speciallydesigned specimens, such as those shown in Figs. 1 and 2.Near-real conditions were simulated by using a beam that was 160cm long and 7 x 10 cm in cross-section. The beam was made from 350 kg cement/m 3, half of which contained no additives, while the other half included 3% CaC12 by cement weight [2], (Fig. 1). In order to study the effect of the Sanod/Scathoa ratio on galvanic macrocouples, they were modelled by surrounding a small carbon steel anode with a stainless steel (AISI 304) cathode and vice versa
(Fig. 2). In this way, the ratio's consistensy was assured. In addition, the potential and icorr of stainless steal and those of the passive structures were very similar.
Fig. 1 - Beam used to measure icoTr and Ecorr in Fig. 2 - Scheme of galvanic macrocouples embedded
concrete with and without chlorides and to in chloride- containing mortar used to study the
illustrate the significance of passive steel/active effect of the Sanod/Scathod ratio and their relative
steel macrocouples.significance to corrosion microcells.
3. RESULTS AND DISCUSSION
3.1 What is the relative significance of galvanic macrocouples and corrosion microcells in RC structures ?
According to several authors [3, 5], the polarization resistance method provides an effective means for estimating the corrosion rate of steel in P,C ; the method is quite rapid, convenient, non-destructive, quantitative and reasonably precise. However, it is uncertain whether it may give rise to serious errors with highly-polarized electrodes by the effect of passive/active area galvanic macrocouples in the reinforcements [6].
Based on the authors' own experience with the behaviour of galvanic macrocouples in PC, the contribution of these macrocouples to overall corrosion is very modest rehtive to that of the corrosion microcells formed in the active areas of reinforcements in the presence of sufficient oxygen and moisture [2, 7, 8]. Thus, it has been experimentally checked that:
(a) Galvanic macrocouples have a slight polarizing effect on anodic areas in wet concrete, whose potential is thereby influenced in only a few millivolts.
(b) On the other hand, macrocouples have a strong polarizing effect on passive areas despite the low galvanic currents involved relative to the overall corrosion current. (c) As a result, galvanic currents can result in grossly underestimated icorr values for the active areas since they are often smaller than 10% of the ico= values estimated from polarization resistance measurements.
(d) The corrosive effect ofcoplanar macrocouples on RC structures only proves dangerous within a small distance from the boundary of active and passive areas. Fig. 3 compares the estimated icorr and ig values, in mortar containing 3 o~ A CaC12, per anode surface unit for a number of anode/cathode surface ratios for AISI 304 stainless steel/carbon steel macrocouples in support of the above conclusions [9].
3.2 By what mechanism do reinforcements corrode in an active state ?
When the passive state is lost, the rate of reinforcement corrosion in inversely proportional to the resistivity of concrete over a wide resistivity range [10]. Because
Fig. 3 - Relative significance of corrosion microcells Fig. 4 - Trends in ico. and Ecorr for (icorr) and galvanic macrocouples (i.) in corrosion specimens exposed to an oxygen-free
of steel embedded in mortar containing no chloride. environment.
Both currents were calculated relative to Sanod
(carbon steel in the macrocouples of Fig. 2).
the environment's relative humidity and ionic additives of concrete determine concrete resistivity, these factors, together with oxygen availability at reinforcement surfaces,control the corrosion rate [11].
The electric resistivity of water-saturated concrete structures is relatively very low, and the corrosion rate is believed to be essentially controlled by the diffusion of dissolved oxygen through the concrete cover up to reinforcements. This is consistent with the widespread belief that the sole possible cathodic reaction in neutral and alkaline solutions is oxygen reduction.
The significance ascribed to the role of oxygen justifies the efforts to determine its diffusion coefficient in concrete[12, 13]. The variety of methods and experimental conditions used for this purpose have led to a wide range of diffusivity values (from 10 -12 to 10 -8 m2/s) for oxygen in
cement paste [14].
Since the diffusion coefficient of oxygen in aqueous solutions (1)O2 = 10 -5 cm2/s-1), is saturation concentration (CO2 = 2.1 x 10 -7 mol/cm 3) and the approximate thickness of diffusion layers in stagnant solutions (8 = 0.01 cm) are wellknown, the limiting diffusion current can be calculated as :
ilo2 = - z FD02C02/r = 8 x 10 -4 A/cm 2 (80 pA/cm 2)
where z is the number of equivalents per mole (4) and F the Faraday (96,500 A.s/eq).
For 1-cm thick mortar covers of average porosity 15%(see Fig. 1 in Part I) [1] and a diffusioja layer thickness of the same order as the cover thickness, 11o2 = 0.12 laA/cm 2, which is quite consistent with the icorr values estimated under pore saturation conditions at the end of the curing
process, both for mortars containing no chloride ions and for those including 2, 4 or 6% C1- [16].
On the other hand, icorr values of ca. 10 liA/cm 2 (see Fig. 9 in Part I) [4] have been obtained by several authors for mortars with chlorides or carbonated mortars
which are incompatible with the rates allowed by the limiting diffusion current of oxygen. Therefore, in some circumstances, alternative cathodic processes allowing for faster kinetics must therefore be involved. In recent work, the concurrence of crevices, chloride ions and dissolved oxygen at the steel/concrete interface was claimed to provide the thermodynamic conditions required for protons to be reduced and the alternative mechanism to occur [11, 17].
There are a number of facts that refute oxygen reduction as being the sole corrosion rate-determining step, namely:
- Under some circumstances, once corrosion in an active
state has started, it develops at the same rate even though oxygen is being removed from the medium (Fig. 4) [11].
- As saturation of concrete pores decrease, concrete resistivity controls ico~r over a wide resistivity range ; therefore, the corrosion rate seems to decrease in proportion to the ease with which oxygen penetrates into the structure(Fig. 5)[10].
On the other hand, there are several arguments in favour of proton reduction in Ca(OH)2-saturated solutions or cement mortars [11] :
- The pH decreases from 12.6 to ca. 5 within crevices at the steel/electrolyte interface upon exposure of the steel to a Ca(OH)2-saturated solution with C1- additions and wellaerated. If sufficient oxygen is available, the pH can drop as low as 1-2.
- The emergence of acid exudates ofpH 1-5 from cracks and macropores in chloride-containing mortar specimens under wet atmospheres at high corrosion rates (5-10 pA/cm2).
- The formation of gas bubbles over iron hydroxide membrane-coated pits when the steal is polarized anodically in a Ca(OH)2-saturated, chloride-contaminated solution at potentials below those required for oxygen release. Everything points to pits with a low enough pH for the anodic current applied to overlap with a corrosion process involving proton reduction as a cathodic half-reaction.
When concrete-embedded steel is corroded in an active state, its corrosion kinetics rise exponentially with increasing pore saturation (Fig. 6), similarly to atmospheric corrosion in bare steel as the environment's relative humidity increases [18]. At some points in the reinfor- cements, a catalytic cycle may take place, e.g., those put forward by Schikorr for atmospheric corrosion of steel [19], with chloride ion rather than SO2-as the catalyst (Fig. 6).
Fig. 5 - Relationship between mortar resistivity Fig. 6 - Influence of the degree of pore saturation
and the corrosion rate of reinforcements. on the corrosion rate of reinforcements.
中文翻译II:
混凝土中钢腐蚀的有关问题
Ⅱ：腐蚀机理和监督、使用年限的预测和保护方法
J.A. Gonzdlez , S. Felifd, P. Rodffguez , W. Lfpez , E. Ramlrez , C. Alonso , C. Andrade
摘要:第二部分阐述几个仍然存在争议的重要问题，尽管已经在混凝土中钢腐
蚀的调查研究投入了大量的工作。特别是这几方面：1)在钢筋混凝土结构中的大电偶和腐蚀微电池对的相对重要性；2)激活状态的钢筋腐蚀机理；3)阻止或停止钢筋腐蚀最好的保护方法；4)一个钢筋混凝土结构使用年限的可靠预测的可能性探索；5)最好的防腐措施和控制方法。这些回答需要试验得出，大部分都由作者们得出。
1.前言
正常条件下强碱混凝土中的钢仍然处于钝化状态。钢筋的钝性能保证钢筋混凝土结构无限的耐久性。然而，有一些能破坏钢的钝性和引起钢筋腐蚀的实验条件。在第Ⅰ部分中讨论到的一些实验结构已经引起了很多争论[1]。第Ⅱ部分的分析虽然没有竭尽全力，但至少是作者的意思，就像有趣的问题有不同的意见一样。
2.材料和方法
读者指出在第Ⅰ部分详细描述了用于这项工作的材料和方法。这里所讨论的大部分实验结果都是从一样的试块和平板中得到的。电偶是由特殊设计的试块确定的，如图1和2所示。用一根长16m，70mm×100mm横截面的梁模拟近真实条件。梁是由每立方米350kg水泥制成，梁的一半含有添加剂，另一半含有水泥的重量的3%的CaCl2[2]，(图1)。为了了解S正极/S负极的比值对大电偶的影响，用在一个小的碳素钢正极环绕一个不锈钢负极并夹紧来模拟。这样，比值的连贯性是可靠的。此外，与钝化结果的电位和不锈钢的i corr是非常相似的。
图1.梁用来分别测量混凝土中含有和不含有氯化物图2.用电耦合牢牢嵌入含有氯化物的砂浆里来研究的i corr和E corr来说明钝化钢/活跃钢耦合的意义。S正极/S负极的作用和腐蚀微电池对的相对意义的方案。
3.结果和讨论
3.1什么是在钢筋混凝土结构中大电偶和腐蚀微电池对的相对重要性？
根据一些作者[3,5]，极化电阻作用为估计钢筋混凝土中腐蚀速度提供了一个有效的方法；这个方法是非常快、方便、非破坏性、适量和相当精确的。然而，
它不确定是否会对高度极化的电极产生严重的错误，通过在钢筋中的大电偶的钝化面积与激活面积的比值的影响。
在作者自己对钢筋混凝土中大电偶性质的实验基础上，这些大电偶对所有的腐蚀是非常适度的，与存在充分的氧气和水分条件下腐蚀微电池对形成激活状态的钢筋比较[2,7,8]。因此，它已被实验验证：
(a)大电偶对潮湿混凝土中的阳极部分由一个轻微的极化作用，只要几毫伏就可以影响它的电位。
(b)在另一方面，大电偶对钝化部分有一个很强的极化作用，尽管低电流的运用相对于所有腐蚀流。
(c)因此，电流可能会导致，非常低估在激活部分的i corr的值，因为它们通常比极化电阻值估算的i corr值的10%还小。
(d)腐蚀剂会引起钢筋混凝土结构上共面的电偶，只能证明从激活面积到钝化面积边缘的一个很短的距离存在危险。
图3是估算的i corr与i g值的比较，在砂浆中含有3%的CaCl2，每个正极表面单元体为许多正极/负极表面比值作为美国钢铁学会304不锈钢/碳素钢电偶的一部分支持以上结论。
图3.腐蚀微电池对(i corr)和电耦合(i g)在包裹在图4.暴露在自由氧环境下试块的i corr和E corr
不含有氯化物砂浆里的钢腐蚀中的相对意义。的变化趋势。
电流都是相对于S负极而计算得到的(在图2的电耦合中的碳素钢)。
3.2钢筋腐蚀的机理是什么？
当钝化状态消失，钢筋的腐蚀速度与混凝土的电阻率成反比例，在一个很宽的电阻率范围内[10]。因为环境中的相对湿度和混凝土的离子型外加剂确定混凝土的电阻率，这些因素与氧气一起在钢筋的表面控制着腐蚀速度[11]。
饱和水混凝土结构的电阻率是相对非常低的，而且腐蚀速度实际上是溶解氧的扩散控制的，通过混凝土包住钢筋实现。这与在中性和强碱条件下唯一可能的负极反应是氧气的还原作业这个理念是一致的。
这个重要性归因于氧气的循环作业，它证明这些作用对确定它在混凝土中的扩散率是正确的[12,13]。各种方法和实验条件用于这个目的，已得出了一定范围的水泥浆中的氧气的扩散率(从10-12到10-8m2/s)[14]。
因为水溶液(CO2=10-5cm2/s-1)中氧气的扩散率是饱和浓度(CO2=2.1×10-7mol/cm3)，不流动环境中( =0.001cm)扩散层的近似密度，都是众所周知的，这个有限扩散流可以这样计算：
其中z是等价的每摩尔(4)的数值，而F就是法拉第(96,500A?s/eq)。
平均孔隙率为15%的1cm厚的砂浆保护层厚度与扩散层厚度一样，与在养护期的最后空隙饱和条件下估算得的i corr值是非常一致的，这些砂浆不含氯化物离子而都含有2,4或6%的Cl-[16]。
另一方面，ca.10μA/cm2的i corr(见第Ⅰ部分图9)[4]已经由一些作者从含氯化物的砂浆或碳酸盐砂浆与氧气有限的扩散流所允许的速度是不协调的。因此，在一些环境下，替代负极的过程必须有更快的动力。在最近的工作中，裂缝、氯化物例子和溶解氧并存在钢与混凝土的交界面，可以为质子的还原和替换机理的发生提供热动力条件[11,17]。
有很多论据反驳氧气的还原作用作为底面腐蚀的定速步骤，即：
—在一些环境下，腐蚀一旦开始，它发展到同一个速度尽管氧气正在从媒介中排除(图4)[11]。
—当混凝土空隙饱和作用降低，混凝土的电阻率控制i corr在一个宽泛的电阻率范围内；因此，腐蚀速度的减小好像与氧气进入结构的难易成反比例(图5)[10]。
在另一方面，有一些论点支持在饱和Ca(OH)2中或水泥砂浆中的质子还原反应[11]：
—PH值由12.6减小到ca.5在暴露的含有Cl-的饱和Ca(OH)2中的钢与电解质溶液的交界面上。如果提供充足的氧气，PH值可以降低到1-2。
—从在潮湿的空气中含有氯化物的砂浆试块的裂缝和大空隙中暴露的PH值1-5的酸性分泌物，腐蚀速度很快(5-10μA/cm2)。
—在蚀坑处涂上氢氧化铁膜的钢在含有氯化物的饱和Ca(OH)2中极化成阳极时会产生气泡，因为电位的降低需要释放氧气。每一个蚀坑点有一个足够低的PH，因参与质子还原反应就像阴极半反应，它们的腐蚀过程与阳极流互相重叠。
当包裹在混凝土中的钢处于腐蚀状态，它的腐蚀动力指数随着空隙饱和作用的上升而升高(图6)，就像裸露在大气中的钢的腐蚀，随着环境的相对湿度的上升而增加一样[18]。
在钢筋上的一些点，催化循环可能被取代等，这些是由Schikorr提出的钢的大气腐蚀[19]，是氯化铁而不是SO42-作为催化剂(图6)。
图5.砂浆电阻与钢筋腐蚀速度的相互关系。图6.孔隙饱和度对钢筋腐蚀速度的影响。
外文出处： 《Exploiting Software How to Break Code》By Greg Hoglund, Gary McGraw Publisher : Addison Wesley Pub Date : February 17, 2004 ISBN : 0-201-78695-8 译文标题： JDBC接口技术 译文： JDBC是一种可用于执行SQL语句的JavaAPI（ApplicationProgrammingInterface应用程序设计接口）。它由一些Java语言编写的类和界面组成。JDBC为数据库应用开发人员、数据库前台工具开发人员提供了一种标准的应用程序设计接口，使开发人员可以用纯Java语言编写完整的数据库应用程序。 一、ODBC到JDBC的发展历程 说到JDBC，很容易让人联想到另一个十分熟悉的字眼“ODBC”。它们之间有没有联系呢？如果有，那么它们之间又是怎样的关系呢？ ODBC是OpenDatabaseConnectivity的英文简写。它是一种用来在相关或不相关的数据库管理系统（DBMS）中存取数据的，用C语言实现的，标准应用程序数据接口。通过ODBCAPI，应用程序可以存取保存在多种不同数据库管理系统（DBMS）中的数据，而不论每个DBMS使用了何种数据存储格式和编程接口。 1．ODBC的结构模型 ODBC的结构包括四个主要部分：应用程序接口、驱动器管理器、数据库驱动器和数据源。应用程序接口：屏蔽不同的ODBC数据库驱动器之间函数调用的差别，为用户提供统一的SQL编程接口。 驱动器管理器：为应用程序装载数据库驱动器。 数据库驱动器：实现ODBC的函数调用，提供对特定数据源的SQL请求。如果需要，数据库驱动器将修改应用程序的请求，使得请求符合相关的DBMS所支持的文法。 数据源：由用户想要存取的数据以及与它相关的操作系统、DBMS和用于访问DBMS的网络平台组成。 虽然ODBC驱动器管理器的主要目的是加载数据库驱动器，以便ODBC函数调用，但是数据库驱动器本身也执行ODBC函数调用，并与数据库相互配合。因此当应用系统发出调用与数据源进行连接时，数据库驱动器能管理通信协议。当建立起与数据源的连接时，数据库驱动器便能处理应用系统向DBMS发出的请求，对分析或发自数据源的设计进行必要的翻译，并将结果返回给应用系统。 2．JDBC的诞生 自从Java语言于1995年5月正式公布以来，Java风靡全球。出现大量的用java语言编写的程序，其中也包括数据库应用程序。由于没有一个Java语言的API，编程人员不得不在Java程序中加入C语言的ODBC函数调用。这就使很多Java的优秀特性无法充分发挥，比如平台无关性、面向对象特性等。随着越来越多的编程人员对Java语言的日益喜爱，越来越多的公司在Java程序开发上投入的精力日益增加，对java语言接口的访问数据库的API 的要求越来越强烈。也由于ODBC的有其不足之处，比如它并不容易使用，没有面向对象的特性等等，SUN公司决定开发一Java语言为接口的数据库应用程序开发接口。在JDK1．x 版本中，JDBC只是一个可选部件，到了JDK1．1公布时，SQL类包（也就是JDBCAPI）
PA VEMENT PROBLEMS CAUSED BY COLLAPSIBLE SUBGRADES By Sandra L. Houston,1 Associate Member, ASCE (Reviewed by the Highway Division) ABSTRACT: Problem subgrade materials consisting of collapsible soils are com- mon in arid environments, which have climatic conditions and depositional and weathering processes favorable to their formation. Included herein is a discussion of predictive techniques that use commonly available laboratory equipment and testing methods for obtaining reliable estimates of the volume change for these problem soils. A method for predicting relevant stresses and corresponding collapse strains for typical pavement subgrades is presented. Relatively simple methods of evaluating potential volume change, based on results of familiar laboratory tests, are used. INTRODUCTION When a soil is given free access to water, it may decrease in volume, increase in volume, or do nothing. A soil that increases in volume is called a swelling or expansive soil, and a soil that decreases in volume is called a collapsible soil. The amount of volume change that occurs depends on the soil type and structure, the initial soil density, the imposed stress state, and the degree and extent of wetting. Subgrade materials comprised of soils that change volume upon wetting have caused distress to highways since the be- ginning of the professional practice and have cost many millions of dollars in roadway repairs. The prediction of the volume changes that may occur in the field is the first step in making an economic decision for dealing with these problem subgrade materials. Each project will have different design considerations, economic con- straints, and risk factors that will have to be taken into account. However, with a reliable method for making volume change predictions, the best design relative to the subgrade soils becomes a matter of economic comparison, and a much more rational design approach may be made. For example, typical techniques for dealing with expansive clays include: (1) In situ treatments with substances such as lime, cement, or fly-ash; (2) seepage barriers and/ or drainage systems; or (3) a computing of the serviceability loss and a mod- ification of the design to "accept" the anticipated expansion. In order to make the most economical decision, the amount of volume change (especially non- uniform volume change) must be accurately estimated, and the degree of road roughness evaluated from these data. Similarly, alternative design techniques are available for any roadway problem. The emphasis here will be placed on presenting economical and simple methods for: (1) Determining whether the subgrade materials are collapsible; and (2) estimating the amount of volume change that is likely to occur in the 'Asst. Prof., Ctr. for Advanced Res. in Transp., Arizona State Univ., Tempe, AZ 85287. Note. Discussion open until April 1, 1989. To extend the closing date one month,
毕业设计（论文）外文文献翻译 文献、资料中文题目：软件开发概念和设计方法文献、资料英文题目： 文献、资料来源： 文献、资料发表（出版）日期： 院（部）： 专业： 班级： 姓名： 学号： 指导教师： 翻译日期： 2017.02.14
外文资料原文 Software Development Concepts and Design Methodologies During the 1960s, ma inframes and higher level programming languages were applied to man y problems including human resource s yste ms,reservation s yste ms, and manufacturing s yste ms. Computers and software were seen as the cure all for man y bu siness issues were some times applied blindly. S yste ms sometimes failed to solve the problem for which the y were designed for man y reasons including: ?Inability to sufficiently understand complex problems ?Not sufficiently taking into account end-u ser needs, the organizational environ ment, and performance tradeoffs ?Inability to accurately estimate development time and operational costs ?Lack of framework for consistent and regular customer communications At this time, the concept of structured programming, top-down design, stepwise refinement，and modularity e merged. Structured programming is still the most dominant approach to software engineering and is still evo lving. These failures led to the concept of "software engineering" based upon the idea that an engineering-like discipl ine could be applied to software design and develop ment. Software design is a process where the software designer applies techniques and principles to produce a conceptual model that de scribes and defines a solution to a problem. In the beginning, this des ign process has not been well structured and the model does not alwa ys accurately represent the problem of software development. However,design methodologies have been evolving to accommo date changes in technolog y coupled with our increased understanding of development processes. Whereas early desig n methods addressed specific aspects of the
转型衰退时期的土木工程研究 Sergios Lambropoulosa[1], John-Paris Pantouvakisb, Marina Marinellic 摘要 最近的全球经济和金融危机导致许多国家的经济陷入衰退，特别是在欧盟的周边。这些国家目前面临的民用建筑基础设施的公共投资和私人投资显著收缩，导致在民事特别是在民用建筑方向的失业。因此，在所有国家在经济衰退的专业发展对于土木工程应届毕业生来说是努力和资历的不相称的研究，因为他们很少有机会在实践中积累经验和知识，这些逐渐成为过时的经验和知识。在这种情况下，对于技术性大学在国家经济衰退的计划和实施的土木工程研究大纲的一个实质性的改革势在必行。目的是使毕业生拓宽他们的专业活动的范围，提高他们的就业能力。 在本文中，提出了土木工程研究课程的不断扩大，特别是在发展的光毕业生的潜在的项目，计划和投资组合管理。在这个方向上，一个全面的文献回顾，包括ASCE体为第二十一世纪，IPMA的能力的基础知识，建议在其他：显著增加所提供的模块和项目管理在战略管理中添加新的模块，领导行为，配送管理，组织和环境等；提供足够的专业训练五年的大学的研究；并由专业机构促进应届大学生认证。建议通过改革教学大纲为土木工程研究目前由国家技术提供了例证雅典大学。 1引言 土木工程研究（CES）蓬勃发展，是在第二次世界大战后。土木工程师的出现最初是由重建被摧毁的巨大需求所致，目的是更多和更好的社会追求。但是很快，这种演变一个长期的趋势，因为政府为了努力实现经济发展，采取了全世界的凯恩斯主义的理论，即公共基础设施投资作为动力。首先积极的结果导致公民为了更好的生活条件（住房，旅游等）和增加私人投资基础设施而创造机会。这些现象再国家的发展中尤为为明显。虽然前景并不明朗（例如，世界石油危机在70年代），在80年代领先的国家采用新自由主义经济的方法（如里根经济政策），这是最近的金融危机及金融危机造成的后果（即收缩的基础设施投资，在技术部门的高失业率），消除发展前途无限的误区。 技术教育的大学所认可的大量研究土木工程部。旧学校拓展专业并且新的学校建成，并招收许多学生。由于高的职业声望，薪酬，吸引高质量的学校的学生。在工程量的增加和科学技术的发展，导致到极强的专业性，无论是在研究还是工作当中。结构工程师，液压工程师，交通工程师等，都属于土木工程。试图在不同的国家采用专业性的权利，不同的解决方案，，从一个统一的大学学历和广泛的专业化的一般职业许可证。这个问题在许多其他行业成为关键。国际专业协会的专家和机构所确定的国家性检查机构，经过考试后，他们证明不仅是行业的新来者，而且专家通过时间来确定进展情况。尽管在很多情况下，这些证书虽然没有国家接受，他们赞赏和公认的世界。 在试图改革大学研究（不仅在土木工程）更接近市场需求的过程中，欧盟确定了1999博洛尼亚宣言，它引入了一个二能级系统。第一级度（例如，一个三年的学士）是进入
姓名： 学号： 10447425 X X 大学 毕业设计（论文）外文翻译 （2014届） 外文题目Developments in excavation bracing systems 译文题目开挖工程支撑体系的发展 外文出处Tunnelling and Underground Space Technology 31 (2012) 107–116 学生XXX 学院XXXX 专业班级XXXXX 校内指导教师XXX 专业技术职务XXXXX 校外指导老师专业技术职务 二○一三年十二月
开挖工程支撑体系的发展 1.引言 几乎所有土木工程建设项目（如建筑物，道路，隧道，桥梁，污水处理厂，管道，下水道）都涉及泥土挖掘的一些工程量。往往由于由相邻的结构，特性线，或使用权空间的限制，必须要一个土地固定系统，以允许土壤被挖掘到所需的深度。历史上，许多挖掘支撑系统已经开发出来。其中，现在比较常见的几种方法是：板桩，钻孔桩墙，泥浆墙。 土地固定系统的选择是由技术性能要求和施工可行性（例如手段，方法）决定的，包括执行的可靠性，而成本考虑了这些之后，其他问题也得到解决。通常环境后果（用于处理废泥浆和钻井液如监管要求）也非常被关注（邱阳、1998）。 土地固定系统通常是建设项目的较大的一个组成部分。如果不能按时完成项目，将极大地影响总成本。通常首先建造支撑，在许多情况下，临时支撑系统是用于支持在挖掘以允许进行不断施工，直到永久系统被构造。临时系统可以被去除或留在原处。 打桩时，因撞击或振动它们可能会被赶入到位。在一般情况下，振动是最昂贵的方法，但只适合于松散颗粒材料，土壤中具有较高电阻（例如，通过鹅卵石）的不能使用。采用打入桩系统通常是中间的成本和适合于软沉积物（包括粘性和非粘性），只要该矿床是免费的鹅卵石或更大的岩石。 通常，垂直元素（例如桩）的前安装挖掘工程和水平元件（如内部支撑或绑回）被安装为挖掘工程的进行下去，从而限制了跨距长度，以便减少在垂直开发弯矩元素。在填充情况下，桩可先设置，从在斜坡的底部其嵌入悬挑起来，安装作为填充进步水平元素（如搭背或土钉）。如果滞后是用来保持垂直元素之间的土壤中，它被安装为挖掘工程的进行下去，或之前以填补位置。 吉尔- 马丁等人（2010）提供了一个数值计算程序，以获取圆形桩承受轴向载荷和统一标志（如悬臂桩）的单轴弯矩的最佳纵筋。他们开发的两种优化流程：用一个或两个直径为纵向钢筋。优化增强模式允许大量减少的设计要求钢筋的用量，这些减少纵向钢筋可达到50％相对传统的，均匀分布的加固方案。 加固桩集中纵向钢筋最佳的位置在受拉区。除了节约钢筋，所述非对称加强钢筋图案提高抗弯刚度，通过增加转动惯量的转化部分的时刻。这种增加的刚性可能会在一段时间内增加的变形与蠕变相关的费用。评估相对于传统的非对称加强桩的优点，对称，钢筋桩被服务的条件下全面测试来完成的，这种试验是为了验证结构的可行性和取得的变形的原位测量。 基于现场试验中，用于优化的加强图案的优点浇铸钻出孔（CIDH）在巴塞罗那的
外文翻译 专业机械设计制造及其自动化学生姓名刘链柱 班级机制111 学号1110101102 指导教师葛友华
外文资料名称： Design and performance evaluation of vacuum cleaners using cyclone technology 外文资料出处：Korean J. Chem. Eng., 23(6), (用外文写) 925-930 (2006) 附件： 1.外文资料翻译译文 2.外文原文
应用旋风技术真空吸尘器的设计和性能介绍 吉尔泰金，洪城铱昌，宰瑾李， 刘链柱译 摘要：旋风型分离器技术用于真空吸尘器 - 轴向进流旋风和切向进气道流旋风有效地收集粉尘和降低压力降已被实验研究。优化设计等因素作为集尘效率，压降，并切成尺寸被粒度对应于分级收集的50％的效率进行了研究。颗粒切成大小降低入口面积，体直径，减小涡取景器直径的旋风。切向入口的双流量气旋具有良好的性能考虑的350毫米汞柱的低压降和为1.5μm的质量中位直径在1米3的流量的截止尺寸。一使用切向入口的双流量旋风吸尘器示出了势是一种有效的方法，用于收集在家庭中产生的粉尘。 摘要及关键词：吸尘器; 粉尘; 旋风分离器 引言 我们这个时代的很大一部分都花在了房子，工作场所，或其他建筑，因此，室内空间应该是既舒适情绪和卫生。但室内空气中含有超过室外空气因气密性的二次污染物，毒物，食品气味。这是通过使用产生在建筑中的新材料和设备。真空吸尘器为代表的家电去除有害物质从地板到地毯所用的商用真空吸尘器房子由纸过滤，预过滤器和排气过滤器通过洁净的空气排放到大气中。虽然真空吸尘器是方便在使用中，吸入压力下降说唱空转成比例地清洗的时间，以及纸过滤器也应定期更换，由于压力下降，气味和细菌通过纸过滤器内的残留粉尘。 图1示出了大气气溶胶的粒度分布通常是双峰形，在粗颗粒（>2.0微米）模式为主要的外部来源，如风吹尘，海盐喷雾，火山，从工厂直接排放和车辆废气排放，以及那些在细颗粒模式包括燃烧或光化学反应。表1显示模式，典型的大气航空的直径和质量浓度溶胶被许多研究者测量。精细模式在0.18?0.36 在5.7到25微米尺寸范围微米尺寸范围。质量浓度为2?205微克，可直接在大气气溶胶和 3.85至36.3μg/m3柴油气溶胶。
项目成本控制 一、引言 项目是企业形象的窗口和效益的源泉。随着市场竞争日趋激烈，工程质量、文明施工要求不断提高，材料价格波动起伏，以及其他种种不确定因素的影响，使得项目运作处于较为严峻的环境之中。由此可见项目的成本控制是贯穿在工程建设自招投标阶段直到竣工验收的全过程，它是企业全面成本管理的重要环节，必须在组织和控制措施上给于高度的重视，以期达到提高企业经济效益的目的。 二、概述 工程施工项目成本控制，指在项目成本在成本发生和形成过程中，对生产经营所消耗的人力资源、物资资源和费用开支，进行指导、监督、调节和限制，及时预防、发现和纠正偏差从而把各项费用控制在计划成本的预定目标之内，以达到保证企业生产经营效益的目的。 三、施工企业成本控制原则 施工企业的成本控制是以施工项目成本控制为中心，施工项目成本控制原则是企业成本管理的基础和核心，施工企业项目经理部在对项目施工过程进行成本控制时，必须遵循以下基本原则。 3.1 成本最低化原则。施工项目成本控制的根本目的，在于通过成本管理的各种手段，促进不断降低施工项目成本，以达到可能实现最低的目标成本的要求。在实行成本最低化原则时，应注意降低成本的可能性和合理的成本最低化。一方面挖掘各种降低成本的能力，使可能性变为现实；另一方面要从实际出发，制定通过主观努力可能达到合理的最低成本水平。 3.2 全面成本控制原则。全面成本管理是全企业、全员和全过程的管理，亦称“三全”管理。项目成本的全员控制有一个系统的实质性内容，包括各部门、各单位的责任网络和班组经济核算等等，应防止成本控制人人有责，人人不管。项目成本的全过程控制要求成本控制工作要随着项目施工进展的各个阶段连续 进行，既不能疏漏，又不能时紧时松，应使施工项目成本自始至终置于有效的控制之下。 3.3 动态控制原则。施工项目是一次性的，成本控制应强调项目的中间控制，即动态控制。因为施工准备阶段的成本控制只是根据施工组织设计的具体内容确
I / 11 本科毕业设计外文翻译 <2018届） 论文题目基于WEB 的J2EE 的信息系统的方法研究 作者姓名[单击此处输入姓名] 指导教师[单击此处输入姓名] 学科(专业 > 所在学院计算机科学与技术学院 提交日期[时间 ]
基于WEB的J2EE的信息系统的方法研究 摘要：本文介绍基于工程的Java开发框架背后的概念，并介绍它如何用于IT 工程开发。因为有许多相同设计和开发工作在不同的方式下重复，而且并不总是符合最佳实践，所以许多开发框架建立了。我们已经定义了共同关注的问题和应用模式，代表有效解决办法的工具。开发框架提供：<1）从用户界面到数据集成的应用程序开发堆栈；<2）一个架构，基本环境及他们的相关技术，这些技术用来使用其他一些框架。架构定义了一个开发方法，其目的是协助客户开发工程。 关键词：J2EE 框架WEB开发 一、引言 软件工具包用来进行复杂的空间动态系统的非线性分析越来越多地使用基于Web的网络平台，以实现他们的用户界面，科学分析，分布仿真结果和科学家之间的信息交流。对于许多应用系统基于Web访问的非线性分析模拟软件成为一个重要组成部分。网络硬件和软件方面的密集技术变革[1]提供了比过去更多的自由选择机会[2]。因此，WEB平台的合理选择和发展对整个地区的非线性分析及其众多的应用程序具有越来越重要的意义。现阶段的WEB发展的特点是出现了大量的开源框架。框架将Web开发提到一个更高的水平，使基本功能的重复使用成为可能和从而提高了开发的生产力。 在某些情况下，开源框架没有提供常见问题的一个解决方案。出于这个原因，开发在开源框架的基础上建立自己的工程发展框架。本文旨在描述是一个基于Java的框架，该框架利用了开源框架并有助于开发基于Web的应用。通过分析现有的开源框架，本文提出了新的架构，基本环境及他们用来提高和利用其他一些框架的相关技术。架构定义了自己开发方法，其目的是协助客户开发和事例工程。 应用程序设计应该关注在工程中的重复利用。即使有独特的功能要求，也
（ 二 〇 一 二 年 六 月 外文文献及翻译 题 目： About Buiding on the Structure Design 学生姓名： 学 院：土木工程学院 系 别：建筑工程系 专 业：土木工程(建筑工程方向) 班 级：土木08-4班 指导教师：
英文原文： Building construction concrete crack of prevention and processing Abstract The crack problem of concrete is a widespread existence but again difficult in solve of engineering actual problem, this text carried on a study analysis to a little bit familiar crack problem in the concrete engineering, and aim at concrete the circumstance put forward some prevention, processing measure. Keyword:Concrete crack prevention processing Foreword Concrete's ising 1 kind is anticipate by the freestone bone, cement, water and other mixture but formation of the in addition material of quality brittleness not and all material.Because the concrete construction transform with oneself, control etc. a series problem, harden model of in the concrete existence numerous tiny hole, spirit cave and tiny crack, is exactly because these beginning start blemish of existence just make the concrete present one some not and all the characteristic of quality.The tiny crack is a kind of harmless crack and accept concrete heavy, defend Shen and a little bit other use function not a creation to endanger.But after the concrete be subjected to lotus carry, difference in temperature etc. function, tiny crack would continuously of expand with connect, end formation we can see without the
Optimum blank design of an automobile sub-frame Jong-Yop Kim a ,Naksoo Kim a,*,Man-Sung Huh b a Department of Mechanical Engineering,Sogang University,Shinsu-dong 1,Mapo-ku,Seoul 121-742,South Korea b Hwa-shin Corporation,Young-chun,Kyung-buk,770-140,South Korea Received 17July 1998 Abstract A roll-back method is proposed to predict the optimum initial blank shape in the sheet metal forming process.The method takes the difference between the ?nal deformed shape and the target contour shape into account.Based on the method,a computer program composed of a blank design module,an FE-analysis program and a mesh generation module is developed.The roll-back method is applied to the drawing of a square cup with the ˉange of uniform size around its periphery,to con?rm its validity.Good agreement is recognized between the numerical results and the published results for initial blank shape and thickness strain distribution.The optimum blank shapes for two parts of an automobile sub-frame are designed.Both the thickness distribution and the level of punch load are improved with the designed blank.Also,the method is applied to design the weld line in a tailor-welded blank.It is concluded that the roll-back method is an effective and convenient method for an optimum blank shape design.#2000Elsevier Science S.A.All rights reserved. Keywords:Blank design;Sheet metal forming;Finite element method;Roll-back method
专业资料 学院： 专业：土木工程 姓名： 学号： 外文出处：Structural Systems to resist (用外文写) Lateral loads 附件：1.外文资料翻译译文；2.外文原文。
附件1：外文资料翻译译文 抗侧向荷载的结构体系 常用的结构体系 若已测出荷载量达数千万磅重，那么在高层建筑设计中就没有多少可以进行极其复杂的构思余地了。确实，较好的高层建筑普遍具有构思简单、表现明晰的特点。 这并不是说没有进行宏观构思的余地。实际上，正是因为有了这种宏观的构思，新奇的高层建筑体系才得以发展，可能更重要的是：几年以前才出现的一些新概念在今天的技术中已经变得平常了。 如果忽略一些与建筑材料密切相关的概念不谈，高层建筑里最为常用的结构体系便可分为如下几类： 1.抗弯矩框架。 2.支撑框架，包括偏心支撑框架。 3.剪力墙，包括钢板剪力墙。 4.筒中框架。 5.筒中筒结构。 6.核心交互结构。 7. 框格体系或束筒体系。 特别是由于最近趋向于更复杂的建筑形式，同时也需要增加刚度以抵抗几力和地震力，大多数高层建筑都具有由框架、支撑构架、剪力墙和相关体系相结合而构成的体系。而且，就较高的建筑物而言，大多数都是由交互式构件组成三维陈列。 将这些构件结合起来的方法正是高层建筑设计方法的本质。其结合方式需要在考虑环境、功能和费用后再发展，以便提供促使建筑发展达到新高度的有效结构。这并
不是说富于想象力的结构设计就能够创造出伟大建筑。正相反，有许多例优美的建筑仅得到结构工程师适当的支持就被创造出来了，然而，如果没有天赋甚厚的建筑师的创造力的指导，那么，得以发展的就只能是好的结构，并非是伟大的建筑。无论如何，要想创造出高层建筑真正非凡的设计，两者都需要最好的。 虽然在文献中通常可以见到有关这七种体系的全面性讨论，但是在这里还值得进一步讨论。设计方法的本质贯穿于整个讨论。设计方法的本质贯穿于整个讨论中。 抗弯矩框架 抗弯矩框架也许是低，中高度的建筑中常用的体系，它具有线性水平构件和垂直构件在接头处基本刚接之特点。这种框架用作独立的体系，或者和其他体系结合起来使用，以便提供所需要水平荷载抵抗力。对于较高的高层建筑，可能会发现该本系不宜作为独立体系，这是因为在侧向力的作用下难以调动足够的刚度。 我们可以利用STRESS，STRUDL 或者其他大量合适的计算机程序进行结构分析。所谓的门架法分析或悬臂法分析在当今的技术中无一席之地，由于柱梁节点固有柔性，并且由于初步设计应该力求突出体系的弱点，所以在初析中使用框架的中心距尺寸设计是司空惯的。当然，在设计的后期阶段，实际地评价结点的变形很有必要。 支撑框架 支撑框架实际上刚度比抗弯矩框架强，在高层建筑中也得到更广泛的应用。这种体系以其结点处铰接或则接的线性水平构件、垂直构件和斜撑构件而具特色，它通常与其他体系共同用于较高的建筑，并且作为一种独立的体系用在低、中高度的建筑中。
毕业设计（论文） 外文翻译 题目西安市水源工程中的 水电站设计 专业水利水电工程 班级 学生 指导教师 2016年
研究钢弧形闸门的动态稳定性 牛志国 河海大学水利水电工程学院，中国南京，邮编210098 nzg_197901@https://www.doczj.com/doc/d912702800.html,，niuzhiguo@https://www.doczj.com/doc/d912702800.html, 李同春 河海大学水利水电工程学院，中国南京，邮编210098 ltchhu@https://www.doczj.com/doc/d912702800.html, 摘要 由于钢弧形闸门的结构特征和弹力，调查对参数共振的弧形闸门的臂一直是研究领域的热点话题弧形弧形闸门的动力稳定性。在这个论文中，简化空间框架作为分析模型，根据弹性体薄壁结构的扰动方程和梁单元模型和薄壁结构的梁单元模型，动态不稳定区域的弧形闸门可以通过有限元的方法，应用有限元的方法计算动态不稳定性的主要区域的弧形弧形闸门工作。此外，结合物理和数值模型，对识别新方法的参数共振钢弧形闸门提出了调查，本文不仅是重要的改进弧形闸门的参数振动的计算方法，但也为进一步研究弧形弧形闸门结构的动态稳定性打下了坚实的基础。 简介 低举升力，没有门槽，好流型，和操作方便等优点，使钢弧形闸门已经广泛应用于水工建筑物。弧形闸门的结构特点是液压完全作用于弧形闸门，通过门叶和主大梁，所以弧形闸门臂是主要的组件确保弧形闸门安全操作。如果周期性轴向载荷作用于手臂，手臂的不稳定是在一定条件下可能发生。调查指出:在弧形闸门的20次事故中，除了极特殊的破坏情况下，弧形闸门的破坏的原因是弧形闸门臂的不稳定;此外，明显的动态作用下发生破坏。例如:张山闸，位于中国的江苏省，包括36个弧形闸门。当一个弧形闸门打开放水时，门被破坏了，而其他弧形闸门则关闭，受到静态静水压力仍然是一样的，很明显，一个动态的加载是造成的弧形闸门破坏一个主要因素。因此弧形闸门臂的动态不稳定是造成弧形闸门(特别是低水头的弧形闸门)破坏的主要原是毫无疑问。
Section 3 Design philosophy, design method and earth pressures 3.1 Design philosophy 3.1.1 General The design of earth retaining structures requires consideration of the interaction between the ground and the structure. It requires the performance of two sets of calculations: 1）a set of equilibrium calculations to determine the overall proportions and the geometry of the structure necessary to achieve equilibrium under the relevant earth pressures and forces; 2）structural design calculations to determine the size and properties of thestructural sections necessary to resist the bending moments and shear forces determined from the equilibrium calculations. Both sets of calculations are carried out for specific design situations (see 3.2.2) in accordance with the principles of limit state design. The selected design situations should be sufficiently Severe and varied so as to encompass all reasonable conditions which can be foreseen during the period of construction and the life of the retaining wall. 3.1.2 Limit state design This code of practice adopts the philosophy of limit state design. This philosophy does not impose upon the designer any special requirements as to the manner in which the safety and stability of the retaining wall may be achieved, whether by overall factors of safety, or partial factors of safety, or by other measures. Limit states (see 1.3.13) are classified into: a) ultimate limit states (see 3.1.3); b) serviceability limit states (see 3.1.4). Typical ultimate limit states are depicted in figure 3. Rupture states which are reached before collapse occurs are, for simplicity, also classified and
7 Rigid-Frame Structures A rigid-frame high-rise structure typically comprises parallel or orthogonally arranged bents consisting of columns and girders with moment resistant joints. Resistance to horizontal loading is provided by the bending resistance of the columns, girders, and joints. The continuity of the frame also contributes to resisting gravity loading, by reducing the moments in the girders. The advantages of a rigid frame are the simplicity and convenience of its rectangular form.Its unobstructed arrangement, clear of bracing members and structural walls, allows freedom internally for the layout and externally for the fenestration. Rig id frames are considered economical for buildings of up to' about 25 stories, above which their drift resistance is costly to control. If, however, a rigid frame is combined with shear walls or cores, the resulting structure is very much stiffer so that its height potential may extend up to 50 stories or more. A flat plate structure is very similar to a rigid frame, but with slabs replacing the girders As with a rigid frame, horizontal and vertical loadings are resisted in a flat plate structure by the flexural continuity between the vertical and horizontal components. As highly redundant structures, rigid frames are designed initially on the basis of approximate analyses, after which more rigorous analyses and checks can be made. The procedure may typically inc lude the following stages: 1. Estimation of gravity load forces in girders and columns by approximate method. 2. Preliminary estimate of member sizes based on gravity load forces with arbitrary increase in sizes to allow for horizontal loading. 3. Approximate allocation of horizontal loading to bents and preliminary analysis of member forces in bents. 4. Check on drift and adjustment of member sizes if necessary. 5. Check on strength of members for worst combination of gravity and horizontal loading, and adjustment of member sizes if necessary. 6. Computer analysis of total structure for more accurate check on member strengths and drift, with further adjustment of sizes where required. This stage may include the second-order P-Delta effects of gravity loading on the member forces and drift.. 7. Detailed design of members and connections.