相信许多留学生对数学代考都不陌生,国外许多大学都引进了网课的学习模式。网课学业有利有弊,学生不需要到固定的教室学习,只需要登录相应的网站研讨线上课程即可。但也正是其便利性,线上课程的数量往往比正常课程多得多。留学生课业深重,时刻名贵,既要学习知识,又要结束多种类型的课堂作业,physics作业代写,物理代写,论文写作等;网课考试很大程度增加了他们的负担。所以,您要是有这方面的困扰,不要犹疑,订购myassignments-help代考渠道的数学代考服务,价格合理,给你前所未有的学习体会。

我们的数学代考服务适用于那些对课程结束没有掌握,或许没有满足的时刻结束网课的同学。高度匹配专业科目,按需结束您的网课考试、数学代写需求。担保买卖支持,100%退款保证,免费赠送Turnitin检测报告。myassignments-help的Math作业代写服务,是你留学路上忠实可靠的小帮手!


物理代写|结构力学代写Structural Mechanics代考|Final Remarks

Ductility provides a literal safety margin for our ‘incorrect’ trial solutions compared to true behaviour, and coupled to the Lower Bound Theorem returning a smaller, safe ultimate load every time, the freedom to select equilibrium solutions is key to its efficacy.

If we are designing the truss for a fixed load in practice, a lower ultimate prediction means using bars with larger cross-sectional areas than is necessary. The truss, we say, will be over-designed in terms of being able to accommodate a higher fixed load (which hopefully is not applied in practice).

This final statement speaks to the remarkable prescience of the Lower Bound Theorem in general as a design tool. Where else, in Engineering, does an incorrect solution result in a margin of safety and increasingly so for a greater departure from the exact solution? The detriment is, of course, a more massive structure.

We will invariably over-design more complex structures, which have many more equilibrium combinations. Rather than trying to seek one of the better ones, we should aim for simplicity if pressed for time where a ‘back-of-the-envelope’ calculation is not anachronistic.

Again, we note that only the final equilibrium state matters; compatibility does not have to be assessed because of ductility, which is simply contrived. In practice, yielding leads to higher stresses after initial yielding, which would result in the junctions between phases in Fig. $6.2$ becoming more rounded, for example.

We also have a perfect structure in which bars neatly connect together without mis-fitting. There will inevitably be small misalignments with some bars having to be stretched or compressed in order to complete building the truss, giving non-zero tensions for zero loading, as we saw in Chapter $5 .$

Any state of self-stress increases the proximity to yielding but does affect the final capacity of individual members. In this regard, deliberate pre-stressing and unforeseen movements of supports dó noot subtract from the ultimatee load.

物理代写|结构力学代写Structural Mechanics代考|Bending Moment (and Shear Force) Diagrams

Often the scourge of undergraduate exercises, drawing bending moment profiles for slender structures is an essential skill. Their variation tells us about how a beam or column is loaded transversely as well as indicating salient values at pertinent locations where damage may be incurred from extreme loading.

In the case of, say, a steel beam, it will submit to permanent yielding of the material at these points, which concentrates into plastic hinges; collapse of the entire structure may follow depending on how the structure adjusts to more loading. Equally important are shear force diagrams – especially for concrete structures, where failure in shear often dominates that of bending.

The usual way to teach construction of bending moment (and shear force) diagrams is through piece-wise equilibrium. We select a given free body, resolve forces and take moments to establish its variation before doing the same with a different free body. We then assemble the complete profile reliably but inefficiently. We shall adopt a more holistic approach.

For small variations in bending moment, $M$, and shear force, $S$, across an element of straight beam of length $\delta x$, Fig. 7.1(a), equilibrium gives their well-known relationships to some externally applied, transverse loading intensity, $w$, as:
$$
\frac{\mathrm{d} S}{\mathrm{~d} x}=w \quad \text { (a), } \frac{\mathrm{d} M}{\mathrm{~d} x}=S \quad \text { (b) } \rightarrow \quad \frac{\mathrm{d}^2 M}{\mathrm{~d} x^2}=w \quad \text { (c). }
$$
These statements convey much information.
First, the directions of $M$ and $S$ obey an explicit sign convention, which we must always declare a priori. Here, $M$ is positive if the beam is locally hogging and curving upwards, and shear forces point downwards on the left side and vice versa rightside. The latter is also linked to the direction of increasing $x$, for if $x$ is reversed in measurement along the beam, so do the positive shear force directions, in order to preserve the statements above. Indeed, our choice in absolute directions for all leads to an absence of minus signs when $w$ acts downwards in the sense of gravity. We can, of course, choose a different scheme, such as one with positive sagging bending moments, which will introduce minus signs.

We can find the shear force profile by differentiating that of bending moment, if it is constructed first. If not, we may integrate shear to find bending moments, which is tantamount to finding the area underneath the shear force profile.

物理代写|结构力学代写Structural Mechanics代考|ENG222

物理代写|结构力学代写结构力学代考|最后备注

.


与真实行为相比,延性为我们的“不正确”试验解提供了字面上的安全边际,并与下界定理相结合,每次返回更小的安全极限负载,选择平衡解的自由是其有效性的关键


如果我们在实际中为固定荷载设计桁架,较低的极限预测意味着使用比必要的更大截面积的杆。桁架,我们说,将过度设计,以能够容纳更高的固定负载(希望没有应用在实践中)


最后这句话说明了下界定理作为设计工具的非凡先见之明。在工程中,一个不正确的解决方案还会导致安全边际,并且越来越多地偏离准确的解决方案吗?当然,损害是更大的结构


我们总是会过度设计更复杂的结构,这些结构有更多的平衡组合。如果时间紧迫,我们应该以简化为目标,而不是试图寻找一个更好的方法,这样“粗略的”计算就不会过时


我们再次注意到,只有最终的平衡态才重要;兼容性不需要评估,因为延展性很简单。在实践中,屈服导致初始屈服后的应力更高,这将导致图$6.2$中相之间的连接变得更圆,例如


我们也有一个完美的结构,酒吧整齐地连接在一起没有错位。为了完成桁架的建造,不可避免地会有一些小的不对中,一些杆必须被拉伸或压缩,为零加载提供非零张力,如我们在$5 .$章中看到的


任何自我压力的状态都会增加屈服的可能性,但确实会影响个体成员的最终能力。在这方面,有意的预应力和不可预见的支架移动dó不能减去最终的负载。

物理代写|结构力学代写结构力学代考|弯矩(和剪力)图


绘制细长结构的弯矩剖面是一项基本技能,这通常是本科生练习的祸害。它们的变化告诉我们梁或柱是如何横向加载的,以及在极端加载可能导致损伤的相关位置的显著值


例如,在钢梁的情况下,它将在这些点上屈服于材料的永久屈服,并集中成塑料铰链;整个结构可能会倒塌,这取决于结构如何适应更多的荷载。同样重要的是剪力图-特别是混凝土结构,在剪切破坏往往主导弯曲破坏


教弯矩(和剪力)图的构造的通常方法是通过分段平衡。我们选择一个给定的自由体,计算力,并在对另一个自由体做同样的事情之前,花点时间建立它的变化。然后,我们可靠地组装完整的配置文件,但效率不高。我们应该采取更全面的方法


对于长度为$\delta x$的直梁单元的弯矩$M$和剪力$S$的微小变化,图7.1(a),平衡给出了它们与一些外部施加的横向荷载强度$w$的众所周知的关系,如:
$$
\frac{\mathrm{d} S}{\mathrm{~d} x}=w \quad \text { (a), } \frac{\mathrm{d} M}{\mathrm{~d} x}=S \quad \text { (b) } \rightarrow \quad \frac{\mathrm{d}^2 M}{\mathrm{~d} x^2}=w \quad \text { (c). }
$$
这些表述传达了很多信息。首先,$M$和$S$的方向遵循显式符号约定,我们必须始终声明它是先验的。在这里,$M$是正的,如果梁是局部拱起和向上弯曲,剪切力指向向下的左边,反之亦然的右边。后者也与增加$x$的方向相联系,因为如果$x$在沿梁的测量中被逆转,那么正的剪力方向也会被逆转,以保持上面的陈述。的确,当$w$在重力的意义下向下运动时,我们对所有物体的绝对方向的选择导致了负号的缺失。当然,我们可以选择一种不同的方案,例如具有正下垂弯矩的方案,这将引入负号


我们可以通过对弯矩的微分得到剪力剖面,如果它是先构造的。如果没有,我们可以积分剪力求弯矩,这等于求剪力剖面下的面积。

物理代写|结构力学代写Structural Mechanics代考

myassignments-help数学代考价格说明

1、客户需提供物理代考的网址,相关账户,以及课程名称,Textbook等相关资料~客服会根据作业数量和持续时间给您定价~使收费透明,让您清楚的知道您的钱花在什么地方。

2、数学代写一般每篇报价约为600—1000rmb,费用根据持续时间、周作业量、成绩要求有所浮动(持续时间越长约便宜、周作业量越多约贵、成绩要求越高越贵),报价后价格觉得合适,可以先付一周的款,我们帮你试做,满意后再继续,遇到Fail全额退款。

3、myassignments-help公司所有MATH作业代写服务支持付半款,全款,周付款,周付款一方面方便大家查阅自己的分数,一方面也方便大家资金周转,注意:每周固定周一时先预付下周的定金,不付定金不予继续做。物理代写一次性付清打9.5折。

Math作业代写、数学代写常见问题

留学生代写覆盖学科?

代写学科覆盖Math数学,经济代写,金融,计算机,生物信息,统计Statistics,Financial Engineering,Mathematical Finance,Quantitative Finance,Management Information Systems,Business Analytics,Data Science等。代写编程语言包括Python代写、Physics作业代写、物理代写、R语言代写、R代写、Matlab代写、C++代做、Java代做等。

数学作业代写会暴露客户的私密信息吗?

我们myassignments-help为了客户的信息泄露,采用的软件都是专业的防追踪的软件,保证安全隐私,绝对保密。您在我们平台订购的任何网课服务以及相关收费标准,都是公开透明,不存在任何针对性收费及差异化服务,我们随时欢迎选购的留学生朋友监督我们的服务,提出Math作业代写、数学代写修改建议。我们保障每一位客户的隐私安全。

留学生代写提供什么服务?

我们提供英语国家如美国、加拿大、英国、澳洲、新西兰、新加坡等华人留学生论文作业代写、物理代写、essay润色精修、课业辅导及网课代修代写、Quiz,Exam协助、期刊论文发表等学术服务,myassignments-help拥有的专业Math作业代写写手皆是精英学识修为精湛;实战经验丰富的学哥学姐!为你解决一切学术烦恼!

物理代考靠谱吗?

靠谱的数学代考听起来简单,但实际上不好甄别。我们能做到的靠谱,是把客户的网课当成自己的网课;把客户的作业当成自己的作业;并将这样的理念传达到全职写手和freelancer的日常培养中,坚决辞退糊弄、不守时、抄袭的写手!这就是我们要做的靠谱!

数学代考下单流程

提早与客服交流,处理你心中的顾虑。操作下单,上传你的数学代考/论文代写要求。专家结束论文,准时交给,在此过程中可与专家随时交流。后续互动批改

付款操作:我们数学代考服务正常多种支付方法,包含paypal,visa,mastercard,支付宝,union pay。下单后与专家直接互动。

售后服务:论文结束后保证完美经过turnitin查看,在线客服全天候在线为您服务。如果你觉得有需求批改的当地能够免费批改,直至您对论文满意为止。如果上交给教师后有需求批改的当地,只需求告诉您的批改要求或教师的comments,专家会据此批改。

保密服务:不需求提供真实的数学代考名字和电话号码,请提供其他牢靠的联系方法。我们有自己的工作准则,不会泄露您的个人信息。

myassignments-help擅长领域包含但不是全部:

myassignments-help服务请添加我们官网的客服或者微信/QQ,我们的服务覆盖:Assignment代写、Business商科代写、CS代考、Economics经济学代写、Essay代写、Finance金融代写、Math数学代写、report代写、R语言代考、Statistics统计学代写、物理代考、作业代写、加拿大代考、加拿大统计代写、北美代写、北美作业代写、北美统计代考、商科Essay代写、商科代考、数学代考、数学代写、数学作业代写、physics作业代写、物理代写、数据分析代写、新西兰代写、澳洲Essay代写、澳洲代写、澳洲作业代写、澳洲统计代写、澳洲金融代写、留学生课业指导、经济代写、统计代写、统计作业代写、美国Essay代写、美国代考、美国数学代写、美国统计代写、英国Essay代写、英国代考、英国作业代写、英国数学代写、英国统计代写、英国金融代写、论文代写、金融代考、金融作业代写。