鋼結(jié)構(gòu)的濟(jì)南雨棚設(shè)計(jì)該怎么做？、

　　How to design a steel structure canopy in Jinan? 、

　　想到此前在光伏車棚結(jié)構(gòu)方案比選時(shí)涉及到一種結(jié)構(gòu)體系——自平衡拉桿系統(tǒng)。這個(gè)看似簡(jiǎn)單的結(jié)構(gòu)體系卻還隱藏了不少結(jié)構(gòu)概念，現(xiàn)在仔細(xì)挖一挖其實(shí)也別有一番風(fēng)味！生活也當(dāng)這樣，哪有那么多的高光時(shí)刻，光鮮亮麗的外表下何嘗不是更多的苦楚與孤獨(dú)，還是當(dāng)學(xué)會(huì)在樸素?zé)o華中尋得峰回路轉(zhuǎn)的那份甘甜。你我皆為庸人，何必自擾之。

　　Previously, when comparing photovoltaic carport structural schemes, a structural system called the self balancing pull rod system was involved. This seemingly simple structural system still hides many structural concepts, and now digging it up carefully actually has a unique flavor! Life should be like this, where there are so many shining moments, beneath the glamorous appearance is not more pain and loneliness, or the sweetness of learning to find twists and turns in simplicity. You and I are both mediocre, why bother ourselves.

　　塵埃落定，我想好好翻一翻林同棪大師的《結(jié)構(gòu)概念與體系》，去追憶一下十多年前懵懵懂懂的感覺(jué)，找找那會(huì)的激情澎湃，追尋大師筆下的結(jié)構(gòu)概念。

　　The dust has settled, and I want to take a good look at Master Lin Tongyan's "Structural Concepts and Systems", to reminisce about the naive feelings of more than ten years ago, to find the passion and excitement of that time, and to pursue the structural concepts in Master Lin's works.

　　峰回路轉(zhuǎn)，我還想用心去多讀讀書(shū)，不分類別。回想一下，畢業(yè)后還真沒(méi)有正兒八經(jīng)讀過(guò)幾本除了以外的書(shū)籍。一直苦苦追尋的究竟為我?guī)?lái)了什么呢？那么功利的學(xué)習(xí)竟也迎來(lái)了這個(gè)行業(yè)真正的寒冬！多么的諷刺和可笑。

　　The road has turned, and I still want to read more books with my heart, regardless of category. Looking back, I haven't really read a few books outside of my major after graduation. What has the profession that I have been relentlessly pursuing brought me? So utilitarian learning has also ushered in the real winter of this industry! How ironic and ridiculous.

　　云淡風(fēng)輕，我還想好好陪陪家人，收回自己那仿佛永遠(yuǎn)長(zhǎng)不大的那副稚嫩與臭脾氣，在這里的用心的投入可能才會(huì)有更多更好的正向反饋。

　　The clouds are light and the wind is gentle. I still want to spend time with my family and take back the immature and bad temper that seems to never grow up. Only by investing my heart here can there be more and better positive feedback.

　　NO.1 結(jié)構(gòu)體系

　　NO.1 Structural System

　　一個(gè)完整的結(jié)構(gòu)大體少應(yīng)有幾大元素：基礎(chǔ)、豎向構(gòu)件、水平構(gòu)件，此為主干，其他皆為枝葉。我們一切的行為都在確保主體平衡的前提下，讓枝葉更為“茂盛”，可以是花枝招展，爭(zhēng)相斗艷；也可以是溫文爾雅，她紅仍她紅，她艷仍她艷。

　　A complete structure generally should have at least a few major elements: foundation, vertical components, and horizontal components, which are the backbone and the rest are branches and leaves. All of our actions are based on ensuring the balance of the subject, making the branches and leaves more "lush", which can be colorful and competing for beauty; It can also be gentle and refined, she is still red, she is still beautiful.

　　室外雨棚可以算是一個(gè)典型的結(jié)構(gòu)小品，結(jié)構(gòu)即建筑，所見(jiàn)即所得！所以如何落得輕巧是結(jié)構(gòu)工程師需要考慮的問(wèn)題。除了主要的梁柱承重構(gòu)件外，我們會(huì)加一些拉/壓桿來(lái)尋求新的內(nèi)部平衡。

　　An outdoor canopy can be considered a typical structural piece, where the structure is the building and what you see is what you get! So how to achieve lightness is a key consideration for structural engineers. In addition to the main load-bearing components of beams and columns, we will add some tension/compression bars to seek new internal balance.

　　對(duì)以上幾種方案進(jìn)行計(jì)算分析，從構(gòu)件應(yīng)力和變形角度比較不同，可以看出方案一在兩個(gè)維度都是。柱底反力皆相同，這也驗(yàn)證了，拉壓桿不過(guò)是改變了體系內(nèi)部的內(nèi)力，對(duì)柱腳而言沒(méi)有幫助。

　　Through calculation and analysis of the above schemes, it can be seen that Scheme One is optimal in both dimensions from the perspectives of component stress and deformation. The reaction force at the bottom of the column is the same, which also verifies that tension and compression bars only change the internal forces of the system and are not helpful for the column base.

　　獨(dú)柱懸挑受力簡(jiǎn)單明確，但我們可以換個(gè)角度來(lái)看結(jié)構(gòu)體型的優(yōu)化。道理很簡(jiǎn)單，想象你抱著小孩的時(shí)候，是不是會(huì)不自覺(jué)通過(guò)微微后仰去調(diào)整來(lái)保持新的平衡。這也類似結(jié)構(gòu)概念設(shè)計(jì)耳熟能詳?shù)拇_保結(jié)構(gòu)質(zhì)心與剛心應(yīng)盡量重合，那是解決結(jié)構(gòu)扭轉(zhuǎn)問(wèn)題。而我們現(xiàn)在解決的是荷載中心與結(jié)構(gòu)抵抗能力盡量吻合，解決的是不平衡荷載傾覆問(wèn)題。

　　The force acting on a single column cantilever is simple and clear, but we can look at the optimization of the structural shape from a different perspective. The reason is simple. Imagine holding a child and unconsciously adjusting your center of gravity by leaning back slightly to maintain a new balance. This is also similar to the well-known structural concept design of ensuring that the center of mass and stiffness of the structure should coincide as much as possible, which is to solve the problem of structural torsion. What we are currently solving is to align the load center with the structural resistance capacity as much as possible, and to address the problem of unbalanced load overturning.

　　立柱傾斜一定角度后，可以看出拉壓桿應(yīng)力變化較小，主要是下柱應(yīng)力有了較大改觀，由612減小到了464，柱底彎矩由128減小到100，總體而言減小幅度約25%，效果很明顯。僅改變下體型沒(méi)想到效果竟如此明顯，這不比簡(jiǎn)單的去摳應(yīng)力比來(lái)的更暢快嗎？而且建筑佬說(shuō)不定更喜歡這種“搔首弄姿”的體態(tài)，哈哈！

　　After tilting the column at a certain angle, it can be seen that the stress change of the tension compression rod is relatively small, mainly due to a significant improvement in the stress of the lower column, which decreased from 612 to 464, and the bending moment at the bottom of the column decreased from 128 to 100. Overall, the reduction is about 25%, and the effect is very obvious. I didn't expect the effect to be so obvious just by changing my body shape. Isn't it more enjoyable than simply removing the stress ratio? And maybe architects would prefer this kind of "posing" posture, haha!

　　NO.2 荷載不利布置

　　NO.2 Unfavorable load arrangement

　　記得在結(jié)構(gòu)靜力手冊(cè)里有一個(gè)篇幅講到活荷載的不利布置，常用的軟件如pkpm或是yjk其實(shí)也有活荷載不利布置的黑匣子選項(xiàng)。許多人知道可能那么回事，卻在實(shí)操中往往容易忽略它的存在。如此，被遺忘的角落可能會(huì)讓你瑟瑟發(fā)抖、夜不能寐。想想那些轟然崩塌的結(jié)構(gòu)不正是在人的不經(jīng)意間發(fā)生的嗎？

　　I remember there is a section in the structural static manual that discusses the unfavorable arrangement of live loads. Commonly used software such as pkpm or yjk also have black box options for unfavorable arrangement of live loads. Many people know that it may be the case, but often overlook its existence in practice. So, the forgotten corners may make you shiver and unable to sleep at night. Isn't the sudden collapse of those structures happening unintentionally by humans?

　　為什么要考慮荷載不利布置，因?yàn)閷?duì)稱的荷載在某些效應(yīng)上是可以彼此平衡的，那么荷載的不利布置就是不均勻?qū)е铝梭w系的不平衡。

　　Why consider the unfavorable arrangement of loads? Because symmetrical loads can balance each other in certain effects, so the unfavorable arrangement of loads leads to the imbalance of the system due to unevenness.

　　拉壓桿體系

　　Tension compression rod system

　　對(duì)于位移控制，我們主要關(guān)注的有兩個(gè)，一是豎向撓度，二是水平向側(cè)移。不同結(jié)構(gòu)/規(guī)范對(duì)應(yīng)構(gòu)件控制的變形限值也不大相同。另外變形要看相對(duì)值，而非值，這就是要理解構(gòu)件控制變形的內(nèi)涵。

　　For displacement control, we mainly focus on two aspects: the maximum vertical deflection and the maximum horizontal lateral displacement. The deformation limits controlled by components corresponding to different structures/specifications are also not the same. In addition, deformation should be based on relative values rather than absolute values, which is to understand the connotation of controlling deformation of components.

　　拉桿需要注意張緊即剛度，否則你是你，我是我，好似不識(shí)！見(jiàn)過(guò)現(xiàn)場(chǎng)拉桿居然還有出現(xiàn)下垂現(xiàn)象的，就好比預(yù)應(yīng)力梁忘記張拉一般，這就和設(shè)計(jì)假定存有天壤之別了！所以對(duì)于拉桿設(shè)計(jì)，一定要確保拉桿有效，一是實(shí)際受力是作為拉桿出現(xiàn)的，別考慮受壓剛度；二是施工是按拉桿的要求來(lái)處理的。若拉桿失效，那么受力體系有變化。

　　Attention should be paid to the tension and stiffness of the pull rod, otherwise you are me and I am you, it seems like I don't know! I have seen the phenomenon of sagging of the tension rod on site, just like forgetting to tension the prestressed beam, which is completely different from the design assumption! So for the design of the tension rod, it is necessary to ensure that the tension rod is effective. Firstly, the actual force is acting as a tension rod, without considering the compressive stiffness; The second is that construction is carried out according to the requirements of the pull rod. If the pull rod fails, there will be a change in the force system.

　　計(jì)算假定與實(shí)際施工是否相符一直是鋼結(jié)構(gòu)設(shè)計(jì)與施工需要關(guān)注的事情，比如上面提到的剛接與鉸接邊界條件和拉桿設(shè)計(jì)預(yù)張力失效的情況。

　　Whether the calculation assumptions match the actual construction has always been a key concern in the design and construction of steel structures, such as the rigid and hinged boundary conditions and the failure of pre tension in tension rod design mentioned above.

　　結(jié)構(gòu)敏感性

　　Structural sensitivity

　　結(jié)構(gòu)敏感性分析主要從剛度著手，和控制撓度一樣的思路，主要關(guān)注橫梁頂點(diǎn)位移及柱頂側(cè)移。

　　Structural sensitivity analysis mainly starts from stiffness and follows the same approach as controlling deflection, focusing on the displacement of beam vertices and the maximum lateral displacement of column tops.

　　通過(guò)分析我們知道了以下幾個(gè)特征：

　　Through analysis, we have learned the following characteristics:

　　梁的豎向撓度控制不是它自身，實(shí)際起作用的是柱及拉桿剛度，所以當(dāng)出現(xiàn)豎向撓度不夠的情況不應(yīng)該是優(yōu)先去加大梁截面尺寸，這種不僅不經(jīng)濟(jì)且改善不可觀；

　　The vertical deflection control of a beam is not its own function, but rather the stiffness of the column and tension rod. Therefore, when there is insufficient vertical deflection, it should not be prioritized to increase the beam section size, which is not only uneconomical but also not significantly improved;

　　柱腳斜桿對(duì)于結(jié)構(gòu)側(cè)向剛度有一定的影響，無(wú)斜桿結(jié)構(gòu)為完全懸臂柱方案，斜桿將柱敏感系數(shù)一下降低50%，顯然拉桿方案更為經(jīng)濟(jì)有效。

　　The diagonal braces at the column base have a certain impact on the lateral stiffness of the structure. The structure without diagonal braces is a fully cantilevered column scheme, and the diagonal braces reduce the sensitivity coefficient of the column by 50%. Obviously, the tension rod scheme is more economical and effective.

　　在側(cè)移和豎向變形兩個(gè)維度，柱傾斜方案構(gòu)件敏感系數(shù)較豎向方案更小，說(shuō)明該方案是有效的。

　　In terms of lateral displacement and vertical deformation, the sensitivity coefficient of the components in the column inclination scheme is smaller than that in the vertical scheme, indicating that this scheme is effective.

　　綜上，我們?cè)俅悟?yàn)證了拉壓桿的存在只解決了結(jié)構(gòu)體系內(nèi)力分配的問(wèn)題，對(duì)整個(gè)系統(tǒng)來(lái)說(shuō)它仍屬于一個(gè)“懸臂柱”，我們從荷載傳遞角度/力流的角度來(lái)分析與設(shè)計(jì)，可能會(huì)讓我們?cè)O(shè)計(jì)更為。

　　In summary, we have once again verified that the existence of tension compression bars only solves the problem of internal force distribution in the structural system. For the entire system, it still belongs to a "cantilever column". We analyze and design it from the perspective of load transmission/force flow, which may make our design more efficient.

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