施工單位多的工作就是驗鋼筋。
The most common work of construction units is to test steel bars.
偶然會發作了這樣的事情，有道梁的主筋，讓工人綁錯了，直徑25的鋼筋，綁成了直徑22mm的了。
Occasionally, such a thing happened. The main tendons of the beams made the workers tie the steel bars with a diameter of 25 to a diameter of 22 mm.
換掉吧，一切的鋼筋都綁扎完成了，模板也支好了，還要拆模板，真實是太費事了。
Change it, all the steel bars are tied up, the template is also supported, but also to remove the template, the real is too troublesome.
后來采取了一種彌補的辦法，另外加一根直徑12mm的鋼筋，直徑小，容易穿進去，輕松的把這個問題處理了！
Later, a remedy method was adopted, and a steel bar with a diameter of 12 mm was added. The diameter of the steel bar was small and easy to penetrate. This problem was handled easily.
其實這里用到了一種辦法：鋼筋代換。
In fact, a method is used here: steel bar replacement.
鋼筋怎樣代換？代換還有哪些考究？
How to replace steel bar? What else is substitution?
這就是今天的話題。
That's the topic today.
1、等截面代換
1. Equal Section Substitution
比方說，小張去買了2把面條，每把1.2g，總共2.4kg。
For example, Xiao Zhang went to the supermarket and bought two sets of noodles, each 1.2g, a total of 2.4kg.
回去以后覺得不適宜，1.2g吃一頓吃不了，吃兩頓不夠，非常不便當。
When I got back, I felt inappropriate. 1.2g meal was not enough, and two meals were not enough. It was very inconvenient.
3把0.8g加起來仍然是2.4kg，這就叫等截面代換。
3 The total of 0.8g is still 2.4kg, which is called isosection substitution.
以下是揭秘時間，一根直徑25mm的鋼筋為什么可以用1根直徑22毫米加1根直徑12mm的鋼筋代換呢？
The following is the time to reveal the secret. Why can a steel bar with a diameter of 25 mm be replaced by a steel bar with a diameter of 22 mm and a diameter of 12 mm?
有一個事情必需說分明，鋼筋的橫截面都是圓形的，這個圓形的橫截面面積就叫做鋼筋的截面積。
There is one thing that must be clearly stated. The cross-section of steel bar is circular. The cross-section area of this circular steel bar is called the cross-section area of steel bar.
查表就曉得，直徑25mm鋼筋截面積490.9，直徑22mm鋼筋截面積380.1，二者相差110.8
As you can see from the table, the cross-sectional area of 25mm steel bar and 22mm steel bar is 490.9 and 380.1 respectively. The difference between them is 110.8.
直徑12mm鋼筋截面積113.1>110.8
The section area of 12mm steel bar is 113.1 > 110.8
3、需求留意的問題，其實就是1點
3. What we need to pay attention to most is actually one point.
曉得了啥叫等強度代換，我們來應用等強度代換省錢。
Knowing what equal strength substitution is, let's use equal strength substitution to save money.
比方說，現澆板的鋼筋，設計是直徑8毫米，一級鋼，間距100毫米。這樣綁扎太費事了，代換一下，直徑20毫米，三級鋼，間距1000毫米。
For example, the cast-in-situ steel bar is designed to be 8mm in diameter, 1st grade steel and 100mm in spacing. It's too tedious to tie up in this way. Replace it. The diameter is 20mm, the third grade steel is 1000mm apart.
那么請問？現澆的樓板，1米遠才放一根鋼筋，會不會塌？
So excuse me? Cast-in-place floor, only a steel bar is placed 1 metre away, will it collapse?
肯定不行！
Surely not!
那怎樣辦？其實鋼筋混凝土設計國度都是有規范的，你是什么構件，小配筋率幾，鋼筋間距幾，梁的1排鋼筋和2排鋼筋受力差幾，等等等等都有設計標準的規則。
What about that? In fact, the design countries of reinforced concrete are standardized. There are design criteria for what kind of components you are, the minimum reinforcement ratio, the spacing of reinforcement, the force difference between the 1 and 2 rows of reinforcement, and so on.
所以講，任何鋼筋的代換，必需辦理設計變卦文件。
Therefore, any steel bar replacement, it is necessary to deal with the design of hexagram documents.
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