Recently, many friends said that when measuring the thread steel, they encountered some minor problems, so I would like to ask what methods of measuring the diameter of the thread steel are.

　　螺紋鋼直徑測量方法

　　Measuring Method of Thread Steel Diameter

　　廢話不多說，施工現場常釆用下面的螺紋鋼直徑測量方法：

　　The following methods of measuring the diameter of threaded steel are often used in the construction site.

　　1、以前老標準用重量法算面積：面積=長度*重量/7.85；

　　1. The old standard used to calculate area by gravimetric method: area = length * weight / 7.85;

　　即用稱稱得的單位長度的鋼筋重量，除以鋼的容重7.85，得到斷面積，再折算出“直徑”。

　　That is to say, the section area is obtained by dividing the weight of steel bars per unit length by the volume weight of steel 7.85, and then the "diameter" is calculated.

　　面積(s)=圓周率π(3.14)*半徑(r)的平方

　　Area (s) = the square of PI (3.14) * radius (r)

　　直徑=半徑*2

　　Diameter = radius*2

　　2、在現場也常用游標卡尺直接量直徑：一側卡肋，一側卡光面，量三個截面計算平均直徑，折減5%即可的辦法。

　　2. Vernier calipers are also commonly used in the field to measure the diameter directly: one side of the caliper, one side of the caliper smooth surface, measuring three sections to calculate the average diameter, which can be reduced by 5%.

　　3、用卡尺直接測量內徑（不含肋），對照五金手冊相應鋼筋的內徑尺寸即可。按GB1499.2的規定，應測量鋼筋內徑d1，不能測肋的尺寸。如公稱直徑12、14、16、18的，其內徑d1分別為11.5、13.4、15.4、17.3，允許偏差±0.4。再如公稱直徑20、22、25的，d1分別為19.3、21.3、24.2，允許偏差±0.5。

　　3. Measure the inner diameter (without ribs) directly with calipers, and compare the inner diameter of the steel bar in the hardware manual. According to GB1499.2, the inner diameter of reinforcing bar D1 should be measured, but the size of ribs can not be measured. If the nominal diameters are 12, 14, 16 and 18, their inner diameters D1 are 11.5, 13.4, 15.4 and 17.3, respectively, with an allowable deviation of <0.4. If the nominal diameter is 20, 22 and 25, D1 is 19.3, 21.3 and 24.2, respectively, and the allowable deviation is (+0.5).

　　帶肋鋼筋橫肋設計原則應符合下列規定：

　　The design principles of ribbed bar transverse ribs shall comply with the following provisions:

　　橫肋與鋼筋軸線的夾角β不應小于45度，當該夾角不大于70度時，鋼筋相對兩面上橫肋的方向應相反；

　　The angle beta between the transverse rib and the axis of the steel bar should not be less than 45 degrees. When the angle is less than 70 degrees, the direction of the steel bar relative to the transverse rib on both sides should be opposite.

　　橫肋公稱間距l不得大于鋼筋公稱直徑的0.7倍；

　　The nominal spacing of transverse ribs shall not be greater than 0.7 times the nominal diameter of reinforcing bars.

　　橫肋側面與鋼筋表面的夾角α不得小于45度；

　　The angle alpha between the side of the transverse rib and the surface of the reinforcing bar shall not be less than 45 degrees.

　　鋼筋相鄰兩面上橫肋末端之間的間隙(包括縱肋寬度)總和不應大于鋼筋公稱周長的20%；

　　The total clearance (including longitudinal rib width) between the ends of the transverse ribs on the adjacent two sides of the reinforcing bar should not be greater than 20% of the nominal circumference of the reinforcing bar.

　　當鋼筋公稱直徑不大于12mm時，相對肋面積不應小于0.055；公稱直徑為14mm和16mm時，相對肋面積不應小于0.060；公稱直徑大于16mm時，相對肋面積不應小于0.065。

　　When the nominal diameter of reinforcing bar is less than 12 mm, the relative rib area should not be less than 0.055; when the nominal diameter is 14 mm and 16 mm, the relative rib area should not be less than 0.060; when the nominal diameter is greater than 16 mm, the relative rib area should not be less than 0.065.

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　　關于螺紋鋼直接測量方法，就是這樣的了。 If you want to know more about steel, pay more attention to us: http://www.angcao.cn/