How To Determine the Cutting Length of Spiral Ring To bind the pile inner bar known as master ring, the spiral ring is mainly applied. Master rings has the same functionality as circular stirrup. In this type of ring, a hook is not used but there is a spiral ring in exterior to bind the pile and it is known as spiral bar. Given below, the step-by-step methods to determine the cutting length of the spiral ring :The calculation is made based on the following data :Dia of pile = 1000mm or 1m Pitch or spacing of spiral bar = 200mm Length of pile = 20m Dia of spiral bar = 8mm Clear cover = 50mm
SOLUTION: Initially, it is required to determine the radius of the spiral and then length of the spiral ring as it completes the one pitch. The distance of the pitch is provided in the data.
After that, determine the numbers of spirals and then the quantities of laps provided in the total length of the spirals.
1: Radius of spiral ring = Radius of pile (d2) – clear cover – half of spiral dia bar = 500 – 50 – 4 = 446 mm Therefore, the length of 1 no of spiral ring will be as follow := 2 x 3.14 x r = 2 x 3.14 x 446 = 2800 mm or 2.8m Ans..
2: Numbers of spiral = length / spacing of pitch + 1 = 20000 / 200 + 1 = 100 + 1 = 101 nos 101 numbers of pitches are finished for spiral bar in this length of provided pile. Therefore, the total length of the spiral bar will be as follow :Total length = no of pitches x radius of the pile = 101 x 2.8m = 282.8m
Laps It is known that the length of one full bar is 12m, therefore, lapping is necessary in this case. numbers of laps = total length of spirals – 1 / length of one bar = 282.8 – 1 / 12 = 23.56 – 1 = 22.56 say 23 nos 23 numbers of laps are necessary
Lap is taken as = 50d ( here d denotes dia of bar) = 50 x 8 = 400mm or 0.4m Total length of spiral bar Total length of laps = 23 x 0.4 = 9.2m Total length of spiral rings = 282.8 + 9.2 = 292m
Weight: = d2/162 x length = 8 x 8 / 162 x 292m = 115.35 kg To get more informative civil engineering article, tutorials and videos; visit my website
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