Thin Wall Circle

on . Posted in Plane Geometry

  • Two circles each having all points on each circle at a fixed equal distance from a center point.
  • Center of a circle having all points on the line circumference are at equal distance from the center point.
  • A thin wall circle is a structural shape used in construction.
  • See Article Link  -  Geometric Properties of Structural Shapes

 

circle thin wall 4

area of a Thin Walled Circle formula

\(\large{ A = 2\; \pi \;r\; t }\)     (Area of a Thin Walled Circle)

\(\large{ r =  \frac{ A }{ 2 \; \pi \; t }   }\) 

\(\large{ t =  \frac{ A }{ 2 \; \pi \; r }   }\) 

Solve for A

radius, r
thickness, t

Solve for r

area, A
thickness, t

Solve for t

area, A
radius, r

Symbol English Metric
\(\large{ A }\) = area \(\large{ in^2 }\) \(\large{ mm^2 }\)
\(\large{ \pi }\) = Pi \(\large{3.141 592 653 ...}\)
\(\large{ r }\) = inside radius \(\large{ in }\) \(\large{mm  }\)
\(\large{ t }\) = thickness \(\large{ in }\) \(\large{mm  }\)

   

circle thin wall 4

Perimeter of a Thin Walled Circle formula

\(\large{ P = 2\; \pi \;r }\)     (outside)  

\(\large{ P = 2\; \pi \; \left(  r - t  \right)  }\)     (inside) 

Symbol English Metric
\(\large{ P }\) = perimeter \(\large{ in }\) \(\large{ mm }\)
\(\large{ \pi }\) = Pi \(\large{3.141 592 653 ...}\)
\(\large{ r }\) = inside radius \(\large{ in }\) \(\large{mm  }\)
\(\large{ t }\) = thickness \(\large{ in }\) \(\large{mm  }\)

   

circle thin wall 4

Radius of a Thin Walled Circle formula

\(\large{ r = \sqrt{  \frac { 2 \; A }{ \pi }  }   }\)     (Radius of a Thin Walled Circle)

\(\large{ A =  \frac {r^2 \; \pi }{ 2 }   }\)

Symbol English Metric
\(\large{ r }\) = inside radius \(\large{ in }\) \(\large{mm  }\)
\(\large{ A }\) = area \(\large{ in^2 }\) \(\large{ mm^2 }\)
\(\large{ \pi }\) = Pi \(\large{3.141 592 653 ...}\)

  

 

circle thin wall 4

Distance from Centroid of a Thin Walled Circle formulas

\(\large{ C_x =  r}\) 

\(\large{ C_y =  r}\)

Symbol English Metric
\(\large{ C_x, C_y }\) = distance from centroid \(\large{ in }\) \(\large{ mm }\)
\(\large{ r }\) = inside radius \(\large{ in }\) \(\large{mm  }\)

   

circle thin wall 4

Elastic Section Modulus of a Thin Walled Circle formula

\(\large{ S =  \frac{ 2 \; \pi \; r \; t }{ 3 }   }\)     (Elastic Section Modulus of a Thin Walled Circle)

\(\large{ r =  \frac{ S \; 3 }{ 2 \; \pi \; t }   }\) 

\(\large{ t =  \frac{ S \; 3 }{ 2 \; \pi \; r }   }\)

Symbol English Metric
\(\large{ S }\) = elastic section modulus \(\large{in^3}\) \(\large{mm^3}\)
\(\large{ \pi }\) = Pi \(\large{3.141 592 653 ...}\)
\(\large{ r }\) = inside radius \(\large{ in }\) \(\large{mm  }\)
\(\large{ t }\) = thickness \(\large{ in }\) \(\large{mm  }\)

     

circle thin wall 4

Plastic Section Modulus of a Thin Walled Circle formula

\(\large{ Z =  \pi \; r^2 \; t   }\)     (Plastic Section Modulus of a Thin Walled Circle)

\(\large{ r =  \sqrt{   \frac{ Z }{ \pi \; t }   }   }\)

\(\large{ t =  \frac{ Z }{ \pi \; r^2 }   }\)

Symbol English Metric
\(\large{ Z }\) = plastic section modulus \(\large{ in^3 }\) \(\large{mm^3  }\)
\(\large{ \pi }\) = Pi \(\large{3.141 592 653 ...}\)
\(\large{ r }\) = inside radius \(\large{ in }\) \(\large{mm  }\)
\(\large{ t }\) = thickness \(\large{ in }\) \(\large{mm  }\)

     

circle thin wall 4

Polar Moment of Inertia of a Thin Walled Circle formulas

\(\large{ J_{z} =  2\; \pi \;r^3 \;t  }\) 

\(\large{ J_{z1} =  6\; \pi \;r^3 \;t  }\) 

Symbol English Metric
\(\large{ J }\) = torsional constant \(\large{ in^4 }\) \(\large{mm^4  }\)
\(\large{ \pi }\) = Pi \(\large{3.141 592 653 ...}\)
\(\large{ r }\) = inside radius \(\large{ in }\) \(\large{mm  }\)
\(\large{ t }\) = thickness \(\large{ in }\) \(\large{mm  }\)

     

circle thin wall 4

Radius of Gyration of a Thin Walled Circle formulas

\(\large{ k_{x} =    \frac { \sqrt {2}  }  {  2  } \; r   }\) 

\(\large{ k_{y} =   \frac { \sqrt {2}  }  {  2  } \; r    }\) 

\(\large{ k_{z} =     r  }\) 

\(\large{ k_{x1} =   \frac { \sqrt {6}  }  {  2  } \; r   }\)

\(\large{ k_{y1} =   \frac { \sqrt {6}  }  {  2  } \; r   }\)

\(\large{ k_{z1} =    \sqrt {3}  \; r   }\)

Symbol English Metric
\(\large{ k }\) = radius of gyration \(\large{ in }\) \(\large{mm  }\)
\(\large{ r }\) = inside radius \(\large{ in }\) \(\large{mm  }\)

    

circle thin wall 4

Second Moment of Area of a Thin Walled Circle formulas

\(\large{ I_{x} =  \pi \;r^3 \;t }\) 

\(\large{ I_{x1} =  3\; \pi \;r^3 \;t  }\) 

\(\large{ I_{y1} =  3\; \pi \;r^3 \;t }\)

Symbol English Metric
\(\large{ I }\) = moment of inertia \(\large{ in^4 }\) \(\large{mm^4  }\)
\(\large{ \pi }\) = Pi \(\large{3.141 592 653 ...}\)
\(\large{ r }\) = inside radius \(\large{ in }\) \(\large{mm  }\)
\(\large{ t }\) = thickness \(\large{ in }\) \(\large{mm  }\)

    

circle thin wall 4

Torsional Constant of a Thin Walled Circle formula

\(\large{ J  =  2\;  \pi \;r^3 \; t    }\)     (Torsional Constant of a Thin Walled Circle)

\(\large{ r  =  \left( \frac{ J }{ 2 \; \pi \; t }  \right)^{ \frac{1}{3} }    }\)

\(\large{ t  =  \frac{ J }{ 2 \; \pi \; r^3 }   }\)

Symbol English Metric
\(\large{ J }\) = torsional constant \(\large{ in^4 }\) \(\large{mm^4  }\)
\(\large{ \pi }\) = Pi \(\large{3.141 592 653 ...}\)
\(\large{ r }\) = inside radius \(\large{ in }\) \(\large{mm  }\)
\(\large{ t }\) = thickness \(\large{ in }\) \(\large{mm  }\)

 

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Tags: Perimeter Inertia Structural Steel Modulus