How to Calculate Area and Inertia Moment using Autocad

بِسْـــــــــــمِ اللّهِ الرَّحْمَنِ الرَّحِيْـــــــمِ

It's long time not to fill my blog, this is my first time during this year to sit in front of my laptop and try to make accessories in my blog :)

In a structure building, especially steel structure. we should know how to calculate area. this is used for us to calculate such as shear force,weldment and others. it would be explain in next post. apparently. ok let's start our discussion based on case. 

There is riser hanging to jacket paltform. Risers are the pipes that are used for the production, drilling and export of oil and gas from seabed. They are a key component for the offshore industry and maintaining theri functionality is central to the success of the production system. Actually there are 3 types of riser clamp depend on function (as far i know), Fix clamp, adjustable clamp and hanger clamp. we are now talking about fix clamp and hanger clamp because we look for the connection that using weld connection. 

during hanging the riser we able to work with riser clamp, and among of them are connected with stub. the connection between stub and riser are using clamp, and other side using weldment connection to horizontal bracket. take a look to below example figure.

Ilustration Riser Clamp at Plan View

In a riser clamp system, at least there are 3 necessary component, riser clamp, stub and bracing where is will be connected. in figure above, plan view ilustration from riser clamp that we are talking about. alright  we will see the connection stub and horizontal bracing, section F.

Section F

Section F describe connection stub to horizontal bracing. the component consist of stub with OD 6-5/8 " and 0.75 WT and stiffener with dimension rectangular (assume) 4"x0.5" there are doubler plate between horizontal brace and stub, however we can ignore it. 

how to calculate the are of them in Cad (because as far i know, with cad, this exactly fast to get area better than hand calculation.)

1. Open your CAD and drawing stiffener and Stub that we describe above

OD stub = 6-5/8" x 0.75 WT
Stiffener = 4"x1/2"
angle     =  45 deg 

Dimesion

2. click command : UCS -> put in center of circular stub [enter/ok]

Location local UCS

3. click command : trim -> trim circular between inner stiffener [enter/ok]

after trimming

3. click command : PE -> M -> select all drawing except inner circular [enter/ok]

click [y] in command convert lines, arcs, and splines to polylines

4. click command : PE -> M -> select all drawing except inner circular [enter/ok]

click [J] in command enter an option (close/join/etc)[enter/ok] twice

4. click command : RE -> select all drawing [enter/ok]

5. click command : SU -> select DRAWING 1(OUTSIDE -CIRCULAR-AND STIFFENER)  [enter/ok] THAN SELECT DRAWING 2 (INNER CIRCULAR)

4. click command : MASSPROP -> select all drawing [enter/ok]

ok, congratulation you made it. if you wanna know that your assumption is correct, please check the centroid. it should be zero, than you are able to make this output for your purpose. 

source : http://rustisdead.blogspot.co.id/2015/07/a-closer-look-at-riser-clamp-protection.html