# Area calculations & what about 12.5m? [closed]

The shown girder is made from plain stone concrete and four 25 mm diameter steel wires. Including the weight of steel wires, determine self weight of the girder if its length is 12.5 m. Neglect the volume of concrete displaced by steel wires

My answer, area of concrete = ((150*1200)+ 4((200*100)+(0.5*100*150))-(4*pi*(12.5)^2))*(1×10^-3)^2=70.44m^2

area of steel = (4*pi*(12.5)^2))*(1×10^-3)^2 = 1.963×10^-3m^2

W = [(70.44×22.6)+(1.96×10^-3×77.3)] = 1.59×10^3KN/m • Have you thought about asking this question on the mathematics SE site? – julian Feb 25 '17 at 1:49
• I'm voting to close this question as off-topic because this is a question of areas and weight calculations related to Mathematics. – 0xec Feb 25 '17 at 5:09
• Well this question has nothing to do with reverse engineering i assume this is your homework question so here are some hints split the shape into basics so it is 3 rectangles and 4 triangles compute the area multiply the ares by length gives you volume muliply the volume by density to get msss and answer it on your own – blabb Feb 25 '17 at 14:48
• But What about asking for it's length which is 12.5m while actually it is 12m? – Just Believe Feb 25 '17 at 17:00
• This question it's not about Reverse Engineering. – Igor Skochinsky Feb 25 '17 at 18:06

Divide the cross-section into 5 parts - 3 rectangles and 2 trapezoids. 