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Struggling

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hi I am having trouble with finding the neutral axis and second moment of a T-beam.

here are the measurements of the beam:

http://img354.imageshack.us/img354/8648/beam6xl.jpg [Broken]

i understand to find the neutral axis you divide the beam into 2 rectangles but iam having problem finding the thickness of the bottom rectangle of the t-beam. how can i find the neutral axis if i can't find the width of the bottom rectangle, because i can't find the area of it. iam totally stuck.

also calcutale the second moment of area

for a member with a rectangular cross section bent about the z axis,

Izz =(1/12)bd^3

to determine the second moment of area of a cross section made of a number of different shapes the parallel axis theorem is used.

Iaa = Izz + Ay^2

what i did was:

Izz = (1/12)6.4(38.1)^3

= 29496.72

but it doesn't make sense i was going to insert this into Iaa= Izz + Ay^2 to get the second moment of the vertical.

can someone please help

here are the measurements of the beam:

http://img354.imageshack.us/img354/8648/beam6xl.jpg [Broken]

i understand to find the neutral axis you divide the beam into 2 rectangles but iam having problem finding the thickness of the bottom rectangle of the t-beam. how can i find the neutral axis if i can't find the width of the bottom rectangle, because i can't find the area of it. iam totally stuck.

also calcutale the second moment of area

for a member with a rectangular cross section bent about the z axis,

Izz =(1/12)bd^3

to determine the second moment of area of a cross section made of a number of different shapes the parallel axis theorem is used.

Iaa = Izz + Ay^2

what i did was:

Izz = (1/12)6.4(38.1)^3

= 29496.72

but it doesn't make sense i was going to insert this into Iaa= Izz + Ay^2 to get the second moment of the vertical.

can someone please help

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