Deflection of 6061-T6 aluminum channel

[moholland04619]

I am planning on building a 9 foot long dock with 6061 aluminum structural channell 5 X 1.75 X .190. the supports to the ground will be 7 feet apart, and there will be 2 parallel channels on each side of the dock spaced 38" apart. My question is how much deflection would I get at the center with a 600 lbs. load. Would I gain much if I used a little bit bigger structural channell 6 X 1.95 X .225 web.

Thanks in advance for any help or advise.

[Kelly_Bramble]

Welcome to Engineers Edge!

Beam Deflection Calculators
Beam Supported Both Ends Distributed Loads

Aluminum Channel Properties

[moholland04619]

I have been trying to use these links, but I don't know the elasticity of the aluminum channel I am using, I have figure of 10,000 ksi but that is just for the type of aluminum I don't think that takes into account the size of the channel

[Kelly_Bramble]

I have been trying to use these links, but I don't know the elasticity of the aluminum channel I am using, I have figure of 10,000 ksi but that is just for the type of aluminum I don't think that takes into account the size of the channel

Well, OK you will need to figure out what aluminum you are planning on using, e.g. 6061, 2024, 7075, etc. The size and shape of the channel is accounted for in the Moment of Inertia number given by a standard reference chart for your channel shape or calculating.

http://www.engineersedge.com/materia...gyration-5.htm

[dalecyr]

You are close to having all the information you need to solve this question...

What number are you coming up with for the Moment of Inertia?

[moholland04619]

I am getting -12.818????

[moholland04619]

Well, OK you will need to figure out what aluminum you are planning on using, e.g. 6061, 2024, 7075, etc. The size and shape of the channel is accounted for in the Moment of Inertia number given by a standard reference chart for your channel shape or calculating.

http://www.engineersedge.com/materia...gyration-5.htm

I am using 6061 aluminum structural channell 5 X 1.75 X .190, I just am not sure about the elasticity figure

[Kelly_Bramble]

Ok, I did the calculations the lazy way. Using Moment of I from http://www.engineersedge.com/standar...properties.htm

I used the C5 x 6.7... My calculations is an estimate, however I think the channel could be bigger for safety assuming I don't have nonsense for numbers.. (Don't hold me to these numbers). Also, you need to consider the weight of the structure on the channel.

Remember "bigger is better".

section-calc.jpg

[dalecyr]

Hey Kelly...
Just checking something; Modulus of Elasticity=30,000,000?

[RWOLFEJR]

6061 T6
E... ~ 10,000,000 psi

[dalecyr]

Yea.... that changes the outcome 'a bit'.

[Kelly_Bramble]

6061 T6
E... ~ 10,000,000 psi

I agree --- http://asm.matweb.com/search/Specifi...ssnum=MA6061t6