How to find the section modulus for point 1 and point 2? 2

[wadeshade]

Regards fellow engineers,
I am a junior engineer who just started my career not long ago. May i know how to find the section modulus for point 1 and point 2? thanks alot !

https://snipboard.io/WMQhTH.jpg

 

[wadeshade]

and also how to find to find the static moment of area for point 2.... thanks !

 

[Agent666]

I'm guessing they mean the elastic section modulus at that location? It's quite a strange way of using the term as the section modulus is a property for the entire section.

But working from

stress = My/I

the y is the distance to the location from the neutral axis to the point 1 and 2.

y/I I/y is the section modulus.

Is that in keeping with what the rest of the calculation requires given the odd terms/definitions?

Perhaps providing the context in which these values are subsequently used will help us determine if this is what they are meaning? For example not entirely sure on the static moment of area for point 2 and what they are asking for.

 

[BridgeSmith]

Agent666, I believe the section modulus is I/y.

Rod Smith, P.E., The artist formerly known as HotRod10

 

[Agent666]

Yes, correct!

Moment / section modulus

 

[mtu1972]

I’ve designed numerous crane girders throughout my career, but they were all wide flange sections.

The crane is a moving load, so you’ll have to look at it in varying positions. Max shear with wheels near supports. Max moment with wheels near midspan. AISC has a diagram to find maximum moment.

Cranes also have longitudinal and transverse lateral loads that need to be considered.

From your other post it appears that you may also have torsion forces on your box girder if the wheels are on the solid bar on the top.

My guess would be that it will be an iterative process (trial and error) to determine a section that satisfies the strength and deflection requirements.

gjc

 

[dhengr]

Wadeshade:
Come on…, this can’t be your question if you are even trying to pretend to be an engineer. Dig out your Engineering Mechanics, Strength of Materials and Structural Analysis and Design textbooks and for the first time, really read and study, learn and understand them. I really hope you didn’t sell those textbooks for the price of a six pack. Settle down a little bit, and start thinking, look it up yourself, study what you should have learned or been taught, and quit crying in your beer.

 

[Ron]

Ditto to dhengr...