What is the correct stress in the concrete column?

  • Thread starter Thread starter anthonyk2013
  • Start date Start date
AI Thread Summary
The discussion revolves around calculating the stress in a concrete column reinforced with steel bars under a load of 20 tons. The user calculates the stress in concrete and steel using their respective areas and Young's moduli, arriving at a value of 154.3 x 10^4 N/m^2. There is confusion regarding the conversion of this value to standard form, as the user notes that their reference states the answer should be 1.54 MN/m^2. Clarification is sought on the physics calculations and the correct interpretation of the results in standard notation. The conversation highlights the importance of understanding unit conversions and stress calculations in structural engineering.
anthonyk2013
Messages
125
Reaction score
0
A concrete column is reinforced with steel bars and carries a load of 20t. The overall cross section area of the column is 0.1m^2 and the steel bars accounts for 3% of this area.
Find the stress in the concrete
If the length is 4m< how much does it shorten.

E of steel 200GN/m^2
E of concrete 20 GN/m^2

Load=20*1000=20000*9.81=196200 or 19.6*10^4

Area of concrete =.1*97%/100=.097m^2
Area of steel=.1*3%/100=.003m^2
Area of concrete=.1*97%/100=.097m^2
steel=s
concrete=c

σs/Es=σc/Ec→σs=σc*Es/Ec→σs=σc*200/20→σs=10*σc

F=σs*As+σc*Ac
19.6*10^4=(10*σc*.003)+(σc*.097)
19.6*10^4=σc(10*.003+.097)
19.6*10^4=σc(.127)

19.6/.127=154.3*10^4
σc=154.3*10^4

My question is, the answer I have in my notes is 1.54MN/m^2. Why is my decimal point wrong?
 
Physics news on Phys.org
I'm not sure if it isn't. 1.54MN is the same as 1.54 x 10^6. 154.3 x 10^4 is the same as 1.54x10^6
 
  • Like
Likes Priscillamadison
Fineline00 said:
I'm not sure if it isn't. 1.54MN is the same as 1.54 x 10^6. 154.3 x 10^4 is the same as 1.54x10^6

Would be able to break that down more, still don't understand. Thanks
 
I just want to stress I'm not so sure on the physics but I feel it is just a error in standard form

Your notes give you the answer 1.54MN/m2, which is 1.54 Mega nm2 which is 1.54x106 N/m2 or 1,540,000 n/m2

Your answer is 154.3x104 N/m2which is 154.3x10,000 which is 1,543,000 N/m2
 
Fineline00 said:
I just want to stress I'm not so sure on the physics but I feel it is just a error in standard form

Your notes give you the answer 1.54MN/m2, which is 1.54 Mega nm2 which is 1.54x106 N/m2 or 1,540,000 n/m2

Your answer is 154.3x104 N/m2which is 154.3x10,000 which is 1,543,000 N/m2

Thanks
 
Appreciate if someone could check the physics work in my problem.
 
anthonyk2013 said:
Appreciate if someone could check the physics work in my problem.

Anyone thanks
 
Back
Top