Deflection, Moment and Reinforcement Relationship

[amaidj]

HI, i have got confused as how to differentiate between deflection and Bending moment and is deflection can be controlled by increase reinforcement? if so how can i calculate deflection after increasing reinforcement? i mean using which formula? or what are the factors that affects to increase deflection capcity if i increase reinforcement in the section?

Thanks A million,

 

[rb1957]

you integrate moment (well, M/EI) to get slope (dy/dx); you integrate slope to get deflection .

reinforcement ? changes I from a constant to I(x) or possibly different constants over different ranges of x ?

another day in paradise, or is paradise one day closer ?

 

[amaidj]

Do you mean if i increase reinforcement the centro-id will change? thereby the I will change?

 

[rb1957]

sure

another day in paradise, or is paradise one day closer ?

 

[amaidj]

Thanks a million man

 

[rapt]

amaidj,

It is not quite that simple. Yes, adding tension reinforcement will increase the inertia so will reduce short term deflection. But it will increase long term deflection due to the increased area of reinforcement causing more shrinkage restraint.

For a lightly reinforced section the overall result will normally be an overall reduction in deflection.

For a heavily reinforced RC member, or a PT member that has low tension stresses at service, the result will often be increased deflection. Often adding compression reinforcement will help reduce deflection more in these cases.