Stiffness Modifiers for Concrete Cores

[BD26]

Hello all,

Some engineers say they are comfortable using 1.0 as a stiffness modifier when analysisng concrete cores of tall buildings under wind loading. Is there any specific guidance on this or is it just what is comfortable. Im working to eurocodes.

My thinking was to look at the analysis results in the uplift condition and if the wall shows tension then to treat it as cracked.

What's everyone else's thoughts on this?

 

[Agent666]

Generally if the moment is over the cracking moment then codes will require you to consider the cracked stiffness. Simply because there is tension doesn't necessarily mean it's cracked as concrete has some limited tensile capacity. The derivation of the cracking moment is based on this tensile strength.