Seismosoft | Earthquake Engineering Solutions

Hello

According to EC 8 1998-1/4.3.1(6) (7), the elastic flexural EJ and shear stiffness GA properties are taken to be equal to one-half of the corresponding stiffness of the uncracked elements. This means for beams (EJ and GA), columns (EJ and GA) and also the elastic flexural (EJ) for walls should be reduced for 0.50  of the uncracked section.   
My question is doese in seismostruct in Pre processor>Project Settings>cracked/uncracked stiffness make this in the background, reduce the stiffness of columns, beams and walls for 0.5?

Best regards

I am not familiar with the particular section of EC8 to which you refer. But I assume it is applicable to an elastic analysis, perhaps elastic response spectrum analysis.

If this is the case, I believe you will have to do this manually. SeismoStruct is general purpose and not, I believe, coded to any particular specification (such as EC8).

One way to manually accomplish this in a response spectrum analysis is to specify a material with E = 0.5 times the actual E.

Another way to accomplish this is to manually compute properties based on the desired level of cracking and use elastic elements.

Dear Dojcin,

I would like to add to Mr. Huff's post the paragraph about cracked stiffness available in SeismoStruct's User Manual: Users may take into account the effect of cracking during the linear analyses, i.e. Eigenvalue and Response Spectrum analyses, by selecting to use sections with cracked stiffness. The cracked stiffness may be defined as a percentage of the corresponding uncracked stiffness, or, in the case of inelastic frame elements only, from the section’s My/θy (bending moment at yield/chord rotation capacity at yield) ratio. In the latter case, users should select the employed Code for the calculation of the chord rotation capacity at yield.