Initial stiffness of pushover curve

[morello]

Hi,

When I checked my pushover curve, I noticed that initial elastic part of curve changes before the structure reaches first yielding occurence during analysis. Is it because of numerical iterations or something else? I'm curious because when I search typical pushover curves from different publications usually it starts to soften after when there is a yielding occurence among the elements.

Thanks.

[seismosoft]

Hi Morello,

The linear elastic part until yielding that is employed by several other programs is a in fact simplification.
SeismoStruct employs the fibre-based modelling, whereby the section is discretised in a number of areas (called monitoring points), each of which employs its stress-strain curve. In your case, the nonlinear initial part of the curve that you get is because of the nonlinear nature of the concrete stress-strain material curve.
Refer to the help of the program for further details

Seismosoft Support

[morello]

Thanks for clear explanation.