analysis skips initial branch of pushover curve

[Samra]

Dear all,
i am trying to do pushover analysis in opensees of a one bay one storey RC frame... i have done a similar analysis using seismostruct.....the pushover that i get has a stiffer pre-cracking branch n then a slightly lower stiffness branch which is prudent....similarly when i am doing pushover in OpenSees, i cannot find the initial stiffer branch no matter how small displacement increment i input......both the softwares give me identical pushovers otherwise...even initial time periods are the same implying that initial stiffness calculated by both the softwares shall match.....please guide me how shall i perform pushover in OpenSees that i do not miss the initial stiffer branch of pushover curve......

Thanx....

[Samra]

here's a pic to explain the problem better....
https://drive.google.com/open?id=0BxvVI ... Wd3UDJ5M00

[bandwidth0zero]

Try using Concrete02 material instead of Concrete01, but be careful with your model... I have issues applying Concrete02 with some combinations of GPs per element, sub elements etc ... I realized that using more elements or more G.P per element may cause premature failure.