Hello, I´m designing two small guardhouses in STAAD.Pro V8i SS5, both are RC structures with slab foundations, they are almost equal in principal geometry, loading and sections, the only thing that changes considerably from one model to the other is the value for the sub-grade modulus which, understandably, does have a noticeable effect in the base pressure summary, aside from that there are some small differences in the distribution of the slab and the secondary frame, but in my opinion these are minor changes that should hardly affect the behavior of the model. The difference in results starts with the reactions in the columns (Beam end forces), for one model the maximum axial force has a value of 11,418.17 kg and for the other one it has a value of 8,857.23 kg, after that I notice that the joint displacements in the beam centers (I´m calculating beam deflection with those values) are also very different with values going from 0.598 cm in one model to 0.266 cm in the other for example, I´m assuming that I´ll be seeing variations along the same lines for drift values and probably also steel reinforcement values. So my question is: What I´m I doing wrong or differently between the two models so that my results change so noticeably or is it normal for them to change like this? The models are attached. If something needs clarification please let me know and I´ll do my best. Thanks in advance for any help.
Caseta de vigilancia Punta de Palmas 21-05-19.stdCaseta de vigilancia Peonías 08-08-19.std