modelling for a RC building
modelling for a RC building
(OP)
Hi all,
I have questions regarding how to develop a numerical modelling of a reinforced concrete building (shear walls is the only seismic force resisting system) using Etabs 3D for seismic analysis. Actually the question is regardless the software that we use, but I am using etabs so I post in etabs forum
The question is whether we consider the basement or not in our model, or rather we should develop the model from ground level or foundation level. Developing from foundation seems to be more precise, but then the question is how we consider the interactions between the basement and surrounding soil? should we consider beams (if available), columns,slabs.. in basement as seismic weight?
Btw, can someone explains me how can I identify the torsional mode in Etabs? by the mode shape or by the modal participating mass ratio? or
Thanks
Lisu
I have questions regarding how to develop a numerical modelling of a reinforced concrete building (shear walls is the only seismic force resisting system) using Etabs 3D for seismic analysis. Actually the question is regardless the software that we use, but I am using etabs so I post in etabs forum
The question is whether we consider the basement or not in our model, or rather we should develop the model from ground level or foundation level. Developing from foundation seems to be more precise, but then the question is how we consider the interactions between the basement and surrounding soil? should we consider beams (if available), columns,slabs.. in basement as seismic weight?
Btw, can someone explains me how can I identify the torsional mode in Etabs? by the mode shape or by the modal participating mass ratio? or
Thanks
Lisu





RE: modelling for a RC building
For response spectrum cases, would make sure you've got your exterior nodes locked so you don't end up running your model with a building taller than it really is. In most circumstances, I wouldn't go through the trouble of modeling the interaction between soil and basement walls in a lateral model unless we've got very large forces for a very small wall area and low passive pressure from the geotech. Otherwise, I would imagine passive resistance on the basement walls would be more than enough to justify just locking those nodes. Could check your x/y reactions to make sure, but I wouldn't imagine it would be an issue.
RE: modelling for a RC building
RE: modelling for a RC building
As for seismic loads, to be more exact, you can set the corresponding mass modifier for the structural elements in basement, equal to 0, as these are assumed not to contribute to the effective seismic mass.
And something more regarding basement walls: With ETABS, you cannot directly apply soil pressure on them. You will have to manually mesh them and apply the corresponding loads to the created nodes.
If someone claims that ETABS does this automatically, do not trust him :)
Have a nice day.
Analysis and Design of arbitrary cross sections
Reinforcement design to all major codes
Moment Curvature analysis
http://www.engissol.com/cross-section-analysis-des...
RE: modelling for a RC building
RE: modelling for a RC building
Usually changing the size of the column may be the solution.
Analysis and Design of arbitrary cross sections
Reinforcement design to all major codes
Moment Curvature analysis
http://www.engissol.com/cross-section-analysis-des...
RE: modelling for a RC building