Strand7 design

[eqgeotech]

I need to make a 2D model of a simple building in strand7 with isolated footings, I have to use 2D plane strain plate elements for designing isolated/spread footings, i am using M32 conrete for footing design, how to determine the viscous damping coefficient of plate element in N.s/m/m3 if the damping ratio is 0.03.

 

[glass99]

eqgeotech: typically a percentage of critical damping is applied to the whole model, not to individual elements of the model. If you are doing a time history analysis, you would adjust the Rayleigh coefficients. If its a response spectrum you change the spectrum. The damping in real structures comes from difficult to predict sources, like loose connections and friction with finishes, not from the inherent damping capability of steel. If you are modeling isolation bearings, you will have to complete a NL time history, which will have some energy dissipation at the bearing element level in addition to the basic 3% damping.

 

[eqgeotech]

glass99: I got what u r saying, but while using Strand7 we need to define properties of elements which we use to make models. So if are using starnd7, and if u go in plates section in property tab, for isotropic materials u need to provide viscous damping value. Kinldy help me with that.

 

[eqgeotech]

glass99: I should use simple plate elements or 2D plane strain elements for designing the footing,I have used beam element for designing the superstructure.

 

[glass99]

In respect to modeling the footings with shell elements, I have no idea. I prefer the foundation spring approach with stiffnesses determined from published and peer reviewed formulas.

 

[eqgeotech]

As I am using Rayleigh Damping for my structure do I need to put viscous damping coefficient in properties for beam and plate, and can u tell me how to increase lateral stiffness for columns in Strand7.