masomenos
Using special joint such we have describe by giving the offsets for joints one by one, for this purpose need a lot of time. Especialy when we have a complex or a big structure.
masomenos Say
"Note that you don't have to divide the frame, you can draw special joints using the 'snap to line' or offset options"
I do not understand ?
To confirm what i said before, you can see that Etabs use the Story shears value to calculate oveturning moment Mx and My.
at differents levels and at the base of the structure.this overall moments is equivalents in value to those you obtain by the equivalent static case using story shears.
It's what i say .A combination or SRSS give always an absolute value and we can't use this result for a calculation of slabe fondation or beam fondation it can't give the overturning effect . So we can use an equivalent static model by using story shears applied as static forces.
it's depend on the meshing of your shell element.If the number of elemnts shell is high the distrubution is more correct.You must divide your beam into the same number of elements as your shell elements.So it work together.
There is anothere way to solve this problem.Make spectrale analysis then take sheare story result and there position, and make a static analysis with the previous sheare story as static force in the new analysis at there respective position, the reaction given at the base of the structure is...
exporting spectral analysis results from Etabs to Safe for slab foundation analysis or beam foundations analysis has no sens because results given by spectral analysis are always in absolute value this means that they are always positive or if multiply by -1 always negative.And by this way it...
The local axes shown is the default one for the input section properties you have defined.If you want anothere one you must select the frames you want to change the direction > assign >local axe then you input the new value of angle.
you can take reactions at supports which are multiply by (-1) and apply them at there position on the beam.the value of spring stiffness which modelise soil must be multiply by the width of fondation (beam). the precision of calcul depend on the number of division of beam.
anothere way is to...
in the case of slab it is not so simple, because we have many type of stress
S11=F11/th-(12*M11/thb^3)*x3.
S22=F22/th-(12*M22/thb^3)*x3.
S12=F12/th-(12*M12/thb^3)*x3 etc...
x3 represente the variation of thickness of slab.
to obtain M11,M22 etc...
we must integrate the stress...
See in "CSI Analysis Reference Manual Page 144 "
*Internal Force and Stress Output*
The Shell element internal forces (also called stress resultants) are the forces and moments that result from integrating the stresses over the element thickness.....etc
As for loading
- when we have a slab i leave the value force/cubic lenght. p=-ky .
- when we have a beam on elastical support we must multiply the value by the width ( b ) of beam and thus we have force/square lenght. p=-ky/b .
Yes there is a relation between coeficient of reaction and resistance of soil p=-k*y
where y is the displacement
p is the pression on the soil
k is the coefficient of reaction.
Yes there is a relation between coeficient of reaction and resistance of soil p=-k*y
where y is the displacement
p is the pression on the soil
k is the coefficient of reaction.
Go to Display >> Show Member Force/stress diagram >> Shell Stesses/Forces if we select Forces we have All Forces M11 M22 which are out of plane moment in kg-cm/cm of lenght.
It's same as when you calculate a beam on elastical supports, you represent soil by coefficient of reaction.
Soil - loose k=0.1-0.5 kg/cm3
- medium dense k=0.5-5
- dense k=5-10
- compact k=10-20
- hard k=20-100
you select joints at...
