Hi, I have two questions for erthquake analysys in Tower:
1.How can i do directional combination according to bulgarian new rules: BDS NPSSZR - 2007?
Modal comnination:
Eedx=SRSS(Edx1,Edx2...Exn) or Eedx=CQC(Edx1,Edx2...Exn)
Eedy=SRSS(Edy1,Edy2...Eyn) or Eedy=CQC(Edy1,Edy2...Eyn)
n=modes
Directional combination
rule is: SRSS(Eedx,Eedy)
2.As an alternative to BDS directional combination i can use on own responsibility EC8 4.3.3.5.1(3).
Eedx"+"0.30Eedy
Eedy"+"0.30Eedx
According to Tower 5 manual this ec8 rule is:
Kx;Ky
1.0;0.3
0.3;1.0
The problem is this:
Tower first calculate directional and than modal calculation, not first modal and then directional.
Example if I write 1.0;0.3 and 0.3;1.0 in earthquake directional factors for model with three modal modes in tower 5.5:
Tower result:
Eedx=SRSS(Edx1,0.3Edy1)"+"SRSS(Edx2,0.3Edy2)+SRSS(Edx3,0.3Edy3)
Eedy=SRSS(Edy1,0.3Edx1)"+"SRSS(Edy2,0.3Edx2)+SRSS(Edy3,0.3Edx3)
Result according to EC8 must be:
SRSS(Edx1,Edx2,Edx3)+0.30*SRSS(Edy1,Edy2,Edy3)
SRSS(Edy1,Edy2,Edy3)+0.30*SRSS(Edx1,Edx2,Edx3)
Can you fix this in Tower 6?
Sorry for my bad english.
Directional combination for eartquake cases in Tower 6
1) Directional combination of two perpendicular earthquakes with SRSS combination is impossible to achieve in Tower... hope someday will
2) I think you can overcome the problem with two separate quake load cases and then combine them in load combination:
Load cases:
QLX, (Kx=1.0, Ky=0.0)
QLY, (Kx=0.0, Ky=1.0)
Load combination:
1.0*QLX+0.3*QLY
0.3*QLX+1.0*QLY
2) I think you can overcome the problem with two separate quake load cases and then combine them in load combination:
Load cases:
QLX, (Kx=1.0, Ky=0.0)
QLY, (Kx=0.0, Ky=1.0)
Load combination:
1.0*QLX+0.3*QLY
0.3*QLX+1.0*QLY
Re: Directional combination for eartquake cases in Tower 6
stivy wrote:
Result according to EC8 must be:
SRSS(Edx1,Edx2,Edx3)+0.30*SRSS(Edy1,Edy2,Edy3)
SRSS(Edy1,Edy2,Edy3)+0.30*SRSS(Edx1,Edx2,Edx3)
Can you fix this in Tower 6?
Sorry for my bad english.
Sorry for delayed response from Radimpex.
You are totally right, we must provide directional combining in seismic load case. Current behavior of Tower 6 allows directional combining through user defined combination of seismic load cases (as user 007 said in previous message). But, doing this on such a way has several significant limitations. One of them is that user is unable to use such defined load-case (actually - a load case combination) in the "Full combination scheme".
We are working on this topic, right now.
regards,
Radimpex team.
btw. your English is perfect
Re: Directional combination for eartquake cases in Tower 6
Should I write in English in future?b.milan wrote:stivy wrote:
Result according to EC8 must be:
SRSS(Edx1,Edx2,Edx3)+0.30*SRSS(Edy1,Edy2,Edy3)
SRSS(Edy1,Edy2,Edy3)+0.30*SRSS(Edx1,Edx2,Edx3)
Can you fix this in Tower 6?
Sorry for my bad english.
Sorry for delayed response from Radimpex.
You are totally right, we must provide directional combining in seismic load case. Current behavior of Tower 6 allows directional combining through user defined combination of seismic load cases (as user 007 said in previous message). But, doing this on such a way has several significant limitations. One of them is that user is unable to use such defined load-case (actually - a load case combination) in the "Full combination scheme".
We are working on this topic, right now.
regards,
Radimpex team.
btw. your English is perfect
http://www.radimpex.co.yu/forum/viewtopic.php?p=567
Hi,
I'm checking horizontal deformations and story drift according to EC8.
In one model I've made seismic case Sy(Sx) with coefficients Kx=0.3 and Ky=1 (Kx=1,Ky=0.3)
In another for Sy(Sx) I took Kx=0 and Ky=1, and created load case 0.3Sx+Sy.
When I compared results I get almost twice bigger values for first model!
What is correct option? This is very sensitive issue,story drift requirement is quite severe, so I would appreciate any advices and help on this matter.
One more issue with story drift: I calculate it as a difference of the storey displacements, which is not quite correct,because response spectrum analysis gives the maximum lateral displacements on each storey.The maximum displacement of each storey does not necessarily result in the maximum interstorey drift ratio because they do not occur at the same time i.e. Difference should be first calculated for each mode and than use srss for the sum of differences. How do you deal with this issue?
I'm checking horizontal deformations and story drift according to EC8.
In one model I've made seismic case Sy(Sx) with coefficients Kx=0.3 and Ky=1 (Kx=1,Ky=0.3)
In another for Sy(Sx) I took Kx=0 and Ky=1, and created load case 0.3Sx+Sy.
When I compared results I get almost twice bigger values for first model!
What is correct option? This is very sensitive issue,story drift requirement is quite severe, so I would appreciate any advices and help on this matter.
One more issue with story drift: I calculate it as a difference of the storey displacements, which is not quite correct,because response spectrum analysis gives the maximum lateral displacements on each storey.The maximum displacement of each storey does not necessarily result in the maximum interstorey drift ratio because they do not occur at the same time i.e. Difference should be first calculated for each mode and than use srss for the sum of differences. How do you deal with this issue?