Good morning Dave,

According to what you comment, I would like to clarify a bit what I understood from your comment, if I perform a dynamic analysis under B31.4 I will not be able to obtain the admissible for efforts within the dynamic response?

Should I then carry out static load cases for earthquakes to be able to evaluate these admissible ones?

Are the loads obtained in the dynamic analysis the ones that I should use to design my supports? Or should I take the charges from the static? the query is that I have values ​​twice the load in static compared to dynamic.

Another query would be that in the majority of cases that have been reviewed, the combinations for the dynamic earthquake modulus are the following

First case

Case = EARTHQUAKE H
Factor = 1
Direction X
Case = SISIMO V
Factor = 2
Direction Y

Second case

Case = EARTHQUAKE H
Factor = 1
Direction X
Case = SISIMO V
Factor = 2
Direction Y

Should I make more combinations?

The Civil area carried out an analysis in SAP as follows:


Own weight D
Fluid (water in pipe) F
Preestres P
Earthquake Spectrum in X Ex
Earthquake Spectrum in Y Ey
Earthquake Spectrum in Z Ez



D + F + P + 0.7Exyz
D + F + P + 0.7Eyxz
D + F + P + 0.7E (-x) yz
D + F + P + 0.7Ex (-y) z
D + F + P + 0.7E (-y) xz
D + F + P + 0.7Ey (-x) z
D + F + P + 0.7E (-x) (- y) z
D + F + P + 0.7E (-y) (- x) z
D + F + P + 0.7Exy (-z)
D + F + P + 0.7Eyx (-z)
D + F + P + 0.7E (-x) and (-z)
D + F + P + 0.7Ex (-y) (- z)
D + F + P + 0.7E (-y) x (-z)
D + F + P + 0.7Ey (-x) (- z)
D + F + P + 0.7E (-x) (- y) (- z)
D + F + P + 0.7E (-y) (- x) (- z)


My pipe is supported on a cable-stayed bridge with cables, the supports were modeled with the stiffness of each cable