Number of automatic loadcombinations

Table of Contents

AxisVM generates all load combinations that are possible in the defined load system. Load combinations that are (supposedly) ‘not critical anyway’ are not suppressed. The influence of the (possibly rather large) number of combinations can only be felt, if it gets extreme (multiple million combinations)

Estimation #

The estimates below are based mostly on the SIA 261 code. The combinations according to EuroCode differ in the load factors (and their application), but the number of combinations remains the same. Load groups without load cases and ungrouped load cases are to be neglected. But load cases without loads are respected.

ULS

Accidental

Seismic

SLS, Rare and frequent*

SLS, quasi-permanent

Geotechnics, Type1/Type2

neglecting variable Groups with Psi2 = 0

NNumber of loadcombinations
GNumber of permanent loadgroups, tensioning **
QNumber of variable loadgroups, moving groups, wind snow loadgroups, Q>1
ANumber of accidental loadgroups, fire, snow (accidental) ***
SNumber of seismic loadgroups
gkNumber of load cases in permanent load group k (simultaneous)
g*kNumber of load cases in permanent load group k (exclusive), tensioning ****, gk * >= 1
qkNumber of load cases in variable load group k (simultaneous), qk>= 1
pkNumber of load cases in variable load group k (exclusive)
akNumber of load case in accidental load group k
skNumber of load cases in seismic load group k

Accuracy #

The estimation can be used as a rough approximation.

CaseCombinations (AxisVM)EstimationDelta
1Building18502260+22.2%
2Bridge2036020936+2.8%
3Industrial805888807840+0.2%
4Fictious92610109127627-1.4%
1 – Building2 – Bridge3 – Industrial4 – Fictious

* different factors, but the same number of combinations

** number of tensioning groups is not relevant, it is only distinguished between tensioning present (1) or not (0)

*** Dependant on the code and national annex to the EuroCode

**** Number of tensioning load cases is not relevant, it is only distinguished between tensioning present (2) or not (0)

Source of information www.ingware.com

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