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Partial load factors for loads when designing glass elements according to prEN16612

Glass in buildings has numerous applications and depending on the level of risk it represents for the users it should be designed according to Eurocode's class of consequences (CC). It is normal that main structural elements are designed to larger factor of safety to provide reliability then the secondary structure and the infill.


In the picture below we can see a typical section through a typical multistory building.



Figure 1 - Typical section through a multistory building


The beams, columns, walls and floors are forming the main structure of a building as it can be seen in the picture above.


These elements are considered structural because they carry themselves and secondary structures and in case of failure, endanger the fundamental stability of the entire or portions of the building.


Secondary structures can be the windows assembly frames, curtain walls or panel support elements which needs to ensure only their own stability, strength and deformations.


A failure in one of these elements would only affect the infill panel or the non-structural elements supported by then without affecting the main structure. Replacing the secondary structure can be done independent from the main structure.


Infill panels are elements used to close a building without offering any stabilizing effect on the main structure.


As failure of secondary structure on infill panels do not have same human or economic consequences it is normal to choose the proper class of consequence described in EN 1990 for each category.



The values of the actions shall be determined in accordance with the appropriate parts of EN

1991.

The design value of the action (design load) shall be:

for ultimate limit state equation 3.a




for serviceability limit state equation 3.b




where:


Fd is the design value of the combination of actions;

G is the value of permanent actions (e.g. self-weight load, permanent equipment);

Qk,1 is the characteristic value of the leading variable action (e.g. imposed load on

floor, wind, snow),

Qk,i is the characteristic value of the accompanying variable action (e.g. wind, snow)

ψ0,i are factors for combination value of accompanying variable actions

ψ1 is the factor for frequent value of a variable action

ψ2,i:is the factor for quasi-permanent value of a variable action

ψG is the partial factor for permanent actions, also accounting for model uncertainties

and dimensional variations

ψQ: is the partial factor for variable actions, also accounting for model uncertainties

and dimensional variations

Table 1 - partial load factors for variable and permanent actions


Table 2 - Ψ factors that reduce the importance of the secondary variable load

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