algerian earthquake resistant regulations « rpa 99 - IISEE

(4.2)
T 2 : characteristic period, associated to the category of the site and given in the table 4.7
η: is the damping correction factor given by the following formula :
≥ 0.7 4.3
where ζ (%) is the critical damping ratio depending on constitutive material, structure type
and importance of infills.
When ζ=5%, we have η =1.
Infill
Tableau 4.3 : Values of ξ (%)
Frames
Shear walls or walls
Reinforced
concrete
metal
reinforced
concrete/masonry
light 6 4
heavy 7 5
10
- R: global behavior coefficient of the structure, given in table 4.4 according to the lateral
force resisting system as defined in 3.4
In case of different lateral force resisting systems in the two considered directions, the
smallest value of R must be used.
- Q: Quality factor
The quality factor of the structure depends on :
- the redundancy and the geometry of the constituent elements.
- the regularity in plan and in elevation.
- the quality of the control of construction.
The value of Q is determined by the formula :
(4.4)
P q is the penalty to be applied depending on whether the criteria of quality q “ is satisfied or
not”. Its value is given in table 4.4
Criteria of quality “q” to verify are:
1. minimal conditions on bracing plans.
- frames system : every plan of frames must include at all floors, at least three (03) bays and
the ratio of two adjacent spans must not exceed 1.5. The frame bay can be constituted of
shear walls
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