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determine the span of the state space of base shear-toque on the shear axial V" Q - F/ 0 directly gives out
the improvable space of the shear capacity of the structural system after yielding.
3). V\ and V\ are the lateral yield and ultimate capacity of the resistant plane passing through the
center of mass. Generally, this parameter represents the sum of the resistant capacity of all lateral planes
closing to the center of mass. From fig.6, it is obvious that the increase of the value V u yc - V v yc means the
increase of the possibility that the pure torsional mechanism will occur after yielding.
and jZ ml \f y, respectively, define the
torsional capacity of the system when pure twist yield and ultimate damage will be occurring. These two
parameters control the maximum and minimum coordinates of the two critical boundaries along the
torque axial. Moreover, the improvement of the torsional capacity of the system after yielding is also
controlled by the value T 0 " - T Q V .
5)- TL = 5^ fy**yi ^ -Ti "XTil^^'i are contr & u ti° n of the torsional capacity provided by the
orthogonal lateral planes at the level of initiating yield and collapse respectively. The possibility of the
pure shear mechanism should be increased with the increase of the value 7^ - 7 1 / particularly during the
stage of inelastic response
Base Torque
Collapse Boundary
-V:
Base Shear
Yield Boundary
Elastic Space
6 y 7 y
Fig.4 Structural parameters controlling the state space of base shear-torque
, IV lv
y* y* determine the strength eccentricity of the system at
two damage levels: before yielding and at the initiating of collapse, respectively. They signify
independently the degree of the strength eccentricity on the two critical levels. Here, x v is considered to
be a constant during the elastic stage while x u p is also defined as a critical value at the instant of initiating
collapse although the strength eccentricity is varied from x y p to its' maximum value, and then decreased
to x" p with the increase of the intensity of the ground excitations gradually during the inelastic stage.