15.5.4.5
The plastic rotation demand is calculated with the yield rotation calculated using the displaced axis rotation and the moment-curvature analysis when performing the linear performance analysis.
The element is automatically calculated according to the plastic rotation demand θ p Equation (15A.2) .
ICONS
E = Concrete modulus of elasticity
h = Section height
I = Moment of inertia
L p = Plastic hinge length
l c = Element net opening
M y = Effective yield moment
M yi = Effective yield momentat i end
M yj = Effective yield moment at j end
Δ = Element translation between nodes
ϕ y = Flow curvature
ϕ t = Total curvature
θ p =Plastic rotation demand
θ i = i joint rotation
θ j = j node rotation
θ y = flow rotation
θ yi = flow rotation at end i
θ yj = flow rotation at end j
θ k = displaced axis rotation
θ ki = displaced axis rotation at end i
Evaluation of existing buildings and design according to Strain (ŞGDT) determining the seismic performance of the linear approximation calculation method used plastic rotation element lead θ p Eq. (15A.2) from being calculated.
![](../__attachments/1134919779/image-20200527-123118.png?inst-v=e297b259-93ee-4526-bee7-06170d782e4d)
In the above equation , ki is the axis rotation of the element at the i end and is calculated from Equation (15A.1) . The value of ki is obtained by subtracting Δ / l c from the value obtained by dividing the translation between the element nodes by the element net span, and the rotation value of the node i . In this way , the value of θ ki is obtained with the values obtained as a result of the linear calculation.
![](../__attachments/1134919779/image-20200527-082033.png?inst-v=e297b259-93ee-4526-bee7-06170d782e4d)
The θ yi value given in Equation (15A.2) is the yield rotation for frame elements and is calculated from Equation (15A.3) . In these equations, M yi and M yj are the effective yield moments at the ends i and j, respectively, and are calculated by the moment-curvature relationship derived from the section material model and the reinforcement layout. EI is the flexural stiffness of the unbroken section and is calculated from the section geometry.
![](../__attachments/1134919779/image-20200527-091315.png?inst-v=e297b259-93ee-4526-bee7-06170d782e4d)
As can be seen above, as a result of the analysis made by linear earthquake calculation, the value of θ ki , the result of the moment curvature analysis calculated according to the section geometry and the reinforcement condition, the yi value is found. In this case, the plastic rotation demand θ pi value is found with the following equation according to Equation (15A.2) .
![](../__attachments/1134919779/image-20200527-124253.png?inst-v=e297b259-93ee-4526-bee7-06170d782e4d)
Evaluation and Design According to Strain of existing buildings as seen (ŞGDT) in determining the approach to seismic performance and linear calculation method used plastic rotation demand θ p , the value is calculated by the approximate expression obtained in a linear method. In this case, when the nonlinear seismic analysis methods applied plastic made by plastic hinge rotation θ p θ obtained by the linear method with p value to show affinity to a specific order but it will be the same.