# Deformation and Plastic Rotation Demand

The strain and plastic rotation demands are determined using the total displaced axis rotation θ_{k} obtained at the element end . Structure performance is determined as a result of unit strain and plastic rotation demands calculated by linear performance analysis in existing structures.

**ICONS**

* h = *Section height

*Plastic hinge length*

**L**_{p}=**M**

_{y }*Effective yield moment*

**=****ϕ**

_{y }*Yield curvature*

**=****ϕ**

_{t }*Total curvature*

**=****θ**

_{p }*Plastic rotation demand*

**=****θ**

_{y }*Yield rotation*

**=****θ**

_{k }*Displaced axis rotation*

**=****15.5.4. Determination of Unit Shape Deformation and Plastic Rotation Demands**

**15.5.4.1 - The** unit deformation and plastic rotation demands of the element sections shall be determined by using the total displaced axis rotation θ _{k} obtained at any element end as a result of the calculation made according to **4.7** or **4.8.2** . The definition of displaced axis rotations at the element ends is given in **ANNEX 15A** .

**15.5.4.2 -** total demand curve end section of the element φ _{t} , **Eq. (15.2)** wherein the bond will be calculated.

**In Eq. (15.2)** , θ _{y is the} displaced axis yield rotation at the element end section , and ϕ _{y} is the flow curvature at the element end section. The definition of displaced axis yield rotations at the element ends is given in **ANNEX 15A** . L _{p is the} length of the plastic joint and shall be taken equal to half the cross-sectional dimension in the effective direction.

**15.5.4.3 -** Effective yield curvature ϕ _{y} and effective yield moment M _{y in} reinforced concrete systems will be calculated by moment curvature analysis.

**15.5.4.4 - For confined** or **unconfined** concrete and reinforcement steel models, if no other selection is made, **ANNEX 5A** can be used .

**15.5.4.5 -** plastic rotation lead section of element θ _{p} , **Eq. (15A.2)** shall be obtained from.

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