 • Linear performance analysis defined in Section 15.5 is performed automatically for existing structures with certain reinforcement layout, material model and knowledge level. • The earthquake calculation is made automatically with the nonlinear methods defined in Section 15.6 for existing structures with certain reinforcement layout, material model and information level.

TBDT Article 15.4.1 according to the existing structures Evaluation and Design According to Strain (ŞGDT) approach applied with the seismic Section 15.5 as defined in the linear calculation or Section 15.6 as defined in the linear calculation method used.

Earthquake Calculation with Linear Calculation Methods defined in TBDY Section 15.5 is also defined as linear performance analysis. Although the earthquake calculation is made linear in linear performance analysis, the results are evaluated with the Assessment and Design According to Shape Change (ŞGDT) approach. For this reason , it should not be confused with the Design Based on Strength (DGT) approach. Linear performance analysis is used to determine the structural performance of existing or strengthened buildings under the effect of earthquakes. While determining the structural performance, the element plastic rotation and unit deformation demands are found with a linear and approximate method. Plastic rotation and strain demands are compared with the limit values.The damage zone of the sections is determined and the performance of the existing or reinforced structure is determined accordingly.

Earthquake Calculation with Non-Linear Calculation Methods described in TBDY Section 15.6 , the purpose of nonlinear calculation methods to be used for determination of structural performance of existing or reinforced buildings under the effect of earthquake and strengthening calculations, plastic deformation and plastic rotation demands regarding ductile behavior for a given earthquake is the calculation of internal force demands on behavior. After the plastic rotation and internal force demands are determined, the damage area of the sections is determined by comparing with the plastic rotation and internal force limit values . In this way, the structural performance at the cross-section and building level is determined. Nonlinear calculation methods are explained in Section 5 of TBDY .