The first formal regulations for assessment and seismic rehabilitation of structures started in 1980's, with the implementation of the results of developed research, and efforts conducted by organizations such as the Applied Technology Council (ATC), Federal Emergency Management Agency (FEMA), American Society of Civil Engineers (ASCE), among others; which have compiled different methodologies for evaluation and rational design of structures subjected to seismic loads. In our country, the Structural Design Code for the Republic of Panama, in its last version (REP-2014) incorporates for the first time design methodologies based on performance, as an alternative lateral force method; and refers to the document An Alternative Procedure for Seismic Analysis and Design of Tall Buildings located in the Los Angeles region. This article specifically presents the nonlinear static procedures for structural performance evaluation of buildings. Nonlinear modelling to generate the seismic capacity curve for a building (pushover curve) will also be described. Similarly, seismic demand characterization by inelastic acceleration spectra for different earthquake levels will be presented. Another important aspect to be studied is the global structural response of lateral displacements, as well as the local response in terms inelastic rotations of the elements. By applying this methodology the engineer can verify whether the structural response (i.e., exhibited damage) satisfies the acceptance criteria established by design codes.