ATC-40 also recommends changing the lateral load pattern to reflect the displaced shape of the building at the end of each phase of the analysis.

It is also possible to consider degrading effects in the simplified procedure described above by reinitializing the analysis at the end of each phase and plotting a new capacity curve. Each new curve begins with a degraded system that accounts for the state of elements at the end of each phase. Figure 21.11b provides a conceptual view of three such capacity curves. The final capacity curve is drawn by connecting the final point on the previous curve to a new point on the next capacity curve at the next displacement increment so as to produce a saw-tooth response as shown in Figure 21.11b. Conversion to ADRS Format

The capacity curve obtained either by the simplified process described in the previous section or by a detailed nonlinear analysis technique is transformed into ADRS format. The following relationships provide the conversion to ADRS format:

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