# Sensitivity Analysis

### From OpenSeesWiki

Created by: Quan Gu (Xiamen University, China), Joel P. Conte (UCSD), Michele Barbato (LSU), Yong Li (UCSD)

This manual is intended to outline the basic commands currently available within the OpenSees interpreter for performing DDM (**Direct Differentiation Method**)-based response sensitivity analysis. This interpreter is an extension of the Tcl/Tk language for use with OpenSees. The existing Tcl commands for Finite Element response-only computation are described in the OpenSees userâ€™s guide available online at http://opensees.berkeley.edu and, thus, are not repeated in this document. The notation used herein is the same as that used in the Tcl commands manual for response-only computation. Only new Tcl commands for DDM-based response sensitivity computation are presented and explained in detail.

This manual is subdivided as follows:

- DDM-Based Response Sensitivity Computation Tcl Commands: commands added to the interpreter for response sensitivity computation.
- Demonstration Examples: four demonstration examples used to illustrate and validate the DDM-based response sensitivity analysis components implemented in OpenSees.
- Extension of an existing material,cross section, and element for DDM-based: the necessary functions needed for implementation of the DDM-based response sensitivity computation are listed and explained.
- Tcl input files for the provided application examples: Tcl input files for the above four application examples.