Adaptive Design Models Considering Lifespan of Buildings
 

H. Allison Smith
    Assistant Professor, Stanford University

Sara J. Wadia
    Doctoral Student, Stanford University
 

ABSTRACT

A new design procedure is proposed which integrates system identification procedures and fuzzy set mathematics with damage and degradation models to formulate an adaptive design model capable of considering the changes a structure experiences during its lifespan.  Using this design model, the original finite element model can adapt to the assumptions inherent in finite element analysis and to the structural degradation that takes place as the system ages.

The adaptive model proposed here, unlike conventional system identification techniques, does not require experimental response data from the as-built structure.  Instead, fuzzy set mathematics is used to represent the level of confidence of various design assumptions, and the vertex method is used to develop a fuzzy set which bounds the structural parameters.  The parameters used in this study are natural frequency, participation factor, damping coefficient, and story displacement.  Membership functions and confidence intervals for the four parameters are determined by performing multiple dynamic analyses involving extreme cases of the model assumptions.  Using the vertex method, the analyses associated with these models establish the bounds of the fuzzy set and define the membership function.

This study enables the prediction a priori of the most probably sources and magnitudes of three types of modeling error: calibration, degradation, and damage.  Three newly developed models are integrated into an iterative design and analysis package which allows the engineering to redesign the structure when the membership function represented the structural parameters becomes unacceptable.
 

Contact Information:

Prof. S. Wadia-Fascetti (swf@neu.edu)
Dept. of Civil & Env. Engineering
Northeastern University
Boston, MA  02115

Reference:

Smith, H. A. and Wadia, S. J., (1992) “Adaptive Design Models Considering Lifespan of Buildings.”  Journal of Intelligent Material Systems and Structures.  3 (4), pp. 585-599, October 1992.

Back to: publications page
Back to: group home page