Damage Assessment of Inelastic Structures under Simulated Critical Earthquakes - Structural Seismic Design Optimization and Earthquake Engineering - page 128

Chapter 6

Damage Assessment of
Inelastic Structures under
Simulated Critical Earthquakes

Abbas Moustafa
Minia University, Egypt

ABSTRACT

Damage of structures can be significantly reduced through robust prediction of possible future earth-
quakes that can occur during the life-time of the structure and through accurate modeling of the nonlinear
behavior of the structure under seismic loads. Modern seismic codes specify natural records and arti-
ficially generated ground accelerations as input to the nonlinear time-history analysis of the structure.
The advantage of using natural records is the inclusion of all important characteristics of the ground
motion (fault properties, path effects and local soil condition) in the design input. This option requires
selecting and scaling a set of proper accelerograms from the available records. However, the site under
consideration may have limited or scarce earthquake data. In such case, numerically simulated ground
motions can be employed as input to the dynamic analysis of the structure. This chapter deals with
the damage assessment of inelastic structures under numerically simulated critical earthquakes using
nonlinear optimization, inelastic time-history analysis, and damage indices.

1. INTRODUCTION

tion techniques. The critical excitation method
relies on the high uncertainty associated with
the occurrence of the earthquake phenomenon
and on the safety requirements of important and
lifeline structures. The earthquake input is taken to
maximize the damage index of the structure while
satisfying predefined constraints that are quanti-
fied from the earthquake data available at the site.
Numerical illustrations for damage assessment of

Damage indices describe the state of the structural
damage and correlate well with actual damage
displayed during earthquakes. The critical ground
motion for a give structure is estimated by solving
an inverse nonlinear dynamic problem in time
domain using constrained nonlinear optimiza-