MEng Dissertation Abstract

1. ABSTRACT
The target of the present Diploma thesis is to perform a parametric study on steel
moment resisting frames, in order to obtain all the qualitative parameters that define their
inelastic response, under earthquake excitation. For this purpose, the steel frames are
subjected to Incremental Dynamic Analysis for a set of 8 real far-field ground motions. In
order to ensure a large and accurate database, an intense scaling was performed, with
respect to the PGA, ranging from 0.05 g to 6 g with a step of 0.05 g. The dynamic analyses
were performed using the OpenSEES software. Three case studies are examined. In the
first two cases, bilinear hysteretic model with 3% hardening was used, with and without
geometric nonlinearity, to evaluate the impact of second order effects on the response of
the frames. In the third case, a hysteretic model with cyclic degradation of strength and
stiffness was used, also taking into account P-D phenomena. The basic aim is to identify
the governing design parameter, for the particular frames, among those examined in this
study. Strength reduction and overstrength factors are examined with respect to global and
local ductility levels. Therefore, a performance based engineering approach is implemented
to this study, defining the performance level of each frame whenever these parameters are
calculated. Statistical tools have been used for increased accuracy and minimum error
margin. Furthermore, the collapse mechanisms of the frames are inspected, so as to
confirm the validity of yield and failure predictions according to each parameter on the
basis of the initial design. Programming techniques were implemented for the automation
of the whole process and the quality control of the obtained results. The analysis results
were afterwards used for the vulnerability assessment of the frames, comparing all three
cases studied herein. Finally, the vulnerability assessment results were used to predict the
direct financial loss within the scope of this study, in order to illustrate the practical
importance of the case studies.