Seismic damage estimation of in-plane regular steel moment resisting and x-braced frames

Abstract

Abstract:Simple empirical expressions to estimate maximum seismic damage on the basis of five well known damage indices for planar regular moment resisting and x-braced steel frames are presented. They are based on the results of extensive parametric studies concerning the inelastic response of a large number of these frames to a large number of ground motions. Thousands of nonlinear dynamic analyses are performed by scaling the seismic records to different intensities in order to drive the structures to different levels of inelastic deformation and finally to collapse. The statistical analysis of the created response databank indicates that the number of stories, period of vibration, stiffness ratio, capacity factor (for moment resisting frames), brace slenderness ratio and column stiffness (for x-braced frames) and characteristics of the ground motion, such as characteristic period and spectral acceleration, strongly influence damage. Nonlinear regression analysis is employed in order to derive simple formulae, which reflect the influence of the aforementioned parameters and offer a direct estimation of the damage indices used in this study.More specifically, given the characteristics of the structure and the ground motion, one can calculate the maximum damage observed in column bases and beams (for moment resisting frames) or in braces (for x-braced frames). Finally, two examples serve to illustrate the use of the proposed expressions and demonstrate their accuracy and efficiency.

Simple Formulae for Damage Estimation of Composite Steel/Concrete Moment Resisting Frames

“…Similar expressions have been proposed by the authors for steel MRFs [19], but research on steel/concrete composite MRFs is still missing. For that reason, a large number of steel/concrete composite MRFs consisting of I steel beams and concrete filled steel tube (CFT) columns are subjected to an ensemble of 100 ordinary (i.e.…”

Evaluating the Behaviour Factor of Medium Ductile SMRF Structures

“…Gravity load on the beams is assumed to be equal to 27.5kN/m (dead and live loads of floors), while steel members are made of grade S235. Data of the frames, including storey number and beam and column sections are presented in Table 1 taken from Kamaris et al [30]. In that table, expressions of the form, e.g., 280-360(1-4) + 260-330(5-6) mean that the first four stories have columns with HEB280 sections and beams with IPE360 sections, whereas the next two higher stories have columns with HEB260 sections and beams with IPE330 sections.…”

Probabilistic Evaluation of Seismic Performance for a Steel Moment Frame Using Damage Indices

“…Roufaiel and Meyer proposed this index in 1987 for concrete structures, although it has been used for steel structures as well [7]. In this model, damage is described as the ratio between the secant stiffness of a member at its onset of failure, and the minimum secant stiffness reached so far in the moment-curvature relationship.…”

“…It can be said that this index is the most famous one with the greatest number of citations from studies concerning both concrete and steel structures [7,4]. In this index, damage is modelled as the linear combination of ductility (excessive deformations) and dissipated energy in loading cycles which takes the following form:…”

“…Their study displays the correlation among values of these damage indices for increasing levels of ground motion intensity. Also, Kamaris et al [7] presented simple empirical expressions to estimate maximum seismic damage on the basis of the five selected damage indices for planar regular moment resisting and x-braced steel frames.…”