Abstract

A documented pushover procedure on asymmetric, single-story, reinforced concrete (RC) buildings using inelastic dynamic eccentricities is extending in this paper on asymmetric multi-story RC buildings, aiming at the Near Collapse state. The floor lateral static forces of the pushover procedure are applied eccentric to the Mass Centers using appropriate inelastic dynamic or design eccentricities (dynamic plus accidental ones) to safely estimate the ductility demands of both the flexible and stiff sides of the building due to the coupled torsional/translational response. All eccentricities are applied with respect to the “Capable Near Collapse Principal System” of multi-story buildings, which is defined appropriately using the well-known methodology of the torsional optimum axis. Moreover, two patterns of lateral forces are used for performing the analysis, where in the second one an additional top-force is applied to consider the higher-mode effects. A six-story, asymmetric, torsionally-sensitive RC building is examined to verify the proposed pushover procedure relative to the results of non-linear dynamic analysis. The outcomes indicate that the proposed pushover procedure can safely predict the seismic ductility demands at the flexible and stiff sides, providing reliable estimates for the peak inter-story drift-ratios throughout the building as well as a good prediction of the plastic mechanism.

Highlights

  • It is noticed that in the recent release of the Italian Building Code (NTC18) [10], new provisions were inserted about the load profiles and the choice of control nodes in pushover analysis that lead to different capacity curves and to different conclusions of the seismic assessment procedure

  • The plan inelastic resulted from the proposed proceThedisplacement plan inelasticprofiles displacement profiles resulted frompushover the proposed pushover procedure compare dure with compare the seismic demand ones produced by Non-Linear Response History Analysis (N-LRHA)

  • A recently proposed procedure of non-linear static analysis on singlerefined in the current paper with a view to serve as a rational seismic assessment tool of story reinforced concrete (RC) buildings using inelastic dynamic eccentricities is extended and appropriately multi-story RC buildings at the Near Collapse (NC) state

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Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. There is not a clear identification of the appropriate (principal) building directions which codes propose for the application of horizontal seismic forces to perform push over analysis Another point related to this method is that codes suggest super-position of non-linear analyses results to consider the spatial seismic action effects. According to the proposed procedure, in order to consider the coupled torsional/translational response, the floor lateral static forces are applying eccentrically to CM, using the inelastic dynamic or design eccentricities, at two in-plan positions: the first one towards the stiff side and the second one towards the flexible side of the building, along each principal direction. The proposed pushover methodology on asymmetric multi-story RC buildings aims directly at the safe estimation of the seismic demands at the NC state in terms of floor inelastic angular deformations and displacements, providing that the building under examination shows sufficient ductility and is regular in elevation according to seismic codes. If the building under examination is not enough ductile or has an irregular layout in elevation, the force-based proposed pushover procedure will highlight all the structural deficiencies as well as the possible plastic mechanisms

Methodology
Non-Linear Model
Three “Capable Near
Normalized
Design
Application
Consideration of the Higher-Mode Effects
Numerical Example of a Six-Story Building
Building
Design of the Six-Story Building
Calculation of Inelastic Dynamic Eccentricities
Verification Procedure
Isec III
I Ithe
Figures and angular
13. Floor angular deformations of caseat1NC:
16. Comparison
Pushover Procedures
19. Capacity
Conclusions

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