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CONTENTS
Volume 1, Number 4, December 2010
 

Abstract
This paper summarizes results of a comprehensive analytical study aimed at evaluating the influence of strong ground motion duration on residual displacement demands of single-degree-of-freedom (SDOF) and multi-degree-of-freedom (MDOF) systems. For that purpose, two sets of 20 earthquake ground motions representative of short-duration and long-duration records were considered in this investigation. While the influence of strong ground motion duration was evaluated through constantstrength residual displacement ratios, Cr, computed from the nonlinear response of elastoplastic SDOF systems, its effect on the amplitude and height-wise distribution of residual drift demands in MDOF systems was studied from the response of three one-bay two-dimensional generic frame models. In this investigation, an inelastic ground motion intensity measure was employed to scale each record, which allowed reducing the record-to-record variability in the estimation of residual drift demands. From the results obtained in this study, it was found that long strong-motion duration records might trigger larger median Cr ratios for SDOF systems having short-to-medium period of vibration than short strong-motion duration records. However, taking into account the large record-to-record variability of Cr, it was found that strong motion duration might not be statistically significant for most of the combinations of period of vibration and levels of lateral strength considered in this study. In addition, strong motion duration does not have a significant influence on the amplitude of peak residual drift demands in MDOF systems, but records having long strong-motion duration tend to increase residual drift demands in the upper stories of long-period generic frames.

Key Words
strong-motion duration; residual displacement ratios; residual drift demands.

Address
Jorge Ruiz-Garcia: Facultad de Ingenieria Civil, Universidad Michoacana de San Nicolas de Hidalgo, Cd.
Universitaria, 58040 Morelia, Mexico

Abstract
The paper presents a study on the numerical simulation of the behaviour of conventional reinforced concrete (RC) beams strengthened by thin fibre-reinforced cementitious matrix (FRCM) jackets. The study covers the cases of retrofitting RC beams with or without stirrups with jackets reinforced with longitudinal and transverse steel reinforcement or with light wire mesh. The strengthened RC beams to be modelled were tested under static monotonic and fully reversing cyclic loading. The numerical results show that the numerical model used predicted quite well the experimental results.

Key Words
fibre reinforced cementitious composites; seismic strengthening; numerical simulation.

Address
K. Georgiadi-Stefanidi, E. Mistakidis, P. Perdikaris and T. Papatheocharis: Dept. of Civil Engineering, University of Thessaly, 38334 Volos, Greece

Abstract
Historical buildings in seismically active regions are severely damaged by earthquakes, since they certainly were not designed by the original builders to withstand seismic effects. In particular the reports after major ground motions indicate that earthquake-induced pounding between buildings may lead to substantial damage or even collapse of colliding structures. The research on structural pounding during earthquakes has been recently much advanced, although most of the studies are conducted on simplified single degree of freedom systems. In this paper a detailed pounding-involved response analysis of three adjacent structures is performed, concerning the main bodies of the

Key Words
pushover analysis; earthquake-induced pounding; colliding structures; masonry building; reinforced concrete building; non-linear behaviour.

Address
Alessandra Fiore and Pietro Monaco: Politecnico di Bari, Department of Civil and Environmental Engineering, Via Orabona 4, 70125 Bari, Italy

Abstract
There are several important considerations that need to be made in the capacity design of RC frame-wall structures. Capacity design forces will be affected by material overstrength, higher mode effects and secondary loadpaths associated with the 3-dimensional structural response. In this paper, the main issues are identified and different means of predicting capacity design forces are reviewed. In order to ensure that RC frame-wall structures perform well it is explained that the prediction of the peak shears and moments that develop in the walls is particularly important and unfortunately very challenging. Through examination of a number of case study structures it is shown that there are a number of serious limitations with capacity design procedures included in current codes. The basis and potential of alternative capacity design procedures available in the literature is reviewed, and a new simplified capacity design possibility is proposed. Comparison with the results of 200 NLTH analyses of frame-wall structures ranging from 4 to 20 storeys suggest that the new method is able to predict wall base shears and mid-height wall moments reliably. However, efforts are also made to highlight the uncertainty with capacity design procedures and emphasise the need for future research on the subject.

Key Words
capacity design; frame wall; dual system; seismic design.

Address
Timothy J. Sullivan: Dept. of Structural Mechanics, Universita degli Studi di Pavia, Via Ferrata 1, Pavia, 27100, Italy

Abstract
The effect of dead loads on dynamic responses of uniform elastic beams is examined by means of a governing equation which takes into account initial bending stress due to dead loads. First, the governing equation of beams which includes the effect of dead loads is briefly presented from the author

Key Words
beams; dead load; initial stress; vibration; dynamic analysis; Galerkin equation; linear and nonlinear; live load; natural frequency; safety.

Address
Hideo Takabatake: Dept. of Architecture, Kanazawa Institute of Technology, Institute of Disaster and Environmental Science3-1 Yatsukaho, Hakusan, Ishikawa Prefecture, 924-0838, Japan


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