Cumulative seismic damage of reinforced concrete bridge piers

The results of the testing were also used in an analytical study of cumulative damage. A simple fatigue-based model, derived from existing theories in the literature, was used to predict cumulative damage in flexural bridge piers. Critical damage measures,such as stiffness degradation, dissipated hysteretic energy, ductility, and fatigue were evaluated againstobserved behavior. It was found that none of these damage measures consistently predict observed damage limit states though fatigue-baesd models demostrated better reliability. It was further observed that the energy-dissipation capacity of members is path-depend, hence, models of seismic damage that rely only on measures of energy dissipation cannot predict failure if it is not related to ductility. findings from this study will provide additional input into the developmentof perfomance-based design specifications wherein design is linked to damage limit states.(AU)

Inelastic response prediction of structures subjected to seismic loads

A brief overview of analytical techniques to carry out an inelastic time-history analysis of structures under seismic loads is presented. The primary objective of the discussions presented in this paper is to explore the adequacy and limits of approximate methods and the enhanced reliability of more refined computational methods. In particular, the use of flexibility-based member models, the choice of multi-parameter hysteretic models, and the effects of energy-dissipation on global structural response will be examined. A sample application of inelastic seismic evaluation of an existing concrete building damaged in the recent Northridge earthquake concludes the paper.(AU)

IDARC2D version 4.0 : A computer program for the inelastic damage analysis of buildings

This report summarizes the modeling of inelastic structures and enhancements to the program series IDARC developed for analysis, design and support experimental studies. This report presents a synthesis of all the material presented in previous reports NCEER-87-0008, NCEER-92-0022 (and in other related reports). This report presents also the new developments regarding modeling of inelastic elements and structures with supplemental dampimg devices, infill panels, etc. (AU)

Evaluation and retrofit of lightly reinforced concrete buildings

One of the major areas of research in the buildings project has been the evaluation of the perfomance and study of the rehabilitation of existing concrete buildings. Most of these structures were designed only for gravity loads, without any consideration of seismic forces. The seismic behavior of typical gravity load designed (GLD) buildings has been studied through a coordinated program of full-scale component tests, reduced-scale shake table model tests, and analytical simulation. Guidelines have been developed and a monograph has been drafted to asist engineers in evaluating gravity-load designed buildings. The rehabilitation study has concentrated on simple techniques especially suited to regions of moderate seismicity.(AU)

IDARC : Computer program for inelastic damage analysis of reinforced concrete structures

The need to evaluate structures which experience behavior as designed by current seismic codes motivated the development of a specialized computer program which models such behavior in an efficient way. The primary modeling technique employed in the computer program IDARC (Inelastic Damage Analysis of Reinforced Concrete Structures) is the representation of the overall behavior of components in terms of macromodels. Each component of the structural system is discretized into a series of macroelements: beam-column elements whose inelastic behavior is characterized by a primarily flexural response, shear-wall elements that may deform inelastically in flexure or shear, floor-slabs that are capable off deforming inelastically in the plane of the diaphragm, and inelastic rotational springs that may be attached at any node. Special-purpose elements, such as viscoelastic braces and other friction devices for hysteretic energy dissipation were also developed.(AU)

Hysteresis model for seismic analysis of non.ductile flat - plate buildings

Recent awareness of the probability of a moderate seismic event east of the rockies has caused concern of the damage potential of the existing stock of ordel flat-slab buildings which were designed to resist gravity load only. In an effort to evaluate the seismic resistance of non-ductile flat plate buildings, an experimental study was conducted to characterize the inelastic hysteretic behavior of typical slab-column connections. Based on test observartions, a general hysteretic model of the slab-column connection was developed. Four control parameters were identified to characterize the hysteresis loops for typical interios and exterior connections respectively. The model was incorporate into an inelastic computer code for seismic analysis of reinforced concrete structures and used in analytical simulations of shear-drift response of single connections. The suitability of the proposed model for evaluatiing the seismic performance of flat-plate buildings is discussed (AU)

IDARC version 3.0 : A program for the inelastic damage analysis of reinforced concrete structures

This report summarizes the significant modeling and program enhancements to the computer coe, IDARC (see Technical Report NCEER-87-0008) for inelastic damage analysis of reinforced concrete frame-wall structures. The base program is capable of analyzing structures in the inelastic range subjected to combined horizontal and vertical excitations, quasi-static cyclic loading, and incrementally applied static loads.(AU)

Gravity-load-designed reinforced concrete buildings : Seismic evaluation of existing construction and detailing strategies for improved seismic resistance

The study provides information on the effects of retrofit strategies involving the confinement of beam-column joints through jacketing, wherein the purpose is to improve column confinement, ensure adequate development length in bottom beam bars, and provide full joint shear capacity. The study also provides a methodology to evaluate structural retrofit through inelastic analysis and damage indicators.(AU)