Evaluation Of A Framed Structure Damaged ByThe 1997 Umbria-Marche Earthquake (original) (raw)

L Seismic Performance Assesment Based on Damage of Structures – Part 1 : Theory Udc 699

2011

The paper presents methodology for safety assessment and design of earthquake resistant structures based on application of damage spectra. The damage spectrum can be used for seismic evaluation of vulnerability of structures with given properties and can provide information of damage potential of the recorded ground motions. Damage spectrum represents a variation of a damage index versus structural period for a single-degree-of-freedom system subjected to an earthquake ground motion. The improved damage index, based on plastic deformation and hysteretic energy dissipation, is applied. It depends on maximal plastic deformation, ductility capacity and function including cumulative damage effects. This function, besides the parameter including influence of deterioration, depends on the history of cyclic deformations and on both cyclic and accumulative ductility.

Seismic performance assessment based on damage of structures, Part 1: Theory

Facta universitatis - series: Architecture and Civil Engineering, 2011

Damage assessment of a deficient reinforced concrete frame subjected to different seismic levels

1st Annual International Conference on Architecture and Civil Engineering (ACE 2013), 2013

Many reinforced concrete (RC) buildings around the world designed and built based on old codes may sustain certain level of damage or even collapse when subjected to earthquakes, as has been evident in recent earthquakes. Decision on strengthening versus demolition can be made based on evaluation of potential damage the building might suffer as a result of earthquake. In this study, the issues of identification, location and quantification of the damage imparted to a tested 3-storey RC frame designed based only for gravity loads are investigated and compared with those from experiment. After calibration, series of different seismic levels based on current seismic codes are applied to the frame and corresponding damage levels and failure mechanisms are obtained. The results demonstrate the potential of using damage index to quantitatively identify and locate the probable damage distribution in the building at a statistically expected earthquake.

A New Damage Model for the Seismic Damage Assessment of Reinforced Concrete Frame Structures

In most existing reinforced concrete structures the deformation capacity deteriorates due to the low cycle fatigue effect. In order to take this effect into account in a seismic assessment, the cumulative damage caused by the energy dissipation has to be quantified. In the paper a new damage model for seismic damage assessment of reinforced concrete frame structures is proposed. It combines deformation and energy quantities at the element level in order to take into account the cumulative damage. In the new model the damage index is expressed as a deformation demand/capacity ratio. The equivalent deformation capacity is used as the available deformation capacity which takes into consideration the influence of cumulative damage. It is defined as a linear function of an energy demand/capacity ratio, and its range of values is between the monotonic and cyclic ultimate drift. In order to apply the new model, data on demands and capacities are needed. Seismic demands can be estimated by ...

Structural damage modelling and assessment

2014

A lot of research work has been done during the last decades, focusing on the structural damage modelling and assessment. This rapidly growing scientific field forms a basis for efficient structural design, health monitoring, and lifetime management. The computer-based modelling and assessment make a quantification of the structural damage evolution possible. It is an important tool for prediction or explanation of damage in a large variety of civil engineering structures. In this context, the structures can be real, planned, or experimental specimens. Several new damage simulation and evaluation approaches, including analytical, numerical, and intelligent procedures, have been considered in the present special issue.

Guidelines for seismic assessment of damaged buildings

Structural post-earthquake functionality is conventionally evaluated by trained engineers via visual inspection of the damage. A building is tagged "Green" (unrestricted access), "Yellow" (restricted access), or "Red" (no access) according to the severity of the observed damage. Whether the damage implies an actual decay in safety level of the building occupants during aftershocks is essentially left to judgment. We propose to use engineering analyses performed prior to an earthquake to determine the level of degradation in building safety implied by several different damage states. We use the loss of capacity (in ground motion terms) associated with each damage state as the quantitative measure of degradation. The likelihood that an aftershock will exceed a specific (reduced) capacity provides an objective criterion for assigning the appropriate tagging condition to that damage state. This knowledge can help engineers decide on the appropriate occupanc...

2012 Emilia earthquake, Italy: reinforced concrete buildings response

Data of the Italian National Institute of Statistics are collected aimed at characterizing Reinforced Concrete (RC) building stock of the area struck by the 2012 Emilia earthquake (number of storeys, age of construction, structural typology). Damage observations, collected right after the event in reconnaissance reports, are shown and analyzed emphasizing typical weaknesses of RC buildings in the area. The evolution of seismic classification for Emilia region and RC buildings' main characteristics represent the input data for the assessment of non-structural damage of infilled RC buildings, through a simplified approach (FAST method), based on EMS-98 damage scale. Peak Ground Acceleration (PGA) capacities for the first three damage states of EMS-98 are compared with registered PGA in the epicentral area. Observed damage and damage states evaluated for the PGA of the event, in the epicentral area, are finally compared. The comparison led to a fair agreement between observed and numerical data.

Observed Seismic Vulnerability of Italian Buildings

AIP Conference Proceedings, 2008

A very large database of post-earthquake building inspections carried out after the main Italian events of the last 30 years has been processed in order to derive fragility curves for 23 building typologies, mostly referring to masonry structures. The records (more than 91000) of this very complete and homogeneous dataset have been converted into a single damage scale with five levels of damage, plus the case of no damage. For each affected municipality a value of PGA and Housner Intensity (I H ) has been evaluated using attenuation laws. Damage probability matrices have been then extracted. These experimental data have been fitted through lognormal fragility curves using an advanced nonlinear regression algorithm also taking into account the relative reliability of each point by the bootstrap technique. The significant concentration of experimental data at low levels of ground motion, associated to the selected analytical expression, determine the peculiar shape of some of the curves, with a very steep initial branch followed by an almost horizontal curve for increasing values of ground motion. Explanations and possible solutions are discussed.

Structural damage evaluation: theory and applications to earthquake engineering

2004

The further development of performance-based earthquake engineering (PBEE) is on the current agenda of the earthquake engineering community. A part of assessing the seismic performance of civil engineering structures involves estimation of seismic damage. The conventional approach to damage estimation is based on fragility functions that relate some chosen parameters of structural response to incurred damage. Therefore, damage prediction is based exclusively on the knowledge of the chosen structural response parameters, meaning that damage analysis is uncoupled from the structural analysis. The structural response parameters selected for use in damage analysis are usually referred to as engineering demand parameters (EDP). In the present study, it is shown that for structural damage estimation, the uncoupled damage analysis has deficiencies that lead to less accurate damage prediction. These shortcomings originate from two sources: first, dependence of practically all EDPs on struct...

Damage-dependent vulnerability curves for existing buildings

Earthquake Engineering & Structural Dynamics, 2013

Seismic behavior of damaged buildings may be expressed as a function of their REsidual Capacity (REC), which is a measure of seismic capacity, reduced by damage. REC can be interpreted as the median value of collapse vulnerability curves. Its variation owing to damage is a useful indication of increased building vulnerability. REC reduction, indicating the lowering of seismic safety after an earthquake (performance loss, PL), represents an effective index for assessing the need of seismic repair/strengthening after earthquakes. The study investigates the applicability of a pushover-based method in the analysis of damaged structures for the case of existing under-designed RC buildings. The paper presents a systematization of the procedure in an assessment framework that applies the capacity spectrum method based on inelastic demand spectra; furthermore, the vulnerability variation of a real building is investigated with a detailed case study. The behavior of damaged buildings is simulated with pushover analysis through suitable modification of plastic hinges (in terms of stiffness, strength and residual drift) for damaged elements. The modification of plastic hinges has been calibrated in tests on nonconforming columns. The case study analysis evidenced that, for minor or moderate damages, the original structural displacement capacity was only slightly influenced, but the ductility capacity was significantly reduced (up to 40%) because of the increased structure deformability. This implied performance loss in the range 10%-20%. For severe damages the PL ranged between 41% and 56%. Local mechanism types exhibit PL nearly double with respect to global mechanism types. realistic estimate of evolving seismic risk during a seismic sequence, suitable modeling of building vulnerability variation should be considered. The variation in building safety owing to seismic damage is implicitly recognized by building tagging procedures, which are applied after major seismic events . In such procedures, post-earthquake safety is generally evaluated by visual inspection, with an expert assessment of damage level, extent and the related building usability by a team of experienced practitioners. However, if varied vulnerability is to be considered within a consistent quantitative assessment framework, analytical modeling of building performance loss (PL) is preferable.

Evaluation Of A Framed Structure Damaged ByThe 1997 Umbria-Marche Earthquake (original) (raw)

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