Seismic damage

Reinforced Concrete (R/C) buildings with masonry infills are amongst the most common structural systems in many countries with regions of high seismicity. The infill walls are usually considered as non-structural elements and, thus, are not taken into account in analytical models. However, numerous researches have shown that they can significantly affect the seismic response of the structures. Moreover, historical earthquakes have shown that successive seismic events may occur in regions of high seismicity. Such a sequence of earthquakes has the potential to increase the damage level of the structures, since any rehabilitation between the successive ground motions is practically impossible due to lack of time. The aim of the present study is to examine the role of masonry infills on the damage response of 3D R/C buildings with various structural systems subjected to seismic sequences. For the purposes of the above investigation a comprehensive assessment is conducted using 54 3-dimensional R/C buildings with different heights, structural systems and distribution of masonry infills. The buildings are analyzed by means of nonlinear time history analysis for 80 bidirectional seismic sequences. In order to account for the influence of the incident angle on the structural response, the two horizontal accelerograms of each ground motion are applied along horizontal orthogonal axes forming 12 different angles with the structural axes. The results revealed that the influence of the successive earthquake phenomenon on the structural damage is larger for the infilled buildings compared to the bare structures. Furthermore, when buildings with masonry infills are analyzed for seismic sequences, it is of great importance to account for the orientation of the seismic motion.

The structure is vulnerable to ground movement during an earthquake and damages the structure. It is important to know the nature of the movement of the ground in order to prevent damage to the structure due to the movement of the ground. The main purpose of Shear wall is to counter the lateral forces acting on the structure and it act as a vertical cantilever beam. The time history method is used for nonlinear dynamic analysis. The nonlinear time history analysis is conducted on four different model using CSI ETABS19, several values of all four models were found out from Structure. IS:1893-2016 guidelines are used for the time history analysis of four model of G+15 storey. Hence, total four models are used to analyse the dynamic response of the building. The result of, story displacement, story drift, storey shear, storey overturning moment and base shear are calculated and compared for all four models.

This paper investigates the role of the masonry infills on the correlation between widely used earthquake Intensity Measures (IMs) and the damage state of 3D R/C buildings taking into account the orientation of the seismic input. For the purposes of the investigation an extensive parametric study is conducted using 60 R/C buildings with different heights, structural systems and masonry infills` distributions. The results reveal that the correlation between the IMs and the seismic damage can be strongly affected by the masonry infills` distribution, depending on the special characteristics of the structural system, the number of stories and the incident angle.

After the phase of knowledge about the church, carried out according to the guidelines described in the first part of the paper, the second part aims to examine the seismic damage. This analyse consists of a survey of the map cracking, observing especially all the inner structural weaknesses of the building. But there are also some structural weaknesses typical of masonries constructions that are common to similar parts in the building. These observations leaded to the identification of the failure mechanisms activated after the earthquake, starting with the 28 mechanisms listed on the Scheda Chiese (“Manuale per la compilazione della scheda per il rilievo del danno ai beni culturali”).

The assessment of structural damage due to seismic actions can be performed analytically by using various methods. Two of these methods, derived from very different approaches, are compared in the present paper. The first is based on the evaluation of the instrumental intensity, proposed by Sandi, and which is calibrated to match the values of the EMS-98 intensity scale. The second is based on the use of the spectral values of the Park-Ang damage index, computed for constant values of the strength coefficient, Cy. The two approaches are compared, based on the damage estimations they provide in the case of the moment magnitude Mw = 7.1 Vrancea earthquake of August 30, 1986, for various structural typologies existing in Romania at the date of this event and for different locations across the country. Each structural typology is described by structure type, height category and the value of seismic forces used in design, according to the three Romanian seismic codes that were enforced during successive time periods before the event. The computed damage is compared with information on actual damage reported after the earthquake. The overstrength demands imposed by the earthquake are also evaluated, in the damage index approach. The advantages and disadvantages of each approach are shown and conclusions are drawn concerning their future potential refinement.

results of the AIJ team on damage evaluation of the buildings around the Bam strong motion station operated by the Building and Housing Research Center (BHRC). The seismic capacity of damaged buildings was approximately estimated. The results show that many residential houses in the investigated area were seismically vulnerable structures such as adobe and simple masonry structures. Poor construction quality was also found in some of the investigated buildings designed according to the current Iranian seismic code. Moreover, good correlation between wall area ratio and damage levels was observed. Therefore, wall area ratio may be applicable for evaluating the seismic capacity and screening retrofit candidates.

In recent years, a number of destructive earthquakes took place around the world. Earth Observation
(EO) -based damage assessment was among the tools used to coordinate relief efforts; most of the published maps,
however, are still based on weather-dependent optical data and visual interpretation. Only recently, methods based
on radar data began to emerge, although not yet consolidated. In this paper we elaborate on a method for damage
assessment on urban areas set up on the occasion of the 2008 Sichuan event and tuned on the 2009 L’Aquila
earthquake; direct investigation of the 2010 Haiti earthquake, providing an even larger statistical base thanks to the
extent of the Port-au-Prince urban area, allowed pinpointing some characteristic behaviours, potentially useful to
improve damage assessment results. In particular, we note how results changed thanks to a more reliable and
accurate revision of ground truth data and outline a possible start point for correction of damage
over/underestimation. Quantitative results are provided.
Keywords. Very High Resolution, Synthetic Aperture Radar, seismic damage assessment, 2010 Haiti earthquake.

The assessment of the seismic performance of a structure depends on the optimal choice of an earthquake Intensity Measure (IM). Given the fact that conventional IMs based only on ground motion information might not be able to successfully predict the seismic response of structures, several advanced structural-specific IMs have been proposed during the past years, taking into account not only earthquake characteristics but also structural information. Moreover, local site conditions may generate large amplifications as well as spatial variations in the ground motions, which influence the intensity measures and in most cases lead to important structural damage. Along these lines the objective of this paper is to study the correlation between well-known structure-specific intensity measures and the inelastic response of multi-story reinforced concrete planar frames taking into account site effects. First, site dependent ground motions are produced considering 2D analysis of the soil pr...

""According to nonlinear dynamic analysis, 3D structures are analyzed under a set of pairs of recorded accelerograms. The orientation of the recorded accelerograms is predetermined by the orientation of the recording instrument, which is, in most cases, arbitrary with respect to the structural axes. Several researchers have investigated the influence of the seismic orientation on inelastic structural response. However, all previous investigations evaluated the structural response on the basis of specific response parameters and without taking into account the influence of the orientation of the ground-motion reference axes.

The present paper investigates the influence of the orientation of the ground-motion reference axes, the seismic incident angle and the seismic intensity level on the inelastic response of asymmetric reinforced concrete buildings. The inelastic structural response is expressed and quantified in form of the modified Park and Ang damage index. A single-storey R/C building is studied. Nonlinear dynamic analyses using ten representative bi-directional ground motions are performed for four different intensity levels: i) real seismic intensity, seismic intensity that causes ii) minor, iii) moderate and iv) severe damage. The ground motions are represented by: a) the recorded accelerograms, b) the corresponding uncorrelated accelerograms, and c) the completely correlated accelerograms. The pairs of the aforementioned accelerograms are scaled according to the procedure prescribed in ASCE 41-06. In order to examine the influence of the seismic incident angle, the two horizontal accelerograms of each ground motion are applied along horizontal orthogonal axes forming an angle θ=0°, 10°, 20°, …, 360° with the structural axes.

The results of this study show that:
(a) The SRSS spectra of the two horizontal components of the recorded, the uncorrelated and the completely correlated accelerograms corresponding to the same ground motion are different. As a consequence, the scaling procedure produces different scale factors for the recorded, the uncorrelated and the completely correlated accelerograms of the same excitation.
(b) The maximum value of the damage index does not necessarily occur when the two horizontal accelerograms act along the structural axes.
(c) The recorded, the uncorrelated and the completely correlated accelerograms corresponding to the same excitation may, in general, lead to different extend of structural damage.
""

Reinforced concrete (RC) flat slabs supported on columns are one of the most widely used structural systems for office and industrial buildings. In regions of medium to high seismic risk RC walls are typically added as lateral force resisting system and to increase the lateral stiffness and strength. Although slab-column connections possess low stiffness and do not contribute substantially to the lateral resistance of the structure, each connection must have the capacity to follow the seismically induced lateral displacements of the building while maintaining the capacity to transfer the vertical loads from the slab to the columns. Otherwise brittle punching failure of the slab occurs and the deformation capacity of the connection determines the deformation capacity of the entire building. This article presents an analytical model to account for the hysteretic behaviour and cumulative damage effects on the moment-rotation relationship of internal slab-column connections without transverse reinforcement when subjected to cyclic loading. The developed model is an extension of a mechanical model proposed earlier by the authors for monotonic loading conditions. The cyclic model assumes that a fixed shear crack governs the behaviour of the slab-column connection and adopts a hysteretic moment-curvature relationship for the radial direction. The main assumptions of the model are based on local deformation measurements from tests. Seismic damage is introduced through a non-cumulative model proposed by others. The model performance is assessed through comparison to tests performed by the authors. The cyclic model predictions are in good agreement with the experimental results and provide higher accuracy than the monotonic model with respect to both the local behaviour and the global behaviour.

The frequency-dependent spectrum based seismic intensity, also called instrumental intensity, is calculated basically from the integration of the square values of spectral acceleration ordinates. The values of the instrumental intensity are calibrated to match the values of the EMS-98 intensity scale, providing a promising analytic indicator for estimating the destructive potential of earthquakes. Previous studies have shown that the proposed index could be used as a basis for the development of a new improved seismic intensity scale. The paper presents a set of maps describing the spatial distribution of instrumental intensity ordinates for three seismic events recorded in 1986 and 1990. These events, generated by the Vrancea source, are the strongest earthquakes in Romania for which accelerographic data was recorded at multiple stations. Intensity maps were generated for separate significant frequency bands, in order to reveal the destructiveness of the considered earthquakes for different building categories. Results were compared and correlated with previous studies on Vrancea earthquakes and with information provided by building damage reports from the considered earthquakes.

The present paper investigates the correlation between a number of structure-specific ground motion intensity measures and the damage state of 3D R/C buildings. To accomplish this purposefour 5-story R/C buildings are studied. The buildings are analyzed by nonlinear time history analysis using 20 bidirectional earthquake ground motions. The two horizontal accelerograms of each ground motion are applied along the structural axes of the buildings. The structural damage is expressed in terms of the maximum interstory drift as well as the overall structural damage index. For each individual pair of accelerograms the values of the aforementioned seismic damage measures are determined. Then, they are correlated with severalstrong motion intensity measures that take into account both earthquake and structural characteristics. The research identified certain intensity measures which exhibited strong correlation with the seismic damage of the four buildings. However, the degree of correlatio...

A key issue in seismic risk analysis within the context<br> of Performance-Based Earthquake Engineering is the evaluation of<br> the expected seismic damage of structures under a specific<br> earthquake ground motion. The assessment of the seismic<br> performance strongly depends on the choice of the seismic Intensity<br> Measure (IM), which quantifies the characteristics of a ground<br> motion that are important to the nonlinear structural response. Several<br> conventional IMs of ground motion have been used to estimate their<br> damage potential to structures. Yet, none of them has been proved to<br> be able to predict adequately the seismic damage. Therefore,<br> alternative, scalar intensity measures, which take into account not<br> only ground motion characteristics but also structural information<br> have been proposed. Some of these IMs are based on integration of<br> spectral values over a range o...

The objective of this paper is the investigation of the influence of the seismic incident angle on the response values of symmetric in plan buildings subjected to bi-directional horizontal ground motion. Firstly, a set of symmetric buildings is studied by means of linear response history analysis. The maximum response values over all incident angles are determined using well established analytical formulae. It is demonstrated that for symmetric buildings possessing equal stiffness along two orthogonal horizontal axes the maximum value of some vectorial response quantities (resultant displacements, resultant moments of some columns) does not depend on the orientation of the seismic action. On the contrary, the seismic incident angle is essential for the rest response quantities of such buildings, as well as for all the response quantities of symmetric buildings with different stiffness along the two structural axes. In addition, the same buildings are analyzed by means of non-linear response history analysis, with seismic components having several different orientations with regard to the structural axes. Similar conclusions are derived for the nonlinear range of behaviour too.

Abstract The presence of unreinforced masonry infills in R/C buildings is well-acknowledged as a critical issue that significantly influences the structures’ seismic response. The observation of post-earthquake damages, as well as numerous experimental and numerical studies, have shown that the irregular placement of the infilled panels can lead to negative effects, which may be crucial for the structural damage. The present paper investigates the effects of the in-plan irregularities caused by the arbitrary placement of masonry infills on the seismic damage of R/C buildings. For this purpose, five typical buildings with a large number of different infills' distributions are analyzed by means of nonlinear time-history analysis and the seismic damage is evaluated. Moreover, a correlation analysis is carried out in order to study the degree of interdependency between the irregularity caused by the infills' and the damage response. The results reveal that it is necessary to account for the effects caused by the infills' irregularities, since the non-uniform placement of the masonry infills can lead to significant increase of the seismic damage.

Abstract The present paper investigates the effectiveness of ten structure-specific IMs in reducing scatter in the estimated maximum interstory drift ratios of 3D R/C buildings. For this purpose four medium-rise buildings are studied. Incremental Dynamic Analyses (IDA) are performed for 97 far-fault bidirectional earthquake records. Moreover, in order to account for the variability in the orientation of seismic motion, the two horizontal accelerograms of each ground motion are applied along horizontal orthogonal axes forming 12 different angles with the structural axes. Statistical evaluation of the results identifies certain IMs which lead to small values of scatter in the seismic response. Moreover, it is shown that the efficiency of the examined IMs depends on the special characteristics of the structures, on the degree of nonlinearity experienced by the building, as well as on the incident angle of the seismic input.

The problem of the seismic damage prediction of reinforced concrete (r/c) buildings utilizing two types of Artificial Neural Networks (ANN) is investigated in the present paper. More specifically, the problem is formulated and solved in terms of the Function Approximation problem as well as of the Pattern Recognition problem using Multilayer Feedforward Perceptron Networks (MFP) and Radial-Basis Function (RBF) networks. The required training data-sets are created by means of Nonlinear Time History Analyses of 90 r/c buildings which are subjected to 65 earthquakes. The selected buildings differ in total height, in structural system, in structural eccentricity as well as the existence or not of masonry infills. The seismic damage index which is used to describe the seismic damage state is the Maximum Interstorey Drift Ratio. The influence of the parameters which are used for the configuration and the training of MFP and RBF networks on the reliability of their predictions is also investigated. The generalization ability of the best configured ANNs is examined by means of two categories of seismic scenarios. The most significant conclusion that turned out is that the trained ANNs can reliably and rapidly classify the r/c buildings into pre-defined damage classes provided they are appropriately configured.