Seismic Vulnerability of Existing RC Buildings and Influence of the Decoupling of the Effective Masonry Panels from the Structural Frames

2012 ◽  
Vol 268-270 ◽  
pp. 646-655
Author(s):  
Fabio de Angelis ◽  
Donato Cancellara
Keyword(s):  
Reinforced Concrete ◽  
Seismic Vulnerability ◽  
Seismic Analysis ◽  
Effective Interaction ◽  
Collapse Mechanism ◽  
Limit States ◽  
Capacity Curves ◽  
Masonry Infills ◽  
N2 Method ◽  
Structural Frame

In the present work we discuss on the seismic vulnerability of reinforced concrete existing buildings. In particular we consider a reinforced concrete building originally designed for only gravitational loads and located in a zone recently defined at seismic risk. According to the Italian seismic code NTC 2008 a displacement based approach is adopted and the N2-method is considered for the nonlinear seismic analysis. In the analysis all the masonry infill panels in effective interaction with the structural frame are considered for the nonlinear modeling of the structure. The influence of the effective masonry infills on the seismic response of the structure is analyzed and it is discussed how the effect of the masonry infills irregularly located within the building can give rise to a worsening of the seismic performance of the structure. It is shown that in the present case a not uniform positioning of the masonry infills within the building can give rise to a fragile structural behavior in the collapse mechanism. Furthermore a comparative analysis is performed by considering both the structure with the effective masonry infills and the bare structural frame. For these two structures a pushover analysis is performed, the relative capacity curves are derived and it is shown that fragile collapse mechanisms can occur depending on the irregular positioning of the effective masonry infills. Accordingly it is discussed how in the present case a decoupling of the effective masonry infills from the structural frame can give rise to a smoother response of the capacity curves. For the examined case of an obsolete building with irregular positioning of the masonry panels, the choice of decoupling the effective masonry panels from the structural frame may facilitate the retrofitting strategies for the achievement of the proper safety factors at the examined limit states.

Seismic Vulnerability of Existing RC Buildings and Influence of the Decoupling of the Effective Masonry Panels from the Structural Frames

2012 ◽  
Vol 256-259 ◽  
pp. 2244-2253 ◽  
Author(s):  
Fabio de Angelis ◽  
Donato Cancellara
Keyword(s):  
Reinforced Concrete ◽  
Seismic Vulnerability ◽  
Seismic Analysis ◽  
Effective Interaction ◽  
Collapse Mechanism ◽  
Limit States ◽  
Capacity Curves ◽  
Masonry Infills ◽  
N2 Method ◽  
Structural Frame

In the present work we discuss on the seismic vulnerability of reinforced concrete existing buildings. In particular we consider a reinforced concrete building originally designed for only gravitational loads and located in a zone recently defined at seismic risk. According to the Italian seismic code NTC 2008 a displacement based approach is adopted and the N2-method is considered for the nonlinear seismic analysis. In the analysis all the masonry infill panels in effective interaction with the structural frame are considered for the nonlinear modeling of the structure. The influence of the effective masonry infills on the seismic response of the structure is analyzed and it is discussed how the effect of the masonry infills irregularly located within the building can give rise to a worsening of the seismic performance of the structure. It is shown that in the present case a not uniform positioning of the masonry infills within the building can give rise to a fragile structural behavior in the collapse mechanism. Furthermore a comparative analysis is performed by considering both the structure with the effective masonry infills and the bare structural frame. For these two structures a pushover analysis is performed, the relative capacity curves are derived and it is shown that fragile collapse mechanisms can occur depending on the irregular positioning of the effective masonry infills. Accordingly it is discussed how in the present case a decoupling of the effective masonry infills from the structural frame can give rise to a smoother response of the capacity curves. For the examined case of an obsolete building with irregular positioning of the masonry panels, the choice of decoupling the effective masonry panels from the structural frame may facilitate the retrofitting strategies for the achievement of the proper safety factors at the examined limit states.

Assessment of the Seismic Vulnerability of Existing RC Buildings and Effect of the Irregular Position of the Masonry Panels on the Fragile Collapse Mechanisms

2012 ◽  
Vol 602-604 ◽  
pp. 1555-1565 ◽  
Author(s):  
Donato Cancellara ◽  
Fabio de Angelis ◽  
Vittorio Pasquino
Keyword(s):  
Seismic Performance ◽  
Seismic Vulnerability ◽  
Effective Interaction ◽  
Frame Structure ◽  
Collapse Mechanism ◽  
Seismic Zone ◽  
Soft Storey ◽  
Collapse Mechanisms ◽  
Masonry Infills ◽  
Displacement Based

The present work deals with the evaluation of the level of seismic vulnerability of reinforced concrete existing buildings situated in high seismic zone and designed for only gravitational loads. For assessing seismic performance, a Displacement Based Approach (DBA) is adopted and in particular the N2-metohd is used, according to Italian seismic code NTC 2008. The effect of the masonry infills on the seismic response of the structure is considered and a nonlinear model is adopted for all the panels considered in effective interaction with the frame structure. It is shown that the effect of the masonry infills, if improperly located within the building, can give rise to a worsening of the seismic performance of the structure. In fact particular locations of the masonry infills within the building can give rise to a fragile structural behavior due to a collapse mechanism of soft storey. A comparative analysis of a building is performed by considering the effects of the masonry infills and by considering the bare structural frame and it is shown that fragile collapse mechanisms can occur depending on the location of the effective masonry infills within the building. Consequently it is discussed how in a vulnerability analysis the procedure of neglecting the masonry infills not always is a procedure which operates for the benefit of security.

scholarly journals Stochastic Dynamic Analysis of Cultural Heritage Towers up to Collapse

Buildings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 296
Author(s):  
Emmanouil-Georgios S. Kouris ◽  
Leonidas-Alexandros S. Kouris ◽  
Avraam A. Konstantinidis ◽  
Stavros K. Kourkoulis ◽  
Chris G. Karayannis ◽  
...  
Keyword(s):  
Cultural Heritage ◽  
Seismic Response ◽  
Seismic Vulnerability ◽  
Limit State ◽  
Collapse Mechanism ◽  
Ultimate Limit State ◽  
Stochastic Dynamic ◽  
Damage State ◽  
Limit States ◽  
Capacity Curves

This paper deals with the seismic vulnerability of monumental unreinforced masonry (URM) towers, the fragility of which has not yet been sufficiently studied. Thus, the present paper fills this gap by developing models to investigate the seismic response of URM towers up to collapse. On mount Athos, Greece, there exist more than a hundred medieval towers, having served mainly as campaniles or fortifications. Eight representative towers were selected for a thorough investigation to estimate their seismic response characteristics. Their history and architectural features are initially discussed and a two-step analysis follows: (i) limit analysis is performed to estimate the collapse mechanism and the locations of critical cracks, (ii) non-linear explicit dynamic analyses are then carried out, developing finite element (FE) simulations, with cracks modelled as interfacial surfaces to derive the capacity curves. A meaningful definition of the damage states is proposed based on the characteristics of their capacity curves, with the ultimate limit state related to collapse. The onset of slight damage-state is characterised by the formation and development of cracks responsible for the collapse mechanism of the structure. Apart from these two, another two additional limit states are also specified: the moderate damage-state and the extensive one. Fragility and vulnerability curves are finally generated which can help the assessment and preservation of cultural heritage URM towers.

scholarly journals Assessment of Seismic Vulnerability of Reinforced Concrete Frame buildings

2018 ◽  
Vol 149 ◽  
pp. 02036
Author(s):  
Cherifi Fatiha ◽  
Farsi Mohammed ◽  
Kaci Salah
Keyword(s):  
Reinforced Concrete ◽  
Seismic Vulnerability ◽  
Reinforced Concrete Frame ◽  
Nonlinear Method ◽  
Seismic Risk Analysis ◽  
Building Inventory ◽  
Concrete Frame ◽  
Capacity Curves ◽  
The North ◽  
Frame Buildings

The seismic activity remains strong in the north of Algeria since no less than 30 earthquakes per month are recorded. The large number of structures built before the introduction of the seismic standards represents a high seismic risk. Analysis of damage suffered during the last earthquakes highlighted the vulnerability of the existing structures. In this study the seismic behavior of the existing buildings in Tizi-Ouzou city, located in the north of Algeria, is investigated. To make this assessment, a database was created following a building inventory based on a set of technical folders and field visits. The listed buildings have been classified into different typologies. Only reinforced concrete frame buildings are considered in this paper. The approach adopted to estimate structures damage is based on four main steps: 1) construction of capacity curves using static nonlinear method “push-over”, 2) estimate of seismic hazard, 3) determination of performance points, and finally 4) deduction of damage levels.

scholarly journals Strengthening Methods of the Existing Reinforced Concrete School Buildings in Medina, Saudi Arabia

2019 ◽  
pp. 1-14
Author(s):  
Mohamed Laissy ◽  
Mohammed Ismaeila
Keyword(s):  
Saudi Arabia ◽  
Reinforced Concrete ◽  
Seismic Performance ◽  
Seismic Vulnerability ◽  
Seismic Analysis ◽  
Shear Walls ◽  
School Buildings ◽  
Analysis Method ◽  
Analysis And Design ◽  
Current Design

Nowadays, evaluation of the seismic performance of existing buildings has received great attention. This paper was carried out to study the effect of strengthening the existing reinforced concrete (RC) school buildings in Medina, Saudi Arabia through assessing the seismic performance and retrofitting where seismic analysis and design were done using equivalent static analysis method according to Saudi Building Code (SBC 301) and SAP2000 software. A Typical five-story RC school building designed according to the SBC301 has been investigated in a comparative study to determine the suitable strengthening methods such as RC shear walls and steel X-bracing methods. The results revealed that the current design of RC school buildings located in Medina was unsafe, inadequate, and unsatisfied to mitigate seismic loads. Moreover, adding steel X-bracing and RC shear walls represent a suitable strategy to reduce their seismic vulnerability.

Seismic Analysis for the Structural Retrofit of “Palazzo della Civiltà Italiana” in Rome EUR, Italy

2010 ◽  
Vol 133-134 ◽  
pp. 753-758
Author(s):  
Tomaso Trombetti ◽  
Claudio Ceccoli ◽  
Giada Gasparini ◽  
Stefano Silvestri
Keyword(s):  
Reinforced Concrete ◽  
Structural Reliability ◽  
Seismic Vulnerability ◽  
Seismic Analysis ◽  
Structural Safety ◽  
Reinforced Concrete Structure ◽  
Construction Technique ◽  
Non Invasive ◽  
Original Configuration

The “Palazzo della Civiltà Italiana” is a monumental building characterized by a reinforced concrete structure composed of parallel (cast in situ) portal frames and composite (reinforced concrete + hollow bricks floors which spans between adjacent portals: a common construction technique in Italy. The floors being characterised by a large span of about 10.0 meters. The construction took place between 1939 and 1943, most likely according to the Italian building code published in 1939. The authors have coordinated a comprehensive experimental campaign aimed at (a) the identification of the characteristics of the structural materials and members, and (b) the identification of eventual damages. Based upon the experimental results a number of analytical and numerical investigations have been developed in order to assess the structural reliability of the “Palazzo” which up to date still is remains in its “original” configuration, as no substantial intervention of structural retrofit or rehabilitation have been implemented so far. These analysis allowed to identify two major reliability issues: (i) the load bearing capacities of the floors do not allow the intended use, and (ii) the seismic vulnerability of the building does not satisfy the reliability standards required by current codes. On the basis of all data acquired and investigations performed, a simple (non invasive) structural retrofit solution capable of bringing the “Palazzo” to the level of structural safety required by current codes is identified.

Effect of damage limit states on the seismic fragility of reinforced concrete frame-shear wall buildings

2021 ◽  
Vol 14 (9) ◽  
pp. 57-68
Author(s):  
Durga Mibang ◽  
Satyabrata Choudhury
Keyword(s):  
Reinforced Concrete ◽  
Dynamic Analysis ◽  
Seismic Vulnerability ◽  
Design Method ◽  
Fragility Curves ◽  
Nonlinear Dynamic Analysis ◽  
Soil Condition ◽  
Shear Wall ◽  
Reinforced Concrete Frame ◽  
Limit States

Assessment of the seismic vulnerability of frame-shear wall buildings can be performed by non-linear dynamic analysis and it needs detailed analytical modeling, structural performance measures and various earthquake intensities. The codal based design method can hardly be used for designing buildings of pre-defined target objectives whereas the Unified performance-based design (UPBD) method can be designed for buildings of pre-defined target objectives. In the current study, the UPBD method for frame-shear wall buildings has been applied for different performance levels (PL) i.e. Immediate occupancy (IO), Life safety (LS) and Collapse prevention (CP) with 1%, 2% and 3% drift in both the directions of the buildings. The nonlinear dynamic analysis of the reinforced concrete (RC) frame-shear wall buildings is performed considering spectrum compatible ground motions (SCGM) as per EC-8 demand spectrum at 0.45g level and type B soil condition. Vulnerability assessment of the frame-shear wall buildings is conducted by generating fragility curves and the probability failure of structure is checked based on different configurations and damage limit states of the structure. Finally, the outcome of the work gives a proper idea of the nonlinear behavior of the dual system so that optimum design could be acquired for achieving higher safety aspects.

scholarly journals Feasibility of Using Neural Networks to Obtain Simplified Capacity Curves for Seismic Assessment

Buildings ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 151 ◽  
Author(s):  
João Estêvão
Keyword(s):  
Neural Networks ◽  
Large Scale ◽  
Seismic Vulnerability ◽  
Seismic Assessment ◽  
Small Scale ◽  
Eurocode 8 ◽  
Seismic Behaviour ◽  
Capacity Curves ◽  
N2 Method ◽  
Building Typology

The selection of a given method for the seismic vulnerability assessment of buildings is mostly dependent on the scale of the analysis. Results obtained in large-scale studies are usually less accurate than the ones obtained in small-scale studies. In this paper a study about the feasibility of using Artificial Neural Networks (ANNs) to carry out fast and accurate large-scale seismic vulnerability studies has been presented. In the proposed approach, an ANN was used to obtain a simplified capacity curve of a building typology, in order to use the N2 method to assess the structural seismic behaviour, as presented in the Annex B of the Eurocode 8. Aiming to study the accuracy of the proposed approach, two ANNs with equal architectures were trained with a different number of vectors, trying to evaluate the ANN capacity to achieve good results in domains of the problem which are not well represented by the training vectors. The case study presented in this work allowed the conclusion that the ANN precision is very dependent on the amount of data used to train the ANN and demonstrated that it is possible to use ANN to obtain simplified capacity curves for seismic assessment purposes with high precision.

A Damage Model for Collapse-Mechanism of Long-Span and High-Pier Continuous Rigid Frame Bridges

2011 ◽  
Vol 219-220 ◽  
pp. 1431-1435
Author(s):  
Kai Zhong Xie ◽  
Guang Qiang Chen ◽  
Li Lin Wei
Keyword(s):  
Reinforced Concrete ◽  
Strong Earthquake ◽  
Seismic Analysis ◽  
Damage Model ◽  
Collapse Mechanism ◽  
Mechanism Analysis ◽  
Long Span ◽  
Collapse Mechanisms ◽  
Rigid Frame ◽  
High Pier

Collapse-mechanism analysis can simulate that bridges enter strong elasto-plastic and large displacement response and collapses phase, so that it is very important for the seismic design of bridges. In this paper, a damage model of reinforced concrete is introduced, and dynamic response and collapse of long span and high-pier continuous rigid frame bridge during strong earthquake is studied with damage model of reinforced concrete by the explicit dynamic analysis code (LS-DYNA). The simulation results indicate the development of the concrete elements from cracking to failure and the bridge from part collapse to the whole collapse of the bridge are studied. The damage and collapse mechanisms during strong earthquake are given of Long Span and High-pier Continuous Rigid Frame Bridges. References are provided for seismic analysis of this kind of bridges.

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