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.

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.

Seismic Vulnerability of Ancient Churches: I. Damage Assessment and Emergency Planning

2004 ◽  
Vol 20 (2) ◽  
pp. 377-394 ◽  
Author(s):  
Sergio Lagomarsino ◽  
Stefano Podestà
Keyword(s):  
Damage Assessment ◽  
Seismic Behavior ◽  
Seismic Vulnerability ◽  
Collapse Mechanism ◽  
Damage Level ◽  
Bell Tower ◽  
Collapse Mechanisms ◽  
Damage Grades ◽  
Definition Of ◽  
The Church

This paper describes a new methodology used to assess seismic damage in the churches of Umbria and the Marches, which is based on 18 indicators, each representative of a possible collapse mechanism for a macroelement. The subdivision of the church into macroelements consists of the identification of architectonic elements in which the seismic behavior is almost independent from the rest of the structure (façade, apse, dome, bell tower, etc.). For each macroelement, by considering its typology and connection to the rest of the church, it is possible to identify the damage modes and the collapse mechanisms. During inspection operations, the surveyors must indicate: (a) the actual macroelements; (b) the damage level; and (c) the vulnerability of the church to that mechanism, related to some specific details of construction. From these data a damage score is defined, which is a number from 0 to 1, obtained as a normalized mean of the damage grades in each mechanism. The analysis of the collected data (more than 1,000 churches in Umbria) allows the definition of the correlation between macroseismic intensity and damage.

scholarly journals Empowering the Indiana Bridge Inventory Database Toward Rapid Seismic Vulnerability Assessment

2021 ◽  
Author(s):  
Leslie Bonthron ◽  
Corey Beck ◽  
Alana Lund ◽  
Farida Mahmud ◽  
Xin Zhang ◽  
...  
Keyword(s):  
Seismic Performance ◽  
Asset Management ◽  
Vulnerability Assessment ◽  
Seismic Vulnerability ◽  
Seismic Analysis ◽  
Dynamic Assessment ◽  
The State ◽  
Assessment Procedure ◽  
Seismic Zone ◽  
Seismic Vulnerability Assessment

With the recent identification of the Wabash Valley Seismic Zone in addition to the New Madrid Seismic Zone, Indiana’s Department of Transportation (INDOT) has become concerned with ensuring the adequate seismic performance of their bridge network. While INDOT made an effort to reduce the seismic vulnerability of newly-constructed bridges, many less recent bridges still have the potential for vulnerability. Analyzing these bridges’ seismic vulnerability is a vital task. However, developing a detailed dynamic model for every bridge in the state using information from structural drawings is rather tedious and time-consuming. In this study, we develop a simplified dynamic assessment procedure using readily-available information from INDOT’s Bridge Asset Management Program (BIAS), to rapidly identify vulnerable bridges throughout the state. Eight additional data items are recommended to be added into BIAS to support the procedure. The procedure is applied in the Excel file to create a tool, which is able to automatically implement the simplified bridge seismic analysis procedure. The simplified dynamic assessment procedure and the Excel tool enable INDOT to perform seismic vulnerability assessment and identify bridges more frequently. INDOT can prioritize these bridges for seismic retrofits and efficiently ensure the adequate seismic performance of their assets.

scholarly journals Rigid-Plastic Analysis of Seismic Resistant T-Frame considering Moment-Shear Interaction

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Ghader Bagheri ◽  
Payam Ashtari ◽  
Farhad Behnamfar
Keyword(s):  
Energy Dissipation ◽  
Collapse Mechanism ◽  
Rigid Plastic ◽  
Soft Storey ◽  
Collapse Mechanisms ◽  
Plastic Mechanism ◽  
Plastic Analysis ◽  
Seismic Resistant ◽  
Global Collapse ◽  
The Moment

To select a seismic resistant system, in addition to strength and stiffness, ductility and energy dissipation are important to be considered. Structures have nonlinear behavior under the influence of moderate and strong earthquakes. One of the primary aims in designing seismic resistant structures is to prevent the formation of undesirable collapse mechanisms such as the collapse in only a few storeys of the structure that leads to low energy dissipation. In order to achieve a global collapse mechanism, modern seismic codes provide simple rules for design, which is called the hierarchy criteria. Although these simple criteria could prevent the formation of a soft storey mechanism, they could not lead to an optimal global collapse mechanism. In these mechanisms, the energy dissipation zones include all the yielding zones such as beams, while all other parts of the structure have remained in the elastic range. TRF (T-resisting frame) is an innovative lateral resistant system introduced for architectural reasons and to provide more energy dissipating capability. This system has several collapse mechanisms due to the moment, shear, or moment-shear behavior of its members. In this paper, within the framework of the theory of plastic mechanism control, the rigid-plastic analysis of the TRF system to achieve the desired collapse mechanism is used by considering the moment-shear interaction. According to these analyses, which are performed on a single storey frame, simple hierarchy criteria are developed to create the desired collapse mechanism. Also, these criteria prevent undesired collapse mechanisms in order to have more energy dissipation and more ductility. Finally, the validity of the proposed criteria has been verified by the pushover analysis.

scholarly journals Optimum Location of Soft Storey in Multi-Storeyed Building

2019 ◽  
Vol 8 (12) ◽  
pp. 2486-2490
Keyword(s):  
Reinforced Concrete ◽  
Seismic Performance ◽  
Carrying Capacity ◽  
Seismic Zone ◽  
Stiffness Ratio ◽  
Optimum Location ◽  
Base Shear ◽  
Soft Storey ◽  
Software Comparison ◽  
Linear Behaviour

The present study is focus on 11-storey reinforced concrete buildings to optimize the location of soft storey under seismic zone-v. The plan of building 40m x 40m is considered. In X- direction and y-direction number of bays is 8 and each bay width is 5m. To observe the non linear behaviour of multistoreyed building will be studied for various position of soft storey by increasing the storey height. Soft storey is provided at 1 st storey, 5 th storey and 10th storey. In this first three models is analyzed by increasing height of storey as 4.5m and other three models is analyzed by increasing height of storey as 5.1m and remaining storey height is kept as 3m are compare with regular building by using ETABS software. Comparison is made for the storey displacement, storey stiffness, base shear and formation of hinge patterns. The result remarks the conclusion that base shear carrying capacity of the structure increases as the soft storey is placed at higher levels and is least when the soft storey is at the ground. The seismic performance of structures is very sensitive to stiffness ratio. The lower the stiffness ratio of soft storey displacement of that structure is high

Seismic vulnerability of prefabricated reinforced concrete frame structure based on local outsource steel tube bolted column–column connection

2020 ◽  
pp. 136943322096845
Author(s):  
Jiaolei Zhang ◽  
Jin Li ◽  
Qi Liang ◽  
Shufeng Li ◽  
Dawei Yuan
Keyword(s):  
Reinforced Concrete ◽  
Seismic Performance ◽  
Seismic Vulnerability ◽  
Damage Model ◽  
Frame Structure ◽  
Reinforced Concrete Frame ◽  
Structural Requirement ◽  
Concrete Frame ◽  
Reinforced Concrete Frame Structure ◽  
Two Parameter

In this paper, the seismic performance of a prefabricated frame structure with a local outsource steel tube bolted column–column connect is evaluated from the perspective of seismic vulnerability theory. Firstly, a simplified model of the prefabricated frame structure was constructed and validated by experiments. Then, a six-story prefabricated reinforced concrete frame structure (PRCS) and a cast-in-situ reinforced concrete frame structure (CRCS) were designed as examples to get the increment dynamic analysis (IDA) of the structure under 12 ground motions, and the two-parameter damage model was used as the structural requirement index. As a traditional structural requirement index-the maximum inter-storey drift angle cannot accurately describe the mechanism of structural damage. Therefore, two types of damage models are compared and analyzed. In addition, in order to evaluate the damage of frame structure effectively, a new damage index weighted combination method is proposed, and its feasibility is verified. Finally, the IDA curve and vulnerability curve with Kunnath two-parameter damage model and the maximum inter-story displacement angle as the requirement index are drawn. The results show that the two-parameter damage model is more accurate than the maximum inter-storey drift angle model in evaluating the seismic performance of the PRCS and CRCS. It shows that the maximum inter-story displacement angle model can overestimate the collapse resistance of the PRCS by 60.7% on average, and the collapse resistance of the CRCS by 75.67% on average. The seismic performance of the CRCS is better than that of the PRCS as the seismic intensity increases. Although the seismic performance of fabricated columns is similar to that of cast-in-place columns, there is still a certain gap in the seismic performance of frame structures.

Displacement Based Approach for the Seismic Retrofitting of a RC Existing Building Designed for only Gravitational Loads

2012 ◽  
Vol 166-169 ◽  
pp. 1718-1729 ◽  
Author(s):  
Donato Cancellara ◽  
Fabio de Angelis ◽  
Vittorio Pasquino
Keyword(s):  
Reinforced Concrete ◽  
Seismic Vulnerability ◽  
Seismic Retrofitting ◽  
Masonry Infills ◽  
Evaluation Phase ◽  
Non Linear ◽  
Rc Building ◽  
Displacement Demand ◽  
Displacement Based ◽  
Existing Structure

The present paper deals with the evaluation of the level of seismic vulnerability of a Reinforced Concrete (RC) building by using a Displacement Based Approach (DBA), in the context of a performance methodology, and by adopting the N-2 method, according to Italian seismic code NTC 2008. The RC building is located in Southern Italy in an area classified as high seismicity zone and designed, in the past, only for gravitational loads. During the evaluation phase the effect of masonry infills is considered by modeling with a non linear analysis all the panels considered in effective interaction with the structural frame. It is highlighted that in the examined case the masonry infills determine a worsening of the seismic behavior of the existing structure. So that it is illusory that by neglecting these panels a general beneficial effect would be obtained. Moreover in such case the neglect of these panels would have guided to a retrofitting strategy which is completely different and would have not answered to the real needs of the structure. The correct evaluation of the seismic response is finalized to the seismic retrofitting by using a traditional strategy, designed through a displacement based approach, for reducing the displacement demand on the existing structure. The adopted retrofitting strategy is represented by steel braces with steel reinforcement elements for the columns. In the non linear model for these elements it has been considered their confinement action for the reinforced concrete columns. The vulnerability level of the structure and the Safety Factor (SF), defined as the ratio between the displacement capacity and the displacement demand, is calculated for the building before and after the seismic retrofitting.

scholarly journals Seismic Vulnerability Assessment using Numerical Simulation for a Residential Buildings – A Case study

2020 ◽  
Author(s):  
Jennifer Mehjebin ◽  
Santhi A.S ◽  
Ganapathy Pattukandan Ganapathy
Keyword(s):  
Seismic Performance ◽  
Vulnerability Assessment ◽  
Structural Damage ◽  
Seismic Vulnerability ◽  
Residential Buildings ◽  
Shear Wall ◽  
Static Force ◽  
Seismic Vulnerability Assessment ◽  
Ground Floor ◽  
Soft Storey

Abstract Seismic vulnerability assessment of an existing building is of high importance for ensuring the safety of the structure and the occupants. An earthquake may not be predictable but seismic performance of a structure can be well- predicted in advance which aids in deciding the correct retrofit technique for a building ensuring the safety of the occupants. A RC building situated in the seismic zone III region of Vellore, Tamil Nadu has been taken into consideration for analysing its seismic vulnerability. The region is yet to catch engineering attention for evaluation of seismic performance of such buildings. With the help of the nearest fault line data, the PGA value was calculated and the value suggested moderate potential damage. The RVS score of the building was categorised in the high probability of Grade Damage 3 i.e. structural damage in moderate range and non-structural damage in heavy range. A detailed numerical analysis was carried out in ETABS using equivalent static force method to simulate the earthquake forces in the structure. Although a dynamic method of analysis considers higher magnitude of earthquake forces based on a more realistic earthquake excitation, equivalent static force analysis is sufficient for a preliminary analysis of the building. The building having a soft storey in the ground floor showed variations in its behaviour on application of earthquake forces in four different case scenarios of shear wall application. The maximum storey drifts were then compared for the building in cases of existing soft storey and with the application of shear wall in the ground floor, staircase walls and with a combination of shear wall in both the locations. The results showed that shear wall in the staircase proved to be the most economical retrofit solution for the building.

Evaluation of Strong Column Factors for RC Frames Based on Seismic Vulnerability Analysis

2013 ◽  
Vol 639-640 ◽  
pp. 854-858
Author(s):  
Hui Ying Wang ◽  
Jian Cai ◽  
Guo Bin Bu
Keyword(s):  
Flexural Strength ◽  
Seismic Performance ◽  
Strong Earthquake ◽  
Seismic Vulnerability ◽  
Vulnerability Analysis ◽  
Frame Structure ◽  
Rc Frame ◽  
Seismic Capacity ◽  
Effective Measure ◽  
Seismic Vulnerability Analysis

Augmenting the flexural strength of columns in the seismic design of reinforced concrete (RC) moment resisting frames is a key measure among all the detailing procedures of seismic capacity design, which induces the desirable beam side-sway mechanism for the structure to dissipate energy during a strong earthquake. The objective of this paper is to assess the influence of various strong column factors which is employed to perform seismic vulnerability analysis to the seismic performance of a six-story deterministic RC frame structure. Seismic vulnerability analyses indicate that augmenting the flexural strength of columns is an effective measure to improve seismic performance of RC frame structures. Increasing strong column factor improves the displacement capacity of structure and induces the biggish grads between the different damage limit states, which provide caution to prevent the abrupt collapse of structure during a strong earthquake. Seismic vulnerability curves provide the quantitative criterion for evaluating the seismic performance of structure and choosing appropriate target strong column factor.

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