scholarly journals Fragility Analysis of Existing Unreinforced Masonry Buildings through a Numerical-based Methodology

2012 ◽  
Vol 6 (1) ◽  
pp. 121-130 ◽  
Author(s):  
Amin Karbassi ◽  
Pierino Lestuzzi
Keyword(s):  
Seismic Vulnerability ◽  
Numerical Models ◽  
Fragility Curves ◽  
Progressive Collapse ◽  
Unreinforced Masonry ◽  
Fragility Analysis ◽  
Stone Masonry ◽  
Masonry Buildings ◽  
Plane Failure ◽  
Element Method

As an approach to the problem of seismic vulnerability evaluation of existing buildings using the predicted vul-nerability method, numerical models can be applied to define fragility curves of typical buildings which represent building classes. These curves can be then combined with the seismic hazard to calculate the seismic risk for a building class (or individual buildings). For some buildings types, mainly the unreinforced masonry structures, such fragility analysis is complicated and time consuming if a Finite Element-based method is used. The FEM model has to represent the structural geometry and relationships between different structural elements through element connectivity. Moreover, the FEM can face major challenges to represent large displacements and separations for progressive collapse simulations. Therefore, the Applied Element Method which combines the advantages of FEM with that of the Discrete Element Method in terms of accurately modelling a deformable continuum of discrete materials is used in this paper to perform the fragility analysis for unreinforced masonry buildings. To this end, a series of nonlinear dynamic analyses using the AEM has been per-formed for two unreinforced masonry buildings (a 6-storey stone masonry and a 4-storey brick masonry) using more than 50 ground motion records. Both in-plane and out-of-plane failure have been considered in the damage analysis. The dis-tribution of the structural responses and inter-storey drifts are used to develop spectral-based fragility curves for the five European Macroseismic Scale damage grades.

Performance-Based Seismic Vulnerability Evaluation of Masonry Buildings Using Applied Element Method in a Nonlinear Dynamic-Based Analytical Procedure

2013 ◽  
Vol 29 (2) ◽  
pp. 399-426 ◽  
Author(s):  
Amin Karbassi ◽  
Marie-José Nollet
Keyword(s):  
Dynamic Analysis ◽  
Seismic Vulnerability ◽  
Fragility Curves ◽  
Progressive Collapse ◽  
Incremental Dynamic Analysis ◽  
Masonry Building ◽  
Performance Levels ◽  
Plane Failure ◽  
Applied Element Method ◽  
Element Method

A thorough four-step performance-based seismic evaluation for a six-story unreinforced masonry building is conducted. Incremental dynamic analysis is carried out using the applied element method to take advantage of its ability to simulate progressive collapse of the masonry structure including out-of-plane failure of the walls. The distribution of the structural responses and inters-tory drifts from the incremental dynamic analysis curves are used to develop both spectral-based (Sa) and displacement-based (interstory drift) fragility curves at three structural performance levels. The curves resulting from three-dimensional (3-D) analyses using unidirectional ground motions are combined using the weakest link theory to propose combined fragility curves. Finally, the mean annual frequencies of exceeding the three performance levels are calculated using the spectral acceleration values at four probability levels 2%, 5%, 10%, and 40% in 50 years. The method is shown to be useful for seismic vulnerability evaluations in regions where little observed damage data exists.

Seismic assessment and improvement of unreinforced stone masonry buildings

2016 ◽  
Vol 49 (2) ◽  
pp. 148-174 ◽  
Author(s):  
Marta Giaretton ◽  
Dmytro Dizhur ◽  
Francesca Da Porto ◽  
Jason M. Ingham
Keyword(s):  
New Zealand ◽  
Seismic Vulnerability ◽  
Unreinforced Masonry ◽  
Seismic Assessment ◽  
Stone Masonry ◽  
Minor Amount ◽  
Assessment Procedure ◽  
Masonry Buildings ◽  
Building Stock ◽  
A Minor

Following the 2010/2011 Canterbury earthquakes considerable effort was applied to the task of developing industry guidance for the seismic assessment, repair and strengthening of unreinforced masonry buildings. The recently updated “Section 10” of NZSEE 2006 is one of the primary outputs from these efforts, in which a minor amount of information is introduced regarding vintage stone unreinforced masonry (URM) buildings. Further information is presented herein to extend the resources readily available to New Zealand practitioners regarding load-bearing stone URM buildings via a literature review of the traditional European approach to this topic and its applicability to the New Zealand stone URM building stock. An informative background to typical stone URM construction is presented, including population, geometric, structural and material characteristics. The European seismic vulnerability assessment procedure is then reported, explaining each step in sequence of assessment by means of preliminary inspection (photographic, geometric, structural and crack pattern surveys) and investigation techniques, concluding with details of seismic improvement interventions. The challenge in selecting the appropriate intervention for each existing URM structure is associated with reconciling the differences between heritage conservation and engineering perspectives to reinstating the original structural strength. Traditional and modern techniques are discussed herein with the goal of preserving heritage values and ensuring occupant safety. A collection of Annexes are provided that summarise the presented information in terms of on-site testing, failure mechanisms and seismic improvement.

scholarly journals Uncertainties in the Seismic Assessment of Historical Masonry Buildings

2021 ◽  
Vol 11 (5) ◽  
pp. 2280
Author(s):  
Igor Tomić ◽  
Francesco Vanin ◽  
Katrin Beyer
Keyword(s):  
Fragility Curves ◽  
Stone Masonry ◽  
Seismic Fragility ◽  
Masonry Buildings ◽  
Plane Failure ◽  
Linear Connections ◽  
Displacement Capacity ◽  
Non Linear ◽  
Out Of Plane ◽  
Historical Masonry

Seismic assessments of historical masonry buildings are affected by several sources of epistemic uncertainty. These are mainly the material and the modelling parameters and the displacement capacity of the elements. Additional sources of uncertainty lie in the non-linear connections, such as wall-to-wall and floor-to-wall connections. Latin Hypercube Sampling was performed to create 400 sets of 11 material and modelling parameters. The proposed approach is applied to historical stone masonry buildings with timber floors, which are modelled by an equivalent frame approach using a newly developed macroelement accounting for both in-plane and out-of-plane failure. Each building is modelled first with out-of-plane behaviour enabled and non-linear connections, and then with out-of-plane behaviour disabled and rigid connections. For each model and set of parameters, incremental dynamic analyses are performed until building failure and seismic fragility curves derived. The key material and modelling parameters influencing the performance of the buildings are determined based on the peak ground acceleration at failure, type of failure and failure location. This study finds that the predicted PGA at failure and the failure mode and location is as sensitive to the properties of the non-linear connections as to the material and displacement capacity parameters, indicating that analyses must account for this uncertainty to accurately assess the in-plane and out-of-plane failure modes of historical masonry buildings. It also shows that modelling the out-of-plane behaviour produces a significant impact on the seismic fragility curves.

scholarly journals Fragility curves for Italian URM buildings based on a hybrid method

2021 ◽  
Author(s):  
A. Sandoli ◽  
G. P. Lignola ◽  
B. Calderoni ◽  
A. Prota
Keyword(s):  
Seismic Vulnerability ◽  
Fragility Curves ◽  
Limit State ◽  
Ultimate Limit State ◽  
Masonry Building ◽  
Masonry Buildings ◽  
Seismic Behaviour ◽  
Building Stock ◽  
Ground Acceleration ◽  
Damage Scenario

AbstractA hybrid seismic fragility model for territorial-scale seismic vulnerability assessment of masonry buildings is developed and presented in this paper. The method combines expert-judgment and mechanical approaches to derive typological fragility curves for Italian residential masonry building stock. The first classifies Italian masonry buildings in five different typological classes as function of age of construction, structural typology, and seismic behaviour and damaging of buildings observed following the most severe earthquakes occurred in Italy. The second, based on numerical analyses results conducted on building prototypes, provides all the parameters necessary for developing fragility functions. Peak-Ground Acceleration (PGA) at Ultimate Limit State attainable by each building’s class has been chosen as an Intensity Measure to represent fragility curves: three types of curve have been developed, each referred to mean, maximum and minimum value of PGAs defined for each building class. To represent the expected damage scenario for increasing earthquake intensities, a correlation between PGAs and Mercalli-Cancani-Sieber macroseismic intensity scale has been used and the corresponding fragility curves developed. Results show that the proposed building’s classes are representative of the Italian masonry building stock and that fragility curves are effective for predicting both seismic vulnerability and expected damage scenarios for seismic-prone areas. Finally, the fragility curves have been compared with empirical curves obtained through a macroseismic approach on Italian masonry buildings available in literature, underlining the differences between the methods.

scholarly journals Seismic vulnerability of traditional masonry building a case study of Byasi, Bhaktapur

2017 ◽  
Vol 4 ◽  
pp. 24-30
Author(s):  
Shyam Sundar Basukala ◽  
Prem Nath Maskey
Keyword(s):  
Seismic Vulnerability ◽  
Linear Time ◽  
Fragility Curves ◽  
Time History ◽  
Masonry Building ◽  
Masonry Buildings ◽  
Masonry Structures ◽  
Rapid Visual Screening ◽  
Visual Screening

Historic buildings of Nepal are mainly constructed from masonry structure. Since masonry structures are weak in tension which leads to the failure of structure. So, to avoid possible damage in environment lives and property it is urgent to conduct vulnerability assessments. Seismic vulnerability of historic masonry buildings constructed in Bhaktapur at Byasi area is carried out for the case study. Five load bearing masonry buildings were selected out of 147 buildings considering opening percentage, storey and type of floor for modeling in SAP 2000 V10 Various methods of rapid visual screening (FEMA 154, EMS 98) are used to determine the vulnerability of the selected building. The Selected Building response is carried out by linear time history analysis. The seismic vulnerability of masonry structures is determined in terms of fragility curves which represent the probability of failure or damage due to various levels of strong ground motions for different damage state slight, moderate, extensive and collapse. From the result of Rapid Visual Screening (RVS) and Fragility curves of the buildings it is found that whole, buildings are found vulnerable from future earthquake.

Fragility Analysis of 3D Reinforced Concrete Frames Based on Endurance Time Method with Derived Standard Deviation

2017 ◽  
Vol 11 (04) ◽  
pp. 1750011 ◽  
Author(s):  
H. A. Tavazo ◽  
A. Ranjbaran
Keyword(s):  
Standard Deviation ◽  
Seismic Vulnerability ◽  
Seismic Analysis ◽  
Fragility Curves ◽  
Computational Cost ◽  
Fragility Analysis ◽  
Easy Access ◽  
Statistical Parameters ◽  
Endurance Time ◽  
Fragility Function

Fragility curves have been developed for seismic vulnerability analysis of structures and can be generated in empirical and analytical forms. To develop analytical fragility curve, the incremental dynamic analysis (IDA) method is considered as an applicable tool for seismic analysis; however, in the cases with high modeling complexity, the computational cost of the IDA method may be very high. Therefore, an alternative method called as endurance time (ET) method can be effectively used for fragility analysis. In this study, a new, accurate and cost effective method has been introduced in order to develop analytical fragility curves based on the ET method. The results reveal that ET-based fragility curves generally agree well with IDA-based fragility curves. In addition, it is revealed that a highly matched fragility function can be fitted on fragility points using ET-based fragility analysis (due to continuity of these points in every 0.01 of IM changes). It is concluded that ET analysis offers convenient and easy access to median and logarithmic standard deviation of IMs and thus fragility function can be produced easily based on these statistical parameters. Furthermore, a new ET-based methodology is presented to consider the previously experienced earthquakes (PEEQs) in generating fragility surfaces.

Implications of cumulated seismic damage on the seismic performance of unreinforced masonry buildings

2014 ◽  
Vol 47 (2) ◽  
pp. 157-170 ◽  
Author(s):  
Amaryllis Mouyiannou ◽  
Andrea Penna ◽  
Maria Rota ◽  
Francesco Graziotti ◽  
Guido Magenes
Keyword(s):  
Nonlinear Dynamic ◽  
Fragility Curves ◽  
Seismic Damage ◽  
Unreinforced Masonry ◽  
Masonry Building ◽  
Masonry Buildings ◽  
Seismic Capacity ◽  
Building Stock ◽  
Dynamic Analyses ◽  
Nonlinear Dynamic Analyses

The seismic capacity of a structure is a function of the characteristics of the system as well as of its state, which is mainly affected by previous damage and deterioration. The cumulative damage from repeated shocks (for example during a seismic sequence or due to multiple events affecting an unrepaired building stock) affects the vulnerability of masonry buildings for subsequent events. This paper proposes an analytical methodology for the derivation of state-dependent fragility curves, taking into account cumulated seismic damage, whilst neglecting possible ageing effects. The methodology is based on nonlinear dynamic analyses of an equivalent single degree of freedom system, properly calibrated to reproduce the static and dynamic behaviour of the structure. An application of the proposed methodology to an unreinforced masonry case study building is also presented. The effect of cumulated damage on the seismic response of this prototype masonry building is further studied by means of nonlinear dynamic analyses with the accelerograms recorded during a real earthquake sequence that occurred in Canterbury (New Zealand) between 2010 and 2012.

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