On the Assessment of the Seismic Vulnerability of Ancient Churches

2015 ◽  
pp. 794-830 ◽  
Author(s):  
Pardo Antonio Mezzapelle ◽  
Stefano Lenci
Keyword(s):  
Structural Changes ◽  
Seismic Vulnerability ◽  
Risk Index ◽  
Limit State ◽  
Ultimate Limit State ◽  
Masonry Building ◽  
Safety Level ◽  
Future Situation ◽  
Equivalent Frame ◽  
The One

The chapter deals with the assessment of the seismic vulnerability of the “San Francesco ad Alto” historical masonry building, a former church located in Ancona (Italy), which is currently used as a Regional Headquarter of the Marche Region by the Italian Army. The interest toward this building comes from a double motivation. From the one side, it underwent a series of structural changes, including the addition of a new floor splitting in two levels the original nave, which makes the structure very peculiar and closer to a classical building than to a church. From the other side, it is no longer used as a church, a fact that changes the hazard aspects. The construction schematically consists of two masonry boxes overlapping, the lower being wider than the upper. It has various characteristic structural elements, such as some semicircular arches, segmental arches, timber floors, a barrel vault, some wooden trusses on the roof and steel ties in retention of the facade and of the external walls. The equivalent frame method is used, and several pushover analyses are performed. The seismic action has been defined considering the building both with strategic (current situation) and with ordinary (possible future situation) importance during earthquakes. The role of the masonry spandrels on the response of the structure has been investigated in depth and the main effects highlighted. The result of the pushover analyses is a seismic risk index (IR), that defines the safety level of the construction with respect to one ultimate limit state (SLU), in particular the so-called limit state of “saving life” (SLV).

scholarly journals On the Assessment of the Seismic Vulnerability of Ancient Churches

2016 ◽  
pp. 1037-1070
Author(s):  
Pardo Antonio Mezzapelle ◽  
Stefano Lenci
Keyword(s):  
Structural Changes ◽  
Seismic Vulnerability ◽  
Risk Index ◽  
Limit State ◽  
Ultimate Limit State ◽  
Masonry Building ◽  
Safety Level ◽  
Future Situation ◽  
Equivalent Frame ◽  
The One

The chapter deals with the assessment of the seismic vulnerability of the “San Francesco ad Alto” historical masonry building, a former church located in Ancona (Italy), which is currently used as a Regional Headquarter of the Marche Region by the Italian Army. The interest toward this building comes from a double motivation. From the one side, it underwent a series of structural changes, including the addition of a new floor splitting in two levels the original nave, which makes the structure very peculiar and closer to a classical building than to a church. From the other side, it is no longer used as a church, a fact that changes the hazard aspects. The construction schematically consists of two masonry boxes overlapping, the lower being wider than the upper. It has various characteristic structural elements, such as some semicircular arches, segmental arches, timber floors, a barrel vault, some wooden trusses on the roof and steel ties in retention of the facade and of the external walls. The equivalent frame method is used, and several pushover analyses are performed. The seismic action has been defined considering the building both with strategic (current situation) and with ordinary (possible future situation) importance during earthquakes. The role of the masonry spandrels on the response of the structure has been investigated in depth and the main effects highlighted. The result of the pushover analyses is a seismic risk index (IR), that defines the safety level of the construction with respect to one ultimate limit state (SLU), in particular the so-called limit state of “saving life” (SLV).

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 Fragility Curves for Italian Urm Buildings Based on a Hybrid Method

2021 ◽  
Author(s):  
Antonio Sandoli ◽  
Gian Piero Lignola ◽  
Bruno Calderoni ◽  
Andrea Prota
Keyword(s):  
Seismic Vulnerability ◽  
Fragility Curves ◽  
Limit State ◽  
Ultimate Limit State ◽  
Masonry Building ◽  
Masonry Buildings ◽  
Seismic Behaviour ◽  
Building Stock ◽  
Ground Acceleration ◽  
Damage Scenario

Abstract A 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 (IM) to represent fragility curves: three types of curve have been developed, each referred to mean, maximum and minim value of PGAs defined for each buildings class.To represent the expected damage scenario for increasing earthquake intensities, a correlation between PGAs and Mercalli-Cancani-Sieber (MCS) 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 A comparative study on a complex URM building: part I—sensitivity of the seismic response to different modelling options in the equivalent frame models

2021 ◽  
Author(s):  
Daria Ottonelli ◽  
Carlo Filippo Manzini ◽  
Corrado Marano ◽  
Emilia Angela Cordasco ◽  
Serena Cattari
Keyword(s):  
Seismic Response ◽  
Dynamic Properties ◽  
Limit State ◽  
Central Italy ◽  
Structural Safety ◽  
Stone Masonry ◽  
Ultimate Limit State ◽  
Masonry Building ◽  
Maximum Acceleration ◽  
Equivalent Frame

AbstractThe paper presents the comparison of the results of nonlinear static analyses carried out using six software packages (SWs) available at professional level and operating in the field of the equivalent frame (EF) approach on a model representative of a complex masonry building. The structure is inspired by the school “P. Capuzi” in Visso (MC, Italy), proposed as one of the benchmark structures in the “URM nonlinear modelling—Benchmark project” funded by the Italian Department of Civil Protection within the context of the ReLUIS projects. The 2-stories building is characterized by an irregular T-shaped plan and load-bearing walls consisting of two-leaf stone masonry with a rather regular bond scheme. The school was severely damaged by the seismic sequence that hit Central Italy in 2016/2017 and essentially exhibited a global in-plane box-type response, with a clear evidence of cracks concentrated in piers and spandrels. The availability of an accurate survey of the crack extension represents a precious and rare reference to firstly address in the paper the rules to be adopted in the EF models for the definition of the structural elements geometry. Then, the comparison of results is made with a twofold aim: firstly, by setting the models adopting shared and consistent modelling assumptions across the SWs; secondly, by investigating the sensitivity of the seismic response to some common epistemic and modelling uncertainties (namely: the adoption of various EF idealization rules for walls, the out-of-plane contribution of piers, the flange effect). In both cases, results are post-processed to define reference values of the achievable dispersion. The comparison is carried out in relation to a wide set of parameters, namely: global parameters (e.g. dynamic properties, pushover curves and equivalent bilinear curves); synthetic parameters of the structural safety (i.e. the maximum acceleration compatible with the ultimate limit state); the damage pattern simulated by SWs.

scholarly journals Analysis of relations between the moduli of elasticity in compression, tension, and static bending of hardwoods

BioResources ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 3278-3288
Author(s):  
João P. B. Almeida ◽  
Vinícius B. M. Aquino ◽  
Anderson R. V. Wolenski ◽  
Cristiane I. Campos ◽  
Julio C. Molina ◽  
...  
Keyword(s):  
Modulus Of Elasticity ◽  
Geometric Model ◽  
Limit State ◽  
Accurate Estimation ◽  
Ultimate Limit State ◽  
Average Modulus ◽  
The One ◽  
Best Fit ◽  
Ultimate Limit ◽  
Two Parameter

Accurate estimation of average modulus of elasticity in compression parallel to the grain (Ec0) is of paramount importance for rational sizing of timber structures, given the use of this property in the estimation of stability of compressed parts (ultimate limit state, ULS) and in calculation of excessive strains (serviceability limit state, SLS). In Brazil, if values cannot be experimentally determined, ABNT NBR 7190 (1997) allows for estimation of Ec0 through relations to average modulus of elasticity both in tension parallel to the grain (Et0) (Ec0 = Et0) and in bending (EM) (Ec0 = EM/0.90). This research aimed to access the efficiency of these relations by testing 30 tropical wood species. The analysis of variance results showed that Ec0 and Et0 were statistically equal. However, Ec0 and EM/0.90 were not statistically equal, and the method of least squares resulted in a coefficient of 0.98, which was 8.89% higher than the one suggested by ABNT NBR 7190 (1997) and close to 1, thus, validating the results of ANOVA, which pointed on the equivalence between Ec0 and EM (Ec0 = EM). As an alternative to simplified equations of the standard, two-parameter regression models were used. The geometric model with R² = 91.67% proved to be the model of best fit, which demonstrated that Ec0 could be calculated as a function of EM.

CONSIDERATION ON TRUSS AND SPLICE JOINT DESIGN MODELS IN EXTREMAL LOADING

2016 ◽  
Vol 3 (1) ◽  
Author(s):  
Lilita Ozola
Keyword(s):  
Limit State ◽  
Ultimate Limit State ◽  
Beam Model ◽  
Tensile Forces ◽  
Uniqueness Of The Solution ◽  
The One ◽  
Sharp Criticism ◽  
Numerical Case Study ◽  
Ultimate Limit

In this study the behavior of elements and joints in hard loaded Warren trusses is analyzed theoretically with the purpose of disclosing the sections and elements which possibly can become extremely stressed under the design load proposed being real before the ultimate limit state. The significance of truss topology selected has been brought forth, since unfavorable loading of a tensioned chord connection is discussed in this paper. Three types of tensioned splice joints have been examined considering expected elongations of bolts in order to determine additional stresses induced due to the redistribution of tensile forces. An assumption of a continuous beam model on elastically deformed discrete supports has been adopted as a design model for the examination of stresses possibly caused in the sections of bolts. It has been proved that a joint with extended end-plates over both flanges of chord I profile may be accepted as the one which is safe and robust enough for use in tensile chords of bearing structures. The joint type with end-plates extended over a more tensioned flange only and the one with connecting bolts all hidden between flanges has been subjected to sharp criticism due to the extremely nonuniform behavior and the overloading of bolts. The results of this numerical case study promote a deeper understanding and help assessing the endplate joint behavior since they lack the uniqueness of the solution recommended by the building codes, which is particularly significant when hard-loaded structures have been designed for covering the spans of public building areas.

Innovative Strategy to Reduce the Seismic Vulnerability of a RC Existing Building: Assessment and Retrofitting

2013 ◽  
Vol 569-570 ◽  
pp. 191-198
Author(s):  
Donato Cancellara ◽  
Fabio de Angelis ◽  
Mariano Modano ◽  
Vittorio Pasquino
Keyword(s):  
Seismic Vulnerability ◽  
Limit State ◽  
Seismic Retrofitting ◽  
Ultimate Limit State ◽  
Existing Building ◽  
Innovative Strategy ◽  
Rc Structure ◽  
Building Assessment ◽  
Displacement Based ◽  
Ultimate Limit

In the present paper we have evaluated the seismic response of a Reinforced Concrete (RC) existing building located in an area classified as high seismicity zone and designed, in the past, only for gravitational loads. We have compared traditional and innovative steel braces for the seismic retrofitting by using a Displacement Based Approach. The innovative steel braces allow a significant improvement of the seismic behavior of the building by providing a better dissipation of the seismic input energy in the structure and thus ensuring a better performance of the RC structure in the elastoplastic range. Unlike the traditional retrofitting, the innovative strategy allows to significantly reduce the plasticization of the structural frame at the ultimate limit state, in order to minimize the post-seismic actions on the structure.

An Equivalent Frame Model for Seismic Analysis of Existing Masonry Building

2011 ◽  
Vol 255-260 ◽  
pp. 2478-2482
Author(s):  
Qi Wang Su ◽  
Yang Xia ◽  
Shi Chun Zhao
Keyword(s):  
Dynamic Analysis ◽  
Seismic Design ◽  
Limit State ◽  
Safety Margin ◽  
Incremental Dynamic Analysis ◽  
Masonry Building ◽  
Frame Model ◽  
Seismic Design Code ◽  
Significant Damage ◽  
Equivalent Frame

Collapse safety is the most important objective of performance-based seismic design. Buildings should have enough safety margin to avoid collapse during severe or mega earthquake. However, current Chinese seismic design code does not have explicit design specification or quantitative evaluation for collapse-resistant capacity. Take a two-story masonry building as an example, an equivalent frame model for pushover and incremental dynamic analysis are established, and the comparison are also studied. In addition, the fragility curves can also be obtained. The analysis results show that the results of plastic hinge mainly appear in ground floor wall between windows and doors. Moreover, the analysis result has good uniformity with seismic damage. Judging from the failure mechanism, pushover and incremental dynamic analysis have very good similarity. In addition , they show elastic deformation is very small and brittleness is very apparent of the masonry building.Seismic vulnerability analysis shows that the significant damage and the near collapse curves are very close to each other .This mean that , once the significant damage limit state is reached ,only small PGA increments are need for reaching the near collapse limit state.

scholarly journals Analysis of structural masonry buildings taking into account the construction sequence loads and soil-structure interaction

2021 ◽  
Vol 14 (6) ◽  
Author(s):  
Anna Christinna Secundo Lopes ◽  
Joel Araújo do Nascimento Neto ◽  
Rodrigo Barros
Keyword(s):  
Soil Structure ◽  
Limit State ◽  
Three Dimensional ◽  
Soil Structure Interaction ◽  
Ultimate Limit State ◽  
Masonry Building ◽  
Support Structure ◽  
Structure Interaction ◽  
Frame Model ◽  
Construction Loads

abstract: The present study assesses conventionally used design standards, analyzing the effects caused by the construction loads, that is, a gradual increase in load and stiffness during construction, and soil-structure interaction (SSI), with soil represented by linear springs, in a structural masonry building over a support structure of reinforced concrete. The equivalent frame model, developed by Nascimento Neto, was used to simulate the support structure and the first masonry floor, and a specific three-dimensional frame model to simulate the other floors. Four analysis models were applied to assess stress distribution at the base of the walls, and the stresses and displacements of the support structure. The results show that introducing SSI and the construction loads causes relief or the possible need to reinforce elements designed in Ultimate Limit State (ULS) and Serviceability Limit State (SLS), as well as uniform settlement.

Integrating Eurocode 7 (load and resistance factor design) using nonconventional factoring strategies in slope stability analysis

2014 ◽  
Vol 51 (2) ◽  
pp. 208-216 ◽  
Author(s):  
Lysandros Pantelidis ◽  
D.V. Griffiths
Keyword(s):  
Shear Strength ◽  
Limit State ◽  
Design Standards ◽  
Safety Level ◽  
Eurocode 7 ◽  
Design Values ◽  
Factor Design ◽  
State Method ◽  
The One ◽  
Load And Resistance Factor

In traditional allowable stress design, as known, the safety factor is calculated with respect to shear strength of soil(s) by dividing the available shear strength by the mobilized stresses. The limit-state method, on the other hand, compares — in the form of the inequality Ed ≤ Rd — the effects of all the actions, Ed, with the corresponding resistance of the ground, Rd. Although this method considers different loading conditions by using suitable combinations of design values, it is still based on direct comparison of the available shear strength with the mobilized stresses. In the present paper, various factoring strategies (in addition to the traditional one with respect to shear strength of soils) are integrated into a limit-state method framework. Eurocode 7 has been chosen for this purpose. The whole procedure aims at giving a more comprehensive insight into the design of slopes and the sensitivity of safety level of slopes to the various parameters. In addition, the proposed methodology, as shown, may result in a safety level of slopes significantly lower than the respective one obtained using the limit-state method in its traditional form. As man-made slopes that conform to design standards often fail in practice, even though conservative input values are used, these failures must be treated with more skepticism by practitioners adopting supplementary design practices such the one presented herein.

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