Vulnérabilité sismique à grande échelle. Typologie typique de bâtiments lausannois

Hajand Zainal
2020
Student project

Seismic assessment of existing buildings is a very important area of research to predict the impact of an earthquake on an area. Over the years, unreinforced masonry buildings have shown to be highly vulnerable to seismic risk. Although Switzerland is considered a low to moderate seismic zone, studies have shown that seismic risk is the country's most significant natural risk. This is mainly due to the fact that the majority of the Swiss real estate stock was built with little or no seismic consideration. This thesis focuses mainly on a typical typology of Lausanne buildings. First, an inventory was taken of buildings with characteristics common to this typology. Five prototypes of buildings most representative of this type of construction were then created. In a second step, a detailed seismic analysis was carried out, in particular using the Extreme Loading for Structures (ELS) software, which uses the applied element method. Finally, fragility curves for each of the prototypes were derived, linking the structure's capacity according to spectral acceleration.

About this result

This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.

Related concepts

Related publications

Hajand Zainal
2020
Student project

Abstract

Official source

https://infoscience.epfl.ch/record/274011?ln=en

About this result

Related concepts (10)

Related concepts

Related publications (8)

Related publications

Spectral acceleration

Spectral acceleration (SA) is a unit measured in g (the acceleration due to Earth's gravity, equivalent to g-force) that describes the maximum acceleration in an earthquake on an object – specificall

Seismic risk

Seismic risk refers to the risk of damage to a building, system, or other entity from an earthquake. Seismic risk has been defined, for most management purposes, as the potential economic, social a

Building

A building or edifice is an enclosed structure with a roof and walls, usually standing permanently in one place, such as a house or factory. Buildings

Seismic vulnerability assessment at large scale city of Basel

Romain Savoy

The Basel region is one of the most seismically active regions in Switzerland. Already devastated by Nature in 1356, the city of Basel is now actively involved in assessing the seismic risk on its buildings in order to protect its patrimony and its population as effectively as possible. Through innovative assessment methods, researchers and scientists throughout Switzerland are working to effectively and accurately assess seismic risk through the three components that define it: hazard, exposure and vulnerability. It is this latter element that is addressed in this report. While the assessments carried out so far deal with the buildings one by one, an essential aspect of Basel's built environment is hidden in the row configurations of many buildings. Indeed, due to the desire to optimize space, many buildings are adjacent to each other, modifying thus their seismic behaviour. This document is therefore a first study of the vulnerability of building rows in order to reveal whether the effects of this particular configuration are beneficial or not. Thanks to epoch plans collected from the archives of the Canton of Basel-Stadt and dynamic simulations based on the Applied Element Method, the consequences on the vulnerability of two types of rows of masonry buildings are estimated. As a conclusion, the impact of introducing new fragility curves on the assessment of damage in the Iselin district makes it possible to highlight the effects of taking into account the row configuration of the buildings it contains.

2020

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

Amin Karbassi, Pierino Lestuzzi

As an approach to the problem of seismic vulnerability evaluation of existing buildings using the predicted vulnerability 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 distribution of the structural responses and inter-storey drifts are used to develop spectral-based fragility curves for the five European Macroseismic Scale damage grades.

2012

In several countries of moderated seismicity, with the re-evaluation of the seismic hazard most unreinforced masonry (URM) buildings with reinforced concrete slabs failed to satisfy the seismic design check. A possible seismically retrofit solution consists of adding RC walls to the existing structure or replacing selected critical URM walls with RC ones. Experimental and numerical studies have shown that this retrofit technique can be very effective since it modifies the global deformed shape of the structure, leading to an increase in the system’s displacement capacity. The paper proposes a Displacement-Based Design methodology for the retrofit of URM structures by replacing selected URM walls by RC walls. The methodology follows the Direct Displacement-Based Design (DBD) approach by Priestley et al. (2007) and is based in particular on the DBD procedure for frame-wall buildings (Sullivan et al., 2005 and 2006). The design procedure consists of three main phases: (i) A preliminary design check of the URM building by means of the DBD approach. (ii) If the structure does not fulfil the design check and exhibits at the same time a dominant shear behaviour, replacing the critical URM wall or walls with RC ones leads to an improved system’s behaviour. (iii) In the final phase, the DBD design of the mixed RC-URM wall structure, in which both the URM and the RC walls are taken into account, is carried out. The design methodology is then investigated through non-linear dynamic analyses of one case study.

2014