Sergio Lagomarsino

• PhD in Structural Engineering
• Professor (Full) at University of Genoa

Unreinforced masonry (URM) buildings are highly susceptible to cumulative damage, as demonstrated by the damage observations collected during and after numerous earthquake sequences. However, most previous numerical studies assessing cumulative damage in URM buildings have failed to fully capture the extent of the phenomenon observed in real events...

The integration/combination of seismic and energy retrofit measures has been a subject of study for the past decade, exhibiting promising prospects. The main objective of these interventions is to mitigate seismic vulnerability while concurrently enhancing the energy performance and efficiency of new and existing buildings. Integrated approaches ca...

Equivalent frame (EF) methods are increasingly used to evaluate the global seismic response of historic masonry buildings. However, applying these methods to arched structures is challenging due to the lack of a standard EF strategy for masonry arches. This paper proposes a novel EF modelling solution for masonry arches in historic buildings subjec...

The draft of the second generation of Eurocode 8 (EC8) proposes three main analysis methods for the design of unreinforced masonry (URM) buildings: the simplified approach based on the rules for the "simple masonry building", the linear static analysis and the nonlinear static analysis. Although these methods have been already adopted in other stan...

Recent earthquakes have highlighted the seismic vulnerability of existing masonry buildings, pointing out the urgent need to design high-performant and non-invasive strengthening interventions. To this aim, reliable numerical models and assessment procedures are necessary to evaluate their effectiveness and quantify the effects on the structural se...

Recent seismic sequences have shown over again that unreinforced masonry (URM) buildings can be susceptible to the effects of cumulative damage due to repeated shaking. These effects, however, are often neglected in seismic assessment, a practice that may lead to underestimation of risk for a given building for a portfolio of buildings. Therefore,...

The present paper outlines the process of identifying the optimal mechanical properties for a retrofitting intervention that aims to mitigate the local mechanism of overturning in a bell gable of a church. The primary goal is to select the optimal properties of a vertical tie-rod with the aim of maximizing the capacity and ductility of the bell gab...

This paper presents, firstly, an overview of the nonlinear static procedures (NSPs) given in different codes and research studies available in the literature, followed by the results achieved by the authors to evaluate the reliability of the safety level that they guarantee. The latter is estimated by adopting the fragility curve concept. In partic...

Seismic events that have occurred in Italy in recent decades have shown the significant vulnerability of the Italian building stock. In particular, residential masonry buildings have suffered serious damage, highlighting the need to plan effective mitigation strategies as soon as possible. In this context, this study aims to evaluate the effectiven...

Post-earthquake damage surveys systematically highlight the seismic vulnerability of monumental structures, calling for simple assessment procedures to address the design of effective retrofitting interventions. The structural complexity characterizing monumental structures, however, makes a reliable prediction of their seismic response a relevant...

Despite the moderate intensity, the series of earthquakes in Zagreb (2020) caused significant social and economic impacts and damage to the built environment. The city of Zagreb has a moderate seismic hazard, but it is highly exposed (densely populated) and the built environment is quite vulnerable (age of structures, low maintenance, illegal const...

This paper focuses on the so-called “flange effect” in unreinforced masonry buildings when the connection among walls is good, thus forming a 3D assembly of intersecting piers (with L-, C-, T-, or I-shaped cross-sections). Given the direction of the horizontal seismic action, the presence of such flanges (the piers loaded out-of-plane) can influenc...

The RINTC (2015-2017) project was a three-year research program aimed at assessing the seismic reliability of code-conforming structures in Italy. It dealt with five structural typologies of residential and industrial buildings: reinforced concrete, masonry, precast reinforced concrete, steel, and base isolated reinforced concrete. To reach its goa...

Recent seismic events worldwide have demonstrated the high vulnerability of existing school buildings and the urgent need to have reliable tools for the rapid seismic performance assessment and damage and loss quantification. Indeed, the significant damage observed on structural and non-structural components may have a significant impact in terms o...

Analytical expressions for the floor spectra evaluation play a key role in the correct definition of the seismic input induced to non-structural elements or local mechanisms in existing buildings. They have to be able properly assessing the possible amplification phenomena, but also correctly describing the effects of nonlinearities due to structur...

Five existing unreinforced masonry buildings, built in different Italian cities in a relatively recent time frame, were selected to study the seismic behaviour of modern existing structures, not designed to withstand seismic actions. The buildings were modelled using an equivalent-frame approach, adopting, and comparing two nonlinear constitutive l...

This work presents a comprehensive strategy for analysing the complex seismic response of five Italian historical URM buildings, corresponding to different periods until 1920s. One distinctive feature of historical buildings is the need for integrating global modelling and local response of structural portions, due to possible activation of local f...

Within the framework of modelling of unreinforced masonry structures, the equivalent frame (EF) approach is widely used for the seismic assessment. However, the definition of modelling rules for the EF idealization of walls is not always straightforward. Such rules are typically applied a priori and they can strongly affect the seismic response. Th...

Recent seismic events worldwide demonstrated the high vulnerability of existing school buildings and the urgent need to have reliable tools for the rapid seismic performance assessment and damage and loss quantification. Indeed, the significant damage observed on structural and non-structural components may have a significant impact in terms of dir...

Analytical expressions for the floor spectra evaluation play a key role for a correct definition of the seismic input induced to non-structural elements or local mechanisms in existing buildings. They have to be able to properly assess the possible amplification phenomena, but also to correctly describe the effects of nonlinearities due to structur...

The seismic assessment of cantilever elements in masonry structures is a relevant topic because of their high vulnerability and since they often involve artistic assets (such as bell-gables, parapets or pinnacles). Due to the complexity of nonlinear dynamics of cantilever systems, displacement-based assessment (DBA) procedures have been developed w...

The paper describes the derivation of fragility curves useful for the seismic risk analyses of existing unreinforced masonry buildings inserted in aggregate. The L-shaped examined aggregate consists of three adjacent structural units that may mutually interact during seismic events. The seismic assessment is focused on the corner unit. The effects...

This study investigated seismic assessments of the Podestà Palace in Mantua (Italy). This masonry palace has a complex geometrical configuration that resulted from the addition of various units stratified over centuries. This feature makes seismic assessment challenging from a modelling perspective due to the interaction among units. Here, an integ...

The last National Risk Assessment NRA for Italy was developed at the end of 2018 by the Department of Civil Protection (DPC) in response to the specific requirement of the Sendai Framework for Disaster Risk Reduction 2015-2030 to periodically adjourn the assessment of disaster risk. The methodology adopted to perform seismic risk assessment and bui...

Within the 2019–2021 research agreement between the Civil Protection Department (DPC) and the Network of University Laboratories for Earthquake Engineering (ReLUIS), the work package WP4 “Seismic Risk Maps—MARS” is specifically devoted to update the 2018 release of the Italian National Seismic Risk Assessment. To this end, the previously considered...

In the framework of seismic risk analyses at large scale, among the available methods for the vulnerability assessment the empirical and expert elicitation based ones still represent one of most widely used options. In fact, despite some drawbacks, they benefit of a direct correlation to the actual seismic behaviour of buildings and they are easy t...

The Department of Civil Protection (DPC), in compliance with the EU decision 1313/2013 and at the request of the Sendai Framework for Disaster Risk Reduction 2015–2030 to update the disaster risk assessments by various countries, released the latest National Risk Assessment for Italy at the end of 2018. Specifically, as regards the seismic risk ass...

Linear procedures (lateral static force method or modal response spectrum analysis) are the standard approach for the seismic design of new structures. On the contrary, nonlinear procedures, in particular incremental pushover analysis, should be used for the seismic assessment of existing buildings, because it is difficult to estimate the behavior...

In the framework of the evaluation of the consequences of an earthquake, the paper provides a procedure for the economic loss assessment in unreinforced masonry (URM) buildings, proposing an analytical approach based on a cost function directly dependent on the damage level associated to different structural elements and identified by specific engi...

The article addresses the seismic vulnerability assessment of a typology of unreinforced masonry buildings constructed in Lisbon between the nineteenth and the twentieth centuries. The main architectural and structural features of these buildings are presented. This supported the identification of the main uncertainties affecting their seismic perf...

This paper presents the results of a monodirectional shaking table test on a full-scale unreinforced masonry cross vault characterized by asymmetric boundary conditions. The specimen represents a vault of the mosque of Dey in Algiers (Algeria), reproducing in detail the mechanical characteristics of masonry, and the constructive details including t...

The nonlinear static procedure (NSP) is commonly adopted by practitioners for the seismic assessment of unreinforced masonry (URM) buildings, although a systematic validation of the procedure when applied to this type of buildings still lacks in the literature. The aim of this paper is to contribute to the validation and the improvement of the NSP...

The purpose of the "Sendai Framework for Disaster Risk Reduction 2015-2030"is to provide the guidelines for the management of multi-hazard risks, in order to substantially decrease the losses of human lives, livelihoods, as well as of economic, physical, social, cultural and environmental assets of persons, businesses, communities and countries. Wi...

Ai fini dello studio della risposta sismica delle costruzioni, riveste un ruolo fondamentale il contributo della sperimentazione in laboratorio su prototipi di strutture in grande scala sottoposte a terremoti naturali o sintetici riprodotti tramite tavola vibrante di grandi dimensioni. In questo contesto, i recenti progressi nelle metodologie di mi...

This article describes the application of the procedure for the derivation of fragility functions presented in the companion article entitled Fragility functions for tall URM buildings around early 20th century in Lisbon. Part 1: methodology and application at building level. The procedure, based on the execution of non-linear analyses, was develop...

Masonry structures, although classically suitable to withstand gravitational loads, are sensibly vulnerable if subjected to extraordinary actions such as earthquakes, exhibiting cracks even for events of moderate intensity compared to other structural typologies like as reinforced concrete or steel buildings. In the last half-century, the scientifi...

In New World colonial countries and territories such as Australia, New Zealand, and the West Coast of North America, the predominant form of unreinforced masonry (URM) construction is relatively modest one or two storey buildings composed of clay brick masonry. While the equivalent frame (EF) approach for modelling the in-plane seismic response of...

The post-earthquake damage assessment represents the first step after an emergency to support not only the safety of people, but also the preservation of buildings through the realization of prompt and effective provisional interventions. The issue is of particular relevance in case of monumental assets such as churches that are the focus of the pa...

The article proposes a procedure for the derivation of fragility functions for unreinforced masonry buildings considering the in-plane and out-of-plane response. Different approaches are considered for the generation of the corresponding fragility functions and for the evaluation of the propagation of uncertainties. The contributions for the disper...

The lack of empirical data regarding earthquake damage or losses has propelled the development of dozens of analytical methodologies for the derivation of fragility and vulnerability functions. Each method will naturally have its strengths and weaknesses, which will consequently affect the associated risk estimates. With the purpose of sharing know...

Seismic assessment of existing buildings is usually treated by international codes and guidelines through a semi-probabilistic approach based on the use of the so-called confidence factor (CF). Many authors revealed the inadequacy of such an approach, proposing alternative procedures based on: the updated calibration of the CF values together with...

This paper summarizes the main results achieved as a result of a PhD research project into the seismic assessment of single-block rocking elements in masonry structures (such as parapet walls, pinnacles, spires, etc…). In particular, this work refers to those elements located in the upper levels of structures. As demonstrated by past earthquakes, t...

Several tools for the prediction and the assessment of the structural behavior of masonry buildings have been developed in recent decades. Numerical tools have been favorably developed and preferred over analytical approaches, given the complex mechanical response of masonry and the irregular geometries of historic masonry buildings. In this chapte...

Several architectural configurations of unreinforced masonry residential buildings are designed according to the different methods proposed in the Italian code: rules for the so-called simple masonry buildings, linear and nonlinear static analyses. Always complying with code requirements, for each building-site combination, the design was made, as...

The damage occurred due to past earthquakes highlighted that the seismic behavior of historic masonry structures characterized by an aggregation of units with an own seismic behavior (e.g. palaces, fortresses, castles, etc.) is strongly affected by their dynamic interaction. At present, no codified and operational tools are available to perform the...

The unreinforced masonry (URM) buildings designed to be conforming with the Italian building code, as illustrated in the companion paper, were analyzed by performing time-history analyses on models realized using an equivalent frame approach and by adopting two different constitutive laws. Both the effect of record-to-record variability and of epis...

This paper proposes a new analytical formulation for computing the seismic input at various levels of a structure in terms of floor response spectra. The approach, which neglects the dynamic interaction between primary structure and secondary element, is particularly useful for the seismic assessment of secondary and non-structural elements. The pr...

Earthquakes have been responsible for the destruction of hundreds of monuments throughout human history. Due to their size, conservation state, and lack of seismic provisions, monuments are particularly vulnerable to the effects of geological hazards. The first step toward the mitigation of the earthquake threat consists of understanding the existi...

The assessment of the seismic vulnerability of existing masonry buildings is today a relevant issue for all the earthquake prone countries, and a proper evaluation of their seismic behavior is therefore needed. In this context, the application of verification procedures based on nonlinear analyses is now widespread and requires reliable and computa...

The paper presents a study on the nonlinear static procedures (NSPs) proposed in codes and literature and their application to irregular unreinforced masonry (URM) buildings. NSPs were originally developed mainly for the seismic design of regular reinforced concrete buildings, on the contrary existing URM buildings often presents structural irregul...

The use of nonlinear static (pushover) analysis in the case of existing irregular masonry buildings is validated through a comparison with results from nonlinear dynamic analyses, assumed as reference because considered as able to represent the actual seismic behavior. After the selection of a regular prototype case study building, different irregu...

La risposta sismica degli edifici in muratura costituisce oggi una delle sfide aperte nel campo della ricerca scientifica la cui modellazione e previsione è distinta da numerose incertezze sia di tipo aleatorio sia di tipo epistemico. La crescente esigenza di dare delle risposte ingegneristicamente sempre più affidabili e che fossero in grado di co...

The preservation and strengthening of historical constructions over time is highly to be supported due to their cultural and heritage value and the potential economic exploitation related to tourism. Old masonry buildings are subjected to slow aging processes, which must be monitored in order to prevent irreversible deterioration of materials and s...

Out-of-plane mechanisms induced by earthquakes are typical of many masonry structures such as standing out elements (spires, battlements of fortresses, etc.) or portions of façade badly connected to the building. The displacement-based assessment procedures in standards are based on the hypothesis of rigid block, which sometimes is unable to repres...

Abstract in English In this paper the seismic analysis of the out-of-plane response of the façade of the San Michele Arcangelo Church in the municipality of Ascoli Piceno, damaged by 2016-2017 Central Italy earthquakes, is developed using incremental static and dynamic methods. The simple rocking of the masonry façade is analyzed by considering a r...

Gli eventi sismici registrati a partire dal 24 agosto 2016 hanno interessato quattro regioni del centro Italia: Abruzzo, Lazio, Marche e Umbria. Nella fase di emergenza particolare attenzione è stata posta alla valutazione del danno e dell'agibilità degli edifici scolastici al fine di consentire una rapida ripresa delle attività scolastiche. Il con...

The masonry buildings constructed between the 19th and 20th centuries in Lisbon are commonly recognized for their eclectic style and structural vulnerability. This article presents the main characteristics of these buildings in the aim of preserving their cultural value. The socio-economic conditions on what they were constructed are identified. Th...

Earthquakes cause severe damage to masonry structures due to inertial forces acting in the normal direction to the plane of the walls. The out-of-plane behavior of masonry walls is complex and depends on several parameters, such as material and geometric properties of walls, connections between structural elements, the characteristics of the input...

Observations after strong earthquakes show that out-of-plane failure of unreinforced masonry elements probably constitutes the most serious life-safety hazard for this type of construction. Existing unreinforced masonry buildings tend to be more vulnerable than new buildings, not only because they have been designed to little or no seismic loading...

The seismic response of masonry vaults is discussed by presenting the results of an experimental campaign on a small-scale model and their numerical simulation though a heterogeneous full 3D non-linear Finite Element (FE) approach. The model relies into a discretization of the blocks by means of few rigid-infinitely resistant parallelepiped element...

This paper evaluates the seismic behaviour of a group of masonry buildings through the application of a simplified method. The method is based on the definition of a vulnerability index supported on few characteristics of the buildings and provides an estimation of the expected damage on the buildings as a function of the intensity of the seismic a...

We undertake the first (to our knowledge) seismic vulnerability method specifically designed for New Zealand Unreinforced Masonry (URM) churches. The vulnerability index (VI) methodology developed by Lagomarsino et al. (2003) for European churches and other monumental buildings has been the basis for our work. The technique entails a macroseismic a...

The reported study focused on modelling the seismic response of two URM buildings that were damaged in the Canterbury earthquake sequence. Static and dynamic nonlinear analyses were undertaken using the equivalent frame approach. Actual time-history records attained during the earthquakes where used to undertake dynamic analyses and facilitate dire...

Since cross masonry vaults represent one of the more widespread types of horizontal structural elements in historical constructions, understanding their behaviour is a crucial precondition for the accurate assessment of the global response of buildings to earthquakes. In spite of the importance of this topic, the complexity of evaluation three-dime...

The paper presents the analysis of the structural and constructive system together with that of the seismic response of the “Gothic house” in ArquataScrivia, that constitutes a rare example of timber framed masonry structure in Piedmont (Italy). Besides a certain diffusion around Europe, which is documented in the 19th century chronicles, in Italy...

A heterogeneous full 3D non-linear FE approach is validated against experimental results obtained on an in-scale masonry cross vault assembled with dry joints, and subjected to various loading conditions consisting on imposed displacement combinations to the abutments. The FE model relies into a discretization of the blocks by means of few rigid-in...

Out-of-plane mechanisms induced by earthquakes are typical of many masonry structures and their seismic assessment requires proper methods of analysis and verification. Different displacement based assessment (DBA) procedures have been already adopted in many codes, to take into account the dynamics of rocking mechanisms, but a systematic compariso...

The paper provides a contribution for the assessment of economic losses in masonry buildings, following a component-based approach, to be implemented within the modern probabilistic seismic risk analysis. It is based on the computation of proper decision variables as the potential economic losses due to the direct repair cost, in order to improve t...

The seismic Performance-Based assessment of existing masonry buildings requires the use of nonlinear models, in order to check the attainment of ultimate limit states. Incremental Dynamic Analysis represents the most accurate method but very few models are available which are able to describe the stiffness and strength degradation, which are typica...

Churches are an important part of New Zealand’s historical and architectural heritage. Various earthquakes around the world have highlighted the significant seismic vulnerability of religious buildings, with the extensive damage that occurred to stone and clay-brick unreinforced masonry churches after the 2010-2011 Canterbury earthquakes emphasisin...

Two introductions and points of view to the work that five Universities are bringing about for the seismic assessment of the Estense Fortress at San Felice Sul Panaro, a synergic study in order to apport as much knowledge as possible to a diffused field of interest such as the Fortress one.

The seismic Performance-Based assessment of existing masonry buildings requires the use of nonlinear models, in order to check the attainment of ultimate limit states. Incremental Dynamic Analysis represents the most accurate method but very few models are available which are able to describe the stiffness and strength degradation, which are typica...

The Canterbury earthquake sequence, in 2010-2011, has highlighted once again the vulnerability of monumental structures, in particular churches, and the importance of reducing their risk from an economic, cultural and social point of view. Within this context, detailed analysis is reported of the earthquake-induced damage to a stock of 48 unreinfor...

The damage assessment of monumental buildings after numerous seismic events in different countries has systematically highlighted the vulnerability of monumental structures, in particular churches, and the critical importance of reducing their risk from an economic, cultural and social point of view. This evidence has been highlighted, once again,...