Francesca da Porto

In-Plane Behavior of Clay Masonry Walls: Experimental Testing and Finite-Element Modeling

Extensive experimental research aimed at defining the in-plane cyclic behavior of three types of load-bearing masonry walls, assembled with perforated clay units, and various types of head and bed joints was carried out. Experimental behavior was modeled with four types of nonlinear finite-element models. Both macromodeling and micromodeling strategies, implementing either isotropic or orthotropic material laws, were adopted. Two simplified criteria were proposed for calibrating the models, one for defining orthotropic properties starting from perforated unit geometry and the other for defining expanded unit and interface element properties in micromodels. The procedures adopted for model calibration established the reliability of various modeling strategies. Results allow some conclusions to be drawn about the reliability of diagonal compression tests for large unit masonry, the stress distribution and different behaviors of masonry made with different head and bed joints, and the influence of unit strength on the in-plane behavior of masonry.

Structural Aspects of The Conservation of Historic Masonry Constructions in Seismic Areas: Remedial Measures and Emergency Actions

Preservation of historic buildings is a demanding task, especially in seismic zones, where vulnerable constructions can suffer severe damages and losses. The last earthquake that struck the Abruzzo region in Italy in 2009 caused a particularly extensive damage. Lessons learned by previous experiences and the knowledge acquired through researches allowed facing the first emergency period involving universities, civil protection, and the Cultural Heritage Ministry. The result of this collaboration was the survey and the realization of emergency interventions for thousands of buildings in few months after the earthquake, waiting for the definition and design of definitive solutions.

Macro-Scale Analysis of Damage to Churches after Earthquake in Abruzzo (Italy) on April 6, 2009

This article focuses on the effects of the earthquake which struck the Abruzzo region (Central Italy) on April 6, 2009, causing considerable damage to many ancient buildings, particularly churches. During the emergency after the earthquake, many churches and other historical monuments (towers, city walls, large town houses, etc.) were surveyed, according to first-level damage survey forms for Cultural Heritage buildings, by multidisciplinary working groups composed of experts from several Italian institutions (Universities, Ministry for Cultural Heritage, Fire Brigade, etc.). This article presents a statistical study on the information collected by the University of Padova during the surveys, which was later inserted and organized in a database, and illustrates data on damage assessment of the buildings in question. It also presents an intuitive overview of the seismic effects on several churches, allowing not only better understanding of the response of these structures to this particular earthquake, but also correlating data on it with its effects on the churches.

Compression and Sonic Tests to Assess Effectiveness of Grout Injection on Three-Leaf Stone Masonry Walls

The results of an experimental campaign on multi-leaf stone masonry panels (scales 1:1 and 2:3), in original conditions and after consolidation with natural hydraulic lime grout injection are presented. The specimens were constructed with one of the most common structural techniques, widely employed on minor historical buildings throughout Europe. Experimental research included a series of destructive (DT) monotonic and cyclic uni-axial compression tests on three-leaf and single-leaf stone masonry panels. Mechanical tests were complemented by non-destructive tests (NDT) on the walls before and after strengthening. Both NDT and DT allowed assessment of the effectiveness of grout injection as a consolidation technique and gave better insights on its influence on the behavior of this type of masonry. An attempt to establish a relation between sonic velocity and mechanical parameters for this specific type of masonry was also carried out.

Simplified seismic assessment of railway masonry arch bridges by limit analysis

In this work, the seismic capacity of single and multi-span masonry arch bridges was assessed by limit analysis. A preliminary statistical survey was carried out on a stock of about 750 railway bridges in Italy, classified according to characteristics and expected collapse mechanisms under seismic excitation. A comprehensive parametric study was carried out on identified homogeneous classes, to calculate limit horizontal accelerations triggering the collapse mechanism in longitudinal and transverse directions. Iso-acceleration envelope curves, representing limit horizontal acceleration of the bridge as a function of geometric parameters, were then derived. These graphs can be used for preliminary seismic safety checking of existing masonry bridges, once the main geometric parameters are available by simple visual inspections and geometric surveys, and can easily be implemented in a Bridge Management System to prioritise seismic retrofitting interventions.

Reinforced concrete and masonry arch bridges in seismic areas: typical deficiencies and retrofitting strategies

In recent years, appraisal of the condition and rehabilitation of existing bridges has become an ongoing problem for bridge owners and administrators in all developed countries. Reliable methodologies are therefore needed in the assessment and retrofit design phases, to identify the vulnerability of each bridge class. The specific problems of common arch bridge types are discussed herein, for both reinforced concrete and masonry structures, proper interventions for their static and seismic retrofitting are illustrated and several examples of applications are provided. Retrofitting is usually coupled with functional refurbishment, according to a methodological approach that takes into account bridge characteristics, state of maintenance and functional requirements, and environmental aspects connected with repair and strengthening systems.

Limit analysis of transverse seismic capacity of multi-span masonry arch bridges

Thousands of road and railway masonry arch bridges are still in service in the Italian and European transportation network, and many of them are located in highly seismic areas. In this work, a kinematic analysis procedure is developed to assess the transverse seismic capacity of multi-span masonry bridges with slender piers, as they may be vulnerable to transverse seismic action. The procedure can calculate the limit horizontal load multiplier of overall collapse mechanisms involving transverse deformation of deck and piers. The procedure is then adopted in a parametric study describing the typical ranges of the main parameters influencing bridge transverse capacity. Parametric analysis yielded a set of iso-acceleration envelope curves which supply the resistant seismic acceleration of a bridge as a function of simple geometric parameters. The resulting graphs can thus be used for preliminary seismic assessments.

Comparison of seismic analysis methods applied to a historical church struck by 2009 L’Aquila earthquake

This paper presents the seismic assessment of a historical church by means of different analysis methods. The church of San Marco, seriously damaged by 2009 L’Aquila earthquake, Italy, is chosen as case-study. The analysis tools adopted and compared are linear and non-linear kinematic analysis, FEM pushover analysis and FEM nonlinear dynamic analysis. The different methods are evaluated regarding their ability to predict the damage and collapse mechanisms actually caused by the earthquake. The accelerograms of the main shock of the 6th April 2009 L’Aquila earthquake are considered for nonlinear dynamic analysis. The influence of relevant construction features, as original disconnection between parts or RC additions, is analysed into detail. Limit analysis is carried out to understand some of the critical collapse mechanisms which are not clearly revealed by FE analysis. The comparison of the analysis methods indicates advantages and limitations of each approach.

L'Aquila 6th April 2009 Earthquake: Emergency and Post-emergency Activities on Cultural Heritage Buildings

The earthquake that struck the Abruzzo region on 6th April 2009 at 3:32 a.m., had its epicentre in the capital of the region, L’Aquila, and seriously affected a wide area around the city, where many historic towns and villages are found. Due to the strategic importance of L’Aquila, a strong and organized civil protection action was necessary to face the emergency. In addition, the structural damage on historic buildings and centres was enormous. Therefore, it was necessary to carry out specific actions aimed at the safeguard of this heritage. These can be shortly listed as: set up of the organizational and decisional structure, damage surveys, temporary interventions to provide the minimum safety conditions, set up of a monitoring plan for some important monuments, set up of a methodology to intervene on complex and connected buildings in the historic centres, definition of adequate materials and techniques to intervene on the damaged buildings.

Cultural Heritage Buildings and the Abruzzo Earthquake: Performance and Post-Earthquake Actions

The architectural heritage was seriously hit by the earthquake that occurred on April 6th 2009 in the Abruzzo region, especially considering the effects on a city with the size and with historical and strategic importance as a capital of a region, L’Aquila. The activities to protect that heritage have been centralized in the structure “Protection of Cultural Heritage” at Di.Coma.C. (Command and Control Quarter), managed by the Civil Protection Department. This allowed the cooperation among different involved subjects (Ministry of Cultural Heritage officers, experts on structural engineering from Universities and Fire Brigade teams), with their own specific knowledge. Keystone of the operating process was the standardization of the damage survey and of its immediate and correct interpretation, through dedicated survey forms for churches and palaces. The experience in the field of temporary safety measures was extremely interesting: ideas for engineering the process were developed, in cooperation with the work of the fire brigade men, that are highly experienced technicians in the “emergency” field. Finally, monitoring plans for some important monuments have been set up for the control of the damage progression and the analysis of the structural behavior of buildings after the earthquake and the execution of temporary interventions: two cases (St. Mark Church and the Spanish Fortress) are discussed.