Enrico Quagliarini

Dry Masonry Strenghtening through Basalt Fibre Ropes: Experimental Results against Out-of-Plane Actions

One of the most important characteristics that historical masonry should have is that of a monolithic behavior. Without these basic feature, no structural analysis could be considered reliable. If this characteristic is absent, strengthening bearing masonry giving it a transversal monolithic behavior is one of the first retrofitting actions to do so as to improve its seismic performance. Hence come out the idea to develop a new consolidation technique specially formulated for historical masonry. Stitching masonry through continuous flexible elements is an innovative technique, able to connect the several masonry components and to attribute to it a monolithic behavior according to the principles that govern the intervention on existing buildings: minimal intervention, compatibility, reversibility, respect of authenticity, matter conservation, control of the visual impact and possibility of recognizing the intervention. Basalt fibers ropes of 4 mm of nominal diameter (declared by manufacturer), have been used in this experimental program as continuous flexible element. The technique has been already tested and proved to be effective for improving the behavior against “in-plane” actions. Good results has been obtained also excluding synthetic adhesives (resins), with an enhancement about reversibility. In this paper, the results of an experimental campaign aimed to evaluate the technique effectiveness against “out-of-plane” loads are presented. Reinforced and unreinforced brick masonry specimens have been tested simulating vertical bending mechanism activation to evaluate the stitches contribute.

In-life prediction of hygrometric behaviour of buildings materials: an application of fractal geometry to the determination of adsorption and suction properties

Abstract In order to describe the hygrometric behaviour of a porous material such as mortar, it is quite common to resort to the diffusion process theory [1] . The equations that are obtained depend on the parameters that linearise the dependence on the gradient of the potential P adopted. Such parameters are not constants, but they greatly depend on the hygroscopic content of humidity inside the material. The hygroscopic content u inside the material depends on the relative humidity of the environment φ in a non-linear way. In short, we indicate the mass flux by m : m=f(u)× grad P, with u=u(φ) . Current research obtains the constitutive link between u and φ by fitting experimental data and there is no theoretical model which can interpret the curves obtained. This paper shows the results of research that, on the basis of fractal geometry, has worked out a mathematical model in order to express the existing link between the water content inside a porous material and the relative humidity of the environment at a given temperature. It shows that the knowledge of the fractal dimension of the pores’ space in a porous medium is enough to work out the suction and adsorption curves characteristic of the medium.

Urban scenarios modifications due to the earthquake: ruins formation criteria and interactions with pedestrians' evacuation

One of the most influencing elements in inhabitants’ earthquake safety definition is represented by the interactions between people and post-event environment in urban scenarios. Understanding and simulating rules for pedestrians’ motion in earthquake evacuation could be useful to inquire the risk assessment introducing the “human” factor influence: integrated “risk maps” could be realized by combining results of similar analyses with the traditional site hazard, buildings vulnerability and exposition indices. This work proposes an innovative approach based on the analysis of these interactions. Two experimentally-based activities are required: an analysis of human behaviors towards the post-earthquake environment; a relation for defining environmental modifications. Results firstly show a summary of man-environment interactions in earthquake evacuations. A possible criterion for path choice in evacuation is also numerically defined. A theoretical agent-based model is developed on these bases and summarizes phases, motion rules and man-environment interactions in earthquake pedestrians’ evacuation in urban scenarios. Secondly, quick criteria for scenario modifications involving ruins formation are proposed and evaluated: for each building, the percentages of internal and external ruins area is a function of its vulnerability and the expected earthquake Richter magnitude. Moreover, the external ruins formation criterion is validated by comparing predicted and effective values of ruins area depth in real cases. The model could be proposed as a tool for evaluating probable pedestrians’ choices in post-event scenarios, in order to reduce the interferences between the built environment and the evacuation process through interventions on buildings, urban fabric and strategies for emergency management.

A Novel and Sustainable Application of Basalt Fibers for Strengthening Unreinforced Masonry Walls

ABSTRACT This paper presents the first results of a study aimed at improving the seismic behavior of unreinforced masonry walls by a novel and sustainable application of basalt fibers. Five masonry panels were tested under out-of-plane actions, one of the common way of failure for masonry walls during an earthquake. Three of them were dry-strengthened by using two different techniques (a “lozenge” stitching and a “reticulum” one), while two unreinforced panels were used as reference. Besides, two other bigger masonry walls were dry-reinforced by “lozenge” stitching and vertical ropes and were tested by putting them horizontally and then loaded. The results indicate the effectiveness of this dry retrofitting system, increasing the performance of masonry wall specimens under out-of-plane actions. Besides, this technique potentially appears fully sustainable, because it is cheap, compatible, reversible, fire, and chemical resistant, it improves but not replaces original materials and, finally, it does not substantially use synthetic adhesives. This last point is very important both for preserving the health of the applicators and in case of fire-load, where synthetic adhesive often fail.

Multi-Agent Simulation Model for Evacuation of Care Homes and Hospitals for Elderly and People with Disabilities in Motion

The progressive population aging provokes an increase of importance in safety aspects for the elderly and the people with disabilities that are housed in care homes and hospitals. Current regulations denote an inadequate approach to safety problems connected to possible evacuation due to events like earthquakes, floods, fires. The law approach implicates that patients are directly carried out by health workers assistants in evacuation. However, many patients can autonomously evacuate, helped by specific facilities for way finding and not assisted by the medical staff. Our research is intended to design “guidance” system for these categories, and to inquiry how these facilities interact with people and influence their motion. The understanding and the simulation of behaviors of this category become essential in order to reach these goal. This work proposes a multi-agent model for evacuation simulation, based on the Social Force motion approach and on experimental data. This paper focuses on joining group behaviors for autonomous elderly. The validation concerns various quantities describing group motion phenomena. The model will be integrated including aspects connected with eventual disabilities in motion for patients.

Effects of Underground Cavities on the Frequency Spectrum of Seismic Shear Waves

A numerical method is proposed to study the scattering of seismic shear waves induced by the presence of underground cavities in homogeneous soils. The method is based on the superposition of two solutions: the solution of the free-wave propagation problem in a uniform half-space, easily determined analytically, and the solution of the wave scattering problem due to the cave presence, evaluated numerically by means of an ad hoc code implemented by using the ANSYS Parametric Design Language. In the two-dimensional setting, this technique is applied to the case of a single cave, placed at a certain depth from the ground level. The frequency spectrum of the seismic shear oscillation on the ground surface is determined for different dimensions and depths of the cave and compared with the spectrum registered without caves. The influence of the cave dimensions and depth on the spectrum amplification is analyzed and discussed.

Cultural Heritage and Earthquake: The Case Study of “Santa Maria Della Carità” in Ascoli Piceno

Received: October 14, 2016 Revised: February 7, 2017 Accepted: April 12, 2017 Abstract: Background: In October 2016, two major earthquakes occurred in Marche region in the Centre of Italy, that resulted in widespread damage. The second one strokes Norcia, Visso, Arquata del Tronto, Accumoli and Amatrice, causing a lot of damages to cultural heritage of the cities of Tolentino, San Severino, Camerino and Ascoli Piceno, where the church of Santa Maria della Carità is located.

Experimental Analysis of Romanesque Masonries Made by Tile and Brick Fragments Found at the Archaeological Site of S. Maria in Portuno

The reuse of ancient ceramic fragments in Romanesque masonries was a common practice in the Medieval era. A cultural impoverishment of the masonry building art characterized this period. Pre-existing structures were often exploited to build new masonries, both for civil and religious purpose. Starting from these general considerations, a specific construction technique of some Romanesque masonries of the Church of S. Maria in Portuno (Italy) and made by tile and brick fragments, was studied by a multidisciplinary approach. Analyses of the chemical, physical, and mechanical properties of the original materials (tile and brick fragments, mortars) were carried out by laboratory tests. Furthermore, some wall specimens were reproduced through the same ceramic materials and construction technique of the original masonries. Compression tests were carried out on these wall specimens so as to understand the influence of this construction technique on their compressive strength, Youngs modulus, and failure mode. The results allowed increased current knowledge on historical materials and on the mechanical behavior of these specific historical masonries. Useful data obtained by experimental characterization of the materials and walls will also allow to guide future restoration works on these masonries.

The properties and durability of adobe earth-based masonry blocks

This chapter deals with adobe technique and its materials for making eco-efficient masonry block. In particular, after a brief historical digression, it presents how manufacturing adobe earth-based masonry blocks, their dimensions, which soil is suitable and which stabilization materials are currently used for enhancing their properties. Then the principal mechanical and hygro-thermal properties of adobe blocks, how to determine them and which parameters influence them are provided. In addition, the present methods of testing adobe blocks for durability are presented and practical advice on maintaining or improving them are suggested. Finally, environmental and economic benefits potentially associated with the use of adobe earth-based masonry blocks, including new ways to reuse bulk industrial waste as stabilizers, are provided.

TiO2 nanocoatings for architectural heritage: Self-cleaning treatments on historical stone surfaces

The development and application of nano-engineered surface treatments on stones could become a useful tool for the realization of smart systems to better preserve and maintain architectural surfaces. Titanium dioxide nanoparticles can be used to realize transparent self-cleaning coatings applicable directly on preexisting surfaces, limiting cleaning actions and conservation processes, thus reducing their costs. The aim of this investigation is to evaluate the potential use of TiO2 on stone surfaces, especially in the field of architectural heritage. An aqueous colloidal dispersion based on titanium dioxide, obtained by sol–gel and hydrothermal processes, was applied by spray coating on travertine, a limestone largely used in buildings, both historical and modern. The maintenance in the original appearance of treated substrates was evaluated monitoring both colour and gloss changes produced by the treatments. Physical changes induced to stone by titanium dioxide were studied by wettability analyses. The efficiency of TiO2 photocatalysis was assessed by depolluting and soiling removal tests under ultraviolet light. The effects of deposited amount of titania on treated surfaces were also evaluated. Obtained results seem to allow the use of selected TiO2 treatments on the selected substrate, travertine, without altering in an evident and harmful way the original properties of limestone. Photoinduced effects (hydrophilicity, degradation of pollutants and decolourization of soiling) are very evident, and the combination of these properties may lead to an actual self-cleaning effect.