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The purpose of this study was to evaluate the effect of environmental temperature and relative humidity on algae biofouling that often occurs on porous and rough fired brick surfaces. Brick samples were chosen since their common use on building facades. Accelerated growth tests were performed under different relative humidities and different temperatures. Results showed the effects of different temperature conditions in terms of algae growth delay and reduction of the covered area. All the relative humidity conditions tested substantially showed no growth from an engineering standpoint. The modified Avrami’s law succeeded in modelling the biofouling under the different environmental conditions.

The purpose of this study was to provide an empirical failure model predicting the microalgae growth on fired bricks surfaces. It was developed through a numerical fitting of experimental data present in literature. It considered the substrate properties related to biofouling (i.e. porosity and roughness) of different bricks under several environmental conditions (i.e. relative humidity and temperature). Results shows that the model is able to simulate the microalgae biofouling by explicitly taking into account such influencing factor. Finally, this empirical failure model is validated on a different dataset from literature and applied to time varying temperature.

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 ofSanta Maria della Caritàis located.Introduction:The church has high historical, architectural and social value for the city of Ascoli Piceno, because it is the only one that is opened to the devotees all time in the day and night. From the structural point of view, the church has a long and important annex to the north, which was later built with respect to the church, and after the L’Aquila earthquakes (2009) damages, the church was subjected to a retrofit intervention, in order to obtain a better “box-like behavior”.Objective:This paper addresses how the relevant annex influenced the seismic response of this historical complex and how, more generally, this kind of asymmetric mass may affect the behavior of historic churches.Results and Conclusion:The results indicate that the presence of annex plays a significant role in the dynamic response of the church and affects the distribution of damages in the whole building. The results of the seismic simulation agree with the observed damage.

Riverine Historic Built Environments (HBEs) in urban centres are relevant scenarios for flood risk, due to the compact layout of their outdoor spaces, that are squares and streets, and their position in flood-prone areas. Differences in HBE layout can provide differences in flood risks, but excluding the response of exposed individuals can lead to risk underestimation or overestimation, as for other hazards. This work is a first attempt to compare how accounting or not pedestrian evacuation behaviours can affect flood risk assessment and emergency strategies evaluation. Parametric configurations of typical HBEs are provided on case-studies, and existing tools for hydrodynamic and pedestrian evacuation simulation are applied to them. Risk indexes for the whole HBE (macroscale) and each outdoor space (microscale) in it are provided. Results show how the risk indexes trends accounting or not pedestrian evacuation behaviours are similar if considering the macroscale, while differences at the microscale exist (about 15 % in absolute terms). Concerning emergency strategies, sheltering seems to decrease the risk for the whole HBE up to 33 % in comparison to leaving the flood-affected area. Results also support where/how to place gathering areas in the HBE.

Since the late 1970s, nonlinear static analysis have had an increasing use in the seismic assessment of existing unreinforced masonry (URM) buildings. Different modelling strategies can be used to evaluate the global seismic response of these buildings, such as the Continuous Constitutive Laws Model (CCLM) and the Equivalent Frame Model (EFM). Despite the CCLM modelling approach seems to be the most suitable at this aim, it needs many input data, which are often quite difficult to be known, and requires a high computational effort. For this reason, the EFM, which is based on strongly simplified hypotheses, is preferred in professional practice, where a small computational burden and a time- and cost-saving structural analysis by using few mechanical parameters is needed. In this paper, a review of its uses and limits is proposed, in order to identify the most critical issues and define its proper use in professional practice when applied to existing URM buildings. As a result, it is highlighted that the EFM can be reasonably used as a first conservative approach for the seismic assessment of existing URM buildings with box behaviour and quite regular opening patterns. Thus, up to now, from this review its use is encouraged in seismic analysis of existing URM buildings after providing them a reduction of their floors and roofs deformability, an adequate wall-to-floor and wall-to-roof connections and a regularization of the opening patterns.

Reliable appraisal of the in situ compressive strength is a key challenge in the seismic assessment of existing RC structures, due to its high variability throughout them and because it often represents the most important strength parameter adopted in the structural analyses. For this reason, in this paper a procedure to obtain a more accurate concrete strength characterization is proposed and applied to several case studies. The method provides a reduction of test results’ variability by taking into account the influence of casting operations on it and may support existing codes for a correct in-place concrete strength evaluation.

From the advent of nanotechnologies in building constructions, many materials were functionalized to create composite material with new properties. Titania (TiO 2 ) is actually the most promising nanotechnology to create composite materials with self-cleaning and anti-microbial properties. TiO 2 was able to limit algae adhesion and their growth, even if, in case of high porous and rough substrata, their inhibitory effect seems to be limited. This way, in this study, silver and copper nano-particulate enhanced an aqueous nano-titania solution were applied on brick specimens and their inhibitory effects were tested during accelerated laboratory tests. Extent of biofouling on specimens’ surface was assessed by measuring the aesthetical alteration and correlations between algal growth and key parameters of substrata were discussed. Results confirm the key role of porosity and roughness on the biofouling process on untreated specimens, and their effect on the photocatalytic power of the tested nano-coatings toward algal adhesion. Results from this study were compared with previous findings in the literature on the same types of specimens only treated with the same aqueous nano-titania solution. No significant improvements were detected by the addition of metal nanoparticles. Experimental curves were overlapped to analytical model calculated by Avrami’s law, and its validity was confirmed where latency time could be observed. Whereas no latency time was detected, that is a very fast adhesion of algal cells occurred, the experimental curves were modelled by using a four parametric logistic model that was able to describe numerically the biofouling process.

The paper presents the results of an experimental campaign aimed at investigating the in-plane and out-of-plane behavior of tuff and fired clay brick masonry panels reinforced by a commercial, not yet tested, Textile Reinforced Mortar (TRM) system. The TRM, consisting of hydraulic lime mortar coupled with a bidirectional glass fabric (total thickness of 30 mm), was applied on both sides of the panels and connected through stainless-steel helical bars. First, a mechanical characterization of the TRM system was carried out, according to recent guidelines (AC434 and CNR-DT215) by means of tensile tests and single-shear bond tests on the two different substrates. Then, the effectiveness of the reinforcement was investigated through uniaxial compression, diagonal compression and three-point bending tests on masonry panels. After that, experimental results were compared to the predictions of recent guidelines and analytical models available in the literature, by using the mechanical parameters obtained from the TRM mechanical characterization. TRM showed to be very effective in increasing the in-plane shear strength of tuff panels, of about 170%, whereas in the case of fired clay brick ones the increase was limited to 33%. Besides, the diagonal compression strength of reinforced specimens seemed to be strongly influenced by the mortar matrix, instead of by the fabric reinforcement, as it usually happens i.e. for Fabric Reinforced Cementitious Matrix (FRCM) systems. Thus, novel simplified analytical formulations to predict the shear strength of reinforced panels by only considering the contribution of the TRM matrix were provided, discussed and compared to current analytical approaches for FRCM systems. As regards the out-of-plane behavior, the TRM system significantly increased the out-of-plane bending strength and ductility of both tuff and fired clay brick panels. The applicability of current analytical approaches, as well as possible amendments, was also investigated. Finally, the compressive behavior of the walls was not substantially modified by the reinforcement, reasonably due to the low axial stiffness of the connectors and, to a minor extent, because they were dry inserted within the masonry and simply folded over the glass fabric.

The dynamics of two Roman stone arches has been studied by means of the Non-Smooth Contact Dynamics method (NSCD), implementing a discrete element numerical model in the LMGC90 code. Schematized as a system of rigid blocks, undergoing frictional sliding and plastic impacts, the arches have exhibited a complex dynamics, because of the geometrical non-linearity and the non-smooth nature of the contact laws. First, harmonic oscillations have been applied to the basement of the arches, and a systematic parametric study has been conducted, aimed at correlating the system vulnerability to the values of amplitude and frequency of the assigned excitation. In addition, numerical analyses have been done to highlight the effects of the friction coefficient and of the blocks geometry on the dynamics, and, in particular, on the collapse modes. Then, the study of the arches stability against seismic excitations has been addressed, and three-dimensional simulations have been performed. Attention has been payed to the occurrence of out-of-plane overturning mechanisms induced by possible bending of the arches. The numerical results have suggested some structural retrofitting actions needed to improve the arches seismic safety.

Basalt is a common material used in constructions since antiquity. Nowadays its fibers (BFs) are going to be used as an alternative to glass, carbon or aramid fibers for strengthening purposes in building engineering. In particular, the use of basalt ropes on historic masonries seems to be a good solution to give them a monolithic behavior. Besides, basalt fibers reinforced polymer (BFRP) rods have emerged as a possible solution to the corrosion problems of steel reinforcement in reinforced concrete for new or damaged structures or to the strengthening of historic masonries by repointing. Anyway, there is till a lack of knowledge about their durability. Thus this paper presents durability tests performed on BF ropes and BFRP rods. The influence of water, acid and alkali aging solutions on the durability and on the mechanical strength of them was verified. In order to increase the durability in alkali environments (i.e.: concrete), a PMMA coating was also applied on the BFRP rods and its effect was assessed too. Results show that alkali environments could seriously affect the durability of BF ropes and BFRP rods, thus a suitable coating should be provided to protect them before their use on such environments.

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.

Structures belonging to the same type and built in the same period may share similar geometrical and spatial characteristics. When these features also affect the seismic response of the buildings, they are referred to as typical seismic vulnerabilities. When a building presents one or more of these typical vulnerabilities, some general and qualitative considerations on its seismic behaviour can be made a priori, considering their actual influence on the seismic behaviour of other similar cases. In this work, we propose and apply a specific procedure based on a priori considerations to a specific building type: the post-World War II Italian Schools. To this purpose, we first improved our knowledge about this type of building, pointing out typical and specific seismic vulnerabilities by studying the standard architectural principles suggested by the main manuals and laws of that time. Then, in order to find how these typological features affect the global seismic behaviour of the examined structures, we analysed a real case study representative of the entire building type. Pushover and Nonlinear Dynamic analyses have been carried out, considering four different models, representing three different configurations that may result from different combinations of the most significant typical vulnerabilities. The result of this work confirms that in the case of post-World War II Italian school buildings, typological vulnerabilities such as wide atriums, eccentric stairs and tall windows, along with irregularity in plan configuration, can strongly affect the global seismic behaviour of the school buildings.

Sustainable cities have to constantly face natural catastrophes, and planning actions should be oriented to quickly manage emergency conditions. Earthquake represents one of the most critical disasters. Earthquake-induced built environment modifications (i.e. building debris) affect the urban paths network availability. Historic centres are relevant scenarios because of their specific features (i.e. Heritage vulnerability; complex and compact fabric). Predicting which paths could be used by rescuers to rapidly reach damaged inhabitants could reduce losses and improve first aid actions. Sustainable semeiotic tools are proposed to quickly esteem the paths availability combining street geometrical features and building damages. Currently, no study provides insights on methods reliability. Hence, this work critically analyses methods outcomes by implementing them, for the first time, on the same real-world sample (Italian historic centres). Rapid tools (satellite images, photographic documentation) are used to compare methods previsions with effective post-earthquake paths availability. Pros and cons of each analysed method are evidenced, underlining that the approach that combines street-building geometry, building vulnerability and earthquake severity seems to give the best results. This could help Local Authorities and Civil Protection Bodies in better developing risk-mitigation strategies concerning, e.g., emergency management (rescuers’ access routes definition) and urban planning (building retrofitting interventions).

Earth has been used as construction material since prehistoric times, and it is still utilized nowadays in both developed and developing countries. Heritage conservation purposes and its intrinsic environmental benefits have led researchers to investigate the mechanical behaviour of this material. However, while a lot of works concern with rammed earth, CEB, and adobe techniques, very few studies are directed towards cob, which is an alternative to the more diffused rammed earth and adobe in specific geographic conditions. Due to this lack, this paper presents an experimental program aimed at assessing the failure mode and the main mechanical properties of cob earth walls (compressive strength, Young’s modulus, and Poisson’s ratio) through monotonic axial compression tests. Results show that, if compared with CEB, adobe, and rammed earth, cob has the lowest compressive strength, the lowest modulus of elasticity, and Poisson’s ratio. Differences are also found by comparing results with those obtained for other cob techniques, underlining both the high regional variability of cob and the need of performing more research on this topic. A strong dependence of material properties on loading rate and water content seems to exist too. Finally, the ability of a common analytical method used for masonry structures (an FEM macromodelling with a total strain rotating crack model) to represent the mechanical behaviour of cob walls is showed.

The goal of this study was to explain the influence of the total porosity and the surface roughness on the susceptibility of clay bricks to biodegradation by phototrophic microorganisms. In addition, this correlation was studied on both specimens treated with TiO2 nanocoating and untreated control specimens. The effect of UV intensity on the photocatalytic power of TiO2 was also investigated. An accelerated fouling test was performed by sprinkling a suspension of Chlorella mirabilis and Chroococcidiopsis fissurarum on sample surfaces. These two test strains were chosen because their representativeness on building clay brick facades subjected to biofouling. The gradual superficial accumulation of algal biomass on treated and control specimens was evaluated by means of image analysis and colour measurement. Two specimens' parameters, namely porosity and roughness, were examined. Results showed that both the specimen microstructure and roughness of the surface play a key role in the colonization of clay bricks because they were able to provide more nutrient to the algal cells anchored to the surface. The TiO2 nanocoating was able to inhibit the biofouling of clay bricks irradiated with UV-A light, except in the case of high porous rough specimens.

The Non-Smooth Contact Dynamics method (NSCD), implemented in the LMGC90 code, has been applied to the study of the seismic response of a medieval church, the S. Maria in Portuno’s Church at Corinaldo (AN, Italy). According to this model, the church masonry has been modelled as a system of rigid blocks, whose sliding motions are governed by the Signorini’s impenetrability condition and by the dry-friction Coulomb’s law. The NSCD method has proved to be a powerful tool for investigating the dynamics induced by ground seismic accelerations. Indeed the numerical results have given a deep insight into the seismic vulnerability of the church, highlighting several possible failure mechanisms. Moreover, the influence of the friction coefficient, which is related to the quality of the mortar, and the effects of connections between adjacent walls have been investigated.

Microalgal growth largely affects the aesthetical properties of building facades worldwide. It causes biodeterioration of building materials and, in a later stage, it can compromise integrity of the elements and their durability. Recently, the use of nanotechnology to prevent the growth of microalgae is rising. One of the most widespread and promising material is titanium dioxide (TiO2). Photocatalytic properties of TiO2 inhibit biofouling of microalgae when this coating is stimulated by UV radiation coming from the sun or from artificial light. In this study, the biocide effect of TiO2 coatings applied on clay brick specimens under weak UV radiation was assessed. Results revealed that TiO2 nanocoating was not able to fully prevent microalgal biofouling, but under optimal UV exposure conditions for the growth of microalgae it efficaciously prevented the adhesion of these microorganisms on the treated substrates through the formation of a superficial water film. This property resulted in a good self-cleaning efficiency of TiO2.

To evaluate the self-cleaning and de-polluting properties of a transparent titania coating, in this investigation a titanium dioxide based suspension was deposited by spray coating on travertine, a porous limestone largely used as building material. To assess compatibility with stone substrates, microstructure analysis, color and gloss measurements, static contact angle analysis and two different water absorption tests were carried out. Self-cleaning and de-polluting activities were assessed by the use of rhodamine B decoloration and NO x degradation tests. The results showed good compatibility with stone surfaces and evident efficiency, allowing the use of titania coatings for real outdoor applications.

In this paper the mechanical properties of earthen bricks produced by manual compaction have been investigated by a combined experimental and theoretical approach. Several compression tests have been executed on specimens of various composition and different dimensions, with the purpose of understanding the role of volume fractions of earth, sand and straw fibre, and the influence of the size effect. An important goal is the application of predictive models of the elastic properties to the considered material, and its assessment. An empiric linear correlation between the compressive strength and the experimental Young’s modulus is proposed.

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.

Environmental pollution is constantly increasing and it causes aesthetical concerns to urban buildings exposed to the atmosphere. Nanometric titanium dioxide (TiO2) has become a promising photocatalytic material owing to its ability to accelerate degradation of many organic contaminants. Application of TiO2 is rising and it found application on building industry. However, photocatalytic properties of this nanotechnology strongly depend on substrate morphology and on its nature. Thus, it is not correct to extrapolate photocatalytic activity on different types of substrate. Moreover, very few information is available about effectiveness of TiO2 coatings after aging phenomena when applied on different substrate. This paper aims to investigate photocatalytic properties of TiO2 applied on clay brick surfaces both after deposition and after aging process. TiO2 characterization was carried out by assessing nano-film morphology, wettability and self-cleaning efficiency before durability test. Self-cleaning ability was also evaluated during aging test in order to evaluate its variation in long term applications. Results show that photocatalytic efficiency of TiO2 remain stable after aging, thus TiO2 shows a good photocatalytic efficiency when it is applied to clay brick substrate. In the long run, photocatalytic efficiency of clay brick specimens treated with TiO2 is seven times higher than untreated specimens.

Titanium dioxide (TiO 2 ) colloidal suspensions applied by spray-coating have been used to deposit transparent self-cleaning coatings on stones with the aim of preserving the original aesthetic features of historical and monumental architectures. Travertine was chosen as the reference substrate. Compatibility with travertine and self-cleaning efficiency were analysed by indoor laboratory tests. The self-cleaning ability of TiO 2 is mostly dependant on the photocatalysis generated by ultraviolet light. The stones were artificially aged through different procedures and the photo-activity of TiO 2 was evaluated before and after the ageing. Results seem to encourage the use of nano-structured TiO 2 for preserving stone during time.

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.

Basalt is an emerging material, whose use is increasing in constructions and civil applications as an alternative to glass, carbon or aramidic fibers. Basalt Fiber Reinforced Polymer (BFRP) rods and Basalt Fiber (BF) ropes are going to be used as an alternative to glass, carbon or aramidic fibers for strengthening purposes but few information about their mechanical performances is present in literature and standard test protocols are missing. Thus, this work tries to provide a test protocol for tensile characterization of BF ropes and a validation of the test protocol used for tensile characterization of not-basalt-FRP rods applied on BFRP rods. This is a very important issue from an engineering standpoint in order to evaluate their applicability for architectural heritage retrofitting, as, for example, in repointing (rods), or in innovative techniques, such as the one actually still being tested in our laboratories, that is aimed to strengthen historic masonry (ropes). Experimental test results obtained are shown. Results seem to confirm that BFRP rods and BF ropes could be a good alternative to other similar products.