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The seismic vulnerability assessment of monumental buildings is a complex task. Several uncertainties mine the reliability of evaluations. Within historical buildings, churches appear as particularly vulnerable objects, prone to instabilities and collapse when undergoing seismic loads. Global and local collapse mechanisms related to in plane and out-of-plane response of walls, respectively, are commonly observed in existing masonry buildings subjected to a seismic event. The main cause is the lack of strong connections among orthogonal walls and between walls and floors, which does not allow a global box-type behaviour of the building. This paper shows an approach to evaluate the vulnerability of churches based on a three-step analysis with increasing detail. The first step is a large-scale analysis to be applied to sets of churches, based on a simplified form comparing 28 mechanisms that can be activated by seismic events. The second step is referred to the evaluation of single churches and related, based on a kinematic approach, to the possibility to have out-of-plane mechanisms. The third step is based on the results of numerical models. It is useful to evaluate the behaviour in detail of some macroelements and to validate the obtained results in the first two steps. [ABSTRACT FROM AUTHOR]

In this framework, the current research work aims to analyse a sub-urban sector of the historic centre of Sant'Antimo, located in the province of Naples (Italy), in order to assess the seismic vulnerability of old masonry buildings in this sector and the expected damage scenarios resulting from seismic events with different characteristics. Moreover, in order to mitigate the identified risk, a set of retrofitting techniques are considered and analysed taking into account their contribution for the reduction of the seismic vulnerability of buildings. The vulnerability analysis is performed through the application of an index-based seismic vulnerability assessment approach integrated into a GIS tool in order to identify the structural units (S.U.) most susceptible at damage. Subsequently, typological vulnerability curves, according to the EMS-98 scale, are obtained for the building stock analysed. Finally, a parametric analysis, varying magnitude and seismogenic site-source distance, is performed to obtain and discuss urban damage and loss estimation scenarios in terms of number of collapsed and unusable buildings, as well as number of human casualties, severe injuries and homelessness. [ABSTRACT FROM AUTHOR]

Masonry has been probably one of the first structural materials used by humankind since the first centuries of civilization in a variety of applications that spans from housing to infrastructures. The results obtained by the shake table testing of scaled models of two historical masonry structures, namely the Old Bridge in Mostar and the ancient Protiron structure in Split, are presented in the paper of Krstevska, Nikoli'c, and Kustura ([9]). In particular, the architecture of the wireless sensor network and the automatized procedure proposed for the continuous processing of the recorded signals are discussed and described with reference to an explicative masonry tower case study. This is true for virtually any kind of civil engineering structure, but it is even exacerbated in the case of masonry heritage structures due to their complex geometries, the non-linear dependence of stiffness properties on environmental conditions, the mechanical complexity and heterogeneous nature of the constituent materials and more. [Extracted from the article]

The paper deals with the seismic investigation of two masonry churches, namely Visitazione and San Giuliano, which are located in Poggio Picenze, a small town about 10 km far from L'Aquila. The seismic response assessment of the churches, which were damaged by the severe seismic event occurred in Italy on 2009 April 6th, has been performed by means of experimental dynamic tests and numerical analyses. Firstly, an experimental campaign based on Ambient Vibration Tests (AVTs), which are non-destructive tests especially applied to historical and monumental buildings for evaluating their modal response, has been carried out on the selected constructions in the framework of a cooperation activity between the Ss. Cyril and Methodius University of Skopje and the University of Naples "Federico II". Such an experimental activity has allowed to obtain the dynamic properties of the examined structures, namely natural frequencies, vibration mode shapes and damping coefficients. The experimental results have been subsequently used to implement a numerical FEM model of the churches in the ABAQUS non-linear analysis software environment. Dynamic linear FEM analyses have been conducted in order to calibrate the experimental results in order to simulate as well as possible the real structural behaviour of inspected churches. Finally, the performed analyses have been of a fundamental importance for both detecting damages into the constructions and programming effective retrofitting interventions. [ABSTRACT FROM AUTHOR]

Since product customization is becoming more and more popular, high process flexibility is required in many industrial sectors. Incremental sheet forming shows versatility and its effectiveness can be improved when coupled with other processes to, for example, change the behavior of the material to be processed. This study combines two technologies, i.e. cold-rolling and incremental sheet forming, for the manufacture of thermoplastic components. Polycarbonate sheets were firstly cold-rolled to reach the desired thickness and then formed incrementally, to study how the first process (which modifies the mechanical behavior of the sheets) influences the second one, e.g. in terms of formability limits and forming forces. To this end, an experimental campaign, covering tensile tests and the manufacture of fixed and variable slope angle frusta by single-point incremental forming, was carried out on parent and cold-rolled sheets. The tests point out the correlation between the tensile behavior and some of the main features of the incremental sheet-forming process, like the maximum formability angle, the forming forces, failures and defects. In conclusion, the study provides a critical interpretation of the results to weight up the pros and cons of this integrated polymer sheet forming process. [ABSTRACT FROM AUTHOR]

The corrosion inhibition effect of non-toxic calcium gluconate at 0.75%, 1.25%, 1.75% and 2.25% concentration on mild steel in artificial seawater (3.5% NaCl) was studied by potentiodynamic polarization, coupon measurement, optical microscopy characterization and open circuit potential measurement. Results obtained showed the inhibiting compound effectively suppressed the corrosion of mild steel with inhibition efficiency value generally above 80% from polarization test and 90% from coupon measurement after 0.75% concentration of calcium gluconate. Calcium gluconate exhibited mixed type inhibition property with dominant anodic inhibition effect. The inhibitor adsorbed onto the steel surface through physisorption mechanism according to Langmuir and Frumkin isotherm models. Calcium gluconate shifted open circuit corrosion potential plot of mild steel to electropositive values compared to the plot of the non-inhibited steel. Corrosion pits in addition to severe worn out morphology on the image of the non-inhibited steel were absent on the inhibited steel with relatively improved surface morphology. [ABSTRACT FROM AUTHOR]

Shrinkage and creep are the main concrete volume changes over time. This unacceptable concrete deformation leads to stress and cracks creation where eventually reduces the service life of concrete structures. According to this, the prediction of shrinkage and creep strain in concrete structures with acceptable accuracy is the significance essential. The extensive investigation accomplished by several researchers has created different relationships and models for forecasting of shrinkage and creep strain based on experimental and analytical observation. Despite effective efforts in this regard, existing models do not have sufficient accuracy for anticipate of shrinkage strain. According to this, in this research, it has been attempted to provide a shrinkage predicting model based on the artificial neural network technique with the application of RILEM database. Also, it has been tried to determine the accuracy of the proposed model in comparison to the existing standard models by statistical analysis. According to the obtained results, by application of the neural network technique, the shrinkage strain could be predicted with acceptable accuracy especial in the extended period. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study on flexural fatigue dynamic behavior of reinforced concrete. Steel fiber is used for the retrofitting and strengthening flexural members, by mixing short smooth steel fiber and hooked-end fiber. By using Vibrophore HFP 150, dynamic loading was scanned at a resonance frequency of 100 Hz. Our objective is to examine the behavior of a specimen of 7 × 7 × 28 by a three-point bending test under high-level stress until it fails. Important research has been conducted to investigate the static and fatigue behavior of reinforcement. It was strengthened initially using one fiber, then using other additives. However, this research is not adequate to examine the flexural fatigue behavior of specimens by mixing different shaped fibers at different percentages. A further improvement in composite concrete performance is observed by mixing two steel fibers under high-level stress. The results are in alignment with the fatigue life data using Weibull distribution. [ABSTRACT FROM AUTHOR]

Historical centers are always composed of masonry building aggregates often designed without respecting seismic design criteria. The current seismic Italian code does not foresee a clear calculation method to predict their static nonlinear behavior. For this reason, in this article the seismic response of structural units into masonry aggregates has been predicted through a simplified modeling approach. The implemented procedure has been calibrated on the results of a numerical model performed by using the Equivalent Frame Method (EFM), implemented within a Finite Element Method (FEM) calculation program, used to investigate a basic building compound representative of the constructive techniques developed in the past decades in the Southern Italy. First, the whole aggregate has been modeled and analyzed in the nonlinear static field in order to evaluate the seismic behavior of both intermediate and head structural units. Later on, the seismic response of these structural units, considered as isolated structures, has been assessed by considering in simplified way their position in the aggregate, as well as the influence of other constructions. Finally, the achieved results on the above single analysis cases have been compared with those deriving from the investigation of the whole building compound, allowing to confirm the effectiveness of the proposed novel analysis procedure. [ABSTRACT FROM AUTHOR]

In the paper, the seismic retrofitting of an existing reinforced concrete school building located in the district of Naples has been examined. The school, which was designed to sustain gravity load only, is composed of seven constructions separated with seismic joints. One of these constructions has been retrofitted with different intervention techniques, namely reinforced concrete walls, steel concentric, eccentric and buckling restrained braces and steel shear panels, whose non-linear behaviour under seismic actions in terms of performance point detection have been evaluated and compared using Capacity Spectrum Method. Finally, the choice of the best intervention technique from economic, structural and environmental point of view has been done utilising an efficient multi-criteria decision-making (MCDM) method, the so-called TOPSIS method. From the performed analyses it was found that buckling restrained braces provide optimal solution for the seismic upgrading of the examined reinforced concrete school building. [ABSTRACT FROM PUBLISHER]

Masonry building aggregates are large parts of the Italian building heritage often designed without respecting seismic criteria. The current seismic Italian code does not foresee a clear calculation method to predict their static nonlinear behavior. For this reason, in this article a simple methodology to forecast the masonry aggregate seismic response has been set up. The implemented procedure has been calibrated on the results of two FEM structural analysis programs used to investigate three masonry building compounds. As a result, a design chart used to correctly predict the base shear of aggregate masonry units starting from code provisions has been set up. [ABSTRACT FROM PUBLISHER]

The Abruzzo earthquake hit the city of L'Aquila and its surroundings on the April 6, 2009. The aim of this study is to analyze the technical features of unreinforced masonry (URM) buildings and assess their seismic behavior during the Abruzzo 2009 seismic event. The damage induced in the URM constructions of L'Aquila and the suburbs was severe and several such buildings collapsed. This study includes an overview of the dynamic characteristics of the earthquake and the seismic history of the region. The seismic performance of URM buildings is discussed on the basis of both the experience in L'Aquila and the village of Castelvecchio Subequo, during the post-emergency support to the Italian Department of Civil Protection (Dipartimento della Protezione Civile [DPC]), and the field investigation carried out with the patronage of the EU COST Action C26 and the cooperation of the PLINIVS Centre of Naples in three areas of the old city of L'Aquila. The main characteristics of URM buildings, the building behavior and damage are described and reviewed with due respect to the characteristics of the earthquake, as well as with reference to the structural and non-structural characteristics of buildings, using the Italian MEDEA procedure. [ABSTRACT FROM PUBLISHER]

Pounding occurs when the adjacent buildings start vibration out of phase during the seismic activity which causes collision amongst the adjacent buildings. There are many mitigation techniques to avoid or minimize the effects of pounding including the provision of minimum separation gap between the adjacent buildings. Although all codes have provided the minimum separation gap requirements for the buildings, still a lot of study is required on this topic. This research aims at finding the minimum gap requirement for midrise buildings in Pakistan. Adjacent Buildings with different geometry and height are modelled in Sap2000 software with varying gap elements. Pushover and In-elastic time history analysis of these buildings are carried out using ground motion of Kashmir earthquake. Buildings are assumed to be resting on stiff soil. Material and sectional properties are also remained same for all cases. In order to reduce the pounding effects of two buildings, they were attached with each other and top displacements of buildings were compared with separate buildings with inadequate gap. Column shear, maximum peak displacements and square root of sum of squares of maximum peak displacements were studied and the results were plotted graphically. It was found out that pounding can occur up to separation gap of six inch. Maximum pounding occurs at the top floor level of smaller building. The requirement for minimum gap in UBC 97 is found out to be conservative. [ABSTRACT FROM PUBLISHER]