A reliable visual inspection method for vulnerability assessment of hyperstatic structures using fuzzy logic analysis

Fuzzy logic applied to the visual inspection of existing buildings has been proposed in relation to simple structures. Isostatic structures are characterized by a unique and known collapse mechanism, which does not vary with geometry or load change. In this paper we apply fuzzy logic to visual inspection for complex structures such as hyperstatic ones in which the collapse mechanism depends not only on the geometry but also on the size and disposition of loads. The goal of this paper is to give relevant weight, in the fuzzy analysis, not only to the single expression of degradation, due to its localization within the element, but also to the structural element itself by assigning a different resistance to the various elements. The underlying aim of the proposed method is to manage, evaluate, and process all the information coming from visual inspections in order to realize a management information system for the evaluation of the safety level of even complex structures

Terrestrial laser scanner for monitoring the deformations and the damages of buildings

The paper presents the use of the terrestrial laser scanner for the study and the assessment of damaged buildings. The terrestrial laser scanner provides the ability to detect the geometric 3D model of a building without any physical contact with the structure. Knowledge of the 3D model will give the opportunity to study the deformation and quantify the damages. Three case studies are presented relating to damaged and/or unsafe buildings: Sivillier Castle (Villasor - Sardinia- Italy), the Bell Tower of Mores (Sardinia-Italy) and industrial building (Cagliari - Italy). The first two cases concern buildings of historical and architectural importance that present a state of compromised conservation; the last, an industrial building compromised by fire. In all cases, a laser scanner survey was carried out that not only provided valuable information but also highlighted structural metric deformation and degradation

Integrated approach for post-fire reinforced concrete structures assessment

In order to assess decay in the mechanical characteristics of re-exposed Reinforced Concrete (RC), it is crucial to recon- struct the temperature time history and the evolution of strain and stress elds. In this paper, the state of the art of assessment methods is presented and applied to a real structure damaged by re. It is a prestressed RC industrial warehouse located in the outskirts of the city of Cagliari (Italy). The collected data of several assessment methods are presented in order to produce the owchart of an integrated approach for post- re investi- gation. Among the various techniques, the authors highlight a thorough laser scanner geometric survey and destructive and non-destructive testing. In addition, the temperature distribu- tion and its time history has been reconstructed by means of optical and Scanning Electron Microscopy, X-ray diffractom- etry, Thermogravimetric Differential Thermo-Analysis and calibrated Colorimetry. Actually, refurbishment is needed, but the structure withstood the re very well. Central columns displayed the most impor- tant damage, and several beams presented important de ec- tions having lost the prestressing actions of the tendons

Analytical and experimental shear evaluation of GFRP-reinforced concrete beams

Reinforced Concrete (RC) technology is advancing towards new frontiers enhancing its sustainability and durability through innovative materials. In particular, the application of Glass Fiber Reinforced Polymer (GFRP) bars, in lieu of steel reinforcement, shows excellent performance, especially in aggressive environments. Nevertheless, current international design guidelines and standards tend to be rather conservative, especially concerning shear reinforcement. This element hinders the technology’s competitiveness, not only in terms of material consumption but also in construction efficiency. This research aims to conduct an analytical comparison and experimental validation of the formulations found in some international standards pertaining to shear capacity in a specific case. The focus is on scenarios involving reduced shear reinforcement and cases where the number of stirrups falls below the minimum recommended by these standards. In the sample beam tests, two distinct flexural GFRP reinforcement ratios were employed to evaluate their influence on shear capacity, leading to diverse failure mechanisms: rupture of longitudinal GFRP bars and concrete crushing. The experimental results were used to compare the North American ACI, French AFGC, and Italian CNR shear capacity design approaches in the case of reduced transversal reinforced ratio. Analytical capacity expressions of the standards above are discussed with some remarks aiming at structural optimization

A proposal for low cost condition assessment method for existing RC bridges

Aging infrastructures require huge budgets to preserve their functionality and the lack of effective maintenance leads to increasing deterioration and therefore higher repair costs. For these reasons, assessing the condition of infrastructures becomes mandatory, with particular attention to the ones still in service even when their life limit has been exceeded. In particular, this problem is really important in Countries, like Italy, in which there are several operating bridges at the end of their service life. In this framework, many companies responsible for the management of road networks have turned their interest towards Bridge Management Systems (BMS). This paper presents a fast and low-cost method for condition rating of reinforced concrete bridges. The proposal is based on visual inspection and non-destructive testing. A specific parameter is designed to take into account the mechanical degradation of materials and the damage location at the structural sub-component level. Some benchmark case studies have been discussed in order to compare the proposed method with other approaches available in literature

Assessment of RC Bridges integrity by means of low-cost investigations

Infrastructure aging is an important problem nowadays, in particular for countries like Italy in which the main motorways were built 50 years ago. Huge budgets are necessary to keep infrastructure and bridges in service. In addition, the lack of a proper and timely maintenance, entails an increase of the deterioration and therefore higher costs of repair. Thus, the need of methods capable of assessing the reliability of the infrastructure in the frame of Bridge Management System (BMS), is patent. The aim of this work is to provide a robust decision-support tool for the analysis of the data collected within the BMS with field inspection. The innovative aspect of the proposal is the introduction of two factors which take into account the location of the damage, and the mechanical characterization of the material in the definition of a Condition Rating Number (CRN). The analysis of an existing Reinforced Concrete (RC) bridge network is presented in order to show the accuracy of this new method

Structural Identification from Operational Modal Analysis: The Case of Steel Structures

In the case of old existing structures where the cultural value is very high, structural health analyses and investigations would be better performed without damages or service interruptions. Thus, modal analysis aimed at identifying eigenfrequencies and eigenmodes represents a very effective strategy to identify structural characteristics. In this paper, an innovative strategy to identify structural parameters exploiting the modal information obtained from operational modal analysis is proposed. The importance of the structural modeling in the problem formulation is highlighted. In the case of a simply supported beam, it was possible to assess the beam steel elastic modulus, while in the case of a cantilever beam, some constraint characteristics have been evaluated as well. In the steel frame case, the focus was on the constraint conditions of the structure determining the flexural stiffness of the springs representing the column base constraints. The method performances are promising for applications in larger structures such as bridges and buildings

Climate Change Impact on Corrosion of Reinforced Concrete Bridges and Their Seismic Performance

As a consequence of climate change impact, a significant variation in terms of temperature, atmospheric humidity, and carbon dioxide concentration levels is happening. This condition leads to several negative effects on the safety and the life cycle of existing concrete structures, such as the increase in the rate of material degradation, due to corrosion phenomena. In fact, the presence of carbonation and corrosion phenomena significantly influence the load-bearing capacity of existing reinforced concrete (RC) structures, under both static and dynamic loads. Among the wide range of existing RC constructions, bridges stand out for their importance. Furthermore, as structures directly exposed to the weather effects, they are more susceptible to these phenomena. In this paper, the influence of corrosion on existing RC motorway viaducts’ seismic behavior, considering the impact of climate change, is investigated, by means of an efficient procedure based on the implementation of 3D simplified finite element models and the use of analytical relations to obtain the amount of reduction in the steel reinforcement area as a function of the age of the bridge and of the different corrosion scenarios analyzed. Several scenarios for the expected variations in CO2 concentrations, temperature, and relative humidity are evaluated, considering that most of the viaducts present in the Italian motorway network were built between the 1960s and the 1970s. The results obtained using the projection of climate change impacts are compared with those calculated considering the corrosion scenarios resulting from the DuraCrete research project, to understand if the evolution of climate change leads to worse scenarios than those previously assessed

Special Issue on Current Challenges in Materials Design

This special issue of the International Journal of Structural Glass and Advanced Materials Research contains new contributions and the extended version of some selected papers presented in the 6th International Workshop on Design in Civil and Environmental Engineering (DCEE2017) held at the University of Cagliari during November 9 - 10 - 11, 2017. Previous conferences of this series have been successfully held in Rome (2016), Taiwan (2015), Lyngby (2014), Worcester (2013), Dajeon (2011)