Abstract:The retrofitting of existing masonry buildings is now a crucial problem for Europe. Indeed, structural safety and energy efficiency should represent the target of any renovation. The proposal of a new synthetic performance parameter is presented and discussed. Following this approach, in this paper, after a review of the main studies available in the literature, a proposal of a new performance parameter approach is presented and discussed. It is capable of taking into account both the structural and thermal aspects of masonry retrofitting. An emblematic set of reinforcements and energy improvements for masonry walls is examined. An example, generalized formulas, and a simultaneous evaluation of the role of multiple structural and thermal parameters on masonry buildings are proposed, with a view to optimize several categories of costs related to the intervention.
Dense point clouds acquired from Terrestrial Laser Scanners (TLS) have proved to be effective for structural deformation assessment. In the last decade, many researchers have defined methodology and workflow in order to compare different point clouds, with respect to each other or to a known model, assessing the potentialities and limits of this technique. Currently, dense point clouds can be obtained by Close-Range Photogrammetry (CRP) based on a Structure from Motion (SfM) algorithm. This work reports on a comparison between the TLS technique and the Close-Range Photogrammetry using the Structure from Motion algorithm. The analysis of two Reinforced Concrete (RC) beams tested under four-points bending loading is presented. In order to measure displacement distributions, point clouds at different beam loading states were acquired and compared. A description of the instrumentation used and the experimental environment, along with a comprehensive report on the calculations and results obtained is reported. Two kinds of point clouds comparison were investigated: Mesh to mesh and modeling with geometric primitives. The comparison between the mesh to mesh (m2m) approach and the modeling (m) one showed that the latter leads to significantly better results for both TLS and CRP. The results obtained with the TLS for both m2m and m methodologies present a Root Mean Square (RMS) levels below 1 mm, while the CRP method yields to an RMS level of a few millimeters for m2m, and of 1 mm for m.
Recycling concrete construction waste is a promising way towards sustainable construction. Indeed, replacing natural aggregates with recycled aggregates obtained from concrete waste lowers the environmental impact of concrete constructions and improves natural resource conservation. This paper reports on an experimental study on mechanical and durability properties of concretes casted with recycled aggregates obtained from two different parent concretes, belonging to two structural elements of the old Cagliari stadium. The effects of parent concretes on coarse recycled aggregates and on new structural concretes produced with different replacement percentages of these recycled aggregates are investigated. Mechanical properties (compressive strength, modulus of elasticity, and splitting tensile strength) and durability properties (water absorption, freeze thaw, and chloride penetration resistance) are experimentally evaluated and analyzed as fundamental features to assess structural concrete behavior. The results show that the mechanical performance of recycled concrete is not related to the parent concrete characteristics. Furthermore, the resistance to pressured water penetration is not reduced by the presence of recycled aggregates, and instead, it happens for the chloride penetration resistance. The resistance to frost–thawing seems not related to the recycled aggregates replacement percentage, while an influence of the parent concrete has been assessed.
ABSTRACT: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.
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 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.
<p>In this paper we compare the results of different methodologies of inspections, made on the deck of a concrete bridge located near Cagliari, along the SS 195 road to Capoterra. From a strategic point of view this structure plays a key role ensuring direct connections from Cagliari to different structures related to industrial and local productions and to an important touristic district. Aim of our work is to obtain a real measure of the vulnerability through two procedures and compare them. The first one is based only on visual inspection while the second one realizes a measure in time of the vulnerability through chemical and physical processes focusing on the carbonation depth.</p><p>With the first procedure we manipulated the data obtained by visual inspection with fuzzy logic, thus using mathematical and logic functions to transform linguistic assessments, inherently subjective, into a numerical result, thus objective, representing the failure probability. This is derived from visual inspection and it’s then compared to the results obtained through the evaluation of the carbonation process in the concrete beams of the bridge. The goal is to verify the reliability of visual inspection through the comparison of the data obtained with the two different approaches and trace a methodology in order to reduce the number of invasive actions and their cost.</p>
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