Analysis of the 2016 Amatrice earthquake macroseismic data

On August 24, 2016, a sudden MW 6.0 seismic event hit central Italy, causing 298 victims and significant damage to residential buildings and cultural heritage. In the days following the mainshock, a macroseismic survey was conducted by teams of the University of Padova, according to the European Macroseismic Scale (EMS98). In this contribution, a critical analysis of the collected macroseismic data is presented and some comparisons were performed with the recent 2012 Emilia sequence

Reliability-based analysis of recycled aggregate concrete under carbonation

Durability represents a crucial issue for evaluating safety and serviceability of reinforced concrete structures. Many studies have already focused on carbonation-induced corrosion of natural aggregate concrete (NAC) structures, leading to several prediction models to estimate carbonation depth. Less research is devoted instead on recycled aggregate concrete (RAC), about which limited experimental works exist aimed at assessing the carbonation coefficient in accelerated tests. Additionally, deteriorating processes are subject to uncertainty, when defining materials, geometry, and environmental actions during the service life of structures. This work presents a reliability-based analysis of carbonation resistance of RACs, using experimental carbonation coefficients derived from the literature, and applied in the full-probabilistic method prosed in fib Bulletin 34. Results demonstrate how aggregates replacement ratio and w/c ratio influence the reliability of RAC carbonation resistance

Techniques for sustainable building materials production: recycling in concrete industry

The excellent mechanical and durability properties, with its large availability and affordable costs, make concrete the most used engineered material, with an estimated worldwide consumption about 6 billion tons per year. The prices of this wide diffusion lie into the relevant environmental emissions associated to concrete industry: concrete production is in fact one of the main responsible of carbon emission in atmosphere, mainly due to cement manufacturing and natural aggregates extraction. Together with the energy requirements, water consumption and generation of construction and demolition waste, these factors contribute to the general appearance that concrete is not particularly compatible with the demands of sustainable development. Several operations can be applied to limit concrete impacts: the replacement of Portland cement with supplementary cementing materials (SCMs) and the use of recycled aggregates in place of natural resources are solutions that may achieve the aim of reducing concrete emissions during all its life cycle. Between the various recycled materials which can be suitable in concrete applications, promising results were obtained when limited quantities of recycled aggregates from construction and demolition wastes (C&DWs) and from electric arc furnace (EAF) slag are used, generally not affecting mechanical properties and environmental compatibility. Nevertheless, in the most of cases a lack of standardized rules hinder their use at market level, in particular when recycled aggregates or mineral additions come from metallurgical industry. In this thesis the use of two types of recycled aggregates for structural concrete production is explored: EAF slag as recycled aggregates and recycled aggregates from C&DW. In addition, the use of supplementary cementing materials is analyzed, paying particular attention on the suitability of the application of co-combustion fly ash in structural concrete. Two extensive experimental campaigns were carried out to analyze the main mechanical and durability-related properties of recycled concrete with EAF slag. Several mixes with increasing substitution ratios were produced, using both the coarse and the fine aggregates. A specific chemical and micro-structural in-depth examination was carried out in order to evaluate the actual stability of the material, the influence of the substitution ratio on hardened concrete properties and to study the aggregates-matrix bond when detrimental cycles were applied to concrete specimens. Once determined the suitability of some of the substitution ratios used, for the first time real-scale reinforced concrete beams with EAF slag were realized and tested for bending and shear failure, and their structural behavior is analyzed and discussed. The second part of the thesis deals with the use of recycled aggregates coming from C&DWs, to assess their influence on the rheological behavior of fresh concrete. An experimental campaign was conducted, and since slump value is often operator-sensitive, a more quantitative estimate was derived in terms of fundamental physical quantities, such as plastic viscosity and yield stress, by means of viscometer measures. The variables analyzed were the aggregates substitution ratio and proportioning method, the super-plasticizer content and the water/cement ratio. Lastly, an experimental campaign was performed to compare the effects of two different (SCMs) on mechanical and durability-related properties of structural concrete. Three mixes were produced, where coal and co-combustion fly ashes were used as partial substitute of cement (20% in volume) and compared with a reference concrete. An environmental impacts’ assessment was also performed, through a Life Cycle Analysis (LCA) framework specifically developed for concrete emissions evaluation, using a cradle-to-gate approach. Assessment is based on Italian LCI data, collected directly from local EAF slag treatment plant, a natural aggregate extractive plant and a C&DW processing plan

Municipal expected annual loss as an indicator to develop seismic risk maps in Italy

This work presents a risk-targeted indicator called Municipal Expected Annual Loss (MEAL) for a quantitative estimation of the seismic risk at territorial level. With MEAL, it is possible to calculate the impact of earthquakes in terms of direct losses, taking account of a wide set of earthquake scenarios on the built environment at municipal level. MEAL is, therefore, able to summarize scenario loss values of each municipality, and define in such a way a risk-targeted metric that can clearly be understood also by different stakeholders dealing with seismic risk management, mitigation, and transfer. The use of MEAL to map seismic risk for the Italian residential building stock is herein presented as a case-study, leading to the development of several maps able to depict seismic risk at different territorial scale levels

A framework for probabilistic seismic risk assessment of NG distribution networks

Lifelines are essential infrastructures for human activities and the economic developm ent of a region. Lifelines vulnerability reduction is an actual question, particularly with reference to NaTech events, like earthquakes. In this regard, worldwide past seismic experiences revealed heavy damages to NG distribution networks. It is therefore essential to perform seismic risk assessment of NG buried pipelines systems with the aim to identify potential criticalities and avoid significant consequences. For such reasons, this work illustrates the proposal of a probabilistic framework for seismic risk assessment of NG lifelines. The proposed procedure is subsequently applied to a specific case study in Italy to highlight its feasibility

State-Of-Research on Performance Indicators for Bridge Quality Control and Management

The present study provides a review of the most diffused technical and non-technical performance indicators adopted worldwide by infrastructure owners. This work, developed within the European COST Action TU 1406—“Quality specifications for roadway bridges, standardization at a European level,” aims to summarize the state-of-art maintenance scheduling practices adopted by bridge owners, mainly focusing on the identification and classification of the most diffused performance indicators (PIs). PIs are subdivided in technical and non-technical ones: for this latter subclass, PIs are classified in environmental, social and economic-targeted. The study aims to be a reference for researchers dealing with performance-based assessments and bridge maintenance and management practices

State-of-research on performance indicators for bridge quality control and management

The present study provides a review of the most diffused technical and non-technical performance indicators adopted worldwide by infrastructure owners. This work, developed within the European COST Action TU 1406—“Quality specifications for roadway bridges, standardization at a European level,” aims to summarize the state-of-art maintenance scheduling practices adopted by bridge owners, mainly focusing on the identification and classification of the most diffused performance indicators (PIs). PIs are subdivided in technical and non-technical ones: for this latter subclass, PIs are classified in environmental, social and economic-targeted. The study aims to be a reference for researchers dealing with performance-based assessments and bridge maintenance and management practices.Peer ReviewedPostprint (published version

Seismic behavior of precast reinforced concrete column-to-foundation grouted duct connections

AbstractThe paper shows the results of an experimental campaign aimed at investigating the cyclic behavior of a column-to-foundation joint for precast concrete elements. The tested connection is realized adopting corrugated steel ducts embedded into the foundation, in which column protruding rebars are anchored by grouting high performance mortar. The experimental program consists in testing six full-scale reinforced concrete square-section columns subject to quasi-static cyclic lateral load with a constant axial compression. A preliminary series of bond tests was carried out to define some experimental variables, i.e., longitudinal rebar diameter and anchorage length. Results of the precast joints are compared with those of two reference cast-in-place specimens with the same geometric characteristics, showing similar hysteretic behavior, energy dissipation and ductility values. Lastly, the plastic hinge height is computed for all the specimens based on experimental concrete strains, and compared to current codes formulations

INCREASING THE DIMENSIONAL STABILITY OF CAO-FEOX-AL2O3-SIO2 ALKALI-ACTIVATED MATERIALS: ON THE SWELLING POTENTIAL OF CALCIUM OXIDE-RICH ADMIXTURES

Advanced thermochemical conversion processes are emerging technologies for materials\u2019 recovery and energetic conversion of wastes. During these processes, a (semi-)vitreous material is also produced, and as these technologies get closer to maturity and full-scale implementation, significant volumes of these secondary outputs are expected to be generated. The production of building materials through the alkali activation of such residues is often identified as a possible large-scale valorization route, but the high susceptibility of alkali-activated materials (AAM) to shrinkage limits their attractiveness to the construction sector. Aiming to mitigate such a phenomenon, an experimental study was conducted investigating the effect of calcium oxide-rich admixtures on the dimensional stability of CaO-FeOx-Al2O3-SiO2 AAMs. This work describes the impacts of such admixtures on autogenous and drying shrinkage, porosity, microstructure, and mineralogy on AAMs. Drying shrinkage was identified as the governing mechanism affecting AAM volumetric stability, whereas autogenous shrinkage was less significant. The reference pastes presented the highest drying shrinkage, while increasing the dosage of shrinkage reducing agent (SRA) was found to reduce drying shrinkage up to 63%. The reduction of drying shrinkage was proportional to SRA content; however, elevated dosages of such admixture were found to be detrimental for AAM microstructure. On the other hand, small dosages of calcium oxide-rich admixtures did not induce significant changes in the samples\u2019 mineralogical evolution but promoted the formation of denser and less fractured microstructures. The results presented here show that calcium oxide-rich admixtures can be used to increase AAM\u2019s volumetric stability and an optimal dosage is prescribed

Structural reliability of masonry arch bridges subject to natural aging

This paper deals with a simplified full-probabilistic methodology for the safety assessment of existing masonry arch bridges. The proposed framework aims to determine the ultimate load-carrying capacity (Ultimate Limit State) of a bridge subject to environmental deterioration, and to establish the influence on the structural reliability.- (undefined