Energy refurbishment planning of Italian school buildings using data-driven predictive models

In the current practice, the design of energy refurbishment interventions for existing buildings is typically addressed by performing time-consuming software-based numerical simulations. However, this approach may be not suitable for preliminary assessment studies, especially when large building portfolios are involved. Therefore, this research work aims at developing simplified data-driven predictive models to estimate the energy consumption of existing school buildings in Italy and support the decision-making process in energy refurbishment intervention planning at a large scale. To accomplish this, an extensive database is assembled through comprehensive on-site surveys of school buildings in Southern Italy. For each school, a Building Information Modelling (BIM) model is developed and validated considering real energy consumption data. These BIM models serve in the design of suitable energy refurbishment interventions. Moreover, a comprehensive parametric investigation based on refined energy analyses is carried out to significantly improve and integrate the dataset. To derive the predictive models, firstly the most relevant parameters for energy consumption are identified by performing sensitivity analyses. Based on these findings, predictive models are generated through a multiple linear regression method. The suggested models provide an estimation of the energy consumption of the “as-built” configuration, as well as the costs and benefits of alternative energy refurbishment scenarios. The reliability of the proposed simplified relationships is substantiated through a statistical analysis of the main error indices. Results highlight that the building's shape factor (i.e., the ratio between the building's envelope area and its volume) and the area-weighted average of the thermal properties of the building envelope significantly affect both the energy consumption of school buildings and the achievable savings through retrofitting interventions. Finally, a framework for the preliminary design of energy refurbishment of buildings, based on the implementation of the herein developed predictive model, is proposed and illustrated through a worked example application. Worth noting that, while the proposed approach is currently limited to school buildings, the methodology can conceptually be extended to any building typology, provided that suitable data on energy consumption are available

Modelling strategies for the numerical simulation of the behaviour of corroded rc columns under cyclic loads

Rebars corrosion phenomena can modify the structural behaviour of reinforced concrete (RC) members and consequently the seismic performance of RC structures. Since many existing RC structures are affected by this phenomenon, the influence of the reinforcement corrosion on the seismic performance is still under examination, especially when the corrosive attack is localized in the dissipative areas of the plastic hinges. In this work, the effect of localized corrosion is numerically investigated, through the adoption of a suitable finite element model, object of validation with the outcomes of an experimental campaign carried out in the Laboratory of the University of Rome “Tor Vergata”, on un‐corroded and corroded RC columns subjected to axial load and cyclic horizontal actions. Particular attention has been paid to the definition of the three-dimensional model and to the modelling of the corroded rebars and their corrosion morphology. Indeed, different modelling strategies are proposed with the aim to properly simulate the cyclic behaviour of the corroded columns. The main results show how more refined strategies taking into account the morphological aspects of the corrosion phenomenon produce a better fit with the experimental results for both Damage Control and Life Safety limit states performance

Structural behaviour of Gerber half-joints subjected to steel corrosion

The Gerber half-joints assessment is today a topical problem since they are widespread in the infrastructure heritage of different countries. These structural elements are often affected by chloride corrosion phenomena due to their positioning under the deck joint. The paper presents some of the results of a wide research survey, developed at the Laboratory of the University of Rome Tor Vergata, aimed at evaluating their behavior when subjected to corrosion decay, up to failure, through experimental tests and analytical models. The experimental behavior of the specimens, designed with different criteria, and subjected to different degree of accelerated corrosion, is discussed. An accurate design phase of the specimens was followed, based on typical Strut and Tie models, to obtain peculiar and different failure mechanisms, involving both brittle and “ductile” crises. Particular care was devoted to the corrosion process, suitably calibrated for providing different degradation scenarios. The obtained results are analyzed and discussed in terms of load-displacement curves and cracking pattern, underlying the influence of corrosion on the failure mechanism. The experimental outcomes show that both design details and reinforcement corrosion could compromise the strength and ductility requirements of the elements and need to be accounted for in analytical and numerical structural assessment of existing corroded Gerber half-joints

Experimental evaluation of the corrosion influence on the structural response of Gerber half-joints

The assessment of the Gerber half-joints (or saddles), widespread in the infrastructure heritage of different countries, is nowadays a topical problem since they are often affected by chloride corrosion phenomena due to their positioning under the deck joint. In this paper, the influence of steel rebar corrosion on the experimental response of Gerber half-joints is experimentally analysed and discussed. In particular, four elements were cast in Laboratory of University of Rome “Tor Vergata” two of which subjected to accelerated corrosion, and then tested up to failure. The specimens were designed with typical strut and tie models, with the aim of achieving different failure modes governed by the concrete crush or by the tensile rebar breaking. Particular care was devoted to the corrosion process, in order to simulate decay scenarios typical of these structures. The experimental outcomes, expressed in terms of load–displacement curves, crack patterns and failure mechanisms show that also medium-slight degree of pitting corrosion can cause great reductions in capacity and ductility of the saddles, modifying, in addition, their failure mechanism. Finally, from the experimental outcomes, the sensitivity of these peculiar structures, not only to the corrosion amount, but also to its spatial distribution among the different steel rebars, and its morphology (pitting or uniform corrosion) is clearly underlined. As a consequence, the necessity to accurately and properly account for the corrosion phenomenon in the structural assessment is remarked

Analysis of failure mechanisms of Gerber half-joint specimens through digital image correlation technique

Reinforced concrete Gerber half-joints are characterized by D-Regions in which the de Saint Venant theory is not valid. Therefore, in the capacity assessment of existing Gerber half-joints, the correct assumptions about the stress fields and the strut-and-tie models play a crucial role. Digital Image Correlation (DIC) is an optical technique for the determination of displacements and strains of specimens subjected to mechanical actions. In this work, the DIC technique is applied within an experimental campaign aimed at identifying the nonlinear behavior of Gerber half-joints according to different construction details. The results obtained using the DIC technique allow to identify the shape of the compression fields (struts) and to predict the development of the crack patterns. Therefore, the outcomes are compared with the expected shapes of the strut-and-tie models and interpreted to analyze the different failure mechanisms oh the half-joints

Effects of the administration of miconazole by different routes on the biomarkers of the "steroidal module" of the Athlete Biological Passport.

This article reports the results obtained from the investigation of the influence of miconazole administration on the physiological fluctuation of the markers of the steroid profile included in the "steroidal module" of the Athlete Biological Passport. Urines collected from male Caucasian subjects before, during, and after either systemic (i.e., oral and buccal) or topical (i.e., dermal) treatment with miconazole were analyzed according to validated procedures based on gas chromatography coupled to tandem mass spectrometry (GC-MS/MS) (to determine the markers of the steroid profile) or liquid chromatography coupled to MS/MS (LC-MS/MS) (to determine miconazole urinary levels). The results indicate that only after systemic administration, the markers of the steroid profile were significantly altered. After oral and buccal administration, we have registered (i) a significant increase of the 5α-androstane-3α,17β-diol/5β-androstane-3α,17β-diol ratio and (ii) a significant decrease of the concentration of androsterone, etiocholanolone, 5β-androstane-3α,17β-diol, and 5α-androstane-3α,17β-diol and of the androsterone/etiocholanolone, androsterone/testosterone, and 5α-androstane-3α,17β-diol/epitestosterone ratios. Limited effects were instead measured after dermal intake. Indeed, the levels of miconazole after systemic administration were in the range of 0.1-12.5 μg/ml, whereas after dermal administration were below the limit of quantification (50 ng/ml). Significant alteration started to be registered at concentrations of miconazole higher than 0.5 μg/ml. These findings were primarily explained by the ability of miconazole in altering the kinetic/efficacy of deglucuronidation of the endogenous steroids by the enzyme β-glucuronidase during the sample preparation process. The increase of both incubation time and amount of β-glucuronidase was demonstrated to be effective countermeasures in the presence of miconazole to reduce the risk of uncorrected interpretation of the results

Experimental behavior of prestressed concrete beams under simultaneous sustained loading and corrosion

The paper presents an experimental study for the evaluation of the flexural response and failure mode of a prestressed concrete (PC) beam subjected to simultaneous sustained loads and corrosion. The obtained results are judged and discussed also through a comparison with the experimental outcomes on a reference sound PC beam, and a companion specimen subjected to artificial corrosion first, and then tested in bending. The three specimens are characterized by a 200 x 300 mm rectangular cross section, a total length of 3700 mm, and a clear span of 2700 mm. The value of the sustained load, applied with a simultaneous accelerated corrosion process of the strands, was chosen, based on the result of the uncorroded reference beam, to achieve a scenario that can occur in a real structure in situ. The flexural response of the tested element was monitored over a period of 70 days, up to failure, and showed to be highly dependent on the localization of the corrosion phenomena affecting the strands, especially when coinciding with the maximum bending moment position. The obtained results are finally compared with the ones obtained on a PC beam with the same geometry and material properties, first subjected to corrosion and then tested in bending. The differences in corrosion morphology and location and in the failure mode of the strand confirm the importance of accounting for the combined effect of reinforcement corrosion and loading when assessing the structural performance of PC beams

Assessing life-cycle seismic fragility of corroding reinforced concrete bridges through dynamic Bayesian networks

Bridge structures are exposed to several chronic and abrupt stressors, among which the combined effects of corrosion and earthquakes pose a major threat to their long-term safety. Probabilistic risk assessment frameworks that quantify and propagate uncertainties inherent to these phenomena are necessary to mitigate this threat. This paper proposes a dynamic Bayesian network for state-dependent seismic fragility functions, capturing corrosion and seismic effects over time. Markovian transitions among deterioration states for different bridge components are developed, combining chloride diffusion and corrosion propagation models with non-stationary Gamma processes. State-dependent fragility curves are derived based on non-linear dynamic time-history analyses given possible degradation configurations of the structure, accounting for uncertainties in material, geometry, and deterioration parameters. Record-to-record variability is captured using synthetic ground motions. Results on a 4-span Gerber bridge showcase the suitability of the framework for describing life-cycle fragility, and its capacity for embedding in advanced algorithmic decision-making workflows is discussed.Architectural Technolog