Improved Lipschitz approximation of HH-perimeter minimizing boundaries

We prove two new approximation results of $H$-perimeter minimizing boundaries by means of intrinsic Lipschitz functions in the setting of the Heisenberg group $\mathbb{H}^n$ with $n\ge2$. The first one is an improvement of a result of Monti and is the natural reformulation in $\mathbb{H}^n$ of the classical Lipschitz approximation in $\mathbb{R}^n$. The second one is an adaptation of the approximation via maximal function developed by De Lellis and Spadaro.Comment: 25 page

Seismic amelioration of existing reinforced concrete buildings. Strategy to optimize the amount of reinforcement for joints

Most of the existing Reinforced Concrete (RC) buildings in Italy were built according to obsolete regulations that were not enough aware of issues related to seismic design so that they need to be upgraded by pursuing either amelioration or full seismic rehabilitation. In doing that, the first step is to figure out what is, based on the results of the initial analysis of the structure in its ante-operam version, the best overall dissipative mechanism that could be ob-tained by a number of suitable and economically convenient local interventions. The choice of the overall dissipative mechanism strongly affects the amount of reinforcement to be adopted for the beam-column joints. For new buildings, the current adopted capacity design philosophy pursues an overall beam-sway mechanism in which plastic hinges first form in beams and at last at the base of the columns. On the contrary,for existing ones, often very irregular and gravity-load-dominated, pursuing such overall mechanism may result either uneconomic or even extremely difficult to implement due to the amount of reinforcement to be inserted in the joints. In such cases, an overall dissipative mechanism allowing, at some extent, columns flex-ural plasticizationshould be accepted and clearly identified in advance. Anyway,such ap-proach needs to be addressed properly in order to avoid the formation of column-sways at one story only that would result very dangerous due to the excessive demand of plastic rotations on the resulting hinges. This paper presents two simple models that may help the designer in deal-ing with the operations above. The formeris a model that allows to understand if, given the existing RC building case-study, either the beam-sway or a hybrid beam-column-sway mecha-nism should be conveniently pursued during the design of the retrofitting intervention. The lat-ter isa model that allows to design a hybrid beam-column-sway overall mechanism involving a suitable number of stories such as to guarantee a uniform and reasonable demand of plastic rotations in the involved columns

Masonry cross vaults: an overview of the historical developments

The cross vault represents one of the most diffused and fascinating structural typologies of the European architectural heritage. Its history began almost two thousand years ago and reached a widespread use during the Middle Ages with the outstanding gothic cathedrals. Without any proper scientific support but only using trial-and-error methods, considering each building as a scaled specimen of a new one to be built, the ancient workmanship achieved a proper competence represented by the so-called rules of thumb. However, despite this long-lasting history, it is only from the eighteenth centuries that scholars have tried to tackle the problem of analytically describing its structural behaviour. In this regard, the first part of the present study is devoted to the evolution of cross vaults from the geometrical and constructive standpoint, whereas the second one describes the historical advancements of its structural behaviour, until the development of modern limit analysis

Optimization of force-limiting seismic devices connecting structural subsystems

This paper is focused on the optimum design of an original force-limiting floor anchorage system for the seismic protection of reinforced concrete (RC) dual wall-frame buildings. This protection strategy is based on the interposition of elasto-plastic links between two structural subsystems, namely the lateral force resisting system (LFRS) and the gravity load resisting system (GLRS). The most efficient configuration accounting for the optimal position and mechanical characteristics of the nonlinear devices is obtained numerically by means of a modified constrained differential evolution algorithm. A 12-storey prototype RC dual wall-frame building is considered to demonstrate the effectiveness of the seismic protection strategy

Essays in Economics of Education

This thesis wants to explore two different aspects of the Italian education system. The first two chapters are focused on the school starting age, the third one analyzes the introduction of the electronic logbook in Italian schools. In chapter 1 I use administrative data from INVALSI test in different grades to study the effects of early enrollment to the primary school, in other words, the effects on student achievement of being enrolled to the first grade at the age of 5 instead of 6. The number of early enrollers is much higher in the South Italy than in the North. To understand the reason of this difference is not the aim of this work. I found that there is strong selection in early enrollment, with early enrollers having higher ability on average. However, early enrollers are younger than regular enrollers at the moment of the test, and even if they are more skilled on average, the effect of age on scores remains significant. As a result, the North-South gap in Invalsi test scores is partially driven by the difference in average age at the moment of the test with students from the south younger than northerners. In chapter 2 I use survey data from a sample of parents in 5 primary schools located in Palermo, where the 50% of the students born between January and April are early enrollers. I found preliminary evidence of peer effects among parents at the moment of the choice for enrollment. In the last chapter I found that the introduction of the electronic logbook increased scores at the INVALSI tests for tenth graders but not for younger students. This could be due to the fact older students have more independence and the electronic logbook helps parents to monitor them

A parametric investigation on the seismic capacity of masonry cross vaults

Considering the relevance and the artistic value of cross vaults in European seismic prone areas, a parametric study on the seismic capacity of this element is presented. In particular, the behaviour of the so-called groin vault is discussed, i.e. intersection at a right angle of two semi-circular barrel vaults. The influence of span, rise, thickness, infill, and masonry tensile strength is investigated with respect to two boundary conditions, representative of typical vault configurations within heritage buildings. The analyses were performed using an upper bound approach of standard limit analysis. For the sake of clarity, the adopted code framework is briefly reviewed.With the aim of identifying the most frequent failure mechanisms, the outcomes of the parametric analysis have been visually inspected and sorted according to the input parameters. Aiming toward a simplified assessment criterion, the resulting list of parameters was subsequently processed through multiple linear regression analyses that can help practitioners in quick seismic evaluation.This work was partly financed by FEDER funds through the Competitivity Factors Operational Programme - COMPETE and by national funds through FCT - Foundation for Science and Technology within the scope of the project POCI-01-0145-FEDER-007633.info:eu-repo/semantics/publishedVersio