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In this study, a structural optimisation problem, addressed through a stochastic multi-objective approach, is formulated and solved. The problem deals with the optimal design of exoskeleton structures, conceived as vibration control systems under seismic loading. The exoskeleton structure is assumed to be coupled to an existing primary inner structure for seismic retrofit: the aim is to limit the dynamic response of the primary structure to prevent structural damage. A non-stationary filtered Gaussian white noise stochastic process is taken as the seismic input. Design variables pertain to the mechanical properties (stiffness, damping) of the exoskeleton structure. Two concurrent and competing objective functions are introduced, in order to take into account not only safety performance but also economic cost considerations. The resulting trade-off is solved searching the Pareto front by way of a controlled elitist genetic algorithm, derived from the Non-dominated Sorting Genetic Algorithm-II. Sensitivities of Pareto fronts and Pareto optimal sets to different system parameters are finally investigated by way of a numerical application.

Aunque el arco surgió como sistema estructural hace más de dos mil años, esta tipología estructural todavía no está muy difundida y se adopta principalmente cuando hay que cubrir grandes luces. La eficiencia de los arcos depende principalmente de la explotación óptima del material, es decir, de la minimización de la excentricidad del estrés, que reduce el volumen y el peso del material estructural. Una estructura eficiente, en estos términos, implica andamios simples y ligeros, contribuyendo así a minimizar los costes de construcción. Aunque hay muchos conocimientos y literatura sobre arcos, todavía hay margen para la optimización del diseño. El presente estudio se enmarca en este contexto y se ocupa del análisis estructural de los arcos circulares planos empotrados bajo una carga vertical distribuida uniformemente y un peso propio. En el primer paso, la solución analítica del comportamiento estático y cinemático de los arcos se estudia por el método de la fuerza. En el segundo paso, se optimiza la forma del arco, asumiendo el volumen del arco, y por lo tanto el peso, como función objetiva. Finalmente se calculan los mínimos de la función objetiva (es decir, los parámetros óptimos de la forma geométrica) para poder utilizarlos con fines prácticos..

This paper presents a simple strategy in order to search for the ideal shape of a generic variable section beam through algorithm-aided design; the latter makes it possible to interconnect the morphological requirements dictated by all the disciplines that contribute to the architectural / structural composition. At this aim, a specific optimization procedure is codified by Grasshopper software. The search for the minimum middle rise of the beam is posed as a single-objective optimization problem, while suitable architectural/geometrical constraints are considered for gaining the optimal shape. The dimensions and characteristics of the beam are taken from an existing structure (nowadays demolished), the BRAZIL PAVILION at the OSAKA Expo (1970) designed by Paolo Mendes da Rocha. The structure was characterized by an important structural span, that was covered by adopting advanced technological methods, shapes and materials.

The work done, lays the foundations for a design methodology that connects the formal and structural aspects of an architecture passing through the parametrization of geometric shapes. To carry out the steps of the design method, the design of a steel pedestrian bridge was experimented. The analysis of the structure made use of the AutoDesk Structural Analysis Robot calculation software; the geometry was parameterized using the AutoDesk Dynamo Studio software (Robot plug-in). The architectural design was carried out using the aforementioned software, managing to connect the formal and the structural part of the project, reaching a focus on the forms of architecture that directly influence the structural functionality. The advantage in this type of design lies in being able to analyze a structure and assign different characteristics to it (from morphology to detail) in real time, managing to connect the project idea directly with a finished product.

A 3.8-year-old Italian girl presenting with high fever and headache developed a decrease in the state of consciousness, apneas, bradycardia thus requiring intensive care and mechanical ventilation. Sandfly fever due to Cyprus virus, previously not reported in a child, outside an endemic area, must be included in the differential diagnosis of acute encephalopathy with apparently no explanation from the usual laboratory work-up.

The optimization of important structural components - such as beams - has always represented a crucial challenge in architectural and structural design, especially considering how the optimization of certain components often involves the loss of control of structural shapes. In this scientific contribution, an analytical model for shape optimization is presented. The shape opti-mization of the test-case, a variable-section beam, is modelled and optimized using two different ap-proaches and solvers: i) MATLAB-GA®, a stochastic, population-based algorithm that randomly searches the optimal solution among population members, by mutation and crossover operators; ii) Gh-Octopus®, a Multi-Objective Evolutionary Optimization solver, which allows the production of opti-mized trade-off solutions between the extremes of each goal, able to support designers in decision mak-ing. The methods combine Computational Geometry and Parametric Design and allow control of the shapes of structural elements while increasing structural performance. The good accordance between the results retrieved by the numerical model implemented on MATLAB-GA® with the numerical model implemented using Gh-Octopus® allowed the validation of the analyt-ical method presented in this contribution., presented at the conference Conceptual Design of Structures 2021, International fib Symposium, Switzerland, September 16-18 2021

Damping Reduction Factor plays a key role in scientific literature and Technical Codes, but till now existing formulations present differences and inconsistences probably because obtained by integration of real recorded events, thus sensible to specific used data. This paper investigates the relation between damping reduction factor and earthquake duration by means of random vibration theory. A stochastic process, that is non-stationary and filtered, is used to model a seismic event. The modulation function is suitably chosen to describe earthquakes characterized by different durations. The stochastic process peak theory allows to calculate damping reduction factor after the definition of the probabilistic response of a simple linear visco-elastic oscillator. The variability with seismic duration for different soil conditions and damping ratios is investigated. The study points out that damping reduction factor is more sensitive to seismic duration in the range of high period and on rigid soil with respect to other conditions. The results show that, if damping ratio or effective duration values are increased, the damping reduction factor value diminishes.

The paper describes the case of 21-month-old child with prolonged fever, vomiting and diarrhoea. After detecting non-typhoidal Salmonella in his stools, medical history has revealed an unexpected source of the infection.

In seismic codes, elastic response spectra are usually defined by adopting a conventional value for the damping ratio equal to 5%. Damping Reduction Factors (DRFs) are then introduced to account fo...

Many classes of engineering problems focus on the process of calibrating mathematical models using observed data. The enormous progress of scientific computation and data-mining techniques ...

The use of in situ strain measurements to reconstruct the deformed shape of structures is a key technology for real-time monitoring. A particularly promising, versatile and computationally efficient method is the inverse finite element method (iFEM), which can be used to reconstruct the displacement field of beam elements, plate and shell structures from some discrete strain measurements. The iFEM does not require the knowledge of the material properties. Nevertheless, it has always been applied to structures with linear material constitutive behavior. In the present work, advances are proposed to use the method also for concrete structures in civil engineering field such as bridges normally characterized by material nonlinearities due to the behavior of both steel and concrete. The effectiveness of iFEM, for simply supported reinforced concrete beam and continuous beams with load conditions that determine the yielding of reinforcing steel, is studied. In order to assess the influence on displacements and strains reconstructions, different measurement stations and mesh configurations are considered. Hybrid procedures employing iFEM analysis supported by bending moment-curvature relationship are proposed in case of lack of input data in plastic zones. The reliability of the results obtained is tested and commented on to highlight the effectiveness of the approach.

Over the last decade, the topic of regional resilience has drawn the attention of public authorities due to the increasing number of natural disasters. The absence of a practical and concrete methodology makes it extremely difficult to evaluate resilience at the regional scale, which involves several concepts such as economics, social sciences, environment, etc. This paper proposes an indicator-based approach to assess the resilience assessment of Italian regions. A set of twelve indicators has been selected among publicly available census data. A time window of ten years was considered in the analysis. Three different resilience indexes were calculated for each region. The first is an overall measure of resilience, while the other two represent resilience during the emergency and the restoration phase following a disaster. Results highlight fundamental aspects that have a higher impact on regional resilience and can be used by decision-makers to effectively allocate resources. The procedure has also been extended to evaluate the regional epidemic risk which can be used as a preliminary tool to develop risk mitigation strategies against biological hazards.

Isatuximab is a monoclonal antibody targeting the transmembrane receptor and ectoenzyme CD38, a protein highly expressed on hematological malignant cells, including those in multiple myeloma (MM). Upon binding to CD38-expressing MM cells, isatuximab is thought to induce tumor cell killing via fragment crystallizable (Fc)-dependent mechanisms, including antibody-dependent cellular cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP), and complement-dependent cytotoxicity (CDC), as well as via direct Fc-independent mechanisms. Here, these mechanisms of action were investigated in MM and diffuse large B-cell lymphoma (DLBCL) cell lines, as well as in peripheral blood mononuclear cells derived from healthy donors, and in MM patient-derived samples. Our findings show that isatuximab-mediated cytotoxicity occurred primarily via ADCC and ADCP in MM cell lines and via ADCC and apoptosis in DLBCL cell lines expressing high levels of CD38. We identified the programmed cell death-1/programmed cell death-ligand 1 (PD-1/PD-L1) pathway and MM cell-secreted transforming growth factor-beta (TGF-β) as tumor cell-related features that could suppress CD38-mediated ADCC. Furthermore, we established that isatuximab can directly activate natural killer (NK) cells and promote NK cell-mediated cytotoxicity via crosslinking of CD38 and CD16. Finally, isatuximab-induced CDC was observed in cell lines with high CD38 receptor density (>250,000 molecules/cell) and limited expression of inhibitory complement regulatory proteins (CD46, CD55, and CD59

Even if arches represent an old structural system adopted in construction practice since two thousand years ago, they are still adopted just if large spans have to be covered. The structural efficiency of arches principally depends on optimal material exploitation, due to the minimization of the thrust curve eccentricity, which reduces structural material volume and weight. Although the millenarian use and a very abundant literature dealing with arches, there is still scope for design optimization, so this study is framed within this context, investigating plane circular arches under uniformly distributed vertical load and self-weight. The arches are simply supported with bending springs at end sections. In a first step an analytical solution of the arch static is derived in dimensionless form. Next, the volume of the arch is minimized. Finally the results are charted to allow their use in a design process.

This paper presents a smooth hysteresis model for reinforced concrete (RC) structural elements based on the differential equation of the Bouc–Wen model. Stiffness degradation and strength degradation are defined by introducing a damage index that includes both dissipated energy and maximum displacement. The pinching effect acts directly on the stiffness of the system and is controlled by an activation energy. The degrading functions are connected to the actual processes with which the damage occurs, thereby giving each parameter a physical meaning. The simple formulation of the model allows a straightforward identification of the best-fitting parameters and an easy interpretation of the results. Applications to the cyclic behaviour of RC structural elements demonstrate that the model is well capable of describing complex hysteretic behaviours involving degradation and pinching effects.

An effective vibration control device, the pendulum tuned mass damper (P-TMD), can be easily realized as a mass supported on rolling or sliding pendulum bearings. While the bearings’ concavity provides the desired gravitational restoring force, the necessary dissipative force can be obtained either from additional dampers installed in parallel with the bearings or from the same friction resistance developing within each bearing between the roller/slider and the rolling/sliding surface. The latter solution may prove cheaper and more compact but implies that the P-TMD effectiveness will be amplitude dependent if the friction coefficient is kept uniform along the rolling/sliding surface, as in conventional friction bearings. In this case, the friction P-TMD will be as efficient as a viscous P-TMD only at a given vibration level, with large performance reductions at other levels. To avoid this inconvenience, this paper proposes a new type of sliding variable friction pendulum (VFP) TMD, called the VFP-TMD, in which the sliding surface is divided into two concentric regions: a circular inner region, having the lowest possible friction coefficient and the same dimensions of the slider, and an annular outer region, having a friction coefficient set to an optimal value. A similar arrangement has been recently proposed to realize adaptive seismic isolation devices, but no specific application to TMDs is reported. To assess the VFP-TMD performance, first its analytical model is derived, rigorously accounting for geometric nonlinearities as well as for the variable (in time and space) pressure distribution along the contact area, and then, an optimal design methodology is presented. Finally, numerical simulations show the influence of the main design parameters on the device behavior and demonstrate that the VFP-TMD can achieve nearly the same effectiveness of viscous P-TMDs, while considerably outperforming conventional uniform-friction P-TMDs. The proposed analytical model can be used to enhance or validate existing models of VFP isolators that assume a constant and uniform contact pressure distribution.

Steel jacketing (SJ) of beams and columns is widely employed as retrofitting technique to provide additional deformation and strength capacity to existing reinforced concrete (RC) frame structures. The latter are many times designed without considering seismic loads, or present inadequate seismic detailing. The use of SJ is generally associated with non-negligible costs depending on the amount of structural work and non-structural manufacturing and materials. Moreover, this kind of intervention results in noticeable downtime for the building. This paper presents a new optimization framework which is aimed at obtaining minimization of retrofitting costs by optimizing the position and the amount of steel jacketing retrofitting. The proposed methodology is applied to the case study of a 3D RC frame realized in OpenSEES and handled within the framework of a genetic algorithm. The algorithm iterates geometric and mechanical parameters configurations, based on the outcomes of static pushover analysis, in order to match the optimal retrofitting solution, intended as the one minimizing the costs and, at the same time, maintaining a specified safety level. Results of the proposed framework will provide optimized location and amount of steel-jacketing reinforcement. It is finally shown that the use of engineering optimization methods can be effectively used to limit retrofitting costs without a substantial modification of structural safety.

In structural engineering beams with non-constant cross-section or beams with variable cross-section represent a class of slender bodies, aim of practitioners’ interest due to the possibility of optimizing their geometry with respect to specific needs. Despite the advantages that engineers can obtain from their applications, non-trivial difficulties occurring in the non-prismatic beam modeling often lead to inaccurate predictions that vanish the gain of the optimization process. As a consequence, an effective non-prismatic beam modeling still represents a branch of the structural engineering of interest for the community, especially for advanced design applications in large spans elements. A straight beam of length l with variable inertia J(z) is provided in figure, subject to a generic live load condition q(z). The vertical displacement y(z) can be obtained from the solution of the differential equation of the elastic line, i.e., taking into consideration the inertia variability and neglecting, as first approximation, any shear contribution. Even if this solution is an approximate one, it is able to deal with the problem in its basic formulation. In this paper a solution for the problem stated is formulated using a series expansion of solutions, in a general load and cross section variability condition. Solution is thus obtained for a generic rectangular cross section beam with a variable height. Analytical solution is presented and evaluated using numerical evaluation of some cases of practical interest.

Current codes of practice, mainly devoted to new structures, do not include information and approaches relevant to old material and products. At the same time, old codes are not applicable since they are not reliability-based. The increasing need for assessment and renovation of existing constructions yields the necessity to develop new approaches for old materials and products that are consistent with the requirements of current codes. In this scenario, the aim of this article is to develop a new semi-empirical formulation for anchorage and lap strength of plain surface bars of R.C. structures that is also consistent with the reliability-based approach included in the forthcoming second generation of Eurocodes. To this aim, by using a reference test database, a novel step-by-step procedure is proposed for the statistical evaluation and optimization of the contribution of each parameter affecting anchorage and lap strength. Moreover, the probabilistic calibration of the proposed expressions is performed and equations for design anchorage and lap strength are proposed. These equations have the same format as that, for ribbed bars, included in the latest draft of the second-generation Eurocode 2. Finally, the proposed formulations are compared with those of previous studies and earlier codes.

The use of wood in timber bridges is increased over the past 20 years, mainly since wood is a renewable and sustainable resource. Nevertheless wood is a natural engineering material that is prone to deterioration caused by fungi decay, insect attack and temperature. For wood and wooden bridges there is in fact a strong correlation between durability of the material and bearing capacity. Deformations in a timber structure are often a good indicator of the structural condition. Within this context, in this study some structural issues dealing with the design of a timber bridge for pedestrians are investigated. In a first step, the bridge shape is designed taking into account various aspects: timber as a bridge material; properties of structural wood products; rain systems for preservation and protection; wearing surfaces for timber decks in order to ensure durability; static and dynamic loads; static scheme. In a second step, the bridge shape is optimized by a procedure based on the calibration of natural modes of vibration.

In structural engineering beams with non-constant cross-section or beams of variable cross-section are represents a class of slender bodies, object of the practitioners interest due to the possibility of optimizing their geometry with respect to specific needs. Despite the advantages that engineers can obtain from their use, non-trivial difficulties occurring in the non-prismatic beam modeling often lead to inaccurate predictions that vanish the gain of the optimization process. As a consequence, an effective non-prismatic beam modeling still represents a branch of the structural engineering of interest for the community, expecially for advanced design applications in large spans elements.

Arch arised as structural system more than two thousand years ago, but, in spite of this, it is still not widely diffused and is mainly adopted in presence of large spans. The structural efficiency of arches primarily depends on optimal material exploitation, i.e. minimization of internal stress eccentricity that reduces structural material volume and weight. An efficient structure, under these terms, leads to simple and light scaffolding, so contributing in minimizing construction costs. So, although literature on arches is already significant, there is still scope for design optimization. This study is framed within this context and deals with the structural analysis of end perfectly-constrained plane circular arches under uniformly distributed vertical load and self weight. In the first step, the analytical solution of arch static and kinematic behaviour is obtained by applying the force method. In the second step, the arch shape is optimized, by assuming the arch volume, and thus the weight, as objective function. Finally minima of the objective function (i.e. optimal geometric shape parameters) are computed and plotted in order to be used for practical purposes. Presented at OPTARCH2019, 1st International Conference on Optimization-Driven Architectural Design, Amman-Jordan, November 5-7 2019.

Arch arised as structural system more than two thousand years ago, but, in spite of this, it is still not widely diffused and is mainly adopted in presence of large spans. The structural efficiency of arches primarily depends on optimal material exploitation, i.e. minimization of internal stress eccentricity that reduces structural material volume and weight. An efficient structure, under these terms, leads to simple and light scaffolding, so contributing in minimizing construction costs. So, although literature on arches is already significant, there is still scope for design optimization. This study is framed within this context and deals with the structural analysis of end perfectly-constrained plane circular arches under uniformly distributed vertical load and self weight. In the first step, the analytical solution of arch static and kinematic behaviour is obtained by applying the force method. In the second step, the arch shape is optimized, by assuming the arch volume, and thus the weight, as objective function. Finally minima of the objective function (i.e. optimal geometric shape parameters) are computed and plotted in order to be used for practical purposes. Presented at OPTARCH2019, 1st International Conference on Optimization-Driven Architectural Design, Amman-Jordan, November 5-7 2019.

Damping reduction factor plays a central role both in scientific literature and seismic codes, but still now proposed formulations show a quite large scatter. The main goal of the present work is to explore a new definition of the damping reduction factor. The concept of stochastic response spectrum is adopted in order to predict the earthquake response of a linear SDoF system, on the basis of the random vibration theory for non-stationary process. The peak of the response of a SDoF system under a non-stationary stochastic process is used to define the stochastic displacement spectrum. The damping reduction factor is thus evaluated as the ratio between the maximum displacement of systems with a given damping and a conventional one subject to the same earthquake.

Recycling of waste tire rubber is a significant environmental problem due to the huge number of waste tires needing disposal. A promising alternative to methodologies usually used for this ...

mportant task in the dynamic assessment of the mechanical systems and its role is central in structural health monitoring. All sensors have to be placed on the structure so that all sought system features be obtained from the experimental tests. Sensors network design is rather diffused in laboratory applications, but there are scarce investigations on real civil structures and they are not so well documented. In order to give a contribution in this framework, the present paper deals with the optimal sensors placement problem on lattice towers. With reference to six of the most diffused existing optimum criteria and according to mechanical and energetic formulations, several sensors network configurations are calculated for two example broadcasting antennas, adopted as benchmark cases of studies. The final topological configurations of the networks are compared and the most relevant differences are discussed. Moreover, the information content behaviour is computed to investigate the connection between sensors network topology and its ability to withstand the presence of undesired signals (e.g., noise) during the measurements. The results here illustrated may be useful for sensors network design for this special class of structures.

In a previous paper “to retrofit or not to retrofit?” (Nuti and Vanzi, 2003) a straightforward procedure able to forecast the economic return of seismic structural upgrading was presented. More recently, the authors realized that the final mathematical results can be much simplified so as to allow back-of-an-envelope computation. The title of this paper tries to highlight precisely this aspect, namely that for many a regular seismic structural upgrading cases, nearly no computation is needed (apart from one subtraction and one multiplication) to assess their economic convenience. These findings are presented and discussed in this paper, together with a state of the art on the cost-studies available in literature and technical codes. The mathematical formulation leading to the proposed approximation is suitably explained, underlining its applicability field and comparing it with the rigorous solution. Also a table and a formula are furnished that alternatively allows to calculate the maximum estimation errors, in order to obtain an upper and lower bound for the maximum amount of money which should be allocated for seismic structural upgrading.Finally an application example is described, dealing with retrofitting of reinforced concrete viaducts, a widespread bridge typology in Italy. The adopted upgrading solution consists of a concrete jacket at the base of some piers, particularly suitable in order to increase their ductility. Keywords: Seismic retrofitting, Structural reliability, Safety, Optimization, Cost minimization