1,721,024 research outputs found
Structural Resilience through Structural Health Monitoring: A Critical Review
Full text linkThis chapter aims to evaluate structural resilience improvements based on structural health monitoring. The entire chapter is organized into two main parts. In the first one, the key stages of the monitoring method are described at varying degrees of difficulty and knowledge levels. A brief digression of established and cutting-edge approaches that may be traced back to the discipline is also included. Next, structural resilience and its dimensions are described by referring to the literature. At the end of this general discussion concerning the theoretical aspect of these disciplines, a bibliographical and bibliometric study of the references is conducted, and the relationship between monitoring and resilience is identified. In this way, any conceptual and practical links present in the existing literature will be highlighted. The second part of the chapter is devoted to the analysis of the conceptual relations between the four dimensions of structural resilience and the four stages of the structural health monitoring discipline. Schemes and examples are provided in this chapter to demonstrate how information at each monitoring stage can be employed for the evaluation of the corresponding resilience dimension
Structural Optimization Through Cutting Stock Problem
Full text linkIn this study, a novel optimization method has been applied to a geodesic dome inspired by real-world similar structures in which the environmental and cost impact has been minimized by reducing raw materials at the production stage. To achieve this goal, the Cutting Stock Problem (CSP) has been embedded inside the global optimization procedure of the entire structure. The CSP is one of the most famous combinatorial optimisation problems in the (one-dimensional) bin packing problems (BPP) class. The main objective is to produce dj copies of each item type j (i.e. elements of the structures with the same cross-sectional Area) by employing the minimum number of bins such that the total weight in any bin does not exceed the capacity. In the civil engineering field, the traditional approach to structural optimization aims to improve the load-bearing capacity and the global performance of the structure itself. This includes, for instance, the maximization of the performance ratio through the minimization of the structure weight. However, this goal doesn’t guarantee maximum efficiency in reusing structural elements and minimising waste during the industrial production phase. To overcome these limits, authors propose a stock-constrained structural optimization in which a heuristic search technique is adopted in order to find the best spatial arrangement of elements composing the structure whit the lowest cut-off waste. Finally, considerations have been discussed by comparing the solution obtained by the traditional weight-minimization approach and the stock-constrained one
Seismic Assessment of a Masonry Bridge: Analysis and Retrofit
No full textThis paper presents a comprehensive study of an ancient masonry arch bridge, including structural verification, condition assessment, and proposed enhancements. The research involves a detailed survey using LiDAR and aerial techniques, mechanical inspections, development of a structural model, and rigorous verification of its seismic response and safety compliance. The study proposes structural improvements targeting identified vulnerabilities and evaluates their feasibility according to the Italian and European Standard Regulations. Comparisons between different retrofitting techniques are discussed, contributing valuable knowledge to masonry arch bridge rehabilitation
Optimal design of steel exoskeleton for the retrofitting of RC buildings via genetic algorithm
Full text linkIn recent decades, steel exoskeletons have gathered significant attention as a seismic retrofitting technique for existing structures. The design methods proposed so far are focused on the identification of the system's overall parameters through simplified models. Although these methodologies provide helpful guidance at the preliminary design stage, they do not consider aspects such as the distribution of the exoskeletons and sizing of their components. To overcome these limitations, an optimization process based on the Genetic Algorithm is proposed in this paper to identify the optimal exoskeleton number and spatial arrangement, and to determine the optimal size of their constituent elements. The algorithm aims to minimize the weight of the retrofit solution while keeping the whole existing structure in the elastic field and ensuring the structural verification of the exoskeleton's elements. The analyses have been conducted using a finite-element code with an Open Application Programming Interface, which allows the models to be handled through automatic routines. The proposed optimization tool has been applied to several case studies, considering two different layouts for the exoskeletons. Finally, the effectiveness of the retrofit method has been demonstrated, and the proposed optimization tool has been able to significantly reduce the weight and cost of the intervention
Robustness investigation of Horizontal Bidirectional Hybrid Damping System applied to long-span bridges under near-fault pulse-like earthquakes
Full text linkThis paper introduces a new integrated Horizontal Bidirectional Hybrid Damping System (HBHDS) incorporating eddy current dampers, metallic yielding dampers, fuse-lock device with a spherical steel bearing, for controlling the longitudinal and transverse vibrations of long-span bridges under near-fault pulse-like earthquakes. Based on the nonlinear time history analysis, the seismic response of a long-span bridge with HBHDS is investigated under different near-fault pulse-like earthquakes and compared to the installed damping system on the as-built bridge. The numerical results indicate that the HBHDS is an effective damping system against the near-fault earthquakes and exhibits a common tendency with similar or even better reductions of structural responses in comparison to installed damping system. Besides, a series of robustness investigations for HBHDS are carried out considering the out-of-service different HBHDS' components. It is found that HBHDS presents superior robustness to considering out-of-service dampers in terms of response reduction and energy dissipation capacity
Vulnerability assessment and lifecycle analysis of an existing masonry arch bridge
No full textThis paper presents a comprehensive study on structural verification and proposed improvements for an ancient masonry arch bridge. The research encompasses multiple stages, starting with a detailed survey utilizing LiDAR and aerial techniques to collect precise data on the bridge’s condition. Mechanical inspections assess deterioration levels and identify critical areas requiring attention. Based on the gathered data, a structural model of the bridge is developed, considering geometric parameters and material properties. The model undergoes rigorous verification procedures to assess its seismic response and ensure compliance with safety standards. The analysis includes identifying potential collapse mechanisms, such as the formation of plastic hinges, which can lead to structural failure. The study proposes structural improvements to enhance the bridge’s performance and safety. These interventions specifically target vulnerabilities identified during the verification process. They include additional support elements, reinforcing critical areas, and utilizing advanced materials to improve tensile strength and durability. The feasibility of the proposed retrofitting solutions will be proved by performing a cost analysis, while environmental impacts are evaluated through an environmental assessment (Lifecycle Assessment — LCA) in which all the main bridge refurbishment phases have been included. Finally, some of the advantages of bridge refurbishment measures are shown by comparing the proposed intervention with a bridge reconstruction in terms of costs and environmental impacts. The outcomes of this study contribute to the existing knowledge on the rehabilitation of masonry arch bridges and serve as a valuable reference for engineers and practitioners involved in preserving architectural heritage
Constructability-based design approach for steel structures: From truss beams to real-world inspired industrial buildings
Full text linkThis paper presents an optimization framework for steel trusses. The authors implemented a penalty-based approach to optimise the size, shape, and topology based on a dynamic grouping strategy to address the constructability challenges. The main contribution of the paper is the use of damped exponential constructability penalties. This approach ensures optimal designs by balancing structural complexity, through standardization in design, and minimizing the total number of members and variety of sections, with the overall structural cost. The paper also presents a detailed analysis that underscores the sensitivity of the optimization convergence to the algorithmic hyperparameters, emphasizing the role of cross-section assignments and stabilization of truss piece counts. The optimization framework is validated on a trussed roof structure based on the findings from the single truss optimization. The best truss topology proved to be the Howe truss configuration, highlighting its efficiency in meeting the defined objective function
Numerical models comparison for fluid-viscous dampers: Performance investigations through Genetic Algorithm
Full text linkFluid-viscous dampers played a crucial role in the protection of new or existing buildings against external actions as earthquakes and winds. In the last decade, several investigations have been conducted aiming to develop accurate numerical models. However, none has been focused on a comprehensive comparison between the most used fluid-viscous damper models considering the variability of their parameters in a mass-production series. In this paper, an identification procedure has been performed by comparing nine different existing literature models with the objective of evaluating their ability to match experimental loops of mass-produced fluid-viscous devices, both in terms of accuracy and robustness. Indeed, the model that is most effective for reproducing the characteristic of a specific specimen may not be representative (i.e., showing larger parameters variability) of the mass production of the same device type. For this purpose, dynamic tests have been developed in the laboratory and the experimental outputs have been adopted as the target function of the procedure. The identification scheme has been designed by implementing an optimization procedure via Genetic Algorithm. Results demonstrate how differential laws better fit the experimental cycles with respect to algebraic ones, and also show how few models in the series can offer a high level of both accuracy and robustness
Enhanced Multi-Strategy Particle Swarm Optimization for Constrained Problems with an Evolutionary-Strategies-Based Unfeasible Local Search Operator
Full text linkNowadays, optimization problems are solved through meta-heuristic algorithms based on stochastic search approaches borrowed from mimicking natural phenomena. Notwithstanding their successful capability to handle complex problems, the No-Free Lunch Theorem by Wolpert and Macready (1997) states that there is no ideal algorithm to deal with any kind of problem. This issue arises because of the nature of these algorithms that are not properly mathematics-based, and the convergence is not ensured. In the present study, a variant of the well-known swarm-based algorithm, the Particle Swarm Optimization (PSO), is developed to solve constrained problems with a different approach to the classical penalty function technique. State-of-art improvements and suggestions are also adopted in the current implementation (inertia weight, neighbourhood). Furthermore, a new local search operator has been implemented to help localize the feasible region in challenging optimization problems. This operator is based on hybridization with another milestone meta-heuristic algorithm, the Evolutionary Strategy (ES). The self-adaptive variant has been adopted because of its advantage of not requiring any other arbitrary parameter to be tuned. This approach automatically determines the parameters’ values that govern the Evolutionary Strategy simultaneously during the optimization process. This enhanced multi-strategy PSO is eventually tested on some benchmark constrained numerical problems from the literature. The obtained results are compared in terms of the optimal solutions with two other PSO implementations, which rely on a classic penalty function approach as a constraint-handling method
Multimodal seismic assessment of infrastructures retrofitted with exoskeletons: insights from the Foggia Airport case study
Full text linkAddressing the seismic vulnerability of infrastructures is critical, especially for those built before the introduction of the current seismic regulations. One of the primary challenges lies in retrofitting these buildings without interrupting their functionality. In this context, the use of exoskeletons for seismic retrofitting represents an effective solution. This approach increases the seismic resistance and ensures the continuous operation of the building during retrofitting. This advantage is especially crucial for critical infrastructures, such as airports. Nevertheless, traditional seismic assessment methods based on pushover analyses might not accurately predict the seismic capacity of complex infrastructures dominated by local vibration modes. To bridge this gap, the study proposes refining the multimodal pushover analysis tailored for seismic vulnerability assessments of large infrastructures with exoskeletons characterized by low modal participation ratios. The Foggia Airport case study exemplifies these points and highlights the practical applications of the discussed advancements. The authors compared two force distributions for push-over analysis, addressing the fine-tuning of exoskeletons to maximize their seismic resistance
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