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Frontiers of structural and Civil Engineering 2024年第1期18卷 66-79页

作者： Yaxin TAO Xiaodi DAI Geert de SCHUTTER Kim Van TITTELBOOM department of structural Engineering and building Materials Ghent UniversityGhent 9052Belgium

Robotic-based technologies such as automated spraying or extrusion-based 3-dimensional(3D)concrete printing can be used to build tunnel linings,aiming at reducing labor and mitigating the associated safety issues,especially in the high-geothermal ***-based 3D concrete printing(3DCP)has additional advantages over automated sprayings,such as improved surface quality and no ***,the effect of different temperatures on the adhesion performance of 3D-printed materials for tunnel linings has not been *** study developed several alkali-activated slag mixtures with different activator modulus ratios to avoid the excessive use of Portland cement and enhance sustainability of 3D printable *** thermal responses of the mixtures at different temperatures of 20 and 40℃ were *** adhesion strength of the alkali-activated material was evaluated for both early and later ***,the structural evolution of the material exposed to different temperatures was *** was followed by microstructure *** indicate that elevated temperatures accelerate material reactions,resulting in improved early-age adhesion ***,higher temperatures contribute to the development of a denser microstructure and enhanced mechanical strength in the hardened stage,particularly in mixtures with higher silicate content.

关键词： alkali-activated material 3DCP tunnel lining high-geothermal environment adhesion

Influence of curing conditions on the shrinkage behavior of three-dimensional printed concrete formwork

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Frontiers of structural and Civil Engineering 2024年第8期18卷 1225-1236页

作者： M.BEKAERT K.van TITTELBOOM G.de SCHUTTER Magnel-Vandepitte Laboratory for structural Engineering and building Materials Department of Structural Engineering and Building MaterialsFaculty of Engineering and ArchitectureGhent UniversityGhent 60 B-9052Belgium

The use of three-dimensional(3D)printed concrete as formwork is becoming more widely applied within the ***,the technology is still not optimized and there are many reports of preliminary cracking during the curing of cast *** is believed to result from differential shrinkage between the printed and cast *** cracks(in the printed concrete or at the interface between the infill and printed concrete)form a preferential path for aggressive substances and can reduce the durability of the combined concrete *** ensure the desired service life of the structure,it is important that the differential shrinkage between cast and printed concrete is *** study investigated the effect of curing conditions on the differential shrinkage behavior of 3D and cast *** influence of prewetting of the dry-cured 3D printed formwork was also *** the experimental program,a vibrated and self-compacting concrete were used as cast *** 3D printed formwork was produced and combined with cast concrete to simulate a concrete *** formwork was cured for 1,7,or 28 d exposed to the air(relative humidity:60%or 95%)or submerged in *** length change of the combined elements was observed over 56 d after concrete casting and throughout the thickness of the *** show that increasing the curing period in dry conditions of the printed concrete leads to an expansion of the formwork on the first day after *** expansion leads to a non-uniform strain evolution throughout the curing period of the combined *** concrete formwork stored in wet conditions does not expand after the casting process but tends to show a decreasing linear deformation within the whole elements.

关键词： 3D concrete printing formwork shrinkage curing

Automated classification of civil structure defects based on convolutional neural network

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Frontiers of structural and Civil Engineering 2021年第2期15卷 305-317页

作者： Pierclaudio SAVINO Francesco TONDOLO department of structural Geotechnical and building EngineeringPolitecnico di TorinoTorino10129Italy

Today,the most commonly used civil infrastructure inspection method is based on a visual assessment conducted by certified inspectors following prescribed ***,the increase in aggressive environmental and load conditions,coupled with the achievement of many structures of the life-cycle end,has highlighted the need to automate damage identification and satisfy the number of structures that need to be *** overcome this challenge,this paper presents a method for automating concrete damage classification using a deep convolutional neural *** convolutional neural network was designed after an experimental investigation of a wide number of pretrained networks,applying the transfer-learning *** and validation were conducted using a database built with 1352 images balanced between“undamaged”,“cracked”,and“delaminated”concrete *** increase the network robustness compared to images in real-world situations,different image configurations have been collected from the Internet and on-field bridge *** GoogLeNet model,with the highest validation accuracy of approximately 94%,was selected as the most suitable network for concrete damage *** results confirm that the proposed model can correctly classify images from real concrete surfaces of bridges,tunnels,and pavement,resulting in an effective alternative to the current visual inspection techniques.

关键词： concrete structure infrastructures visual inspection convolutional neural network artificial intelligence

Deep convolutional neural network for multi-level non-invasive tunnel lining assessment

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Frontiers of structural and Civil Engineering 2022年第2期16卷 214-223页

作者： Bernardino CHIAIA Giulia MARASCO Salvatore AIELLO department of structural Geotechnical and Building EngineeringPolytechnic University of TurinTorino10129Italy

In recent years,great attention has focused on the development of automated procedures for infrastructures *** efforts have aimed at greater speed and reliability compared to traditional methods of assessing structural *** paper proposes a multi-level strategy,designed and implemented on the basis of periodic structural monitoring oriented to a cost-and time-efficient tunnel control *** strategy leverages the high capacity of convolutional neural networks to identify and classify potential critical *** a supervised learning framework,Ground Penetrating Radar(GPR)profiles and the revealed structural phenomena have been used as input and output to train and test such ***-based analysis and integrative investigations involving video-endoscopy,core drilling,jacking and pull-out testing have been exploited to define the structural conditions linked to GPR profiles and to create the *** degree of detail and accuracy achieved in identifying a structural condition is *** a result,this strategy appears of value to infrastructure managers who need to reduce the amount and invasiveness of testing,and thus also to reduce the time and costs associated with inspections made by highly specialized technicians.

关键词： concrete structure GPR damage classification convolutional neural network transfer learning

Fuzzy-entropy based robust optimization criteria for tuned mass dampers

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Earthquake Engineering and Engineering Vibration 2010年第2期9卷 285-294页

作者： Giuseppe Carlo Marano Giuseppe Quaranta Sara Sgobba department of Environmental Engineering and Sustainable Development Technical University of Bari department of structural Engineering and geotechnics University of Rome "La Sapienza" Faculty of Engineering International University UNINETTUNO

Tuned mass dampers (TMD) are well known as one of the most widely adopted devices in vibration control passive strategies. In the past few decades,many methods have been developed to find the optimal parameters of a TMD installed on a structure and subjected to a random base excitation process,but most of them are usually based on an implicit assumption that all of the structural parameters are deterministic. However,in many real cases this simplification is unacceptable,so robust optimal design criteria becomes aviable alternative to better support engineers in the design process. In Robust Design Optimization (RDO) approaches,indeed the solution must be able to not only minimize the performance but also to limitits variation induced by uncertainty. Most of the currently available RDO methods are based on a probabilistic description of the model uncertainty,even if in many cases they are not able to explicitly include the influence of all the possible sources of uncertainties. Therefore,in this study,a fuzzy version of the robust TMD design optimization problem is proposed. The consistency of the fuzzy approach is studied with respect to the available non-probabilistic formulations reported in the literature and an application to an example of a robust design of a linear TMD subjected to base random vibrations in the presence of fuzzy uncertainties. The results show that the proposed fuzzy-based approach is able to give a set of optimal solutions both in terms of structural efficiency and sensitivity to mechanical and environmental uncertainties.

关键词： tuned mass damper random vibration robust design fuzzy variable expected value fuzzy entropy

Modeling of shear walls using finite shear connector elements based on continuum plasticity

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Frontiers of structural and Civil Engineering 2017年第2期11卷 143-157页

作者： Ulf Arne GIRHAMMAR Per Johan GUSTAFSSON Bo KALLSNER Division of Wood Science and Engineering Lulea University of Technology Skellefiea 93187 Sweden Division of structural Mechanics Department of Building Sciences Lund University Lund 22100 Sweden department of building Technology Linnceus University Vaxjo 35195 Sweden

Light-frame timber buildings are often stabilized against lateral loads by using diaphragm action of roofs, floors and walls. The mechanical behavior of the sheathing-to-framing joints has a significant impact on the structural performance of shear walls. Most sheathing-to-framing joints show nonlinear load-displacement characteristics with plastic behavior. This paper is focused on the finite element modeling of shear walls. The purpose is to present a new shear connector element based on the theory of continuum plasticity. The incremental load-displacement relationship is derived based on the elastic-plastic stiffness tensor including the elastic stiffness tensor, the plastic modulus, a function representing the yield criterion and a hardening rule, and function representing the plastic potential. The plastic properties are determined from experimental results obtained from testing actual connections. Load-displacement curves for shear walls are calculated using the shear connector model and they are compared with experimental and other computational results. Also, the ultimate horizontal load-carrying capacity is compared to results obtained by an analytical plastic design method. Good agreements are found.

关键词： shear walls wall diaphragms finite element modelling plastic shear connector analytical modelling exoerimental comoarison

Application of a Machine Learning Algorithm for the structural Optimization of Circular Arches with Different Cross-Sections

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Journal of Applied Mathematics and Physics 2021年第5期9卷 1159-1170页

作者： Jonathan Melchiorre Amedeo Manuello Bertetto Giuseppe Carlo Marano department of structural building and geotechnics Politecnico di Torino. Corso Duca degli Abruzzi Torino Italy

Arches are employed for bridges. This particular type of structures, characterized by a very old use tradition, is nowadays, widely exploited because of its strength, resilience, cost-effectiveness and charm. In recent years, a more conscious design approach that focuses on a more proper use of the building materials combined with the increasing of the computational capability of the modern computers, has led the research in the civil engineering field to the study of optimization algorithms applications aimed at the definition of the best design parameters. In this paper, a differential formulation and a MATLAB code for the calculation of the internal stresses in the arch structure are proposed. Then, the application of a machine learning algorithm, the genetic algorithm, for the calculation of the geometrical parameters, that allows to minimize the quantity of material that constitute the arch structures, is implemented. In this phase, the method used to calculate the stresses has been considered as a constraint function to reduce the range of the solutions to the only ones able to bear the design loads with the smallest volume. In particular, some case studies with different cross-sections are reported to prove the validity of the method and to compare the obtained results in terms of optimization effectiveness.

关键词： structural Optimization Genetic Algorithm Boundary Value Problem Arch Volume Minimization

Damage detection on framed structures: modal curvature evaluation using Stockwell Transform under seismic excitation

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Earthquake Engineering and Engineering Vibration 2015年第2期14卷 265-274页

作者： R.Ditommaso F.C.Ponzo G.Auletta department of Structures Geotechnics Engineering Geology University of Basilicata School of Engineering University of Basilicata

The key parameters for damage detection and localization are eigenfrequencies, related equivalent viscous damping factors and mode shapes. The classical approach is based on the evaluation of these structural parameters before and after a seismic event, but by using a modern approach based on time-frequency transformations it is possible to quantify these parameters throughout the ground shaking phase. In particular with the use of the S-Transform, it is possible to follow the temporal evolution of the structural dynamics parameters before, during and after an earthquake. In this paper, a methodology for damage localization on framed structures subjected to strong motion earthquakes is proposed based on monitoring the modal curvature variation in the natural frequency of a structure. Two examples of application are described to illustrate the technique: Computer simulation of the nonlinear response of a model, and several laboratory(shaking table) tests performed at the University of Basilicata(Italy). Damage detected using the proposed approach and damage revealed via visual inspections in the tests are compared.

关键词： damage detection S-transform band-variable fi lter

Optimal seismic retrofit model for steel moment resisting frames with brittle connections

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Earthquake Engineering and Engineering Vibration 2018年第4期17卷 835-847页

作者： Hyo Seon Park Se Woon Choi Byung Kwan Oh department of Architectural Engineering Yonsei University Center for structural Health Care Technology in building Yonsei University department of Architecture Catholic University of Daegu department of Civil and Environmental Engineering Princeton University

Based on performance-based seismic engineering, this paper proposes an optimal seismic retrofit model for steel moment resisting frames（SMRFs） to generate a retrofit scheme at minimal cost. To satisfy the acceptance criteria for the Basic Safety Objective（BSO） specified in FEMA 356, the minimum number of upgraded connections and their locations in an SMRF with brittle connections are determined by evolutionary computation. The performance of the proposed optimal retrofitting model is evaluated on the basis of the energy dissipation capacities, peak roof drift ratios, and maximum interstory drift ratios of structures before and after retrofitting. In addition, a retrofit efficiency index, which is defined as the ratio of the increment in seismic performance to the required retrofitting cost, is proposed to examine the efficiencies of the retrofit schemes derived from the model. The optimal seismic retrofit model is applied to the SAC benchmark examples for threestory and nine-story SMRFs with brittle connections. Using the retrofit efficiency index proposed in this study, the optimal retrofit schemes obtained from the model are found to be efficient for both examples in terms of energy dissipation capacity, roof drift ratio, and maximum inter-story drift ratio.

关键词： steel moment resisting frame performance-based seismic engineering optimal seismic retrofit evolutionarycomputation

Energy tunnels:concept and design aspects

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Underground Space 2018年第4期3卷 268-276页

作者： Marco Barla Alice Di Donna department of structural Building and Geotechnical EngineeringPolitecnico di TorinoCorso Duca degli Abruzzi 2410129 TorinoItaly

Geotechnical structures are increasingly employed as energy geostructures in Europe and *** being constructed for their primary structural role,they are equipped to exchange heat with the ground and supply thermal energy for heating and cooling of buildings and de-icing of *** technology can play a fundamental role in the current challenge of addressing the increasing need for clean and renewable sources of *** study investigates the possibility of thermal activation of tunnel ***,attention will be paid on a new energy segment,which can be used together with tunnel boring machine tunneling to create so-called energy *** and mechanical designs need to be developed by making effective use of computational methods to quantify the exploitable heat and assess the possible consequences on the surrounding ground and the structure *** on how to proceed in this direction will be provided in this study,showing how thermo-hydro and thermo-mechanical numerical analyses can be used to achieve a proper and effective design of energy *** examples of possible applications will also be presented.

关键词： Energy tunnel Geothermal energy Heating and cooling Geotechnical design