http://hdl.handle.net/10993/84 Search this channel search https://orbilu.uni.lu/simple-search http://hdl.handle.net/10993/43978 Title: Draft prEN 1994-1-1: 042020 + comments, Document <br/> <br/>Author, co-author: Schäfer, Markus; Hicks, Stephen; Banfi, Mike; Kurz, Wolfgang; Martin, Pierre-Olivier <br/> <br/>Abstract: Development of second generation for Eurocode 4, part 1: prEN 1994-1-1: April 2020 Wed, 05 Aug 2020 11:48:43 GMT http://hdl.handle.net/10993/43861 Title: Development of innovative concrete mixtures aggregates <br/> <br/>Author, co-author: Chewe Ngapeya, Gelen Gael; Waldmann, Daniele Thu, 16 Jul 2020 16:01:23 GMT http://hdl.handle.net/10993/43860 Title: Availability of recycled material: Characterization of the building stock in Luxembourg - Assessment of concrete volumes - Availability of the future mineral waste stock based on stochastic scenarios <br/> <br/>Author, co-author: Bogoviku, Lorenc; Waldmann, Daniele Thu, 16 Jul 2020 15:57:39 GMT http://hdl.handle.net/10993/43469 Title: Finite deformations govern the anisotropic shear-induced area reduction of soft elastic contacts <br/> <br/>Author, co-author: Lengiewicz, Jakub; de Souza, Mariana; Lahmar, Mohamed A.; Courbon, Cédric; Dalmas, Davy; Stupkiewicz, Stanislaw; Scheibert, Julien <br/> <br/>Abstract: Solid contacts involving soft materials are important in mechanical engineering or biomechanics. Experimentally, such contacts have been shown to shrink significantly under shear, an effect which is usually explained using adhesion models. Here we show that quantitative agreement with recent high-load experiments can be obtained, with no adjustable parameter, using a non-adhesive model, provided that finite deformations are taken into account. Analysis of the model uncovers the basic mechanisms underlying anisotropic shear-induced area reduction, local contact lifting being the dominant one. We confirm experimentally the relevance of all those mechanisms, by tracking the shear-induced evolution of tracers inserted close to the surface of a smooth elastomer sphere in contact with a smooth glass plate. Our results suggest that finite deformations are an alternative to adhesion, when interpreting a variety of sheared contact experiments involving soft materials. Wed, 10 Jun 2020 13:48:39 GMT http://hdl.handle.net/10993/43449 Title: Implementation of a new strain split to model unilateral contact within the phase field method <br/> <br/>Author, co-author: Nguyen, Thanh Tung; Yvonnet, Julien; Waldmann, Danièle; He, Qi-Chang <br/> <br/>Abstract: A new orthogonal decomposition of strain tensor into compressive/tensile parts is implemented in the phase eld model to maintain the physical crack propagation behavior. An e cient operator split scheme with the introduction of projection tensors is proposed to facilitate the numerical implementation of the new spectral decomposition. Formulations of the present failure model accounting the unilateral contact condition are given analytically and explicitly, which implies an extremely robust computational model. In particular, compared to the existing models, the present framework is general, which can be applied to all possible elastic behavior, such as isotropic, orthotropic, and totally anisotropic elastic material. A detailed comparison of fracture response predicted by the present models with the literature approaches is then provided. It is shown that orthogonal decomposition is able to simulate various failure scenarios. Especially, this formulation shows a very remarkably prediction compared to experimental observation for the case of compression load. Mon, 08 Jun 2020 06:18:19 GMT http://hdl.handle.net/10993/43311 Title: Neuere Methoden zur Identifikation und Lokalisierung von Schäden an vorgespannten Betonbrücken <br/> <br/>Author, co-author: Maas, Stefan; Nguyen, Viet Ha; Kebig, Tanja <br/> <br/>Abstract: Zuerst wird ein rein statistischer Schadensindikator basierend auf der Hauptkomponentenanalyse vorgestellt. Wichtig sind Referenzmessungen im ungeschädigten Zustand, um Veränderungen zu identifizieren. Bevor die Messdaten mit den Rechenmodellen kombiniert werden, müssen Temperatureffekte kompensiert werden, um dann die Schäden zu erkennen und zu lokalisieren. Ein „Model-Updating“ Prozess eines speziellen Finite-Elemente- Modells passt die Steifigkeitsmatrix an die gemessenen Eigenfrequenzen oder an die progressive Absenkung unter Eigengewicht an. Sun, 31 May 2020 03:30:02 GMT http://hdl.handle.net/10993/43243 Title: Optimisation of the mechanical properties of Miscanthus lightweight concrete (Top 10 Journal) <br/> <br/>Author, co-author: Pereira Dias, Patrick; Waldmann, Danièle <br/> <br/>Abstract: In this paper, Miscanthus fibres are used to develop lightweight concrete. The amount of Miscanthus and cement, as well as the water/cement ratio, are varied to analyse the behaviour of the mixture concerning the physical and mechanical properties. The Miscanthus was pre-treated with a silicate sealant or a cement-based fluid. The current paper analyses the impact of the pre-treatment of the Miscanthus fibres on the compressive strength as well as on the long-term deformations. The specimens with a pre-treatment based on a silicate sealant reached a compressive strength of 19.3 MPa, which is higher than the compressive strength of a conventional LC 16/18, a Young's Modulus above 9.9 GPa and a shrinkage deformation of 2244 μm/m. Nevertheless, considering the density the pre-treatment showed not to be beneficial. Sat, 23 May 2020 15:57:43 GMT http://hdl.handle.net/10993/43231 Title: Condition assessment of bridge structures by damage localisation based on the DAD-method and close-range UAV photogrammetry <br/> <br/>Author, co-author: Erdenebat, Dolgion <br/> <br/>Abstract: The provided dissertation presents a so-called “Deformation Area Difference (DAD)” method for condition assessment of existing bridges, especially for the detection of stiffness-reducing damages. The method is based on the one hand on conventional static load deflection experiments and on the other hand on a high-precision measurement of the structural deflection. The experimental load on the bridge should be generated within the serviceability limit state in order to enable a non-destructive inspection. In the course of the laboratory tests, the most innovative measuring techniques were applied, whereby the photogrammetry has delivered promising results. With the help of additional studies on the influences of camera quality and calibration, the measuring precision of photogrammetry could be brought to its limits. Both the theoretical investigations and the laboratory tests showed the successful use of the DAD method for the identification of local damages. Therefore, the first in-situ experiment was carried out on a single-span, prestressed bridge in Luxembourg. The knowledge gained from this was combined with statistical investigations based on finite element calculations and artificially generated measurement noise effect in order to determine the application limits, such as the achievable measurement precision, identifiable degree of damage, required number of measurement repetitions, influence of the damage position, optimal size of the structural deformation, etc. The development of the DAD method ready for application usefully supplements the state of the art and contributes to the reliable assessment of the bridge condition. Wed, 20 May 2020 10:03:11 GMT http://hdl.handle.net/10993/43216 Title: Application of the DAD method for damage 1 localisation on an existing bridge structure using 2 close-range UAV photogrammetry <br/> <br/>Author, co-author: Erdenebat, Dolgion; Waldmann, Danièle <br/> <br/>Abstract: A novel damage detection and localisation method, the so-called Deformation Area Difference method for localisation of damages in bridge structures is introduced. The method is based on static load-deflection experiments with the prerequisite of high precise deflection measurement. This study presents the first experiences of applying the DAD method on a real bridge structure. The investigated structure is a prestressed concrete slab bridge with a span of about 27 m, which was built in 2013. The loading on the bridge is applied using six heavy trucks, each weighing up to 32 t. A wide range of the modern measurement technologies were used to achieve high precision measurements of the bridge deflection along the longitudinal axis, namely the photogrammetry using a big size drone, laser scanner, total station, levelling and displacement sensors. The performed load-deflection test was non-destructive since the maximum deformation did not exceed the serviceability limit state. The exercise of the novel damage detection and localisation method on a real structure initiated further optimisation opportunities of the DAD method and the study of its limits. Several boundary conditions and methodical influence factors related to the applicability of the proposed method were analysed, such as impacts of measurement precision, damage degree, the position of damage, and the number of measurement repetitions. Fri, 15 May 2020 06:42:52 GMT http://hdl.handle.net/10993/43215 Title: Monotonic axial compressive behaviour and confinement mechanism of square CFRP-steel tube confined concrete <br/> <br/>Author, co-author: Wang, Yanlei; Cai, Gaochuang; Si Larbi, Amir; Waldmann, Danièle; Tsavdaridis, Konstantinos Daniel; Ran, Jianghua <br/> <br/>Abstract: Steel tube confined concrete (STCC) is widely used in the vertical members of high-rise buildings such as columns. The axial load is not directly resisted by the steel tube in STCC, but is resisted via the interfacial frictional stress between steel tube and concrete core, which is different with that of concrete filled steel tube (CFT) members and would effectively suppress the outward local buckling of steel tube at early stage. Recently, fibre-reinforced polymer (FRP) confined STCC presents a potential to enhance the ductility and durability of such vertical elements. This paper presents an experimental study on monotonic axial compressive behaviour of carbon FRP (CFRP) confined STCC (CFRP- STCC) stub column and an analytical study on the confinement mechanism of and the ultimate axial bearing capacity of the elements. A three-stage confinement mechanism involving the different contributions of the steel tube and the CFRP wrap in CFRP-STCC elements was proposed based on the test results. A prediction model of the ultimate axial bearing capacity of CFRP-STCC stub columns was developed subsequently. Results show that the presence of CFRP wrap enhances effectively the load-bearing capacity and the ductility of steel tube confined plain concrete and reinforced concrete elements, and significantly prevents the local buckling of the steel tubes in the elements. The proposed prediction model of ultimate axial bearing capacity assesses test results with a great agreement. Fri, 15 May 2020 06:31:59 GMT http://hdl.handle.net/10993/42888 Title: BIM-Based End-of-Lifecycle Decision Making and Digital Deconstruction: Literature Review <br/> <br/>Author, co-author: Akbarieh, Arghavan; Jayasinghe, Laddu Bhagya; Waldmann, Danièle; Teferle, Felix Norman <br/> <br/>Abstract: This article is the second part of a two-part study, which explored the extent to which Building Information Modelling (BIM) is used for End-of-Lifecycle (EoL) scenario selection to minimise the Construction and Demolition Waste (CDW). The conventional literature review presented here is based on the conceptual landscape that was obtained from the bibliometric and scientometric analysis in the first part of the study. Seven main academic research directions concerning the BIM-based EoL domain were found, including social and cultural factors, BIM-based Design for Deconstruction (DfD), BIM-based deconstruction, BIM-based EoL within LCA, BIM-aided waste management, Material and Component Banks (M/C Banks), off-site construction, interoperability and Industry Foundation Classes (IFC). The analysis highlights research gaps in the path of raw materials to reusable materials, i.e., from the deconstruction to M/C banks to DfD-based designs and then again to deconstruction. BIM-based EoL is suffering from a lack of a global framework. The existing solutions are based on local waste management policies and case-specific sustainability criteria selection. Another drawback of these ad hoc but well-developed BIM-based EoL prototypes is their use of specific proprietary BIM tools to support their framework. This disconnection between BIM tools and EoL tools is reportedly hindering the BIM-based EoL, while no IFC classes support the EoL phase information exchange. Wed, 01 Apr 2020 09:06:02 GMT http://hdl.handle.net/10993/42623 Title: Development of a BIM-based web tool as Material and Component bank for a sustainable construction industry <br/> <br/>Author, co-author: Jayasinghe, Bhagya; Waldmann, Danièle <br/> <br/>Abstract: The construction industry consumes an enormous amount of global resources and produces more waste than any other sector. The need to move toward sustainable development in construction requires significant changes in construction and demolition (C&D) waste management. The estimation of waste, recycling materials and reusable components could be vital in waste management, achieving huge efficiency in the construction industry. Moreover, a typical building comprises of an extensive amount of materials and components with various characteristics. This study proposes a Building Information Modelling (BIM) based system to allow the circular economy by storing information of the materials and components of buildings and by effectively managing the recycling of materials and reuse of components. A tool which serves as Material and Component (M&C) bank is developed with PHP and MYSQL by making use of a web browser able to extract the materials and component information of a building through the BIM model. This information is vital for several uses such as quantification of C&D waste and assessing for the design for deconstruction. It can also be used to obtain the information of reusable condition of the components and instructions for the reconstruction. Tue, 25 Feb 2020 08:34:37 GMT http://hdl.handle.net/10993/42589 Title: Impact of pile punching on adjacent piles: Insights 3 from a 3D coupled SPH-FEM analysis <br/> <br/>Author, co-author: Jayasinghe, Bhagya; Waldmann, Danièle; Shang, Junlong <br/> <br/>Abstract: Pile punching (or driving) affects the surrounding area where piles and the adjacent piles can be displaced out of their original positions due to horizontal loads, leading to hazardous outcomes. This paper presents a 3D coupled Smoothed Particle Hydrodynamics and Finite. Element Method (SPH-FEM) model, which was established to investigate pile punching and its impact on adjacent piles subjected to lateral loads. This approach handles the large distortions by avoiding mesh tangling and remeshing, contributing greatly high computational efficiency. The SPH-FEM model was validated against field measurements. Results of this study indicated that the soil type in which piles were embedded affected the interaction between piles during the pile punching. A comprehensive parametric study was carried out to evaluate the impact of soil properties on the displacement of piles due to the punching of an adjacent pile. It was found that the interaction between piles was comparatively weak when the piles were driven in stiff clays; while the pile-soil interactions were much more significant in sandy soils and soft clays. Thu, 20 Feb 2020 13:11:51 GMT http://hdl.handle.net/10993/42585 Title: Von Effizienz bis Flexibilisierung – ein erfolgreicher Weg mit viel Energie <br/> <br/>Author, co-author: Schäfer, Michael; Gretzschel, Oliver; Hansen, Joachim Thu, 20 Feb 2020 04:30:10 GMT http://hdl.handle.net/10993/42580 Title: Mikroschadstoffe im Sauer-Einzugsgebiet: Lösungswege abseits der klassischen Eliminationsverfahren <br/> <br/>Editor: Hansen, Joachim; Knerr, Henning Thu, 20 Feb 2020 04:30:07 GMT http://hdl.handle.net/10993/42476 Title: IMPROVEMENT OF THE LOAD-BEARING CAPACITY OF DRY-STACKED MASONRY <br/> <br/>Author, co-author: Chewe Ngapeya, Gelen Gael <br/> <br/>Abstract: Mortar bonded masonry is one of the oldest construction technics traditionally used around the world. However, dry-stacked masonry (DSM) is a competitive system that confers significant assets to masonry in the sense that, concisely, it saves construction time, requires less skill labourers and ease the construction as well as the de-construction. Despite all this major benefits, the current use of DSM is hindered by the geometric imperfections of the block units and the lack of adapted design codes. Indeed, the block geometric imperfections, i.e. the bed-joint roughness and the height difference, cause a significant uneven load-distribution in DSM, which generally leads to a premature cracking and a drop of the wall compressive strength. On the other hand, the lack of adapted design codes entail significant safety hazards in the construction of such masonry walls. In view of the foregoing, through systematic numerical, experimental and analytical investigations, the present thesis aims to analyse the impacts of the block bed-joint imperfections on the mechanical response of DSM axially loaded. Furthermore, the current thesis aims to develop a strategy to overcome the block geometric imperfections and alleviate its impacts on the load-bearing capacity of DSM. Finally, the present thesis intends to develop a design model for predicting the load-bearing capacity of DSM, while taking into account the effects of the block geometric imperfections for a safe design. First of all, at the beginning of the research project, a new dry-stacked masonry block is designed and labelled ‘M-Block’. The impact of the bed-joint roughness and the block height variation on the stress distribution in a DSM is analysed through numerical modelling. It is shown that the block height difference yields five potential load cases that block units may suffer upon the axial compression of a DSM wall. Accordingly, it is also shown that a nominal DSM wall can exhibit different load percolation paths and different damages. Further, a strategy is presented to overcome the bed-joint imperfections, increase the actual contact area in the bed-joints and ultimately improve the load-bearing capacity of DSM, by adding a material layer (the ‘contact layer’) on the raw DSMb. The capacity of the contact layer to increase the actual contact and level the stress distribution was first investigated through numerical models then evidenced through experimental tests on masonry triplets. The contact layer was also investigated for improving the load-bearing capacity of dry-stacked masonry, with satisfactory results obtained on wallets tested in the lab. As the finite element modelling is cumbersome and the experimental investigations onerous and laborious, an analytical model has then been developed for predicting the load-bearing capacity of DSM. A statistical modelling has been developed for determining a factor δh, which stands for the reduction of the nominal section of a DSM generated by the block height variation. Experimental tests were also performed on masonry triplets for measuring the ultimate actual contact in the bed-joints and defining a factor δr, which stands for the reduction of the nominal contact area generated by the block bed-joint roughness. The two defined parameters were then exploited to establish the design model that takes into account the block imperfections in the prediction of the load-bearing capacity of DSM. The design model was shown quite well capable of predicting the load-bearing capacity of DSM with a mean accuracy of 93% - 106% and a standard deviation of 12% - 10%. Wed, 12 Feb 2020 12:45:13 GMT http://hdl.handle.net/10993/42184 Title: Slim-floor beam bending moment resistance considering partial shear connection <br/> <br/>Author, co-author: Zhang, Qingjie; Schäfer, Markus <br/> <br/>Abstract: Having the advantage of flat lower surface, high stiffness and integrated fire resistance, slim-floor composite beams are widely used and favoured in many design solutions. The current bending design methods are mainly derived from plastic design methods for classical composite beam with consideration of the special features for slim-floor beams such as the transverse bending of bottom flange when used as support for slabs. Alternatively, more advanced strain-limited design method or FE-method can be used. In the case of full shear connection, with deep position of neutral axis and great compression zone height, there is a risk that plastic design method may overestimate the bending resistance of the cross section compared to the strain-limited design method. In the case of the partial shear connection, shear design diagram for slim-floor beams obtained by means of the strain-limited design can also differ significantly from the one obtained by plastic design method, thus further research on slim-floor beams is still necessary. Mon, 27 Jan 2020 10:02:33 GMT http://hdl.handle.net/10993/42179 Title: Investigation of the moment redistribution for steel concrete continuous beams <br/> <br/>Author, co-author: Yolacan, Taygun Firat; Schäfer, Markus <br/> <br/>Abstract: This study investigates moment redistribution phenomenon for pin ended double-span steel-concrete continuous composite beams and arise a question about moment redistribution for the continuous beams subjected to partially distributed or concentrated loading conditions. The overall objective of the study is to propose a methodology to fulfil the technical gaps adopted by Eurocode-4, which considers the redistribution for only uniformly load condition. A robust iterative algorithm is developed to obtain moment-curvature relations of the standard composite cross-sections. Flexural stiffness-curvature relations of the cross-sections are predicted through the moment-curvature relations. Flexural stiffness distribution along the composite beams is determined with curvature compatibility. Fourth order differential load-deflection equation is evaluated with finite difference solution scheme for continuous beam conditions and variable flexural stiffness along the beam length. A non-iterative incremental load-deflection algorithm is developed to calculate moment distribution in continuous beams with variable flexural stiffness. A benchmark example is solved with Eurocode- 4 provisions to validate the developed algorithms. Moment redistribution from hogging (negative) zone to sagging (positive) zone of uniformly loaded double-span continuous composite beam is illustrated considering the degree of flexural stiffness degradation in the composite medium. A question is arisen for moment redistribution in the continuous beams subjected to partially distributed or concentrated loading conditions. Mon, 27 Jan 2020 09:04:07 GMT http://hdl.handle.net/10993/41924 Title: Continuous solution of poroelastic problems using Artificial Neural Networks <br/> <br/>Author, co-author: Dehghani, Hamidreza; Zilian, Andreas Wed, 22 Jan 2020 15:28:04 GMT http://hdl.handle.net/10993/41912 Title: Poroelastic material characterisation by means of Artificial Neural Network <br/> <br/>Author, co-author: Dehghani, Hamidreza; Zilian, Andreas <br/> <br/>Abstract: Poroelastic problems require multiscale and multiphysics techniques that are expensive and time-consuming, which result in either several simplifications or costly experimental tests. The latter motivates us to develop a more efficient approach to address more complex problems with an acceptable computational cost. In this manuscript, first, the necessary equations derived from Asymptotic homogenisation for poroelastic media are mentioned. Then, the variational formulation of the cell problems is carried out and solved by the open-source FE package FEniCS. This is followed by presenting the advantages and downsides of macroscale properties identification via asymptotic homogenisation and the application of Artificial Neural Network (ANN) to solve the issues stated as its downsides by means of bypassing the process of solving the cell problems. Finally, we study a practical example, namely, spatial dependent porosity (in macroscale) to demonstrate the feasibility of using the provided framework to include more details. Further applications, including growth and remodelling, are subjects of future articles. Wed, 22 Jan 2020 14:48:08 GMT