TY - CONF A1 - Kowitz, Astrid A1 - Wu, Cheng-Chieh A1 - Hille, Falk A1 - Helmerich, Rosemarie A1 - Kadoke, Daniel A1 - Gründer, Klaus-Peter A1 - Hauser, S. A1 - Schwarzinger, H. ED - Pastramă, Ş. D. ED - Constantinescu, D. M. T1 - Impact on a micro-reinforced UHPC: Experimental studies versus numerical modeling N2 - Within the presented research project, experimental and numerical investigations were performed to develop a thin-shelled, modular, mobile element system made of a micro-reinforced ultra-high-performance ductile concrete (DUCON®). Material parameters were experimentally determined to adapt the material model within the numerical analysis applying the Drucker-Prager relationship. Afterwards, for validation of the numerical models, quasi-static and high-velocity impact tests were performed on plate-like structures. Finally, a suitable geometry of transportable barrier elements will be designed, which provides a maximum of resistance against impact by a minimum of weight and a maximum of mobility. T2 - 35th Danubia-Adria Symposium on Advances in Experimental Mechanics CY - Sinaia, Romania DA - 25.09.2018 KW - E-modulus KW - Impact KW - UHPC KW - DUCON® KW - Quasi-static and dynamic tests KW - Micro-reinforcement KW - Ductility KW - Mobile elements KW - Numerical modeling KW - Stereo photogrammetry KW - Compressive strength PY - 2018 UR - https://www.das2018.ro/ SN - 978-606-23-0874-2 SP - 11 EP - 12 PB - Editura Printech CY - Bucarest, Romania AN - OPUS4-47001 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kullolli, Borana A1 - Cuéllar, Pablo A1 - Baeßler, Matthias T1 - Numerical modelling of soil-structure interfaces N2 - The governing load bearing mechanism of multi-pile foundations is often the shaft friction. Under cyclic loading the soil particles next to the foundation rearrange and tend to compact leading to a decrease of the surrounding normal stress. The reduction of the normal stress leads to a lower threshold for shear stress (friction fatigue), which results in a degraded shaft bearing capacity. The common interface models used for numerical simulations (e.g. Mohr-Coulomb) are not able to capture such behavior. This work aims to develop an interface material model that incorporates such features of the contact behavior at the soil-structure interface. T2 - Alert Geomaterial Workshop CY - Aussois, France DA - 01/10/2018 KW - Soil-structure interaction KW - Interface KW - Material model KW - Numerical modelling PY - 2018 AN - OPUS4-47066 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kullolli, Borana T1 - A generalized plasticity model adapted for shearing interface problems N2 - The response of many geotechnical systems, whose structural behavior depends on shearing effect, is closely related to soil structure interaction phenomenon. Experimentally it is found that the localisation of these effect happens at a narrow soil layer next to the structure. Numerically, this behavior can be modelled through interface elements and adequate constitutive models. In this work, a constitutive model in the framework of Generalized Plasticity for sandy soils has been chosen to be adapted for the interface zone. From the direct shear experiments a sandy soil at loose and dense states under different normal pressures is considered. The adapted constitutive model is able to reproduce contraction and dilatation of the soil according to its relative density and it shows a good agreement with the experimental data. T2 - Numerical Geotechnics CY - Porto, Portugal DA - 25/06/2018 KW - Interface model KW - Cyclic axial shearing KW - Numerical model PY - 2018 AN - OPUS4-47068 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kullolli, Borana A1 - Cuéllar, Pablo A1 - Baeßler, Matthias T1 - Soil-structure interaction of offshore foundations N2 - The response of many geotechnical systems, whose structural behavior depends on granular friction and a shearing effect with the ground, is characterized by a complex soil-structure interaction at their interfaces. Experimentally it is found that this interaction is highly non-linear, state-dependent and localized within a narrow layer of soil next to the structure, whereby cyclic loads can play a key role. Numerically, this behavior is often modelled with overly simplified models of interface elements that neglect cyclic effects within the soil. This work introduces a new perspective with an adequate constitutive model in the framework of Generalized Plasticity for sandy soils for an improved consideration of the interface mechanics. T2 - PhD Day BAM CY - Berlin, Germany DA - 31/05/2018 KW - Interface KW - Soil-structure interaction KW - Numerical model PY - 2018 AN - OPUS4-47069 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kullolli, Borana A1 - Stutz, H. H. A1 - Cuellar, Pablo A1 - Baeßler, Matthias A1 - Rackwitz, F. ED - Cardoso, A. S. ED - Borges, J. L. ED - Costa, P. A. ED - Gomes, A. T. ED - Marques, J. C. ED - Vieira, C. S. T1 - A generalized plasticity model adapted for shearing interface problems N2 - The response of many geotechnical systems, whose structural behavior depends on shearing effect, is closely related to soil structure interaction phenomenon. Experimentally it is found that the localisation of these effect happens at a narrow soil layer next to the structure. Numerically, this behavior can be modelled through inter-face elements and adequate constitutive models. In this work, a constitutive model in the framework of Gen-eralized Plasticity for sandy soils has been chosen to be adapted for the interface zone. From the direct shear experiments a sandy soil at loose and dense states under different normal pressures is considered. The adapted constitutive model is able to reproduce contraction and dilatation of the soil according to its relative density and it shows a good agreement with the experimental data. T2 - Conference CY - Porto, Portugal DA - 25.06.2018 KW - Numerical modelling KW - Soil-pile interaction KW - Interface KW - Shearing PY - 2018 SN - 978-1-138-33198-3 VL - 1 SP - 97 EP - 102 PB - NUMGE CY - Porto, Portugal AN - OPUS4-45721 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - THES A1 - Luong, Thi Mai Hoa T1 - Identification of the state of stress in iron and steel truss structures by vibration-based experimental investigations N2 - Safety evaluation of truss structures depends upon the determination of the axial forces and corresponding stresses in axially loaded members. Due to presence of damages, change in intended use, increase in service loads or accidental actions, structural assessment of existing truss structures is necessary. This applies particularly to iron and steel trusses that are still in use, including historic and heritage monuments. Precise identification of the stresses plays a crucial role for the preservation of historic trusses. The assessment measures require non–destructiveness, minimum intervention and practical applicability. The axial forces in truss structures can be estimated by static calculations using the method of joints, method of sections or finite element method, if accurate information about parameters such as external loads, geometrical characteristics, mechanical properties, boundary conditions and joint connections are known. However, precise information about these parameters is difficult to be obtained in practice. Especially in the cases of historic constructions, reasonable assumptions about the uncertain parameters may not be acquired. Motivated by the preservation of existing truss−type constructions composed of axially loaded slender members, the present work aims to develop a non–destructive methodology to identify the axial forces or corresponding stress states in iron and steel truss structures. The approach is based on vibration measurements and the finite element method combined with optimization techniques. After a state of the art review, numerical and experimental studies were carried out on three partial systems of truss–type structures. The investigated systems included single bars, a two–bar truss−like system and a five–bar truss. They were developed step–by–step as built–up truss−type constructions that are constituted of individual members connecting at joints. The examined aspects included the effects of structural loading on the dynamic performance of truss structures, modelling of joint connections, mode pairing criteria, selection of updating parameters and definition of an objective function, as well as the use of different optimization techniques. Concerning the axial force effects on the structural dynamic responses, the effects of the stress stiffening become more complicated for multiple–member truss systems with increasing complexity. The coexistence of both compressive and tensile forces in trusses has counteracting effects on the modal parameters. These effects cause variation of natural frequencies and interchange of modes when the loads or corresponding member forces are changed. To examine the axial force effects on the structures at different stress states, in the numerical study and laboratory experiments, loads were applied progressively to the investigated truss−like systems. Regarding the modelling of joints for truss–type structures, the joint flexibility affects the structural dynamic responses. Therefore, the numerical models of truss−type structures include joint models with variable rotational springs to represent semi–rigid connections. Considering the mode pairing criterion, the mode pairing is performed by adapting an enhanced modal assurance criterion with the calculation of the modal strain energy. The criterion allows the selection of desired clusters of degrees of freedom related to specific modes. With respect to the model updating strategies, the selection of updating parameters and the choice of an appropriate objective function are identified to be significantly important. In addition, three different optimization techniques were applied to compare their suitability for the inverse axial force identification and estimation of joint flexibility of truss structures. The results of the numerical study and laboratory tests show that nature–inspired optimization methods are considered as promising techniques. A methodology consisted of a two–stage model updating procedure using optimization techniques was proposed for the determination of multiple member axial forces and estimation of the joint flexibility of truss–type structures. In the first stage optimization, the validation criterion is based on the experimentally identified global natural frequencies and mode shapes of the truss. Additionally, the axial forces in selected individual members of the truss are used. They are estimated from the natural frequencies and five amplitudes of the corresponding local mode shapes of the members using an analytically−based algorithm. Based on the results of the identified axial forces in the first stage, a second optimization procedure for the joint stiffnesses is performed. In this stage, the modal parameters of the global natural frequencies and mode shapes are used as validation criterion. From the results of the laboratory experiments, the identified axial forces by the proposed methodology agree well with the experimentally measured axial forces of the investigated systems at different stress states. Moreover, based on the numerical verification, the identified joint stiffnesses indicate reasonably the joint flexibility in relation to the pinned or rigid conditions. To assess the relevance of the proposed methodology on existing structures in real−life conditions, an in–situ experiment was carried out on a historic Wiegmann–Polonceau truss in the city of Potsdam. The in–situ experiment shows that uncertainties relating the mechanical and geometrical properties of historic trusses as well as the experimental sensor setup can influence the accuracy of the axial force identification. In the present work, recommendations are given for the development of a guideline of measuring concepts and assessment strategies applied to existing truss structures. The intention is to integrate the proposed methodology as part of the Structural Health Monitoring for historic truss–type constructions. T3 - BAM Dissertationsreihe - 159 KW - State of stress KW - Beanspruchungszustand KW - fachwerkartige Stahltragwerken KW - Schwingungsmessungen KW - Finite-Elemente-Modellkalibrierung KW - Optimierungsmethoden KW - Truss structures KW - Vibration measurements KW - Finite element model updating KW - Optimization techniques PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-449615 SN - 1613-4249 VL - 159 SP - 1 EP - 195 PB - BAM Eigenverlag CY - Berlin AN - OPUS4-44961 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mevel, L. A1 - Viefhues, Eva A1 - Döhler, M. A1 - Hille, Falk T1 - Asymptotic analysis of subspace-based datadriven residual for fault detection with unceratin reference N2 - The local asymptotic approach is promising for vibration-based fault diagnosis when associated to a subspace-based residual function and efficient hypothesis testing tools. It has the ability of detecting small changes in some chosen system parameters. In the residual function, the left null space of the observability matrix associated to a reference model is confronted to the Hankel matrix of output covariances estimated from test data. When this left null space is not perfectly known from a model, it should be replaced by an estimate from data to avoid model errors in the residual computation. In this paper, the asymptotic distribution of the resulting data-driven residual is analyzed and its covariance is estimated, which includes also the covariance related to the reference null space estimate. The importance of including the covariance of the reference null space estimate is shown in a numerical study. T2 - 10th IFAC Symposium on Fault Detection, Supervision and Safety for Technical Processes SAFEPROCESS 2018 CY - Warsaw, Poland DA - 29.08.2018 KW - Fault detection KW - Uncertainty in reference KW - Residual evaluation KW - Statistical tests KW - Vibration measurement PY - 2018 AN - OPUS4-46505 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Moosavi, Robabeh A1 - Grunwald, Marcel A1 - Redmer, Bernhard A1 - Nerger, Deborah A1 - Hille, Falk A1 - Kühn, T. A1 - Hering, M. T1 - Damage investigations of concrete under impact load using laminography N2 - We examine the behavior of reinforced concrete components subjected to impact induced loading conditions which might be caused by vessels collisions such as aircraft fuel tanks The concrete plates were impact damaged at TU Dresden and shipped to BAM At BAM laminar tomography as the imaging method is used to determine and quantify the damage state An automatic crack detection method based on template matching is applied to find the cracks and we aim to develop a new method using machine learning Algorithms In addition numerical models are developed to understand the experiment and to predict the damage structures based on failure mechanisms. T2 - DCMS Summer School MATERIALS 4.0 CY - Dresden, Germany DA - 10.09.2018 KW - Laminography KW - Crack detection KW - Reinforced concrete KW - 3D imaging PY - 2018 AN - OPUS4-48637 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Reimold, W. U. A1 - Crosta, A. P. A1 - Hasch, M. A1 - Kowitz, Astrid A1 - Hauser, N. A1 - Sanchez, J. P. A1 - Simoes, L. S. A. A1 - de Sanchez, G. J. A1 - Zaag, P. T. T1 - Shock deformation confirms the impact origin for the Cerro do Jarau, Rio Grande do Sul, Brazil, structure N2 - Cerro do Jarau is a conspicuous, circular morpho‐structural feature in Rio Grande do Sul State (Brazil), with a central elevated core in the otherwise flat “Pampas” terrain typical for the border regions between Brazil and Uruguay. The structure has a diameter of approximately 13.5 km. It is centered at 30o12′S and 56o32′W and was formed on basaltic flows of the Cretaceous Serra Geral Formation, which is part of the Paraná‐Etendeka Large Igneous Province (LIP), and in sandstones of the Botucatu and Guará formations. The structure was first spotted on aerial photographs in the 1960s. Ever since, its origin has been debated, sometimes in terms of an endogenous (igneous) origin, sometimes as the result of an exogenous (meteorite impact) event. In recent years, a number of studies have been conducted in order to investigate its nature and origin. Although the results have indicated a possible impact origin, no conclusive evidence could be produced. The interpretation of an impact origin was mostly based on the morphological characteristics of the structure; geophysical data; as well as the occurrence of different breccia types; extensive deformation/silicification of the rocks within the structure, in particular the sandstones; and also on the widespread occurrence of low‐pressure deformation features, including some planar fractures (PFs). A detailed optical microscopic analysis of samples collected during a number of field campaigns since 2007 resulted in the disclosure of a large number of quartz grains from sandstone and monomict arenite breccia from the central part of the structure with PFs and feather features (FFs), as well as a number of quartz grains exhibiting planar deformation features (PDFs). While most of these latter grains only carry a single set of PDFs, we have observed several with two sets, and one grain with three sets of PDFs. Consequently, we here propose Cerro do Jarau as the seventh confirmed impact structure in Brazil. Cerro do Jarau, together with Vargeão Dome (Santa Catalina state) and Vista Alegre (Paraná State), is one of very few impact structures on Earth formed in basaltic rocks. KW - Serra da cangalha KW - Recovery experiments KW - Piaui state KW - Santa-marta KW - Features KW - Pressure KW - GPA KW - Sandstone KW - Geology PY - 2018 DO - https://doi.org/10.1111/maps.13233 SN - 1086-9379 VL - 54 IS - 10 SP - 2384 EP - 2394 PB - Wiley AN - OPUS4-50029 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Said, Samir A1 - Auersch, Lutz T1 - Prediction of explosion-induced ground and building vibrations - measured wave velocities, transfer functions and attenuation N2 - Explosion-induced ground vibrations have been measured at several places. Results about the wave propagation are shown in this contribution. The particle velocities of the soil have been measured at up to 1000 m distance from the explosion and are presented as time records (seismograms) and one-third octave band spectra (transfer functions). The results are compared with the results of hammer impacts. The seismograms clearly show different wave types, compressional waves of the air, the water and the soil, and the Rayleigh wave. The hammer impacts yield good results up to 100 m and incorporate higher frequencies at about 50 Hz, whereas the explosion results in a ground vibration with frequencies around 10 Hz and a longer range of influence. Explosion and hammer excitations are evaluated for the wave velocities of the soil by using the wavenumber and the spatial auto-correlation method. The attenuation of the ground vibration amplitudes A with distance r can well be presented by a power law A ~ r -q. This type of amplitude-distance law and the corresponding power q > 1 are substantiated in the contribution. The influence of the charge weight W is evaluated as an additional power law A ~ W -p for each measuring site. The power is found quite similarly around q  0.6 as all sites have a medium soft soil such as sand and clay. The obtained amplitude-charge-distance law can be used to predict the explosion-induced ground and building vibrations at other sites. T2 - International Congress on Sound and Vibration (ICSV25) CY - Hiroshima, Japan DA - 08.07.2018 KW - Soil properties KW - Amplitude-charge weight laws KW - Amplitude-distance laws KW - Explosion-induced ground vibrations KW - Hammer impact KW - Prediction of explosion induced ground and building vibration PY - 2018 AN - OPUS4-45508 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Said, Samir A1 - Auersch, Lutz T1 - Prediction of explosion-induced ground and building vibrations - measured wave velocities, transfer functions and attenuation N2 - Explosion-induced ground vibrations have been measured at several places. Results about the wave propagation are shown in this contribution. The particle velocities of the soil have been measured at up to 1000 m distance from the explosion and are presented as time records (seismograms) and one-third octave band spectra (transfer functions). The results are compared with the results of hammer impacts. The seismograms clearly show different wave types, compressional waves of the air, the water and the soil, and the Rayleigh wave. The hammer impacts yield good results up to 100 m and incorporate higher frequencies at about 50 Hz, whereas the explosion results in a ground vibration with frequencies around 10 Hz and a longer range of influence. Explosion and hammer excitations are evaluated for the wave velocities of the soil by using the wavenumber and the spatial auto-correlation method. The attenuation of the ground vibration amplitudes A with distance r can well be presented by a power law A ~ r -q. This type of amplitude-distance law and the corresponding power q > 1 are substantiated in the contribution. The influence of the charge weight W is evaluated as an additional power law A ~ W -p for each measuring site. The power is found quite similarly around q  0.6 as all sites have a medium soft soil such as sand and clay. The obtained amplitude-charge-distance law can be used to predict the explosion-induced ground and building vibrations at other sites. T2 - International Congress on Sound and Vibration (ICSV25) CY - Hiroshima, Japan DA - 08.07.2018 KW - Prediction of explosion induced ground and building vibration KW - Explosion-induced ground vibrations KW - Hammer impact KW - Soil properties KW - Amplitude-distance laws KW - Amplitude-charge weight laws PY - 2018 SN - 978-83-7880-552-6 SN - 2329-3675 SP - 1 EP - 8 PB - Silesian University of Technology Press CY - Gliwice, Poland AN - OPUS4-45506 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schneider, Ronald A1 - Rogge, Andreas A1 - Thöns, S. A1 - Bismut, E. A1 - Straub, D. T1 - A sampling-based approach to identifying optimal inspection and repair strategies for offshore jacket structures N2 - Identifying optimal inspection and repair strategies for offshore jacket structures is a challenging task. We pre-sent an approach, which is based on recent developments in the field of risk-based operation and maintenance planning at the structural system level. The approach utilizes heuristics to define inspection and repair strate-gies at the system level and to reduce the search space of possible strategies. For each defined strategy, the expected service life cost of inspection, repair and failure is evaluated based on simulated inspection and re-pair histories. Subset simulation is applied to compute the conditional repair and failure probabilities required for this analysis. It also forms the basis for simulating inspection and repair histories. The strategy that mini-mizes the expected service life cost is the optimal one in the set of pre-selected strategies. The underlying condition and performance model accounts for the stochastic dependence among the deterioration states of the different structural elements and the structural redundancy. The approach is demonstrated in a case study considering a jacket-type frame. In this study, we essentially vary the inspection interval, the minimum num-ber of inspected components and the target reliability, and identify the combination that minimizes the ex-pected total service life cost. T2 - The Sixth International Symposium on Life-Cycle Civil Engineering (IALCCE 2018) CY - Gent, Belgium DA - 28.10.2018 KW - Steel structures KW - Fatigue KW - Reliability KW - Risk KW - Inspection planning PY - 2018 AN - OPUS4-46432 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Shamsuddoha, M. A1 - Hüsken, Götz A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten A1 - Baeßler, Matthias T1 - Workability and mechanical properties of ultrafine cement based grout for structural rehabilitation: A parametric study on the partial replacement with SCMs N2 - Grouting is a universal repair and strengthening technique, which is constantly used for structural remediation of concrete components, trenches, mine subsidence, dam joints, restoration of masonry structures, and geological stabilizations. Having an extremely small particle size of only few microns, ultrafine cements are ideal for grouting applications due to their superior permeability and compressive strength properties of the hardened cement paste compared to that of the less-expensive, but coarser ordinary Portland cements. Supplementary cementitious materials (SCMs) are often used to replace ultrafine cement in order to modify certain properties and to reduce costs. The aim of this experimental study is to investigate the effect of three supplementary materials: microsilica (MS), fly ash (FA), and metakaolin (MK) on the workability, and mechanical properties of an ultrafine cement based grout with a constant water-binder ratio and constant superplasticizer content. Maximum percentages of replacement with ultrafine cement were 6% by volume of cement for MS and 16% for FA, and MK. In general, results suggest that the workability is improved by addition of FA, whereas is reduced, when modified with MS and MK. The compressive strength of grout after cement replacement remains comparable to that of pure cement grout. However, there is a tendency of the MS to positively affect the compressive strength opposite to FA, whereas flexural strength is positively affected by FA. Based on the results, it is evident that grouts with Hägerman cone flow more than 500 mm and compressive strength of more than 90 MPa after 28 days can be produced. T2 - International Conference on Concrete Repair, Rehabilitation and Retrofitting (ICCRRR 2018) CY - Cape Town, South Africa DA - 19.11.2018 KW - Analysis of variance KW - Box-Behnken KW - Grouting KW - Repair KW - Supplementary cementitious materials PY - 2018 AN - OPUS4-46712 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Shamsuddoha, Md A1 - Hüsken, Götz A1 - Pirskawetz, Stephan A1 - Baeßler, Matthias A1 - Kühne, Hans-Carsten A1 - Thiele, Marc T1 - Remediation of Cracks Formed in Grouted Connections of Offshore Energy Structures under Static Loads N2 - The future energy demand necessitates the exploration of all potential energy sources both onshore and offshore. Global trend has shifted towards offshore energy, which can be obtained from either carbon intensive or renewable options, hence requiring structures such as rigs, platforms, and monopiles. Most of these structures adopt easily installable construction techniques, where lower foundation need to be connected with the super structure by mean of grouted composite joints. Generally, these composite connections have exterior sleeve, interior pile and infill grout. Being located in remote offshore conditions, connections can experience considerable adverse loading during their lifetimes. Degradations were reported inside similar connections, which were installed in last three decades. Besides, grouting in the offshore sites may often be proven difficult, which eventually leads to reduced capacity of connections in the long run. Thus, repair and rehabilitation of such connections should be planned ahead to minimize operational delays and costs in the future. This study aims at characterizing the nature of crack generation in grouted connections and thereby identifying the potential of repair using suitable repair material. Scaled grouted joints were manufactured using a novel mold, and connections were loaded under static load to visualize the main failure pattern. The failure mechanism and loading capacity are found compatible to previous results from earlier literature. Grouted connection was then repaired using cementitious injectable grout. The effectiveness of the repair system is also discussed. T2 - Twenty-eighth (2018) International Ocean and Polar Engineering Conference CY - Sapporo, Japan DA - 10.06.218 KW - Offshore KW - Energy KW - Grouted Connection KW - Cracks KW - Repair KW - Rehabilitation PY - 2018 AN - OPUS4-45226 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Shamsuddoha, Md A1 - Hüsken, Götz A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten A1 - Baeßler, Matthias T1 - Superplasticizer and shrinkage reducing admixture dosages for microfine cement in grout systems N2 - Grouts have numerous applications including crack repair as maintenance in construction industries. Microfine cements are intensively used for high strength mortar and grout products. They are ideal for injection grouting in structural repair. Such grouts should have suitable rheological properties to be injectable, especially those used in repair and rehabilitation. The use of superplasticizers (SP) in these products is thus becoming increasingly crucial to achieve favorable workability and viscosity properties. A difficulty in such grouts is the plastic shrinkage due to finer particles used. It is thus necessary to determine optimum SP and shrinkage reducing admixture (SRA) dosages for a microfine cement based grout. In this study, a saturation dosage was decided from two Polycarboxylate ether (PCE) based SPs in relation to neat cement using slump flow and rheological parameters. A range of grout mixtures was formulated containing micro silica (MS) and fly ash (FA), and tested for suitable rheological and mechanical parameters. Based on the results, a grout mixture with MS and FA was selected to determine optimum SRA content. According to the results, a SP dosage of 3% by weight of neat cement is sufficient to achieve saturation. The grout material including MS and FA can produce comparable properties to neat cement grout. MS is found to improve compressive strength within the range considered, whereas a higher FA content provides favourable rheological properties. Finally, a SRA dosage of 4%, which could reduce the shrinkage by about 43% after 28d days, is determined for the grout system. T2 - 2nd International Conference on Building Materials and Materials Engineering (ICBMM 2018) CY - University of Lisbon, Portugal DA - 26.09.2018 KW - Grout KW - Mix design KW - Shrinkage KW - Crack repair KW - Microfine cement PY - 2018 AN - OPUS4-46155 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Shamsuddoha, Md A1 - Hüsken, Götz A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten A1 - Baeßler, Matthias ED - Alexander, M.G. ED - Beushausen, H. ED - Dehn, F. ED - Moyo, P. T1 - Workability and mechanical properties of ultrafine cement based grout for structural rehabilitation: A parametric study on the partial replacement with SCMs N2 - Grouting is a universal repair and strengthening technique, which is constantly used for structural remediation of concrete components, trenches, mine subsidence, dam joints, restoration of masonry structures, and geological stabilizations. Having an extremely small particle size of only few microns, ultrafine cements are ideal for grouting applications due to their superior permeability and compressive strength properties of the hardened cement paste compared to that of the less-expensive, but coarser ordinary Portland cements. Supplementary cementitious materials (SCMs) are often used to replace ultrafine cement in order to modify certain properties and to reduce costs. The aim of this experimental study is to investigate the effect of three supplementary materials: microsilica (MS), fly ash (FA), and metakaolin (MK) on the workability, and mechanical properties of an ultrafine cement based grout with a constant water-binder ratio and constant superplasticizer content. Maximum percentages of replacement with ultrafine cement were 6% by volume of cement for MS and 16% for FA, and MK. In general, results suggest that the workability is improved by addition of FA, whereas is reduced, when modified with MS and MK. The compressive strength of grout after cement replacement remains comparable to that of pure cement grout. However, there is a tendency of the MS to positively affect the compressive strength opposite to FA, whereas flexural strength is positively affected by FA. Based on the results, it is evident that grouts with Hägerman cone flow more than 500 mm and compressive strength of more than 90 MPa after 28 days can be produced. T2 - International Conference on Concrete Repair, Rehabilitation and Retrofitting (ICCRRR 2018) CY - Cape Town, South Africa DA - 19.11.2018 KW - Grouting KW - Repair KW - Box-Behnken KW - Supplementary cementitious materials KW - Analysis of variance PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-464769 DO - https://doi.org/10.1051/matecconf/201819907006 SN - 2261-236X VL - 199 SP - 07006-1 EP - 07006-7 PB - MATEC Web of Conferences AN - OPUS4-46476 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Shamsuddoha, Md A1 - Hüsken, Götz A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten A1 - Baeßler, Matthias T1 - Ternary mix design of grout material for structural repair using statistical tools N2 - Repair is an indispensable part of the maintenance of structures over their lifetimes. Structural grouting is a widely used remediation technique for concrete components, trenches, mine subsidence, dam joints, restoration of masonry structures, and geological stabilizations. A structural grout system should be injectable in narrow spaces and hence include ingredients with finer particles. Ultrafine cements are ideal for these type of demanding grouts due to their superior properties compared to that of the less expensive, but coarser ordinary Portland cement (OPC). Supplementary cementitious materials (SCMs) are often used to replace OPC clinker based binder in order to modify certain properties and to reduce costs. The most commonly used SCMs are fly ash (FA), and ground granulated blast furnace slag (GGBS). For various special applications microsilica (MS), and metakaolin (MK) are also used. Identifying the optimum replacement contents of OPC by SCMs are a challenge during the design of such grouts. The aim of this experimental study is to investigate the effect of the selected SCMs (FA, MS and MK) on the slump flow, time of efflux, viscosity, shrinkage, and compressive and flexural strength of ultrafine cement based grouts with constant water-binder ratio and superplasticizer content. The test program was formulated using Box-Behnken design principles. Maximum percentages of replacement with ultrafine cement was 6% by volume of cement for MS and 16% for FA, and MK. The results suggest that most investigated grouts have the potential to be used for structural applications. The appropriate quadratic models are then formulated through statistical tools and presented as response surfaces. The trends indicate that fly ash improves the rheological properties, whereas microsilica and metakaolin positively affect shrinkage and mechanical properties to some extent. Based on the influence of SCMs and priorities among the properties, Decision Matrix Analysis (DMA) is carried out to select the most suitable ones among the SCMs. The analysis suggests that microsilica and fly ash are more suitable as SCMs than metakaolin without affecting the properties. KW - Grouting KW - Microsilica KW - Fly ash KW - Metakaolin KW - Workability KW - Viscosity KW - Strength KW - Mix design KW - Box-Behnken KW - Decision matrix analysis PY - 2018 DO - https://doi.org/10.1016/j.conbuildmat.2018.08.156 SN - 0950-0618 SN - 1879-0526 VL - 189 SP - 170 EP - 180 PB - Elsevier Ltd. AN - OPUS4-45922 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Shamsuddoha,, Md A1 - Hüsken, Götz A1 - Pirskawetz, Stephan A1 - Baeßler, Matthias A1 - Kühne, Hans-Carsten A1 - Thiele, Marc T1 - Remediation of Cracks Formed in Grouted Connections of Offshore Energy Structures under Static Loads N2 - The future energy demand necessitates the exploration of all potential energy sources both onshore and offshore. Global trend has shifted towards offshore energy, which can be obtained from either carbon intensive or renewable options, hence requiring structures such as rigs, platforms, and monopiles. Most of these structures adopt easily installable construction techniques, where lower foundation need to be connected with the super structure by mean of grouted composite joints. Generally, these composite connections have exterior sleeve, interior pile and infill grout. Being located in remote offshore conditions, connections can experience considerable adverse loading during their lifetimes. Degradations were reported inside similar connections, which were installed in last three decades. Besides, grouting in the offshore sites may often be proven difficult, which eventually leads to reduced capacity of connections in the long run. Thus, repair and rehabilitation of such connections should be planned ahead to minimize operational delays and costs in the future. This study aims at characterizing the nature of crack generation in grouted connections and thereby identifying the potential of repair using suitable repair material. Scaled grouted joints were manufactured using a novel mold, and connections were loaded under static load to visualize the main failure pattern. The failure mechanism and loading capacity are found compatible to previous results from earlier literature. Grouted connection was then repaired using cementitious injectable grout. The effectiveness of the repair system is also discussed. T2 - Twenty-eighth (2018) International Ocean and Polar Engineering Conference CY - Sapporo, Japan DA - 10.06.2018 KW - Offshore KW - Energy KW - Grouted Connection KW - Cracks KW - Repair KW - Rehabilitation PY - 2018 SP - 120 EP - 126 AN - OPUS4-45227 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Song, Jiaojiao A1 - Auersch, Lutz T1 - Track-soil calculation and measurement of damaged and repaired slab tracks N2 - Calculation of the behaviour of damaged slab tracks have been performed with ANSYS and with a combined finite-element boundary-element Programme. Different damage lengths have been analysed and the best fit to the measurements has been chosen. T2 - Seminar on Railway Engineering CY - Tongji University Shanghai, People's Republic of China DA - 21.09.2018 KW - Slab track KW - Track damage KW - Boundary element method KW - Train passage PY - 2018 AN - OPUS4-46405 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Viefhues, Eva A1 - Döhler, M. A1 - Hille, Falk A1 - Mevel, L. ED - Simani, S. ED - Patan, K. T1 - Asymptotic analysis of subspace-based data-driven residual for fault detection with uncertain reference N2 - The local asymptotic approach is promising for vibration-based fault diagnosis when associated to a subspace-based residual function and efficient hypothesis testing tools. It has the ability of detecting small changes in some chosen system parameters. In the residual function,the left null space of the observability matrix associated to a reference model is confronted to the Hankel matrix of output covariances estimated from test data. When this left null space is not perfectly known from a model, it should be replaced by an estimate from data to avoid model errors in the residual computation. In this paper, the asymptotic distribution of the resulting data-driven residual is analyzed and its covariance is estimated, which includes also the covariance related to the reference null space estimate. The advantages of the data-driven residual are demonstrated in a numerical study, and the importance of including the covariance of the reference null space estimate is shown, which increases the detection Performance. T2 - 10th IFAC Symposium on Fault Detection, Supervision and Safety for Technical Processes SAFEPROCESS 2018 CY - Warsaw, Poland DA - 29.08.2018 KW - Subspace-based method KW - Fault detection KW - Uncertainty in reference KW - Residual evaluation KW - Statistical tests KW - Vibration measurements PY - 2018 DO - https://doi.org/10.1016/j.ifacol.2018.09.610 SN - 2405-8963 VL - 51 IS - 24 SP - 414 EP - 419 PB - Elsevier AN - OPUS4-46303 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -