TY - CONF A1 - Hüsken, Götz A1 - Pirskawetz, Stephan A1 - Meinel, Dietmar ED - Banjad Pecur, Ivana ED - Baricevic, Ana ED - Stirmer, Nina ED - Bjegovic, Dubravka T1 - Experimental characterization of the fracture behavior of UHPFRC T2 - Proceedings of the 1st International Conference on Construction Materials for Sustainable Future N2 - Ultra-high performance fiber-reinforced concretes (UHPFRCs) are most suitable for applications with extreme mechanical loads. These extreme conditions require ductile behavior under tensile loading, which is obtained solely by the working mechanism of steel fibers. Profound knowledge on the working mechanism of the steel fibers is necessary to optimize this material. Usually, this knowledge is obtained by means of classical destructive measuring techniques. Adopting measuring techniques from non-destructive material testing helps to analyze and to identify the different stages of the fracture mechanism of UHPFRC in detail. The application of different non-destructive measuring techniques is shown exemplary on tensile tests conducted on an UHPFRC mix and its applicability for analyzing the fracture behavior of such concretes is discussed. The main focus is on the characterization of the relevant failure modes under tensile loading by the different measuring techniques and the comparison with classical measuring techniques (e.g. extensometer). The tensile tests have been analyzed by optical deformation measurements using digital image correlation (DIC), acoustic emission analysis (AE), and 3D computed tomography (CT). T2 - 1st International Conference on Construction Materials for Sustainable Future (CoMS_2017) CY - Zadar, Croatia DA - 19.04.2017 KW - UHPFRC KW - Tensile strength KW - Acoustic emission analysis KW - Optical deformation measurement KW - 3D computed tomography PY - 2017 SN - 978-953-8168-04-8 SP - 293 EP - 299 AN - OPUS4-39910 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hüsken, Götz A1 - Pirskawetz, Stephan A1 - Meinel, Dietmar T1 - Experimental characterization of the fracture behavior of UHPFRC N2 - Ultra-high performance fiber-reinforced concretes (UHPFRCs) are most suitable for applications with extreme mechanical loads. These extreme conditions require ductile behavior under tensile loading, which is obtained solely by the working mechanism of steel fibers. Profound knowledge on the working mechanism of the steel fibers is necessary to optimize this material. Usually, this knowledge is obtained by means of classical destructive measuring techniques. Adopting measuring techniques from non-destructive material testing helps to analyze and to identify the different stages of the fracture mechanism of UHPFRC in detail. The application of different non-destructive measuring techniques is shown exemplary on tensile tests conducted on an UHPFRC mix and its applicability for analyzing the fracture behavior of such concretes is discussed. The main focus is on the characterization of the relevant failure modes under tensile loading by the different measuring techniques and the comparison with classical measuring techniques (e.g. extensometer). The tensile tests have been analyzed by optical deformation measurements using digital image correlation (DIC), acoustic emission analysis (AE), and 3D computed tomography (CT). T2 - 1st International Conference on Construction Materials for Sustainable Future (CoMS_2017) CY - Zadar, Croatia DA - 19.04.2017 KW - UHPFRC KW - Tensile strength KW - Acoustic emission analysis KW - Optical deformation measurement KW - 3D computed tomography PY - 2017 AN - OPUS4-39913 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Shamsuddoha, Md A1 - Baeßler, Matthias A1 - Hüsken, Götz A1 - Pirskawetz, Stephan A1 - Kühne, Hans-Carsten A1 - Thiele, Marc ED - Banjad Pecur, Ivana ED - Baricevic, Ana ED - Stirmer, Nina ED - Bjegovic, Dubravka T1 - Identification of failure pattern in cylindrical grouted connection for wind structures - a pilot study T2 - Proceedings of the 1st International Conference on Construction Materials for Sustainable Future N2 - At present, Wind Turbine Generators (WTGs) operating in onshore and offshore wind farms are primary sources of renewable energy around the world. Cylindrical grouted sleeve connections are usually adopted in these WTG structures to connect the upper structure and foundation for ease of installation. These structures including grouted connections experience considerable adverse loading during their lifetimes. Settlements were reported inside similar connections used in energy structures especially oil and gas platforms, which were installed in last three decades. Thus, repair and rehabilitation of such connections in existing wind structures should also be planned ahead to keep them operating in the future. The nature of failure and crack generation in grouted connections are crucial prior to adopt a strengthening strategy. This pilot study is carried out to actualize the failure mechanism in the grouted connection, when subjected to axial loading. A novel reusable scaled cylindrical grouted connection with shear keys was designed and tested for its load bearing behaviour. The mechanical test was accompanied by classical measuring techniques (e.g. displacement transducer) as well as non-destructive measuring techniques (e.g. digital image correlation (DIC), acoustic emission analysis (AE)). The failure mechanism incorporating slippage of the shear keys and cracking of the grout was investigated. The capacity and applicability of such test mould were also discussed. The knowledge is expected to pave way towards repair of deteriorated grouted connections with similar geometry and failure pattern. T2 - 1st International Conference on Construction Materials for Sustainable Future (CoMS_2017) CY - Zadar, Croatia DA - 19.04.2017 KW - Grouted connections KW - Cracks KW - Failure KW - Strengthening strategy KW - Digital image correlation KW - Acoustic emission analysis PY - 2017 SN - 978-953-8168-04-8 SP - 544 EP - 551 AN - OPUS4-39914 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hüsken, Götz A1 - Shamsuddoha, Md A1 - Pirskawetz, Stephan A1 - Baeßler, Matthias A1 - Kühne, Hans-Carsten A1 - Thiele, Marc T1 - Identification of failure pattern in cylindrical grouted connection for wind structures – a pilot study N2 - At present, Wind Turbine Generators (WTGs) operating in onshore and offshore wind farms are primary sources of renewable energy around the world. Cylindrical grouted sleeve connections are usually adopted in these WTG structures to connect the upper structure and foundation for ease of installation. These structures including grouted connections experience considerable adverse loading during their lifetimes. Settlements were reported inside similar connections used in energy structures especially oil and gas platforms, which were installed in last three decades. Thus, repair and rehabilitation of such connections in existing wind structures should also be planned ahead to keep them operating in the future. The nature of failure and crack generation in grouted connections are crucial prior to adopt a strengthening strategy. This pilot study is carried out to actualize the failure mechanism in the grouted connection, when subjected to axial loading. A novel reusable scaled cylindrical grouted connection with shear keys was designed and tested for its load bearing behaviour. The mechanical test was accompanied by classical measuring techniques (e.g. displacement transducer) as well as non-destructive measuring techniques (e.g. digital image correlation (DIC), acoustic emission analysis (AE)). The failure mechanism incorporating slippage of the shear keys and cracking of the grout was investigated. The capacity and applicability of such test mould were also discussed. The knowledge is expected to pave way towards repair of deteriorated grouted connections with similar geometry and failure pattern. T2 - 1st International Conference on Construction Materials for Sustainable Future (CoMS_2017) CY - Zadar, Croatia DA - 19.04.2017 KW - Grouted connections KW - Cracks KW - Failure KW - Strengthening strategy KW - Digital image correlation KW - Acoustic emission analysis PY - 2017 AN - OPUS4-39915 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pirskawetz, Stephan A1 - Hüsken, Götz A1 - Curosu, I. A1 - Mechtcherine, V. ED - Mechtcherine, V. ED - Slowik, V. ED - Kabele, P. T1 - Combination of Digital Image Correlation and Acoustic Emission for Characterizing Failure Modes in Strain-Hardening Cement-Based Composites (SHCC) T2 - Strain-Hardening Cement-Based Composites N2 - The tensile behavior of strain-hardening cement-based composites (SHCC) is usually investigated on macroscopic scale by means of direct tension tests or bending tests. Additionally, the micromechanical properties of the composites are often described based on single fiber tension and pull-out tests. Such investigations, performed both on macroscopic and microscopic scales, are based on ‘classical’ force and displacement measuring techniques. Advanced test methods such as digital image correlation (DIC) and acoustic emission analysis (AE) may facilitate the identification and the analysis of the failure mechanisms in SHCC, which is important for both monitoring loaded SHCC elements and further material development and optimization. In this study, these two techniques are combined to characterize the failure mechanisms of three different types of SHCC in direct tension tests. The results are related to data of stress and strain measurements. It is shown that DIC provides detailed spatially resolved and stress related strain measurements. Furthermore, it is demonstrated that AE allows for the localization of active cracks, quantification of the damage accumulation under increasing stresses, and characterization of the dominant crack bridging mechanisms and failure modes observed in the different types of SHCC. T2 - 4th International RILEM Conference on Strain-Hardening Cement-Based Composites (SHCC4) CY - Technische Universität Dresden, Germany DA - 18.09.2017 KW - Cementitious composites KW - Strain-hardening KW - Fiber reinforcement KW - Tension KW - Multiple cracking KW - Acoustic emission analysis KW - Digital image correlation PY - 2017 SN - 978-94-024-1194-2 DO - https://doi.org/10.1007/978-94-024-1194-2 VL - 15 SP - 300 EP - 307 PB - Springer Science+Business Media B.V. CY - Dordrecht, The Netherlands AN - OPUS4-42129 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hüsken, Götz A1 - Shamsuddoha, Md A1 - Pirskawetz, Stephan A1 - Hofmann, Detlef A1 - Baeßler, Matthias A1 - Kühne, Hans-Carsten T1 - Potential of a Repair System for Grouted Connections in Offshore Structures: Development and Experimental Verification JF - Marine Structures N2 - Grouted connections are intensively used in offshore rigs, platforms as well as jacket and monopile offshore wind turbine structures. Being located in remote offshore conditions, these connections can experience considerable adverse loading during their lifetimes. Degradation was reported inside similar connections, which were installed in the last three decades. Grouting in the offshore sites may often be proven difficult, which eventually leads to reduced load-bearing 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 this study, scaled grouted connections were manufactured using a novel mould, whose integrity were monitored using digital image correlation (DIC). The connections were loaded under static load to visualize the main failure pattern using distributed fibre optic sensors and acoustic emission (AE) analysis. Grouted connections were then repaired using a cementitious injectable grout. The effectiveness of the grout injection was monitored using dye penetration technique. Finally, specimens are reloaded to identify the potential of such repair for grouted connections. KW - Offshore KW - Grouted connection KW - Fibre optic sensors KW - Acoustic emission analysis KW - Cracks KW - Repair KW - Rehabilitation KW - Static loading PY - 2021 DO - https://doi.org/10.1016/j.marstruc.2021.102934 VL - 77 SP - 102934 PB - Elsevier Ltd. AN - OPUS4-52059 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -