TY - THES A1 - Hirschmüller, Sebastian T1 - Beech circular hollow laminated veneer lumber sections for temporary soil nailing applications N2 - Beech Laminated Veneer Lumber (LVL) circular hollow sections for use as temporary geotechnical soil nailing systems are developed within this thesis. Due to their permanent subsoil cement embedment, combined with high water saturation and permanent loading, the timber sections will lose strength and stiffness over time. Taking into account a duration of load factor for permanent loading of two years, it is recommended to reduce the short term tensile and bending strength of beech circular hollow sections to be used as geotechnical soil nails by 80%. In addition to the determination of material properties on small, clear specimens and full-sized cross-sections, an appropriate surface gluing quality between the veneers is fundamental to this subsoil application of the permanently cement-embedded, engineered timber product. The circular cross-section geometry and the permanently high-alkaline environment of the structural member is not covered by presently standardised testing and conditioning methods for examining LVL surface bond line quality. Standardised test methods had to be modified to determine bonding parameters for the circular, hollow LVL sections. As cement grout ensures the bond between the wooden nails and soil for the mobilisation of a soil reinforcement effect, a reliable connection between cement and wood is required. However, soluble wood constituents may inhibit cement hydration in the contact surface between the timber nails and cement. Pull-off tests on clear LVL specimens with different cement and wood surface modifications as well as the results of large-scale push-out tests are therefore presented. But to permanently ensure the contact between the wood and cement, a high degree of saturation above wood fibre saturation is necessary to keep the hollow sections in a swollen state without moisture-dependent wood shrinking. As no publications of wood moisture development in subsoil were available, long-term tests were performed, measuring the moisture content of subsoil-stored LVL in dependence on the soil moisture content, the suction and the precipitation during a time span of one year. Besides a negative cement influence on the material strength, a positive effect of cement coating on subsoil fungal destruction was realised, resulting in a significantly increased lifetime of cement-coated wood compared to uncoated wood. For temporary soil nailing applications, fungal wood deterioration was found to be of minor importance. But the reduced material strength due to a severe alkaline attack of wood demands a re-consideration of current soil nailing design methods, usually based on a mechanical limit equilibrium analysis of a rigid body motion where just tensile forces of the reinforcement elements are considered, and accompanying forces like bending moments and shear forces are neglected. Distributed fibre optic strain measurements of a steel-reinforced soil nail wall during a time span of six weeks reveal considerable nail curvatures, which are negligible in the case of ductile soil nails with low diameters, but are a significant factor for beech circular hollow laminated veneer lumber sections of larger diameters and brittle material behaviour. KW - Beech Laminated Veneer Lumber KW - Circular hollow sections KW - Temporary soil nailing KW - Furnierschichtholzrohre KW - Buche KW - Temporäre Bodenvernagelung Y1 - 2019 UR - https://online.tugraz.at/tug_online/wbAbs.showThesis?pThesisNr=66478&pOrgNr=953# ER - TY - JOUR A1 - Hirschmüller, Sebastian A1 - Pravida, Johann A1 - Marte, Roman A1 - Flach, Michael T1 - Long‐term material properties of circular hollow laminated veneer lumber sections under water saturation and cement alkaline attack JF - Wood Material Science and Engineering N2 - Innovative beech laminated veneer lumber (LVL) circular hollow sections for the use as temporary geotechnical soil nailing systems are currently being developed. Due to the permanent subsoil cement embedment, combined with high water saturation and permanent loading, the timber sections will lose strength and stiffness over time to a degree currently unknown. This paper presents the tensile and bending material properties of flat and curved beech LVL under various periods of immersion in a water–cement grout solution aiming at inducing both water saturation and long-term alkaline attack of the timber. In total, 824 and 279 samples were tested in tension and bending, respectively. Results show that samples manufactured from 3 mm thick veneers result in tensile strength and stiffness 17% and 24% higher, respectively, than samples manufactured from 2 mm thick veneers. A reduction in the initial bending and tensile strength of up to 70% was found after 90 days of water saturation and cement contact. Taking into account a duration of load factor for permanent loading of two years, it is recommended to reduce the short-term tensile and bending strength of beech circular hollow sections to be used as geotechnical anchors by 80%. KW - Timber engineering KW - Laminated veneer KW - Water saturation KW - Cement alkaline attack Y1 - 2019 UR - https://doi.org/10.1080/17480272.2018.1434830 VL - 14 IS - 3 SP - 142 EP - 156 ER - TY - CHAP A1 - Monsberger, Christoph A1 - Lienhart, Werner A1 - Marte, Roman A1 - Hirschmüller, Sebastian ED - Sohn, Hoon T1 - Monitoring of soil nailed slope stabilizations using distributed fiber optic sensing T2 - Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2018 N2 - Soil nailing systems are a common way to stabilize slopes and construction pits. Their design is usually based on the mechanical equilibrium of a rigid body motion and therefore, only tensile stresses are considered and accompanying forces like bending (shear stresses) in the soil nails are neglected. Continuous strain measurements along nails could verify this assumption, but may not be performed using conventional sensing technologies. This paper reports about monitoring of a soil nailed slope stabilization using distributed fiber optic sensing. Soil nails in different anchoring horizons were instrumented and autonomously monitored over several weeks, in which the construction pit was excavated continuously. After the excavation, the final load bearing capacity of one selected nail was determined within a classical geotechnical load test. In addition to the field measurements, the bending behavior of the instrumented nail system was analyzed under laboratory conditions. The presented studies demonstrate the high potential of distributed fiber optic sensing systems and their capability to extend traditional measurement methods in foundation engineering applications. KW - Timber engineering KW - Soil nailed slope stabilizations KW - Distributed fiber optic sensing Y1 - 2018 U6 - https://doi.org/10.1117/12.2296674 VL - 10598 ER - TY - JOUR A1 - Hirschmüller, Sebastian A1 - Pravida, Johann A1 - Marte, Roman A1 - Flach, Michael ED - Springer, T1 - Adhesive properties of laminated veneer lumber poles for use in temporary soil nailing: development and evaluation of a test method for curved structures in a high‐alkaline environment JF - Wood Science and Technology N2 - Innovative circular, hollow, laminated veneer lumber (LVL) beech sections for use as temporary geotechnical soil reinforcement members are currently being developed. Appropriate surface gluing quality between the veneers is fundamental to this subsoil application of the permanently cement-embedded, engineered timber product. The circular cross-section geometry and the permanently high-alkaline environment of the structural member is not covered by presently standardized testing and conditioning methods for examining LVL surface bond line quality. The sample conditioning and tensile shear test method compliant with EN 302-1 (Adhesives for load-bearing timber structures—test methods—part 1: determination of longitudinal tensile shear strength, European Committee for Standardization, Brussels, 2013) was modified to determine bonding parameters for circular, hollow LVL sections. Bond line curvature, groove cutting depth and sample geometry were found to greatly influence stress distribution, percentage of wood failure and tensile shear strength. Short-term alkaline treatment of test samples did not significantly influence the bonding performance, wood failure percentage, tensile shear strength and fracture patterns. To improve tensile shear strength, adhesives with different material rigidities were used and compared. An orthotropic, elastic numerical analysis revealed a greater influence of adherent elasticity than adhesive elasticity on the stress distribution within the bond line. With regard to determining the bond line integrity of curved veneer poles, a sample geometry compliant with EN 302-1 (2013) was developed and numerically evaluated. KW - Timber engineering KW - Laminated veneer KW - Temporary soil nailing Y1 - 2018 UR - https://doi.org/10.1007/s00226-018-0997-y VL - 52 IS - 4 SP - 1061 EP - 1092 ER - TY - CHAP A1 - Hirschmüller, Sebastian A1 - Marte, Roman A1 - Pravida, Johann ED - Eberhardsteiner, Josef ED - Winter, Wolfgang ED - Fadai, A. ED - Pöll, Martha T1 - Laminated veneer lumber poles for temporary soil nailing ‐ investigation of material properties T2 - Proceedings of the World Conference on Timber Engineering. World Conference on Timber Engineering. Vienna, 22.‐25.08. Vienna N2 - Within a current research project at Rosenheim University of Applied Sciences and Graz University of Technology the possibilities of using beech wood laminated veneer lumber poles as soil anchors for temporary soil nailing systems are investigated. Therefore tensile and bending properties of laminated veneers with high moisture and permanent cement contact concerning the influence of veneer bending rectangular to the fibre are determined. For investigation of material properties under different climate conditions tensile tests on small and faultless single beech wood veneers as well as tensile tests on 6 layered 3 mm samples and 9 layered 2 mm samples were carried out. Therefore all samples were stored in extreme climate conditions like high moisture content and permanent cement contact. Six layered samples with 3mm thick veneers show a slightly higher strength and stiffness under dry conditions as well as at a moisture content of the samples above fibre saturation. A strength reduction factor concerning temporary geotechnical applications is suggested which considers the influence of long term loading, veneer bending, water saturation and cement destruction on tensile properties of laminated veneer lumber poles. KW - Timber engineering KW - Laminated veneer KW - Temporary soil nailing Y1 - 2016 ER - TY - JOUR A1 - Hirschmüller, Sebastian A1 - Marte, Roman A1 - Pravida, Johann A1 - Flach, Michael ED - Springer, T1 - Inhibited wood degradation of cement‐coated beech Laminated Veneer Lumber (LVL) for temporary in‐ground applications. JF - European Journal of Wood and Wood Products N2 - This paper investigates the long-term tensile properties of laminated veneer lumber (LVL) beech sections coated with cement and exposed to fungal decay. A set of LVL coupon (dog-bone) samples was stored in compost, tested in tension after 6 and 12 months and compared to reference samples stored at 20 °C and 65% relative humidity. Results showed that after 26 weeks of compost exposure, a fungus of the Ascomycota genus was identified in cement-coated samples using a molecular biology polymerase chain reaction (PCR) technique, which analyses the internal transcribed spacer (ITS) region of the ribosomal DNA. However, no visual deterioration was noticed. Still in cement-covered samples and after 12 months of exposure, a common white rot fungus was determined by DNA chip technology, but no fungal wood decay was visible in areas where the applied coating had a thickness of at least 5 mm. Decay in uncoated LVL samples was significant with the samples having an average residual strength equal to 7%. This compares to the tensile strength of coated samples, which only decreased by 65% relative to the reference samples. Strength and stiffness of coated samples did not differ significantly between 6 and 12 months of exposure. Preliminary investigations tend to show that the strength reduction in cement-coated samples is due to an alkaline degradation of the wood. The observed influence of the coating thickness on the visual fungal decay can probably be ascribed to the protection mechanism due to a physical fungal barrier with a high pH. KW - Timber engineering KW - cement‐coated beech Laminated Veneer Lumber KW - Wood and wood products Y1 - 2018 UR - https://doi.org/10.1007/s00107-018-1325-9 VL - 76 IS - 5 SP - 1483 EP - 1494 ER - TY - CHAP A1 - Hirschmüller, Sebastian A1 - Pravida, Johann A1 - Marte, Roman A1 - Flach, Michael ED - Universität Stuttgart, T1 - Laminated veneer lumber poles for use in temporary soil nailing. Investigation of adhesive properties. T2 - Holzbau Forschung und Praxis. 6. Doktorandenkolloqium 2016 N2 - Within a current research-project the possibility of using laminated veneer lumber beech wood poles as temporary soil anchors in foundation engineering is investigated. Within this project adhesive properties of laminated veneer lumber beech wood poles are determined. For use in temporary ground applications the influence of veneer bending, veneer thickness and intensive cement contact is concerned. As standard version two different adhesive systemsmelamine formaldehyde resin (MUF) and a 1-component polyurethane adhesive (PUR) were investigated and compared. Melamine formaldehyde resin glued samples with 3 mm thick veneers and 1.0N/mm² press force show a higher tensile shear strength but also a higher adhesive failure percentage than polyurethane glued samples. In case of melamine formaldehyde resins the closed time has a great influence on bond line quality. A long closed time reveals a low penetration of adhesive in the cells and a low embedding on the wood surface. For curved structures best results were achieved with a bonding pressure of 1.0 N/mm². A significant difference in strength between the concerned MUF and PUR adhesive system was not recognized. KW - Timber engineering KW - Laminated veneer KW - Temporary soil nailing Y1 - 2016 ER - TY - JOUR A1 - Hirschmüller, Sebastian A1 - Pravida, Johann A1 - Marte, Roman A1 - Flach, Michael ED - Springer, T1 - Adhesive properties of laminated veneer lumber poles for use in temporary soil nailing: bonding performance of curved structures in a high‐alkaline environment JF - Wood Science and Technology N2 - Circular hollow sections of beech-laminated veneer lumber (LVL) for the use as temporary geotechnical soil nailing systems are currently being developed. Due to their permanent subsoil cement embedment, investigations of the bond line quality of the timber sections are essential. This paper presents the bonding properties of flat and curved beech LVL after cyclic conditioning in a water–cement grout solution aimed at inducing short- and long-term alkaline attack of the timber. In total, 409 and 69 samples were tested in tensile shear tests after short-term and long-term conditioning, respectively. Three different adhesive systems, a one-component polyurethane adhesive, a melamine–urea–formaldehyde adhesive and a melamine–urea–formaldehyde adhesive modified by means of (polyvinyl)-acetate adhesive were investigated and compared. Short-term conditioning by submersion in boiling cement suspension was found to be a reliable method for testing the bonding performance rather than long-term conditioning. In the case of tensile shear tests of samples subjected to long-term treatment, wood material strength was the decisive criterion. Generally, tensile shear test samples of all investigated adhesives achieved reliable bonding for a pressing force up to 1.0 MPa. No relationship was recognised between the determined bonding failure and the wood properties tensile shear strength, wood failure percentage, fracture pattern and bulk density of veneers adjacent to the bond line. For the determination of the bond line integrity of curved veneer poles, it was necessary to test bonding quality in a combined test using curved and flat samples and to compare tensile shear strength with data determined on reference samples in the same veneer population without bond line. KW - Timber engineering KW - Laminated veneer KW - Temporary soil nailing KW - High‐alkaline environment Y1 - 2018 UR - https://doi.org/10.1007/s00226-018-1031-0 VL - 52 IS - 5 SP - 1289 EP - 1311 ER - TY - CHAP A1 - Eierle, Benno A1 - Schikora, Karl T1 - Computational Viscoelasticity for Aging Materials T2 - Tagungsband ECCM 1999, München KW - aging materials Y1 - 1999 ER - TY - BOOK A1 - Pfau, Jochen A1 - Tichelmann, Karsten T1 - Dry Construction: Principles, Details, Examples T3 - DETAIL Practice, Edition Detail KW - Dry Construction KW - Trockenbau Y1 - 2008 PB - Birkhäuser ER - TY - CHAP A1 - Auer, Veronika A1 - Zscheile, Mathias T1 - Designing the beech wood supply chain. Vortrag auf der BioEconomy Conference 11. Mai 2017 in Halle/Saale. T2 - BioEconomy Conference. Sciences Campus Halle, BioEconomy Cluster. Halle/Saale, 11.05.2017 N2 - Bio-based products show a great potential to reduce the dependence on fossil resources. Germany currently has a forerunner role in the EU, using biomass as the same resource base for material and energetic utilisation. Beech wood is hyped in both ways: In material usage directly e.g., in the building sector to balance the possible scarcity of soft wood in the future, as well as indirectly as a feedstock for biorefineries, representing a long-term alternative to the fossil-based industry, and secondly, as energetic use due to its excellent burning quality. The BIOECONOMY CLUSTER sees itself as an actor in a difficult tension field within implementation of the wood-based Bioeconomy. With a total stocking volume of about 635 million m3, beech is the most abundant hardwood tree species in Germany. Nevertheless, beech wood-based biorefineries compete in a difficile tension field. One crucial factor is the reliable supply of raw materials - a consistent biomass quality, season-independent availability and efficient logistics of the raw material. However, the production processes are technically feasible; thus, finally, there is no guarantee for selling the bio-based products to the obtained price. How to overcome the strong tension field in the beech-based Bioeconomy? Different selected examples show possible approaches. To manage the wood-based Bioeconomy and the beech wood supply chain effectively, the influencing of factors and the managing of the same is crucial. KW - Bioeconomy KW - Beach Wood Y1 - 2017 ER - TY - CHAP A1 - Auer, Veronika A1 - Zscheile, Matthias A1 - Engler, Benjamin A1 - Haller, Peer A1 - Hartig, Jens A1 - Wehsener, Jörg A1 - Husmann, Kai A1 - Erler, Jörn A1 - Thole, Volker A1 - Schulz, Tino A1 - Hesse, Elfi A1 - Rüther, Norbert A1 - Himsel, Alexandra ED - Eberhardsteiner, J. ED - Winter, W. ED - Fadai, A. ED - Pöll, M. T1 - BIOECONOMY CLUSTER: resource efficient creation of value from beech wood to bio-based building materials. T2 - WCTE 2016. CD-ROM Proceedings of the World Conference on Timber Engineering. KW - Holz KW - Bioeconomy KW - Beach wood KW - Wooden Building Y1 - 2016 ER - TY - JOUR A1 - Eierle, Benno A1 - Krewinkel, K. T1 - Safety barriers made of glass – evidence by calculation rather than testing? JF - tür-tor-fenster report KW - Glass safety barriers Y1 - 2013 IS - 5/2013 SP - 10 EP - 14 PB - VFZ Verlag CY - Dortmund ER - TY - JOUR A1 - Eierle, Benno T1 - Structural Calculations for Windows made easy JF - tür-tor-fenster-report KW - windows Y1 - 2009 IS - 2/2009 PB - VFZ Verlag CY - Dortmund ER - TY - CHAP A1 - Eierle, Benno T1 - Detail Design and Execution of HH-Columns for the Tall Buildings of HERRIOT's in Frankfurt T2 - 6th International Symposium on Utilization of High Strength / High Performance Concrete, Leipzig, Germany, 2002 KW - HH-Columns Y1 - 2002 ER - TY - GEN A1 - Auer, Veronika A1 - Husmann, Kai ED - Auer, Veronika T1 - Perspectives of a future-proof logistics applied to the natural raw material supply in the Cluster Region (Plan C). Postersession. KW - Bioökonomie KW - Cluster Region KW - raw material supply Y1 - 2015 ER -