@article{HirschmuellerPravidaMarteetal.2018, author = {Hirschm{\"u}ller, Sebastian and Pravida, Johann and Marte, Roman and Flach, Michael}, title = {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}, series = {Wood Science and Technology}, volume = {52}, journal = {Wood Science and Technology}, number = {4}, editor = {Springer,}, pages = {1061 -- 1092}, year = {2018}, abstract = {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.}, language = {en} } @article{HirschmuellerPravidaMarteetal.2019, author = {Hirschm{\"u}ller, Sebastian and Pravida, Johann and Marte, Roman and Flach, Michael}, title = {Long-term material properties of circular hollow laminated veneer lumber sections under water saturation and cement alkaline attack}, series = {Wood Material Science and Engineering}, volume = {14}, journal = {Wood Material Science and Engineering}, number = {3}, pages = {142 -- 156}, year = {2019}, abstract = {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\%.}, language = {en} } @inproceedings{MonsbergerLienhartMarteetal.2018, author = {Monsberger, Christoph and Lienhart, Werner and Marte, Roman and Hirschm{\"u}ller, Sebastian}, title = {Monitoring of soil nailed slope stabilizations using distributed fiber optic sensing}, series = {Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2018}, volume = {10598}, booktitle = {Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2018}, editor = {Sohn, Hoon}, doi = {10.1117/12.2296674}, year = {2018}, abstract = {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.}, language = {en} } @techreport{HirschmuellerWalser2023, author = {Hirschm{\"u}ller, Sebastian and Walser, Georg}, title = {Rettung von Großvieh bei Brandereignissen landwirtschaftlicher Geb{\"a}ude in Holzbauweise; Teilvorhaben 1: Bauliche und konstruktive Grundlagen}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:861-opus4-20627}, pages = {55}, year = {2023}, abstract = {Innerhalb des Teilvorhabens 1 (TV 1) des Verbundprojektes wurde ein Beitrag zu den baulichen und konstruktiven Grundlagen einer effektiven Rettung von Großvieh bei Brandereignissen erstellt und M{\"o}glichkeiten einer effektiven Brandfr{\"u}herkennung sowie Vorschl{\"a}ge f{\"u}r bauliche Maßnahmen erarbeitet. In enger Zusammenarbeit mit den Verbundpartnern der Hochschule Weihenstephan-Triesdorf sowie der Arbeitsgruppe Pr{\"a}ventionsingenieure e.V. wurden, soweit feststellbar, in einem ersten Schritt Daten zu Branderhebungen, aufgetretenen (Tier-)Sch{\"a}den und Brandursachen erhoben. Unter Beachtung vorhandenen Betriebsstrukturen und der nutztierartabh{\"a}ngigen, tierphysiologischen Aspekte wurden Vorschl{\"a}ge f{\"u}r konstruktive und bauliche Durchbildungen von baulichen Anlagen zur Verbesserung einer effektiven Rettung und Nachbetreuung von Großvieh, insbesondere in der Entstehungsphase von Brandereignissen, erarbeitet. Die nach eingehender Analyse bestehender Objektstrukturen erarbeiteten Vorschl{\"a}ge zur Verbesserung der Rettung von Nutztieren wurden konstruktiv in Praxisversuchen validiert. Insbesondere aus dem durchgef{\"u}hrte Pilotversuch der Evakuierung einer Rinderherde konnten R{\"u}ckschl{\"u}sse f{\"u}r weitere baulich-konstruktive Anpassungsmaßnahmen f{\"u}r m{\"o}gliche Evakuierungsstrategien gezogen werden.}, language = {de} }