Versuche zur Tragfähigkeit von Ankerplatten mit einbetonierten Kopfbolzendübeln in schmalen Stahlbetonstützen

Müssen große Lasten von Stahl‐ in Betonbauteile eingebracht werden, sind Ankerplattendetails mit aufgeschweißten Kopfbolzendübeln oft praktikable Lösungen. Dies gilt auch für die Befestigung von Stahlträgern an Stützen aus Stahlbeton. Hier können die Ankerplatten z. B. bauseits an der Schalung befestigt und mit dem Ortbeton einbetoniert werden. Die Dimensionierung dieser Einbauteile kann, wie auch die Berechnung von nachträglich installierten Befestigungsmitteln, derzeit nach Europäischen Technischen Zulassungen (ETA) erfolgen. Im Unterschied zu nachträglich installierten Befestigungen ist für die Ankerplatte mit einbetonierten Kopfbolzendübeln eine rechnerische Nutzung der Tragfähigkeit der Bewehrung möglich. Allerdings führen die diesbezüglichen Regelungen – im Vergleich zu den in den Versuchen ermittelten Tragfähigkeiten – rechnerisch zu stark eingeschränkten Tragfähigkeiten. Dies beruht einerseits auf der Reduktion der Tragfähigkeit wegen geringer Randabstände und andererseits auf der stark eingeschränkten Nutzbarkeit der Bewehrung. Im folgenden Beitrag werden Versuchsergebnisse vorgestellt, welche den Einfluss der Betondruckfestigkeit, der Verankerungslänge, der Lastexzentrizität sowie der Bewehrungsmenge und ‐position auf das Versagensgeschehen und die Tragfähigkeit zeigen. Results of Experimental Investigations on the Load‐Bearing Capacity of Steel Anchor Plates with in Concrete Encased Headed Studs in Reinforced Narrow Concrete Columns Anchor plates with welded shear studs are often used to transfer high loads from steel to reinforced concrete elements. This is for example the case for the fixation of steel beams to reinforced concrete columns. The anchor plates are fixed on site on the formwork and cast in‐place in the concrete. The design is calculated according to European Technical Approvals like the design of post‐installed anchors. In contrast to post‐installed fastenings, the utilisation of the reinforcement of in concrete encased headed studs is theoretically possible. But the regulations of the ETAs lead to great reductions in the analysed load‐bearing capacities compared to the capacities, obtained in tests. These tests have been conducted to investigate the load bearing behaviour and failure modes of anchor plates, especially in narrow reinforced concrete columns. In the following article the results of the experimental investigations are presented, which show the influence of concrete compression strength, shear stud length, load eccentricity as well as amount and position of reinforcement.     

Optimized topology extraction of steel-framed DiaGrid structure for tall buildings

This study presents an optimal angle and a topology extraction of diagonal members in a DiaGrid structural system for tall buildings. The angle and topology of diagonal members are achieved by using a computer-oriented SIMP topology optimization. The objective function for the design optimization is to both maximize Eigenfrequency for resisting dynamic responses and minimize mean compliance for static responses. Relative densities subjected to SIMP penalty law are used for both optimization design variables and material properties, and then finite element analysis is carried out by using the relative element density. Frequency and mean compliance sensitivities with respect to relative density are straightforwardly derived by discrete sensitivity formulations. Based on the design sensitivity analysis, an initial topology with a given fixed support is shifted toward a final topology charged by almost voids (0) and solids (1) during every optimization procedure. An optimal DiaGrid topology with the highest stiffness is finally determined to resist both static and dynamic behaviors. Numerical examples with varied fixed support models are studied to find out optimal angles and topologies of diagonal members for a DiaGrid system design.     

Reaction of the titanocene alkyne complex Cp2Ti(η2-Me3SiC2SiMe3) with selenium dioxide: Preparation and characterization of a novel tetranuclear titanium complex with selenium and oxo bridges

The low valent titanocene(II) source Cp₂Ti(η²-Me₃SiC₂SiMe₃) 1 reacts with selenium dioxide (2) to obtain a tetranuclear selenium and oxygen bridged titanocene(IV) [{Cp₂Ti(µ²-O; µ²-Se)CpTi}₂(µ²-O)] 6. The molecular structure was confirmed by X-ray analysis.     

Preparation of water-stable submicron fibers from aqueous latex dispersion of water-insoluble polymers by electrospinning

Submicron polystyrene (PS) fibers were prepared by electrospinning of an aqueous dispersion of PS latex and a small amount of poly(vinyl alcohol) (PVA) and subsequent extraction by water. Depending on particle size, surfactant, ratio of PS:PVA, and applied voltage fibers of different morphology and water stability were obtained. Analysis of latex fibers by TEM revealed hexagonal packaging of particles within the fibers.     

Adsorption of rutin onto a food-grade styrene–divinylbenzene copolymer in a model system

Adsorption of quercetin-3-O-rutinoside (rutin) onto Amberlite^® XAD 16HP was studied applying a modified D-optimal design. Temperature, pH value, rutin concentration and resin amount were studied as independent factors determining rutin adsorption. Using the mathematical model resulting from the analysis of the D-optimal design the optimal conditions for rutin adsorption onto the styrene–divinylbenzene copolymer were determined. Furthermore, the model equation was successfully applied to calculate the Langmuir and Freundlich isotherm parameters of this particular solute–sorbent system. In addition, the data obtained from the D-optimal design allowed the calculation of ΔG, ΔH and ΔS for the adsorption process. The results presented in this study are of utmost importance for a better understanding of adsorption phenomena. The more detailed knowledge of such sorbent systems is required to improve the cost-effectiveness of industrial processes for the recovery of secondary plant metabolites, such as polyphenols, based on resin adsorption technology.     

Analytik von Gangliosiden unter besonderer Berücksichtigung der Milch

Gangliosides are sialic acid containing lipid compounds of a very complex nature, which are involved in many physiological processes. Gangliosides are very important constituents of membrane material in animal tissue, where they occur at very low concentrations. Improved analytical procedures are therefore required to study their behaviour, their role in living systems and their isolation for further investigations. In this paper, all analytical methods which may be important in the analysis of gangliosides are summarized and discussed. These include extraction, purification, enrichment and chromatographic procedures. In bovine milk, three gangliosides of known structure are present. Their isolation, structure and analytical importance (buttermilk) are also reported.     

Design and Conception of a Membrane Pilot Plant for the In Situ Treatment of Bioleaching Solutions

Today's mining activities are facing deposits of decreasing metal content and an increase of complexity. Biohydrometallurgy is an industrial application that uses microorganisms to facilitate the release of metals from mineral ores, especially sulfide ores. A testing site for in situ bioleaching was established in an underground mine to recover indium and germanium from a zinc sulfide ore vein. The downstream processing of the pregnant leaching solution is also realized as in situ application by means of a membrane pilot plant, which was exclusively designed for this special application.     

Liquid Flow Visualization in Packed‐Bed Multiphase Reactors: Wire‐Mesh Sensor Design and Data Analysis for Rotating Fixed Beds

Wire‐mesh sensors are increasingly used for flow imaging in packed beds. In this study, a capacitance wire‐mesh sensor is applied to measure the cross‐sectional liquid phase distribution in a rotating fixed‐bed reactor. The liquid filling level is derived as a crucial parameter defining the operational window of the reactor concept. Contrary to the standard sensor configuration, wireless data transfer and autonomous power supply is integrated. Furthermore, appropriate data processing is required to visualize the liquid flow of the three‐phase system (nitrogen, cumene and γ‐Al₂O₃ particles).     

Protein‐based stable isotope probing (protein‐SIP) in functional metaproteomics

The community phenotype as the sum of molecular functions of organisms living in consortia strongly depends on interactions within these communities. Therefore, the analyses of the most significant molecules in terms of the phenotype, the proteins, have to be performed on samples without disrupting the meta‐species environment. Due to the increasing genomic information, proteins provide insights into a potential molecular function and the phylogenetic structure of the community. Unfortunately, the lists of identified proteins are often based first on the technical capacity of the used methods or instruments, and second on the interpretation of them by the assignment of molecular functions to proteins in databases. Especially in non‐model organisms the functions of many proteins are often not known and an increasing number of studies indicate a significant amount of uncertainty. To decrease the dependency on assumptions and to enable functional insights by metaproteome approaches, the metabolic labeling from an isotopically labeled substrate can be used. Since the metabolites deriving from the substrate are very rarely species‐specific, the incorporation of the stable isotope into proteins can be used as a surrogate marker for metabolic activity. The degree of incorporation can be determined accurately on the peptide level by mass spectrometry; additionally, the peptide sequence provides information on the metabolic active species. Thereby, protein‐stable isotope probing (protein‐SIP) adds functional information to metaproteome approaches. The classical metaproteome approaches will be reviewed with an emphasis on their attempts towards functional interpretation. The gain from functional insights into metaproteomics by using metabolic labeling of stable isotopes of carbon, nitrogen, and sulfur is reviewed with a focus on the techniques of measurement, calculation of incorporation and data processing. © 2012 Wiley Periodicals, Inc. Mass Spec Rev 31:683–697, 2012