Stettner C.,Zilch Muller Ingenieure GmbH |
Dauberschmidt C.,Hochschule Munich
Beton- und Stahlbetonbau | Year: 2017
Load bearing base plates of underground car parks – Aspects in the planning and possibilities for an effective reinforcement design. There is a certain insecurity existent among planners of load bearing base plates for underground car parks: on the one hand they try to meet the requirements in regard to water impermeability and durability against chloride exposure by fulfilling strict requirements in regard to maximum crack width and late restraints. This leads to high reinforcement contents of the base plates, as shown in a parameter study. On the other hand the planner is obliged to plan economically. A possible way out of this dilemma is shown in the draft of the DBV fact sheet ”Car Parks“ and the watertight guideline: the design principle (EGS) ”planning cracks“ allows the reduction of the minimum reinforcement by e. g. targeted placement of crack-inducing elements and reinforcement design. Another discussed aspect of this paper is to verify the tightness against chloride ingress of different concrete mixtures. It is proven that the approach of the standard to ensure the durability by using high strength concrete is not constructive. It is rather to suggest to reduce the strength of the concrete with choosing a suitable binder. Copyright © 2017 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin
Durr A.,Hochschule Munich |
Walter S.,Wastl Lippacher Ingenieur GmbH
Stahlbau | Year: 2017
Lateral-torsional buckling of crane runway beams built-up by rolled profiles combined with angle sections on the top flange. Crane runway beams of overhead travelling cranes are subjected to biaxial bending and torsion due to the crane operation with the wheel loads ane the eccentric horizontal loads. The crane runway girders are proned for lateral-torsional buckling due to this loading situation. Therefore the verification for lateral-torsional buckling is often dimensioning for the design of crane runway beams for overhead travelling cranes. In the case of the application of rolled sections, the required lateral stiffness of the top flange is often not sufficient even for light crane operations and medium span lengths. In order to increase the lateral stiffness on the top flanges of these crane runway beams, the rolled sections can be strengthened by welding angle profiles on both sides of the top flange. This type of construction is a widespreaded application for crane runway beams especitally for medium and heavy crane operations. However, the assessment method for lateral-torsional buckling is for this type of crane runway beam more difficult because of the simple symmetrical cross-section togehter with the the loading situation with biaxial bending and torsion. Within the scope of this article, the different possibilities for the assessment methods of lateral-torsinal buckling are shown for crane runway beams built-up by rolled profiles combined with angle sections on the top flange and are compared on the basis of a example calculation. In addition the results of a comprehensive parameter study  on the effectiveness of the different assessment methods are summarized. Copyright © 2017 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin
Vestner S.,Ingenieurburo Prof. Dauberschmidt and Vestner MbH |
Dauberschmidt C.,Hochschule Munich
Bautechnik | Year: 2014
Cathodic Protection (CP) of reinforced concrete members is an established repair method in parking buildings. Compared to a traditional repair (by removal of the chloride-contaminated concrete) this corrosion protection concept has some technical and economic advantages but also disadvantages, which have to be taken into account at the choice of the repair concept and which also have to be discussed with the client. CP is as generally accepted rule technology, even though an approval in the individual case must be obtained mostly. While there are numerous application examples and rules for the application on the surface of decks or on column and wall feet, special construction elements or points of detail are common in reinforced concrete members making a planning and application "off the peg" impossible. For some of these points of detail solutions are presented and discussed: this is on one hand protecting the rear reinforcement layer of false ceilings with separating cracks by installing the CP-system on the top of the ceiling. On the other hand is presented as columns with high static loads, which have a high degree of damage of the reinforcement, can be repaired using a combination of reinforcement addition and cathodic protection. Furthermore bar anodes can be used to protect inaccessible places. The CP of metallic installation parts have to be planned with a special attention on a proper current distribution. Here results of a sample are presented. Finally, the application of slotted anodes for the repair of underground car parks are presented. This design allows a CP repair without having to change the component dimension and applying an additional load. © Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin.
Dauberschmidt C.,Hochschule Munich |
Vestner S.,Ingenieurburo Prof. Dauberschmidt and Vestner mbH
Bautechnik | Year: 2015
Abstract Planning of underground floor slabs, special attention must be paid on the durability of the construction as a result of the severe chloride exposure. This durability has to be ensured by a thick concrete cover with a chloride dense concrete or by the application of a surface protection system. Further measures have to be taken to prevent chlorides to penetrate into cracks. These measures are specified within the existing rules and regulations. In the design of new DBV Guide to Good Practise, Design Principles are provided, from which construction alternatives can be derived. For the implementation of the Design Principles at the construction of underground floor slabs three examples are given. Copyright © 2015 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin.
Rapp S.,Hochschule Munich |
Rapp S.,Friedrich - Alexander - University, Erlangen - Nuremberg |
Heinrich G.,TU Ilmenau |
Domke M.,Vorarlberg University of Applied Sciences |
Huber H.P.,Hochschule Munich
Physics Procedia | Year: 2014
In the production process of microelectronic devices and high efficiency solar cells, local openings in thin dielectric layers are required. Instead of photolithographic, laser based processing enables to open these dielectric layers locally in a low-cost mass production step. In this work, thin silicon nitride layers deposited on planar silicon wafers are processed by single infrared Gaussian shaped 660 fs laser pulses. The transparent silicon nitride layer, becoming absorptive at fluences higher than 0.3 J/cm2, is selectively removed by confined ablation at fluences below that value. At pulse peak fluences exceeding 1.0 J/cm2 a "SiNx island" is created by direct ablation in the spot center. In this article, the selective SiNx ablation by a combination of confined and direct laser ablation at the medium pulse peak fluence of 0.5 J/cm2 is investigated. To clarify the influence of the nonlinear absorption in the pulse center, the ablation behavior is investigated by time-and space-resolved pump-probe microscopy experiments. The results show phase changes in the silicon and in the silicon nitride in the first picoseconds after excitation, the ablation onset at around 10 ps and the subsequent mechanical material motion after a few nanoseconds. The actual silicon nitride layer removal starts after around 10 ns, whereas confined ablation processes are the driving mechanisms even in the nonlinearly absorbing spot center. A comparison of the energetic ablation efficiency of the SiNx layer system to further dielectric thin films shows no detrimental influence of the nonlinear absorbance. © 2014 The Authors. Published by Elsevier B.V.
Schaeck S.,BMW AG |
Stoermer A.O.,BMW AG |
Kaiser F.,BMW AG |
Koehler L.,Hochschule Munich |
And 2 more authors.
Journal of Power Sources | Year: 2011
Micro-hybrid electric vehicles were launched by BMW in March 2007. These are equipped with brake energy regeneration (BER) and the automatic start and stop function (ASSF) of the internal combustion engine. These functions are based on common 14 V series components and lead-acid (LA) batteries. The novelty is given by the intelligent onboard energy management, which upgrades the conventional electric system to the micro-hybrid power system (MHPS). In part I of this publication the key factors for the operation of LA batteries in the MHPS are discussed. Especially for BER one is high dynamic charge acceptance (DCA) for effective boost charging. Vehicle rest time is identified as a particular negative parameter for DCA. It can be refreshed by regular fully charging at elevated charge voltage. Thus, the batteries have to be outstandingly robust against overcharge and water loss. This can be accomplished for valve-regulated lead-acid (VRLA) batteries at least if they are mounted in the trunk. ASSF goes along with frequent high-rate loads for warm cranking. The internal resistance determines the drop of the power net voltage during cranking and is preferably low for reasons of power net stability even after years of operation. Investigations have to be done with aged 90 Ah VRLA-absorbent glass mat (AGM) batteries. Battery operation at partial state-of-charge gives a higher risk of deep discharging (overdischarging). Subsequent re-charging then is likely to lead to the formation of micro-short circuits in the absorbent glass mat separator. © 2010 Elsevier B.V.
Durr A.,Hochschule Munich |
Durr A.,Hochtief Group |
Gong F.,Hochtief Group
Stahlbau | Year: 2016
Plant structures in industrial facilities can reach a height of 150 m. The towers are commonly built as a framework structure in steel or concrete. However, as an alternative, the columns of these structures can be built as composite construction. In recent years, the concrete filled steel tubes, i. e. the so-called mega composite columns, have been investigated extensively by HOCHTIEF. In this paper, two types of cross-sections, the rectangular and circular hollow-section, are explained and compared in detail from a static, structural and manufacturing point of view. Moreover, the most significant characteristics in the design and construction of mega composite columns are highlighted within this paper. © 2016 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin.
PubMed | Hochschule Munich, TU Munich, The Smith Kettlewell Eye Research Institute and Fachgebiet Computerlinguistik
Type: Journal Article | Journal: Der Ophthalmologe : Zeitschrift der Deutschen Ophthalmologischen Gesellschaft | Year: 2016
Reading performance that can be measured by reading tests depends on whether reading material with or without contextual continuity is used.The goal of this study was to create a German version of the SKread test and to evaluate it in a clinical setting.The evaluation of the SKread test was first performed on two groups of visually healthy subjects of different ages: a junior group of 25 persons with ages between 20 and 30 years (mean= 25.84 years, SD 2.41 years) and a senior group of 25 persons with ages between 51 and 84 years (mean= 62.40 8.46 years). The same measurements were also performed on a group of 18 patients with age-related macular degeneration (AMD) with ages between 75 and 95 years (mean= 81.89 5.48 years). The reading performance was also measured using Radner charts.Using reading material without syntactic continuity considerably slowed down the reading speed and increased the error rate. Median reading rates of 11.53 characters/s (CPS) for the junior group and 8.96 CPS for the senior group were clearly lower than those for the Radner charts (22.02CPS and 18.48CPS, respectively). In the AMD patients, a statistical analysis of the error rates showed a highly significant difference between the Radner charts and the SKread test (p= 0.00014). Furthermore, by analyzing the errors made in the SKread test information could be obtained about the position of central scotomas. The test-retest reliability of the SKread was very good.Information about the position of a central scotoma can be acquired by using the SKread test and an analysis of reading errors, which can augment effective clinical monitoring in AMD and subsequent visual rehabilitation.
Steinmann R.,Hochschule Munich
Betonwerk und Fertigteil-Technik/Concrete Plant and Precast Technology | Year: 2014
BIM is a method for optimized design, construction, and operation of buildings. The objective is to make decision-relevant information on processes available as early and as transparently as possible in order to recognize conflicts early and to prevent misunderstandings and incorrect decisions. The networking of information enables design trades and construction teams to work together much more closely than in the past. Integrated utilization of the BIM method, however, gives rise to new responsibilities for its users. Downstream trades must rely on the information provided by trades earlier at work. Since users employ such information directly, new responsibilities arise that must be regulated in contracts. Many successful projects carried out based on BIM show, however, that this hurdle is manageable and that economic advantages clearly dominate.
Julich F.,Hochschule Munich |
Koch A.W.,TU Munich |
Roths J.,Hochschule Munich
Technisches Messen | Year: 2012
With spreading of the fibre-Bragggrating (FBG) based sensor technology the demand for highly accurate sensors is growing. This study shows the limitation of the accuracy of standard FBG-sensors (FBGS) and an approach is presented to the development of highly accurate FBGS. FBGs inscribed into highly birefringent (HiBi) optical fibres show promising properties to reach an accuracy higher than Standard-FBG. In this study FBGs were inscribed into several HiBi-fibres and the effective refractive indices as well as the birefringence were determined. These investigations are important to establish a reproducible fabrication process for HiBi-FBGs that can be used for highly accurate fibre based measurements. © Oldenbourg Wissenschaftsverlag.