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The eccentricity charts presented in this paper have been developed on the basis of experimental investigations in order to enable a realistic calculation method of the ultimate load of flat brickwork vaulted floors with standard structural software. The vault is modelled as a three-hinged arch with eccentric hinges in order to thus represent the non-linear behaviour of the load-bearing structure. Furthermore the hinge configuration, which is adapted with the eccentricity charts, takes into account the degree of plastification of historic masonry, existing load-induced damage, any displacement of the abutments and the location of the thrust line.
Two examples are described to explain the applicability of this method, and the results are compared with results from other modelling approaches. This makes clear that the eccentricity charts enable realistic structural analysis of flat brickwork vaults with various geometries and with highly efficient use of time.

Preloaded bolts are used to achieve slip-resistant shear connections. The actual preload force in each bolt has a direct influence on the fatigue and slip resistance of the connection. The strain gauge method is examined for practical assessment of the actual preload because its use is no longer limited by the demands on adhesive curing conditions. The main objective of the paper is to describe how measured strain in the bolt shank and statistical variation of the nominal mechanical and geometrical properties of the bolt are used to determine the actual bolt preload without calibrating every single bolt. The calibration factors established by laboratory and in situ measurements exhibit rather small scatter. The minimum bolt preload required is achieved with a 95 % probability of being exceeded in a bolted connection on a Dutch highway bridge (Middachterbrug).

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Masonry is a building material primarily suited for building structures under compressive load and therefore it is mainly used for vertical load transfer. The decisive characteristic to assess the load bearing capacity of such building members is their compressive strength. It can either be derived experimentally from compression tests on wall specimens or by calculation. In this paper, firstly the current procedure in the derivation of compressive strength values based on experimental compression tests is described. Furthermore, empirical approaches and theoretical models for determining the masonry compressive strength, which have been developed in the past, are presented.

EN 13791 applies when assessing the in situ compressive strength of structures and precast concrete components. According to the code itself, it may be adopted when doubt arises about the compressive strength of a concrete. For assessing the structural safety of existing structures, however, the method given in EN 13791 does not seem to be applicable and may lead to an unsafe approach for determining the characteristic concrete strength. This paper presents an alternative method for determining the characteristic concrete strength from cylinders obtained in situ. The method proposed is based on EN 1990 (Eurocode basis of design) and the corresponding Annex D. The method according to EN 13791 is outlined in this article. Moreover, the practical implementation of the method in accordance with clause 5.2 of EN 1990 is explained and an example is given. Finally, both methods are compared with each other. It is demonstrated that EN 13791 does not apply to safety assessments of existing concrete structures and the use of this code may lead to unsafe situations.

The evaluation of the abrasiveness of soil is not unified or standardised at the moment. Mostly used are complex index processes with greatly simplified model bodies and simplified test conditions such as the LCPC abrasimeter test. These processes can however at best measure the efficiency of the wear mechanism and are not capable of reflecting the strength of the bonding of the internal fabric, an essential factor determining the level of operational demands, i.e. the resistance to excavation. These index processes therefore offer no advantages over evaluation processes based on conventional soil mechanics parameters. Quite the opposite, these mostly prototype tests imply new problems that are inevitable with the testing methods. The paper thus presents at the end an extended method of evaluating wear to excavation tools and the conveyance or transport of excavated spoil.
Die Beurteilung der Abrasivität von Lockergesteinen ist bis heute nicht vereinheitlicht oder normiert. Verbreitet sind vor allem komplexe Indexverfahren mit stark vereinfachten Modellkörpern und vereinfachten Versuchsrahmenbedingungen wie z.B. der Drehflügelversuch LCPC. Diese Verfahren können aber allenfalls die Wirksamkeit des Verschleißmechanismus abbilden und sind nicht in der Lage, die Festigkeit des Gefügeverbands als maßgeblichen Einflussfaktor auf die Größe der Beanspruchung, d.h. den Abbauwiderstand zu erfassen. Derartige Indexverfahren besitzen daher keine Vorteile gegenüber Bewertungsverfahren, die auf herkömmlichen, bodenmechanischen Kennwerten beruhen. Ganz im Gegenteil implizieren diese, meist prototypartigen Versuche neue, versuchsspezifische Probleme. Der Beitrag stellt daher abschließend einen erweiterten Bewertungsansatz zur Verschleißbewertung von Abbauwerkzeugen sowie der Abförderung bzw. dem Abtransport von gelöstem Abbaugut vor.

Both the technical boundary conditions and the usual advance rates achieved during hard rock TBM shield drives severely limit the ability of the on-site-personnel to document the geological conditions and the system behaviour at appropriate intervals. A systematic and continuous short-term investigation of the rock mass conditions is performed on the construction lot KAT2 of the Koralm Tunnel (obtained by impact drillings and geophysical methods). The difference in scales and the fact that no continuous inspection of the ground conditions can be performed lead to a gap between the prognosis and the observed behaviour and a direct comparison is seldom possible.
Based on the daily comparison between the observed behaviour and the analysed machine data, a state-of-the-art interpretation method has been developed. This method allows reliable conclusions regarding the primary aspects of the system behaviour and thus enables deductions on the geological/geotechnical conditions which have been encountered. The identification of the relevant parameters and suitable analysis methods has been performed in a “trial and error” manner: machine parameters deemed relevant in theory have been continuously compared with the observations on site and depending on the results, found usable or discarded.
Reliable knowledge about the face stability, qualitative degree of fracturing of the rock mass, occurrence of over excavation in the cutter head area, the state of the annular gap and the blockiness of the rock mass can be deduced by applying this method. The results are used on daily basis by the on-site geologist and geotechnical engineer in order to verify the prognosis and recommend additional/auxiliary construction measures.
Sowohl die technischen Rahmenbedingungen als auch die üblichen Vortriebsgeschwindigkeiten einer Tunnelvortriebsmaschine mit Schild (TVM-S oder TVM-DS) im Hartgestein beschränken die Fähigkeit des verantwortlichen Personals, die geologisch-geotechnischen Verhältnisse bzw. das Systemverhalten anhand der augenscheinlichen Inspektion und der geotechnischen Messdaten zu erfassen. Da am Baulos KAT2 des Koralmtunnels eine systematische und lückenlose Vorauserkundung betrieben wird, entsteht dadurch eine “Lücke” zwischen der Prognose (anhand der Bohrungen und/oder der geophysikalischen Methoden) und den beobachteten Verhältnissen.
Auf Grundlage bestehender Veröffentlichungen konnten für die täglichen Vergleiche zwischen dem beobachteten Systemverhalten und den analysierten Maschinendaten im Zuge des kontinuierlichen Vortriebs KAT2 ein Verfahren entwickelt werden, das zuverlässige Aussagen über die wesentlichen Aspekte des Systemverhaltens beim kontinuierlichen Vortrieb erlaubt und somit Rückschlüsse hinsichtlich der aufgefahrenen geologisch-geotechnischen Verhältnisse ermöglicht. Die Identifikation der relevanten Parameter und der Auswerteverfahren erfolgte im “Trial-and-error”-Verfahren: Alle theoretisch relevant erscheinenden Maschinenparameter wurden mit den Beobachtungen vor Ort verglichen und in den endgültigen Satz von aussagekräftigen Parametern aufgenommen bzw. als unbrauchbar verworfen.
Zuverlässige Aussagen über die Ortsbruststabilität, den qualitativen Zerlegungsgrad, die Profilmaßhaltigkeit im Bohrkopfbereich, den Zustand des Ringspalts und die Blockigkeit des Gebirges können mit diesem Verfahren getroffen werden. Die Ergebnisse werden täglich von den verantwortlichen Geologen und Geotechnikern verwendet, um die Prognosen zu verifizieren, das Prognosemodell stetig fortzuschreiben und zu verfeinern und nach Erfordernis Zusatz- bzw. Sondermaßnahmen zu empfehlen.

Partial safety factors for resistance applied in the design equation of semi-probabilistic formats can be obtained from the evaluation of a test database. These partial safety factors are influenced by two factors, the material uncertainty and the model uncertainty. This topic is covered in a former publication [1]. It includes the determination of a partial factor for the model uncertainty of unreinforced masonry shear walls. In this study the authors examine the next step, and calculate the partial factor of resistance applying the same method, as recommended in EN 1990 - Annex D. In addition to the Coefficient of Variation (COV) for the model uncertainty, the calculation of the resistance partial factor considers deviations in geometry, as well as loading and material properties. The influence of the material uncertainty on structural performance is considered in the calculation by means of a weighted average of all COV values for various types of material properties, based on the number of relevant failure modes in the test database. In the last step, the resistance partial factors for models defined in DIN EN 1996-1-1/NA and DIN EN 1996-1-1/NA - Annex K are calculated by applying the probabilistic methods recommended in EN 1990 - Annex D and the model bias.

Experiments in structural engineering can play an important role in the prediction and characterization of the material properties and behaviour of structural components. In order to cover all aspects in tests and use the results for design purposes, several methods have been included in EN 1990 Annex D for design based on test data. The calculation of characteristic values and design values for material resistance are the main aspects. In this study, the recommended methods in Annex D of EN 1990 for resistance of the material will be used to extract the partial safety factors for masonry structures based on the formulation of design and characteristic values. A database including more than 100 tests on unreinforced masonry shear walls will be used to evaluate the results. The resistance model for shear walls based on the recommendation in the Eurocode will be compared with the test results. The main aim will be to compare the model prediction and the test results. Deviation of the prediction from the test is caused by model error or model uncertainty. The test database includes results for three types of masonry units - fired clay, calcium silicate and autoclaved aerated concrete. The evaluation of partial factors for masonry shear models will be undertaken based on the scatter and the model bias for the whole database. Further analysis will also be performed for each type of masonry unit for classification of the outcome.

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The design/verification method in the Eurocodes is based on the partial safety concept. Eurocode 6 suggests a constant partial safety factor for the material &ggr;M for all design/verification problems, without consideration of model uncertainty in the design/verification formula. In the following, a model partial safety factor is determined for the problem of unreinforced masonry walls mainly subjected to vertical loading. For that purpose, the newly proposed formula for EC 6, annex G will be considered [1-3]. In order to cover all aspects in tests and to use the results for design purposes, several methods have been included in EN 1990 Annex D for design based on test data. In this study, the recommended methods in Annex D of EN 1990 for resistance of the material are used to extract the partial safety factors. A database including more than 119 experimental tests on unreinforced masonry shear walls is used to compare the model prediction and the test results and to determine the model partial safety factor.

The paper presents the damage model of German Research Unit 537 which was used as a working hypothesis for the development of a user-friendly design model. Excerpts from the laboratory experiments and numerical calculations processed in project A of the research unit are presented here. The excerpts include the quantification of self-corrosion, geometrical effects in the macrocell corrosion, development of corroding steel surface and pit depth as well as the quantification of the resistivity of the concrete and the corrosion of steel in cracked concrete.