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Punching shear resistance of flat slabs with combined reinforcement utilising steel fibres and stirrups To reinforce areas subject to punching shear, punching shear reinforcement systems such as stirrups or double‐headed anchors are commonly used. An alternative is to utilise steel fibre reinforced concrete (SFRC), which can achieve a similar increase in load‐bearing capacity as stirrups. In the current German codes, a combined utilisation of SFRC and punching shear reinforcement is excluded due to a lack of experimental data to validate a design approach. On the other hand, both Model Code 2010 and Annex L of the next generation of Eurocode 2 already contain design principles that consider steel fibres and punching shear reinforcement additively. However, the suitability in terms of reliability/safety and economic efficiency has not yet been sufficiently validated due to missing experimental results. In order to close the existing gap, a total of eight large‐scale punching shear tests with combined reinforcement (stirrups, steel fibres) were carried out by the Chair of Concrete and Masonry Structures at the Technical University of Munich (TUM) following initial positive findings from preliminary tests. This paper describes and discusses in detail the setup, testing procedure and main results and findings of these experimental investigations. [ABSTRACT FROM AUTHOR]

The use of steel‐concrete composite structures with a high installation grade is becoming increasingly popular in building and industrial construction. To reduce construction height building services are routed through web openings in the girders. However, these openings represent local points of interference where, in the case of composite girders, parts of the acting shear forces are transferred from the web of the steel profile into the concrete slab. This results in additional, local stresses in the remaining steel girder and in the concrete chord, which must be considered in the design of the floor girders and shear connectors. Web openings in composite girders are not addressed in the current European design standard for steel‐concrete composite construction (EC 4). Only with the introduction of the second generation of Eurocodes in the coming years this case will be normatively regulated. During the preparation of the standard further questions about the load‐bearing behaviour arose, as the existing design approaches usually only consider a selection of possible failure scenarios or neglect essential verification steps. A joint research project between the University of Kaiserslautern‐Landau and RWTH Aachen University aims to develop a suitable design concept for composite girders with web openings. Model and beam tests accompanied by numerical simulations will provide further information on the complex local and global load‐bearing behaviour of the composite girders. This paper presents the results of experimental investigations and numerical simulations on the influence of large web openings on the global load‐bearing behaviour of the shear connectors in the composite joint. Based on 60 pull‐out tests and numerical simulations, the load‐bearing behavior of head bolt anchors under combined shear and tensile loading was researched and evaluated. [ABSTRACT FROM AUTHOR]

Harmonization in geotechnics – a consistent design method The different used design approaches of EN 1997 are based on different traditions and philosophies in the European countries regarding to the type and time of factoring actions and resistances. The resulting variety of formats for the design approaches will also be retained in the future standards generation. Therefore, the goal of a harmonized design approach with a uniform level of safety is not achieved. In this article, the so called MRFA design approach is presented which is based on the basic equations of EN 1990 providing an own partial safety factor for each parameter (actions, effect of actions, ground resistances and geotechnical parameters). To determine these partial safety factors, reliability calculations were carried out for common geotechnical structures with different boundary conditions and for different limit states in such a way that a certain probability of failure is not exceeded. The method is explained in an application example. [ABSTRACT FROM AUTHOR]

Composite dowels as shear connectors between steel profiles and concrete sections have been investigated for decades. The long‐term aim is to implement a consistent design concept within Eurocode 4 ‐ covering both, the fields of bridge and building construction. Especially in building construction, where the concrete slabs are dimensioned increasingly slimmer in contrast to bridge construction, the composite dowels are positioned unavoidably close to free concrete surfaces. This causes additional failure modes, leading to the overall failure of the structure, which have not been entirely investigated yet. At University of Kaiserslautern more than 30 push‐out tests were performed within a joint research project in cooperation with RWTH Aachen University. These tests were focused on the resistance of composite dowels close to the concrete surface in dependence of varying influence parameters. Some results showed a significant reduction in shear strength and deformation capacity, mostly accompanied by the spalling of the concrete cover. Simultaneously, numerical simulations were calibrated and utilized to get a deeper understanding of the load transfer mechanisms and to interpolate between existing experimental results. On the basis of experimental measurements and numerical simulations a load transfer model was developed with a corresponding design approach to calculate the theoretical resistance. [ABSTRACT FROM AUTHOR]

A major part of central European infrastructure buildings was designed decades ago and has different needs of strengthening. Increasing traffic volume, increasing axle loads, and a growth in transport volume as well as more restrictive design rules are the reasons why the support regions of existing bridges and flat slabs often show a lack of punching resistance today. At the University of Innsbruck, a system for subsequent strengthening by the use of concrete screws was developed. Various laboratory tests showed that the system leads to a significant increase of punching resistance with minimal efforts for its installation. This article deals with the development of a numerical model that can predict the punching loads of unstrengthened and screw‐strengthened punching plates. Further the punching loads from the laboratory tests and the simulations are compared to the predictions of a design approach. The presented novel design approach is an advancement of the existing Eurocode 2 provisions and allows the influence of the screws on the punching resistance to be taken into account. The comparison shows that the numerical model predicts the punching resistances in an appropriate way and the design approach predicts them on the safe side. The presented design approach was included into the technical assessment for the concrete screws of the system reLAST as post‐installed punching reinforcement system [Z‐15.1‐340 (2019)] in order to be applicable in practice. [ABSTRACT FROM AUTHOR]

In a conventional wall frame system, shear walls typically exhibit less deformation capacity under earthquakes than the frame. In this study, an innovative prefabricated slotted composite shear wall was proposed, abbreviated as CDSW. Featured with concrete‐filled‐tube (CFT) wall segments, I‐shaped steel connectors, vertical slots and bolted connections with the frame, the CDSW has significantly improved deformation capacity, energy dissipation capacity and construction efficiency compared with conventional shear walls. Its seismic behaviors were investigated through applying quasi‐static cyclic loads, where the specimen exhibited satisfactory cyclic response. Based on the test results, finite element analysis (FEA) models were established to validate the test results, and 12 parametric FEA cases were conducted to optimize the parameters of CDSWs. A new design method of a CDSW with highly accurate formulas was proposed based on a new parameter termed as equivalent stiffness ratio (ESR). With ESR, the stiffness and internal force of a CDSW can be obtained with satisfactory precision. Based on the analytical result and the new design formulas, it can be concluded that the ESR between 0.706 and 1.25 is recommended for practical engineering applications, which took into consideration the governing factors of yield and peak strength, stiffness, deformation capacity and energy dissipation. Additionally, the installation of the upper and lower sets of connectors at about 40% and 60% of the height of CDSW is suggested, respectively. [ABSTRACT FROM AUTHOR]

In Austria, the Guideline for "Technical Protection against Rockfall", named ONR 24810 provides guidance to assess rockfall hazard (at object scale) by determining a so‐called design block size. The aim of this article is to critically review the concept of design block size and to suggest alternatives. The design block size is derived from a block size distribution and event frequency, both of which may be very uncertain. Modelling a single "constant" design block may result in trajectories far away from reality. The design approaches of ONR 24810 and Eurocode 7 are compared. A case study is presented and discussed. Reducing input parameters at the beginning of the design approach results in apparent characteristic energy levels and bounce heights, which are not characteristic, as defined by EC7. By disregarding all small and the biggest blocks, valuable information of maximum energy levels and bounce heights is lost. The entire block size distribution should be used for rockfall simulations, rather than a single block size. Fragmentation should be considered, if applicable. [ABSTRACT FROM AUTHOR]

Post‐strengthening with concrete screws – Numerical investigations and comparison with a design approach's results A strengthening system using concrete screws as a post‐installed punching reinforcement was developed at the University of Innsbruck. The system leads to a significant increase in the punching resistance. Compared to the demands of current standards especially the support regions of existing bridges and slabs often show a lack of punching shear resistance. The effectiveness and efficiency of the new strengthening system were investigated in four series of laboratory tests. The tests showed that the installation of the system leads to a significant increase of the punching resistance. This contribution deals with the development of a numerical model that can predict the punching loads of screw‐strengthened plates. The modelling of the laboratory tests shows that this model is able to predict the punching load of unstrengthened plates as well as of screw‐strengthened plates in an appropriate way. The punching loads from the laboratory tests and the simulations are compared to the predictions of a design approach. This approach allows to take the screws influence on the punching resistance into account of calculations. The recalculations of the tests show that the design approach predicts the punching resistances on the safe side. [ABSTRACT FROM AUTHOR]

Large aperture sparse array has the ability of mainlobe interference suppression. However, sparse array causes grating lobe problem. If the array is steering at the target and the mainlobe interference is located at the grating lobe, the adaptive filter will produce a grating lobe zero phenomenon that severely reduce the target energy. This study proposes a design approach of large aperture sparse array for mainlobe interference cancellation. By properly designing the number of auxiliary receiving antennas, the baseline of the large aperture sparse array, the aperture of auxiliary receiving antennas, the position of auxiliary receiving antennas and carrier frequency of radar transmitting signal, the grating lobes can be suppressed effectively, thus decreasing the system complexity and cost while cancelling the mainlobe interference. Simulations and field experiments have illustrated the effectiveness of the proposed design approach. [ABSTRACT FROM AUTHOR]

This paper proposed a design approach for piezoelectric-transformer-based power supplies. Initially, an analytical approach is used to derive the Mason equivalent circuit parameters of a PT. This is coupled with a semi-automated procedure to decide the appropriate physical dimensions of the PT. The procedure is applied to a typical low-power power supply specification, whereupon a specific transformer is design, verified using COMSOL and used as a simulated converter in SPICE. Results show that the design can be successfully implemented while maintaining efficient zero-voltage switching operation. [ABSTRACT FROM AUTHOR]

Abstract: Investigations on the load bearing behavior of composite dowels positioned close to the free concrete surface. Composite dowels are an economic alternative to headed studs with various advantages. Modern concrete slabs are dimensioned increasingly thinner and often include several additional functions, for example air conditioning or thermal activation of concrete surfaces. For those applications composite dowels can be positioned horizontally in the concrete slab. Existing investigations on composite dowels describe different failure modes of composite structures such as splitting of the concrete, local compression of the concrete, pry‐out of a concrete cone or plasticizing of the steel teeth. At University of Kaiserslautern composite dowels with positions close to the free surface of the concrete slab were investigated experimentally by push‐out‐tests and on the basis of numerical simulations. In addition, the positive influence of a spiral reinforcement between the steel teeth was analyzed. Further primary and secondary failure mechanisms were observed for this specific position of the composite dowels. These investigations and a design approach will be presented within the paper. [ABSTRACT FROM AUTHOR]

Abstract: Introduction of the Direct Strength Method into the design of cold formed steel members according to EN 1993‐1‐3. Cold formed steel members have a varied area of applications in steel lightweight constructions but are subject to local and global instabilities due to compressive and bending stress. The design method of the European Standard EN 1993‐1‐3 is based on the Method of Effective Widths covering local and distortional buckling. Unfortunately, an EN 1993‐1‐3 design is time‐consuming and prone to errors, furthermore the results are often conservative. This paper is going to introduce a new, practical design method for cold‐formed steel sections that combines the established European regulations of global instabilities with the Direct Strength Method (DSM) described in the North American standard AISI Standard 100 regarding local stability analysis. Based on comparative studies of mono‐symmetric cross‐sections it is possible to demonstrate that this new method offers a great potential of improving the design of cold‐formed sections, additionally improves the economic efficiency of lightweight steel sections. More theoretical and experimental investigations are needed, deeper leading questions are to answer, until this method is able to supplement the European standard. [ABSTRACT FROM AUTHOR]

Customer experience (CX) is a differentiation strategy often chosen by companies. But several aspects can hinder the realization of this strategic change: Existing routines, strong silo thinking among departments, and other circumstances work against the creation of a holistic CX. There is very little guidance in the literature about becoming more customer centric in practice. Within design practice, customer‐centric thinking and working are key aspects. Therefore, this article addresses the question of how a design approach can facilitate a company's change process from the abstract strategic direction of focusing on CX to a way of working in practice. The article is based on a practice‐led case study of an airline company where the first author worked from within the company to test solutions directly in daily practice. We conclude that in order to move from the strategic direction of a CX focus to an applicable proposal, designers can support both top‐down and bottom‐up processes. A trial‐and‐error approach and boundary objects can be useful in finding emotional triggers for employees to reflect about their own roles. [ABSTRACT FROM AUTHOR]

This paper presents a design approach for seismic rehabilitation of frames having a beam-collapse mechanism using a technique termed minimal-disturbance seismic rehabilitation. This technique pursues enhancing the seismic performance of buildings with the intention of improving the continuity of business. It minimizes obstruction of the visual and physical space of building users and the use of heavy construction equipment and work requiring fire permit (welding/cutting). The developed design approach is simple to use. Yet it leads to designs that limit the beams' plastic rotations to allowable values, while minimizing the number of locations where devices are installed and the devise dimensions. Furthermore, the effectiveness of the design approach and the rehabilitation technique is numerically studied through retrofitting a four-story steel moment-resisting frame. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

On the load bearing behavior of the self-regulating interactive membrane foundation system The paper reports on a new foundation system, the self-regulating membrane foundation, for embankments on deep soft soil deposits, such as stockpiles or infrastructure embankments. The load bearing behavior of the system was analyzed by means of centrifuge model tests and comprehensive numerical simulations, such as global sensitivity analyses and parametric studies. The results of those analyses and the derived design approach are presented in the paper. The paper concludes with a validation of the design approach, by comparison with results of the numerical simulation. [ABSTRACT FROM AUTHOR]

Flat band slow light is achieved in a silicon photonic crystal waveguide with large normalised delay bandwidth product (NDBP) while maintaining smaller values of group velocity dispersion. By altering the waveguide width through shifting the position of two rows of air holes adjacent to the waveguide, it is possible to achieve a high NDBP value. The NDBP values of 0.40, 0.41 and 0.43 over bandwidths of 11, 14 and 18 nm are, respectively, reported. Towards the applicability of the proposed slow light waveguide for buffering applications on silicon, buffering capacity as high as 140 bits can be achieved with the proposed design approach.z [ABSTRACT FROM AUTHOR]

The 9 km long Chenani-Nashri Tunnel, currently under construction, is the longest road tunnel in India and is part of the planned four-lane widening of the NH-1A between Udhampur and Banihal in the state of Jammu and Kashmir. Bypassing the existing NH-1A from km 89 to km 130, the tunnel crosses a sub-Himalayan formation with a maximum overburden of 1,050 m. With an escape tunnel running parallel to the main tunnel, excavation is performed by Leighton-Welspun Contractors using the drill and blast method. Geodata Engineering (GDE) is providing consultancy services for detailed design and construction supervision including 3D-geotechnical monitoring. Back-analyses of already-excavated sections are performed to better understand the behaviour of the heterogeneous rock mass in which the tunnels are excavated. The numerical models are fed with the actual geological and geomechanical conditions encountered during excavation and the monitoring results. The 3D-monitoring system, specially implemented by GDE for this project, has played a key role in understanding the real rock mass behaviour, allowing the highlighting of potential risks, selecting the correct tunnel support class, checking of the effectiveness of countermeasures, identification of the tunnel stretches in which the final lining needs to be reinforced and providing cost-effective solutions to speed-up the construction process. [ABSTRACT FROM AUTHOR]

The Second Avenue Subway Project is a major capital expansion project of the New York City subway that will provide a dedicated line for the east side of Manhattan. The project is approximately 13.7 km long including 16 stations, and its estimated cost is about 17 billion US-$. Under the current design of the whole subway route, ten stations will be cut-and-cover and six mined caverns. The excavated diameter of the bored tunnels is 6.6 m and the caverns span ranges from 12 to 21 m. As the geology of Manhattan varies along its length, the subway will pass through both hard rock and soft ground and there will be multiple rock/soil interfaces along the alignment. This paper presents details of planning, design and construction of the first phase of Second Avenue Subway in the very dense urban environment of Manhattan. Der Bau der Second Avenue Subway ist ein wichtiges Erweiterungsprojekt der New York City Subway und wird eine Linie für die östliche Seite Manhattans bereitstellen. Das Projekt ist ungefähr 13,7 km lang und beinhaltet 16 Haltestellen. Die geschätzten Kosten liegen bei etwa 17 Mrd. US-$. Nach aktuellem Entwurf der Gesamtstrecke der Erweiterung sind zehn Haltestellen in offener Bauweise und sechs bergmännisch ausgebrochene Kavernen herzustellen. Der Ausbruchdurchmesser der maschinell aufgefahrenen Tunnel beträgt 6,6 m und die Spannweiten der Kavernen zwischen 12 m und 21 m. Da die Geologie Manhattans sich entlang der Trasse ändert, durchquert die Subway sowohl Hartgestein als auch weichen Untergrund. Außerdem gibt es zahlreiche Fels/Boden-Übergangsstellen entlang der Trassierung. Dieser Beitrag stellt Einzelheiten der Planung, des Entwurfs und des Baus der ersten Phase der Second Avenue Subway in der sehr dichten städtischen Umgebung Manhattans dar. [ABSTRACT FROM AUTHOR]

Copyright of Geomechanik und Tunnelbau is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geomechanik und Tunnelbau is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geomechanik und Tunnelbau is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Design approach of wideband envelope termination (ET) for high efficiency RF power amplifiers (PAs) is discussed, considering power loss subject to design constraints including envelope bandwidth, inductor quality factor, and transistor output impedance. Analysis shows that the optimum ET topology depends on the design constraints. For LTE‐advanced transmission with 80 MHz channel bandwidth, a novel wideband ET is designed using an AC‐terminated third‐order LC filter (LCF‐ET), providing 3 dB envelope impedance bandwidth of 150 MHz. Measured results demonstrate 1.75 dB envelope power loss and −39.2 dB normalised root‐mean‐square error with the LTE envelope signals. For the LTE signal with 10.3 dB peak‐to‐average power ratio, the average power efficiency of an ideal Class‐A RF PA with the LCF‐ET prototype is calculated as 33.4% from the measured 1.75 dB envelope power loss, which exceeds 4.7% and 24.0% average power efficiency of conventional Class‐A and Class‐B PAs without ET. [ABSTRACT FROM AUTHOR]

A new methodology is reported for designing functional observers to detect actuator faults of a class of time‐delay systems where the matrix pair (A, C) is not observable. First, a generalised state transformation is used to transform the system into new coordinates where the delay term associated with the state vector is injected into the system's output and input. Then, a minimum‐order functional observer is designed to construct a residual function that can trigger system faults. The finding is significant as it is now possible to detect faults of time‐delay systems where the pair (A, C) is not required to be observable. A numerical example is given to illustrate the effectiveness of the proposed design approach. [ABSTRACT FROM AUTHOR]