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How safe are our structures? – Conceptual paper of the DGGT Working Group 2.15 "Reliability‐Based Methods in Geotechnical Engineering" The future Eurocode 7 will explicitly allow the use of reliability‐based methods in geotechnical planning and design. In Germany, there is hardly any experience in the practical application of such methods so far and thus the reservations towards these methods are plenty. The new DGGT Working Group (WG) 2.15 "Reliability‐Based Methods in Geotechnical Engineering" has set itself the goal of providing a practical access to those methods by means of practice‐oriented instructions and recommendations as well as accompanying training and further education courses. The aim is to clarify the possibilities and limitations and, above all, to exploit their potential. This article presents the general principles as well as the future fields of work of the WG 2.15. Starting with the introduction of relevant technical terms, the implementation of reliability‐based methods within the current codes of practice and regulations is shown. Using the life cycle of a geotechnical structure, the uncertainties in geotechnical designs and assessments are described. Subsequently it is outlined, in which situations and to what extend reliability‐based methods can aid engineers, clients and inspectors in verification and decision‐making processes. In the future, WG 2.15 will develop recommendations on individual topics and publish them successively. [ABSTRACT FROM AUTHOR]

Hydraulic heave in round excavation pits with relief boreholes – calculation approach The use of relief boreholes to reduce the effect of a vertical upward flow has proven to be a constructive measure to avoid the risk of hydraulic heave in excavation pits in groundwater. The applicable standards and regulations, however, only provide general information on the use of relief boreholes. A concept for the verification against hydraulic heave failure using relief boreholes is missing as well as defined information on the arrangement of the relief boreholes and the influence of the excavation geometry. Therefore, the aim of the research work at the Chair of Geotechnical Engineering of RWTH Aachen University was to develop a concept for the proof against hydraulic heave failure with the arrangement of relief boreholes. The result was a calculation approach that determines the decisive fracture body under consideration of the flow conditions due to the relief boreholes. This fracture body can then be used for the proof against hydraulic heave failure. Based on this, dimensioning diagrams were finally generated for typical excavation pit geometries in dimensionless representation. [ABSTRACT FROM AUTHOR]

New definition and measurement of the boundary layer thickness on a wall – Determination of thermodynamic and aerodynamic quantities This publication describes the theoretical basis and a measuring device to measure the convective heat transfer coefficient and the shear stress on a wall exposed to the flow. For this purpose, the Convective Heat Transfer Meter (CHM) measures the temperature gradient within the flow boundary layer. For exponential time processes, the time constant τ is defined as the period of time after which a quantity A(t) has declined to a fraction of 1/e of the initial value, with the Eulerian number being 2.718... Analogous to this, the boundary layer thickness d is proposed for spatial processes with exponential approximation instead of the time constant τ. Such a process occurs in the viscous boundary layer area of a wall exposed to flow. The flow velocity U(y) running parallel to the wall surface is decelerated due to the viscosity of the air and the friction of the wall surface until it reaches the condition of adhesion to the wall surface. The newly defined boundary layer thickness d is the distance from the wall y = d for which the local flow velocity U(y=d) has reached the fraction of (1–e–1) from the macroscopic flow velocity U(y=∞). In contrast to the frequently used boundary layer thickness δ, for which the threshold is by definition 99 % of U(y=∞), the new definition of the boundary layer thickness d offers advantages in terms of its measurability and the determination of the convective heat transfer and the determination of the shear stress on bodies in contact with the flow. [ABSTRACT FROM AUTHOR]

Validation of the AVISA model Despite advanced design technologies, construction on cohesive soils is still a challenge. Especially when dealing with cyclic loading conditions combined with the time‐dependent behavior of cohesive soils, such as offshore structures or even dams, the tools to predict the long‐term deformations of fine‐grained soil are limited. Due to the complex influence of loading rate, preloading, and soil structure, it is necessary to understand the effects of these influences on cohesive materials through laboratory testing and describe them numerically through accurate and physically based constitutive equations. Researchers (continue to) develop many hundreds of material models each year. Most of them are used for PhDs and not investigated further. In this work, such a model, developed in the first author's PhD, is be validated. The performance of the AVISA model has been previously demonstrated on experiments of various fine‐grained soils. In this paper, a new experimental study on Malaysia Kaolin is used for the validation of the model. Furthermore, the reproducibility of the so‐called Krey and Tiedemann criteria, parameters φ′s , c′ und φ′ is investigated by simulations of simple shear tests. It should be noted that many constitutive models for fine‐grained soils fail in this task. [ABSTRACT FROM AUTHOR]

Steel tube struts in braced excavations – Simplified design for cross section class 4 Steel tubes are often used as excavation struts. When designing long struts without intermediate supports, tubes with large diameter and small wall thickness are particularly economical. This may lead to reaching the limit of cross section class 4 requiring a shell buckling analysis according to EN 1993‐1‐6. In this article a simplified design method using section‐related buckling stresses based on EN 1993‐1‐6 Annex D is described. Ready‐to‐use section‐related buckling stresses are given for commonly used steel tubes of cross section class 4. [ABSTRACT FROM AUTHOR]

Summary: Concrete‐filled stainless steel tube (CFSST) members combine the advantages of stainless steel materials and concrete‐filled steel tube (CFST) members. Therefore, it has a broad range of applications than CFST members in the marine environment and other scenarios requiring great durability and corrosion resistance. However, there are limited researches on the large‐sized CFSST members. In this paper, 30 circular CFSST members with varying steel ratios (3.7% ≤ α ≤ 10.3%), diameters (500 mm ≤ D ≤ 900 mm), and strength of concrete (fcu = 40 MPa, 50 MPa) are studied on the size effect under axial compression. For peak axial stress, peak axial strain, and composite elastic modulus, size effects are investigated. According to the results, the peak axial stress and peak axial strain of the members increase with the increase in diameter. The modulus of composite elasticity essentially stays constant as the diameter increases, showing that there is no obvious size effect on the composite elastic modulus. The size effect of peak axial stress and peak axial strain is influenced by the steel ratio. Increasing the steel ratio tended to decrease the size effect. According to the generated data, it was found that the current codes of Chinese and European underestimate the ultimate bearing capacity of CFSST short columns significantly. To this end, the resistances of the large‐sized austenitic CFSST columns with a low steel ratio are well predicted by the proposed design model after being modified, based on GB 50936‐2014 and EN 1994‐1‐1 design codes. [ABSTRACT FROM AUTHOR]

Failure criteria for foam‐grouted gravel under multiaxial loading Foam grouting is an innovative method for improving the mechanical properties of cohesionless, coarse‐grained soils. Despite this, only a few experimental studies have been conducted to assess the failure of foam‐injected soils under multiaxial loading. This paper aims to fill this gap in knowledge. The stiffness and strength of the natural soil, which serve as reference values for the evaluation of the improvement effect due to the injection, are derived from drained triaxial tests. The mechanical behaviour of the foam‐injected soil is investigated using uniaxial, triaxial, and splitting tensile tests. The foam‐injected soil, exhibits significantly higher strength and stiffness but lower ductility than the untreated soil. The ductility of the foam‐injected soil increases with increasing lateral pressure. The splitting tensile strength is only a small fraction of the compressive strength. The adequacy of the failure criteria Mohr‐Coulomb, Hoek‐Brown and Lade for the description of the failure of foam‐injected coarse‐grained soils is verified. All three failure criteria are basically suitable to describe the state of failure in triaxial compression. For compressive and tensile loading, the Hoek‐Brown and Lade failure criteria seem to be more appropriate compared to Mohr‐Coulomb. [ABSTRACT FROM AUTHOR]

Simple and fast dynamic model for the prediction of PV self‐consumption The widespread use of renewable energy plays a crucial role in increasing the energy efficiency of the building stock. The significantly decreased PV system prices and the high flexibility in electricity use for all loads in a building, i.e., space heating (and cooling) and domestic hot water in combination with heat pumps, auxiliary energies, household appliances, and also increasingly electric mobility leads to a wide use of PV. However, the integration of PV into the building is complex and requires the use of electrical and/or thermal energy storage and appropriate control strategies. Therefore, evaluating and optimizing the part of PV electricity that is used directly or stored in the building is a challenging task. Thus, for a detailed analysis of PV and energy storage at the building level, extensive building and system simulations were performed using reference buildings. [ABSTRACT FROM AUTHOR]

The room‐side heat transfer of a building is essential for calculating and simulating heat loss through radiation and convection in interior spaces, and also for preventing mould growth and condensation. By means of Computational Fluid Dynamics (CFD) simulations, this study investigates the effect of floor heating, mixing ventilation, furniture, room geometry, and their combinations on the interior heat transfer coefficient (HTC) of a typical office room. The results show an inhomogeneous distribution of the HTC on the exterior walls. HTC values are generally below the German standardised value for thermal protection, which means an overestimation of the heat loss when the standardised value is applied. However, compared to the standardised value for preventing mould growth, the minimum surface‐averaged HTC behind closets is 63 % lower, potentially leading to mould growth and condensation. [ABSTRACT FROM AUTHOR]

Building Performance Simulation at RWTH Aachen University – Series: Building simulation and calculation tools in teaching This series of articles presents the use of computer programs in university teaching of building physics and building technology for architects and civil engineers. Since 2013, the subject "Building Performance Simulation" has been offered at RWTH Aachen University at the Institute of Energy Efficiency and Sustainable Building E3D. The target group is the core courses "Civil Engineering", "Environmental Engineering" and Business Administration and Engineering: Civil Engineering in the Master's program at the Faculty of Civil Engineering. The aim of the current course is to teach the students the theoretical and practical basics of building performance simulation. For this purpose, the theoretical basics are prepared in a modular way and presented in detail in the lecture. In the exercise, the basics of programming are taught or refreshed. Subsequently, modular subcomponents for a simulation are implemented in the Modelica language. This enables the students to progress through the complex collection of topics in an appropriate manner and to deal in depth with topics that would certainly be neglected in a purely application‐oriented view of an existing building simulation program. [ABSTRACT FROM AUTHOR]

Development of a model to evaluate the environmental properties of common outdoor plasters and mortars A requirement of the Construction Products Regulation (CPR) in the European Union states that construction materials and works must be designed in a way that throughout their entire life cycle, they have no exceedingly high negative impact on the environment. The objective of the current work was to develop a model capable to evaluate the environmental properties of outdoor plasters and mortars. Therefore, the extensive database recollected during 10 years of field and laboratory experiments by Fraunhofer IBP for these products was used as a basis and for validation, respectively. A three‐stage model was set up. In "Level 1", runoff volumes are calculated for a specific façade. In "Level 2", leached inorganic substances and their concentrations in runoff water are identified. As a final step, the evaluation of the environmental risk of stormwater runoff from façades covered with plasters and mortars takes place in "Level 3" using a groundwater risk assessment including leachate prognosis. It could be shown that vanadium, chromium and lead can be leached from mineral plasters and mortars during rain events in relevant concentrations. However, the evaluation showed that within usual application scenarios threshold values at a defined point of compliance are not expected to be exceeded. [ABSTRACT FROM AUTHOR]

Harmonization in Geotechnics – a statistical method to determine representative values for ground properties considering prior knowledge In the revised version of Eurocode 7 (prEN 1997‐1:2021‐11), the value for the geotechnical parameter to be applied in the design will in future be referred to as the representative value, which can be derived from the characteristic or nominal value. While the nominal value is determined using conventional estimation methods, the characteristic value is determined using statistical methods. For this purpose, an applicable statistical method is recommended in prEN1997‐1:2021‐11. In this article, a statistical method is explained that fulfils all requirements according to prEN 1997‐1:2021‐11 and also allows the possibility of taking into account prior information. Compared to the statistical method in prEN 1997‐1:2021‐11, the new method is to be considered more robust, as shown in application examples. [ABSTRACT FROM AUTHOR]

For the numerical calculation of the stability of structures in soil The use of the finite element method (FEM) for the design and recalculation of geotechnical structures is steadily increasing. For both slopes and retaining walls, the advantages of the FEM are already used for accurate determination of the deformations and stresses of structures in the serviceability limit state (SLS). The application in the ultimate limit state (ULS) is currently still a research topic for structures with soil‐structure interaction, such as retaining walls. An extended strength reduction, where component strength is reduced in addition to the shear parameters of the soil, is intended to account for the influence of the structure in ULS‐simulations. In addition to the component strength, other parameters, such as the external load‐bearing capacity of anchors or the contact friction between soil and component, play a role for determination of the governing failure mechanism. Using a Python script, the strength reduction approach implemented in PLAXIS 2D is re‐implemented and verified exemplarily on a braced excavation pit and a tie‐back quay wall. By extending the own strength reduction implementation with additional parameters, which are relevant for the stability of geotechnical structures, their influence on the stability calculation and the resulting failure mechanisms is investigated. [ABSTRACT FROM AUTHOR]

On the application of earth resistance models of p‐y curves and DIN 4085 for the design of laterally loaded piles in layered soils The design of laterally loaded piles in Germany is based on a simplified subgrade reaction modulus or the method by Blum. With these methods the lateral pile deflection cannot be calculated very accurately. Internationally the so‐called p‐y approach is widely used, which is based on nonlinear spring stiffnesses to define the subgrade reaction modulus. In this paper the p‐y approach is described in detail and the application of each calculation model is discussed. For the consideration of the effect from multi‐layered soils the approach by Georgiadis is used. The earth resistance determined by this procedure is then compared with the spatial earth resistance from DIN 4085. Because DIN 4085 just offers equations for homogenous soils, the relevant equations are extended for layered soils. In a parameter study on typical soil conditions the decisive differences of the individual approaches are shown and discussed. [ABSTRACT FROM AUTHOR]

Diese Artikelserie stellt den Einsatz von Computerprogrammen in der Hochschullehre der Bauphysik und Gebäudetechnik für Architekten und Bauingenieure vor. Das Fachgebiet Bauphysik (Fachbereich Architektur Stadtplanung Landschaftsplanung) der Universität Kassel bietet im Bereich der Lehre Vorlesungen und Seminare primär für Architekturstudent:innen im Bachelor und Master an. Die Veranstaltungen sind meist auch für Student:innen der Ingenieurwissenschaften an der Universität Kassel belegbar. Je nach Studiengang und Abschluss werden Softwareprogramme abgestuft angewendet. [ABSTRACT FROM AUTHOR]

Indoor climate study in the "heavy" Golden Hall in Nuremberg and in the "light" glass enclosure of the Busmann Chapel in Dresden On the basis of the simplified energy and moisture balance of a building the model and program CLIMT (Climate‐Indoor‐Moisture‐Temperature) for the practicable calculation of the indoor air temperature and relative humidity has been developed. Moreover the climatic generator CLIG is an userfriendly program in order to generate binary climatic dates (hourly values of temperature, relative humidity, shortwave direct radiation on chosen freely surfaces etc.) The results have been validated with hourly values of measurements in actual buildings in Germany: The "Golden hall" below the "Zeppelin terrace" in renovation since 2015 by the city building department Nuremberg and the glass housing around the Busmann chapel replica in Dresden. The correlation between calculation and measurement of temperature and humidity is nearly perfect. That is important for the planning of rehabilitation measures and the using of both buildings as museal spaces. [ABSTRACT FROM AUTHOR]

Prediction of sound insulation of external walls with external thermal insulation compound system – Development of a prediction model for light and heavy massive basic walls as contribution to the revision of ÖNORM B 8115‐4 External thermal insulation compound systems (ETICS) are not only a cheap opportunity to reduce thermal losses through external walls, but have, depending on the material, a significant impact on the weighted sound reduction index of these building components as well. The prediction model at hand for the weighted sound reduction index of external walls has already been adopted into the revision of the Austrian standard for acoustic prediction methods, ÖNORM B 8115‐4, representing the present status. The mentioned model not only implies a significant leap in accuracy, but also addresses all massive walls commonly used in Austria for the first time. It can be applied for the prediction of the weighted sound reduction index of external walls made from concrete, bricks or mass timber in a simple and transparent way. Moreover, it can be used for prediction of the spectrum adaptation term Ctr, which is of importance for the characterisation of the traffic noise frequency spectrum. The presented comprehensive prediction model results from the combination of previous material specific research activities of the authors to this topic. [ABSTRACT FROM AUTHOR]

Compression behavior of sand‐silt mixtures The choice of an appropriate material model for mixed‐grained soils is crucial for the design of a challenging geotechnical structe. For the development of an accurate material model, the experimental investigation of the soil is indispensable. Hereby, the compression behavior of sand‐clay mixtures is investigated on the basis of oedometer tests of mixtures with different fines contents. It can be observed that with increasing fines content, the compressibility of the material increases significantly. Nevertheless, an exponential relationship between equivalent void ratio e* and vertical strain has been established independently of the fines content. On this course, the deformation model of Ohde (1939) was generalized to mixtures by considering e*. The simulations with hypoplasticity for granular soils and with the AVISA‐model for fine‐grained soils show a need for the coupling of the preconsolidation pressure as well as the normal consolidation line at a 1:1 ratio of sand to silt depending on the fines content. [ABSTRACT FROM AUTHOR]

Use of software tools at the Chair of Building and Indoor Climate Technology at RWTH Aachen University – Series: Building simulation and calculation tools in teaching This series of articles presents the use of computer programs in university teaching of building physics and building technology for architects and civil engineers. The goal of sustainably providing a healthy indoor climate determines research and teaching at the Chair of Building and Indoor Climate Engineering at RWTH Aachen University. Computer‐aided analysis and simulation techniques are important tools for implementing energy‐efficient and environmentally friendly construction, retrofitting and operation of buildings and neighborhoods with all their complex interactions in the overall system. Students are introduced to the fundamentals of modeling and simulation. The course covers the consideration of all life cycle phases of the building. The knowledge can be further deepened in final theses. The developed tool chains and open source libraries of the institute guarantee a good manageability of the software tools without too long training periods for the students. [ABSTRACT FROM AUTHOR]

The limitations of the overheating risk assessment procedures according to DIN 4108‐2:2013 The methodology of DIN 4108‐2 for assessing the overheating probability of a critical room no longer reflects scientific and technical standards. There is increasing criticism in the literature. The article explains the methodology and background of DIN 4108‐2 and summarizes known application limits and shortcomings from the literature. These concern both assumed boundary conditions and the representation of the relevant physical effects and assessment criteria. Furthermore, the paper claims that the building use and geometry must be integrated in a more differentiated manner as a relevant category in the consideration of the overheating risk. On analyzing five practical examples, contradictions between the results of the simplified method, the simulations with boundary conditions according to DIN 4108‐2 and the simulations with building‐specific boundary conditions are shown. By means of a comparison of measurement and simulation results for one of these example rooms, the limitations of the simulation analyses are also addressed. The aim of this illustration is to mediate between the scientific discussion, which is based on highly idealized cases, and the practice‐related planning challenges, where the applicability of these assessment approaches is often unclear. [ABSTRACT FROM AUTHOR]

Rock stress determination by means of the overcoring method. Part 1: Triaxial strain cells – Recommendation No. 14 (revised) of the Commission on Rock Testing of the DGGT The Commission on Rock Testing of the Deutsche Gesellschaft für Geotechnik e. V. (German Geotechnical Society) is compiling instructions for rock mechanical laboratory and field tests as well as for monitoring in rocks and geotechnical structures on‐site. The presented revision of recommendation No. 14 covers the determination of rock stresses by means of overcoring tests and considers the development of this method since the publication of recommendation No. 14 in 1990 [1]. Further, requirements for the measuring instruments and the procedures regarding the execution and evaluation of these tests are specified. Reference is made to the ISRM Suggested Method, in which overcoring tests are dealt with [2, 3]. Recommendation No. 14 is divided into two parts. This first part deals with overcoring tests using triaxial strain cells. The second part covers overcoring tests using borehole deformation gauges. [ABSTRACT FROM AUTHOR]

Development of a Python script for strength reduction with numerical methods The application of numerical methods in geotechnics until now is mostly limited to the prediction of the deformation behaviour of structures regarding the serviceability limit state. The ultimate limit state has so far been handled rudimentarily (e.g. for homogeneous slopes and piled raft foundations), using numerical methods, such as the finite element method. In the present paper, therefore, the basis for the application of a unified method for parallel strength reduction on structural elements and a reduction of the shear parameters of the soil is discussed. In a first parametric study, a script based on the Python programming language for reducing the shear parameters of the soil is verified by comparison with approved methods for calculating the overall stability of slopes. Subsequently, the application boundaries of the Python script are extended to reduce the strength parameters of structural elements within a slope at risk of stability in the framework of a second parametric study. Based on this, an assessment of probable first failure mechanism (soil or structural failure) is made. Finally, the results of the two parametric studies are put into a causal context, considering a numerical verification with discussion of future research approaches. [ABSTRACT FROM AUTHOR]

Consideration of rigid inclusions at the proof of overall‐stability Rigid inclusions are hydraulically bound, unreinforced pile‐like elements, which are used to reduce settlements and to improve the overall‐stability. Due to the non‐existing reinforcement and the small diameters, rigid inclusions are not adapted for bearing lateral stresses. The present article explains the lateral load‐bearing behaviour of rigid inclusions. In a short overview existing approaches for consideration of rigid inclusions at the proof of overall‐stability are shown and worked out, that the contribution of rigid inclusions is often overestimated. A numeric model for investigation of the lateral load‐bearing behaviour of unreinforced, pile‐like elements is presented. As a result of systematic studies on the numeric model, the activation of the ulitmate transverse force is being explained in a simple mechanical model and outlined, which failure mechanisms will be relevant for consideration. Based on the findings from the mechanical model, fundamental guidelines for design of structures on rigid inclusions are being given. Two approaches for consideration of rigid inclusions at the proof of overall‐stability in Bishop's slip‐circle method are introduced. The applicability of the approaches is been demonstrated on a published damage case. [ABSTRACT FROM AUTHOR]

Urban Mining Index – planning and assessment tool for circular construction With the Urban Mining Index, a planning tool for circular construction has been developed at the University of Wuppertal. It is the first system that makes the circularity of building constructions quantitatively measurable and includes both the quality of circular material use as well as the deconstruction effort and the economic efficiency of selective deconstruction in the evaluation. A matrix in the form of a user‐friendly Excel tool was developed for the systematic recording of building constructions, with which the circularity potential and the CO2 footprint can be calculated and evaluated at component and building level. Over the entire life cycle of a building, all incoming materials and all resulting valuable and waste materials are calculated and evaluated according to the quality levels of their subsequent use. The proportion of circular building materials in the total mass of all materials used in the life cycle of the building quantifies the result: the Urban Mining Indicator. In first model projects, such as the new building for the town hall in Korbach, the optimisation for resource‐saving sustainable construction could be demonstrated with the "UMI". [ABSTRACT FROM AUTHOR]

Algorithm for assessment of greenhouse gas emissions of housing companies with extrapolated dates While goals for the reduction of greenhouse gas emissions are increasing, housing companies also see themselves under a social obligation to implement further measures for the energy optimization of their buildings. The starting point for the reduction goals set out in the German Federal Climate Change Act is the reference year 1990. For the companies, this poses the challenge that systematic recording of their consumption data only began during the 2000s. A well‐founded assessment in the context of the climate protection goals is therefore difficult to make. The developed algorithm enables a backward assessment of greenhouse gas emissions based on statistical metadata. For this purpose, the already recorded consumptions for the generation of heating and hot water are adjusted (interannual weathers and vacancy rate) and evaluated with regard to their greenhouse potential. Based on a representative data basis, the area‐specific greenhouse gas emissions can extrapolate to the reference year by the help of the developed method. The obtained range of values can for example serve as basis for future modernization decisions. A comparison of the determined graph with the investment expenditures of the company under consideration was able to confirm the applicability of the procedure. [ABSTRACT FROM AUTHOR]

The classification of soundproofing with the measure DnT,w with use of the weighted apparent sound reduction index R'w Buildings must ensure sound insulation appropriate to their use. This sound insulation is regulated by building regulations. In Germany, this is regulated by DIN 4109 Part 1 with a specification of a "minimum sound insulation". Additional requirements are referred to as "increased sound insulation". However, increased sound insulation does not necessarily lead to increased soundproofing. Soundproofing and sound insulation are not equivalent terms in this respect. This article shows that a direct assignment of the quantities R'w and DnT,w is only possible for certain geometric ratios of room volume and separating area (V/S). If a permissible deviation between R'w and DnT,w is accepted, a classification of the sound insulation values (R'w) with fixed class limits can be made. This makes it possible to classify the sound insulation with reference to the descriptive parameter DnT,w using the weighted apparent sound reduction index R'w. [ABSTRACT FROM AUTHOR]

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Diese Artikelserie stellt den Einsatz von Computerprogrammen in der Hochschullehre der Bauphysik und Gebäudetechnik für Architekten und Bauingenieure vor. An der TU Kaiserslautern wird der E‐Learning‐Kurs „Building Simulation in Design and Operation" für die Master‐Studierenden im Studiengang „Immobilien und Facilities – Management und Technik" angeboten und ist dort im Pflicht‐Curriculum verankert. Darüber hinaus können Studierende des Bauingenieurwesens und des Umweltingenieurwesens den Kurs als Wahlpflichtfach belegen. Der Fokus wird auf das Durchführen von Parametervariationen auf Basis von fertigen Modellen gelegt. [ABSTRACT FROM AUTHOR]

Impact sound insulation – Normalized impact sound pressure level L'n and standardized impact sound pressure level L'nT in comparison In DIN 4109, the impact sound insulation, expressed with the characteristic quantity of the weighted standard impact sound level L'n,w, is used to describe the impact sound protection. A, for the purpose of the description of the impact sound protection more useful characteristic variable, represents the weighted standard impact sound level L'nT,w. By analytical comparison of both parameters, it is shown which boundary conditions must be observed for the application of the equations. The differences from the equation of measurement results are shown on the basis of a measurement data set of 69 impact sound measurements carried out on ceilings of different types. The evaluation of the measurement results has shown that there can be considerable differences for the same design and for the same receiving room. It has also been shown that a simplified conversion of both parameters from the single values can cause errors of ±2 dB. If a limitation of the "error" is to take place, the surface of the floor considered must be limited. For a tolerated deviation of ±2 dB, the considered surface area is limited to less than 22.5 m2 depending on the room height from 2.20 m – 4.0 m. If larger rooms are considered, significantly larger deviations can occur. [ABSTRACT FROM AUTHOR]

Fire performance of insulating materials made from renewable resources – Part 2: Investigations on the use as compartment filling in timber panel constructions In the previous article on the research project "more than just insulation – additional benefits of insulating materials made from renewable resources", the experimental investigations on the initiation, process and extinguishing behavior of smoldering processes, the effect of flame retardants and the emissions released in the combustion process were presented. In this paper, the investigations on the structural use of renewable insulation materials, instead of the previously required non‐combustible insulation, is presented in the context of wood panel construction. First, the final large‐scale fire test on the natural fire behavior of wood panel building components with renewable insulation materials is presented. Then, the development of analytical and numerical models for the separating function is illustrated. The paper concludes with an outlook on the research project "PyroProBiD", in which advanced transport and reaction models are being developed. [ABSTRACT FROM AUTHOR]

Level of development and attribution of the specialized model subsoil – Recommendations No. 2 of the working group 2.14 (DGGT) "Digitalization in geotechnical engineering" The second recommendation of the working group 2.14 "Digitalization in geotechnical engineering" defines the level of development with respect to the life cycle of the specialized model subsoil. Furthermore, the minimum requirements regarding the implementation of geometrical and semantical data (attribution) into the model are discussed. For consequent use of the specialized model subsoil in context with BIM it is necessary to standardize the data with respect to the model level as well as the object level by means of properties which have to be defined. These recommendations describe the essential requirements for standardized geotechnical properties which still have to be developed. Therefore, data‐related requirements for creation as well as the attribution of the specialized model subsoil are discussed. [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]

Slope stability with regard of the stress‐strain behaviour during shearing The state of equilibrium of a slope is often evaluated with help of limit equilibrium methods. Here, it is neglected that a deformation in the shear zone has to take place before the maximum shear resistance is reached. The shear stress development depends amongst others on soil density and hydraulic conditions. Consequently, the mobilization of the shear resistance in the shear zone is not homogeneous, which can lead to an overestimation of the slope stability. This report shows a calculation method which couples the development of the slope stability with shear strain in the shear zone. For illustration purposes, two simple examples of a slope with a planar slip surface are shown. [ABSTRACT FROM AUTHOR]

Technical‐biological bank protection measures – Design concept for the engineering practice To improve the ecological condition of inland waterways, extensive bank redesigns are planned over the next few years. More natural bank protection measures using plants are to replace the existing rip rap where possible to create more habitats for plants and animals and more structural diversity. So far, relatively little experience has been gained with technical‐biological bank protection measures on waterways with the current shipping impacts. On the basis of various research results and experience from a large‐scale nature experiment on the river Rhine near Worms, a first design concept for the engineering practice of the waterway and shipping administration was developed, taking into account the experience on small rivers without shipping. The concept was also integrated into a software. This means that bank protection with plants can now be dimensioned in addition to riprap revetments. The special features of living building materials, the hydraulic effects, the geotechnical failure mechanisms to be investigated and the individual design steps are presented below. [ABSTRACT FROM AUTHOR]

With a new concept for the critical void ratio, barodesy yields promising simulations of element tests. Some shortcomings of this theory hitherto when simulating the behaviour of sand can be overcome by generalizing the widespread assumption that the critical void ratio is a function of the mean stress. Barodesy deviates from established lines of thought in soil mechanics. The interested reader can judge from this article whether this paradigm shift is worthwhile. [ABSTRACT FROM AUTHOR]

Flanking sound transmission of highly insulated hollow clay bricks with a light framed gypsum board separating wall Understanding flanking sound transmission along exterior walls is important to ensure an appropriate sound insulation between dwellings. The flanking sound transmission in massive construction is determined by the direct sound reduction index of the single elements and the vibration reduction index of the junction. For cases constructed with a separating wall of light framed gypsum board, the junction attenuation can be quite low. Therefore, a closer look was taken at the flanking sound transmission along an outer wall constructed of hollow clay bricks, where the separating element was a light framed gypsum board wall. The effect of modifications of this T‐junction on the junction vibration reduction index was determined in the flanking facility of the Stuttgart University of Applied Sciences. For the standard butted T‐junction, the velocity level along the outer wall – outer wall path stays constant. This suggests the use of the minimum value of the vibration reduction index Kij,min. Modifications of the junction, such as introducing joints and blocking masses, can increase the junction attenuation significantly. It is also shown that reducing the length of the outer walls, to simulate windows and doors as found in the real world, increases the normalized flanking level difference. Note, that these "reduced" measurements, although more realistic, over predict the flanking attenuation relative to the standard measurement method. [ABSTRACT FROM AUTHOR]

Fluid Flow Glazing in building envelopes The research project InDeWaG (Industrial Development of Fluid Flow Glazing Systems) has been funded for three‐and‐a‐half‐years by the European Union within the framework of the program HORIZON 2020. The focus of this project is an insulating glazing unit filled up with a water‐glycol fluid circulating within one of the IGU cavities. The glass units have been developed for both, the usage within façades and as interior separation walls. They are conceived to serve for both heating and cooling. The aim is to combine these units with other technologies in HVAC systems, such as Photovoltaic and high‐efficiency heat exchangers leading to minimized total energy consumptions of buildings without restrictions of daylight autonomy. The paper describes the idea behind fluid flow glazing. It focusses on the consideration of the single glazing units within the framework of thermal building simulation. First results of a demonstrator pavilion, in operation for one year, will be explained. [ABSTRACT FROM AUTHOR]

Impacts on rigid barriers by flow‐like gravitational mass movements The climate‐change‐induced influences on the environment represent an increasing importance and challenge for the evaluation of flow‐like rock avalanches. Extreme conditions for settlement areas in the alpine region result in the necessity to erect protective structures. Rock avalanches increasingly threaten people and infrastructure in settlement and economic areas in Alpine regions. The design impact based on empirical models, areas of influence, deposition sites and flow depth can be roughly estimated. Very different (mostly unknown) input parameters are required for the different numerical programs based on continuum mechanics. For a more precise definition of the relevant parameters, model tests are often carried out to validate the different design models. The basis of the present model experiment is the experimental setup and the investigations at the University of British Columbia which were replicated and extended at the University of Innsbruck. [ABSTRACT FROM AUTHOR]

Approach to determine ultimate stress mobilization in the Interface of rigid inclusion head and load transfer platform One field of application for rigid inclusions is the soil improvement for large‐area structures such as (fibre‐) reinforced slabs of logistics centers and other complexes. To optimise the slab (thickness and reinforcement), a load transfer platform (LTP) is usually installed above the columns. The aim of the LTP is to decouple the rigid inclusions from the structure and to enable a shallow foundation design of the slab. The interaction between columns, LTP and slab must be taken into account, which can cause additional stresses in the LTP and in the slab. In this paper, the approach proposed by french ASIRI recommendation for a granular LTP over rigid inclusions is presented, considering the conventional failure mechanism according to German standard DIN 4017. In a parameter study, influencing variables on the limit state of the LTP be evaluated. In addition, the results of FE calculations on an axisymmetric unit cell with a stiffness reduction of the surrounding soil are used. The FE calculations show that the allowable limit stress increase with a reduction of the LTP thickness, but up to the critical height additional bending moments in the slab must be taken into account. The bending moment increases with a reduction of the LTP thickness. [ABSTRACT FROM AUTHOR]

Investigations on thermal protection in summer – Part 3: Modeling of complex geometries and different material properties of shading systems A series of three articles investigates the thermal protection of buildings in summer using different methods and boundary conditions. Part 1 compares the code compliance methods prescribed by DIN 4108‐2 and considers future climate data. Part 2 deals with multi‐dimensional approaches to model shading systems. Part 3 presents a new approach to model shading systems that consist of non‐standard geometries and highly reflective materials. In part 3 external shading systems are investigated with respect to their geometry and material properties using the method of BSDF matrices which has been presented in part 2. One focus of the investigation is set on the choice of the calculation approach to generate the BSDF. The radiosity approach is compared with numerical raytracing as means to generate the necessary metrics in the shortwave and longwave range of radiation. Based on the building simulation results the impact of the chosen method as well as the influence of different geometries, highly reflective surfaces, and a low‐e coating on the back side of the blinds is assessed. Finally, the resulting differences are put into the context of code compliance calculations regarding thermal protection of buildings in summer time. [ABSTRACT FROM AUTHOR]

Spectrum adaptation term C and Ctr – Comparison of the single‐number ratings for airborne sound insulation in buildings R'w and DnT,w In order to take into account different sound level spectra of different noise sources, such as those for noise in a building and those for traffic noise outside a building, so‐called spectrum adaptation term can be added to the respective single‐number value of the sound insulation. With the characteristic size R'w, as well as the standard sound level difference DnT,w a new single specification is thus possible, which should better represent the actual sound insulation. A close examination shows that spectrum adaptation terms cannot be applied by simple equation, but that the required spectrum adaptation terms must in principle be determined for the corresponding applicable number specification according to DIN EN ISO 717‐1. For the present study, a measurement data set of 43 quality tests for airborne sound insulation was used and a deviation of ±1 dB between the C‐ and Ctr‐values was found. A simplified conversion of the single‐figure information as shown e.g. in DIN 4109‐2 cannot be transferred to the spectrum adaptation terms. [ABSTRACT FROM AUTHOR]

Climate data as an essential component for the assessment of summer thermal insulation Test reference years are hourly meteorological data developed by the German Weather Service for a complete year, which, depending on the type of application, reflect a representative weather pattern. The test reference years are an essential component for the assessment of summer heat insulation. The current approach of the test reference years always leads to difficulties, as they are very simplified and generalized. Due to climate change and the resulting extreme weather conditions, the use of suitable climate data is essential. Here, the newly developed location‐specific test reference years of the German Weather Service from 2017 represent a possible alternative. [ABSTRACT FROM AUTHOR]

Thermal comfort: standard compliant modelling of natural ventilation in adaptive time step solvers Natural ventilation can help maintain thermal comfort during summer periods. In simulation models for thermal comfort analysis, occupant behaviour related to natural ventilation is often included through definition of ventilation rule sets, included in building codes such as DIN 4108‐2. For example, windows are opened when room temperature exceeds a given limit while at the same time outside temperatures remain below a threshold. However, these rules were so far defined with respect to fixed step time integration methods. Straight‐forward implementation of such rules in error controlled adaptive time step integration solvers (e.g. included in THERAKLES, DELPHIN, COMSOL, MODELICA‐solvers etc.) fails. The article discusses strategies and model variants that work with such modern solvers and discusses new model parameters such as the delay time or dead‐band size. The impact of these parameter choices is illustrated with sensitivity studies using the thermal room model THERAKLES. [ABSTRACT FROM AUTHOR]

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Investigations on thermal protection in summer – Part 2: Comparison between modeling with reduction factor (FC‐factor) and bidirectional approach (BSDF‐method) A series of three articles investigates the thermal protection of buildings in summer using different methods and boundary conditions. Part 1 compares the code compliance methods prescribed by DIN 4108‐2 and considers future climate data. Part 2 deals with multi‐dimensional approaches to model shading systems. Part 3 presents a new approach to model shading systems that consist of non‐standard geometries and highly reflective materials. In part 2 the venetian blind system, which in part 1 has already been investigated in building simulation using a shading factor (FC‐factor), is now modelled using a three‐dimensional approach, called the BSDF‐method. This approach considers the solar transmittance of the complex fenestration system depending on solar altitude and azimuth and hence represents a much more precise calculation method. In a detailed analysis the basic differences of both approaches are presented and a special focus is set on the secondary heat flux to the room. The two modelling methods are then compared with respect to code compliance for thermal protection in summer, where besides the mandatory climate data (TRY 2010) a future climate data set (TRY 2035) was used as well. [ABSTRACT FROM AUTHOR]

Heat pumps play a key role in decarbonizing the heat supply for buildings. To exploit heat pump's potential in a resource‐efficient way, high coefficients of performance (COP) are required. For air‐source heat pumps, the COP is subject to outside temperature, building dynamics, and user demands. To achieve high COPs, it is necessary to design heat pumps to meet the demands and to optimize operation in terms of COP. In this study, we compare design methods according to DIN EN 15450 and VDI Guideline 4645. Based on these, heat pump systems (heat pump, auxiliary heater and thermal storages) are designed for an example building, and a controller is set up. Following VDI Guideline 4650, an Annual Performance Factor (APF) is used for comparison on the basis of dynamic simulations. For the same building, the study proves both systems to ensure supply temperatures at APFs about 3.5 to 4. In order to achieve optimal APF, a consideration of operation already in the design should be suggested. [ABSTRACT FROM AUTHOR]

Comparison of different energy certificate calculation types with the real consumption Three different methods of calculating the energy certificate were considered for 23 existing buildings and also compared with the actual energy consumption. The result of 69 energy certificates and 23 energy consumption bills for existing residential buildings were put in relation. Some individual calculated energy certificate results agree well with the actual consumption, however, regardless of the calculation method, there are deviations of up to 350 % from the real consumption. The three different energy certificate calculation methods were also set in relation to one another in order to determine the best possible type of calculation. This made it clear that the accuracy of the results of the type of calculation also depends on the size of the building. It turned out that the categorization of the construction method also plays a decisive role in the results and so the abolition of the "very heavy construction method" in the OIB guideline 6 with the 2019 version is not justified. In addition, suggestions for improvement are presented with regard to the orientation of the components, the integration of digital sun position and shading options, the household electricity requirement, the energy indicator according to the number of users and zoning. [ABSTRACT FROM AUTHOR]

A newly developed design concept for plane earthwork structures on pile foundations is presented. This design concept is based on a complex mathematical background that has been derived using fundamental mechanical principles. The mechanical system comprises the arching effect in a plane earthwork structure on punctual supports. It incorporates the effect of an elastic membrane that is formed by orthogonal ribs of geogrids, the modulus of subgrade reaction between the piles and the elastic settling of the piles. Some practical design examples are shown. The important aspects of the analysis and the design are pointed out. The complete mathematical background and a comprehensive design tool for free use have been prepared and are provided through a download link: https://gft‐pes.blogspot.com. [ABSTRACT FROM AUTHOR]

Investigation on thermal protection in summer – part 1: Comparison of the evaluation methods taking into account future climate data A series of three articles investigates the thermal protection of buildings in summer using different methods and boundary conditions. Part 1 compares the code compliance methods prescribed by DIN 4108‐2 and considers future climate data. Part 2 deals with multi‐dimensional approaches to model shading systems. Part 3 presents a new approach to model shading systems that consist of non‐standard geometries and highly reflective materials. In part 1 an analysis of the existing code compliance methods is conducted, in particular of the simplified table‐based method and the simulation‐based approach. Both methods are assessed and compared regarding the impact of important aspects and measures (climate region, orientation, window‐to‐wall ration, ventilation, thermal mass, shading systems). In the dynamic simulation not only the current weather data (TRY 2010) but also weather data describing the period from 2021 to 2050 (TRY2035) are used. [ABSTRACT FROM AUTHOR]

Development of a virtual reality environment for interactive thermal room simulation This article describes an approach in which the modeling and simulation process for the indoor climate of buildings takes place entirely in a virtual reality (VR) environment. In this way, the simulation expert is immersively involved with regard to the spatial design, spatial perception and interaction with the spatial model. The simulated indoor climate resulting from the interactions and other variables such as energy demands are visualized in the VR environment as a feedback to the user. To implement the described approach in terms of software, the Modelica tool Dymola was integrated with the game engine Unity to form a complete system, with bidirectional data exchange taking place between the two programs. The building model of the Modelica library BuildingSystems forms the basis of the building physics calculations in Dymola. In Unity, a head‐mounted display was integrated to implement the VR simulation environment, and the two modes "modeling" and "simulation" were prototypically implemented and evaluated in a simulation scenario. [ABSTRACT FROM AUTHOR]