Silolasten nach der neuen DIN 1055‐6

Silo loads according to the new DIN 1055‐6 An overview and some background information are given to the new DIN 1055‐6 “Actions on Structures: Actions on Silos and Tanks”. Following the rules of EN 1991‐4 the determination of silo loads is adjusted to the new safety philosophy of DIN 1055‐100. In some cases new load rules have been introduced or existing rules have been replaced. In particular this concerns patch loads for thin‐walled steel silos, loads in squat and intermediate standard silos, hopper loads or loads for large eccentricity of discharge.     

Die Parkhauslasten in DIN 1055-3

Leads for Multi-Storage Car Parks in DIN 1055-3 The following explanations will summarise the background of the regulations for multi-storey car parks of category F, as defined in German standard DIN 1055-3 “Actions on structures – selfweight and imposed loads”. Based on comparative calculations, recommendations will be given regarding the allocation of effective spans to load distribution areas of slabs. Using this information, the designer will be able to successfully apply the German standard, category F, to multi-storey car parks.     

Die neue Schneelastnorm DIN 1055‐5, kritisch hinterfragt

Die neue Schneelastnorm DIN 1055‐5:7/2005 brachte vor allem in den höhergelegenen Orten der Zone 3 erhebliche Erhöhungen der Schneelast, die bis zum Zweifachen der bisher anzusetzenden Belastung reicht. Auch die neuen Formeln für die Belastung von aneinandergereihten Dächern, von Shed‐ und Tonnendächern sowie die Behandlung von Höhensprüngen und Trauflasten erscheint problematisch. In diesem Beitrag wird versucht, Unstimmigkeiten der Norm aufzuzeigen. The current snow load standard DIN 1055‐5 – a critical review. The current snow load standard DIN 1055‐5:7/2005 caused a considerable increase of snow load, particularly in more elevated areas located in zone 3. It doubles the amount of snow load capacity – compared to the old standard. The new equations for calculating snow loads for adjacent roofs, shed roofs and arched roofs as well as the handling differences in altitude and gutter load seems problematic. This paper tries to show the inconsistencies of current standard.     

Die Bedeutung der Tragwerkseigenschaften im Gesamtsicherheitskonzept – am Beispiel der Dachkonstruktion der AWD‐Arena in Hannover

The significance of structural behaviour in the global safety concept exemplified at the roof construction of the AWD Arena in Hanover. The wide‐span roof structures of modern sports arenas demand a high level of safety. So the assessment of structural behaviour, “robustness” and residual load‐bearing capacity, as specified in the Eurocodes (EC 1), in the new DIN 1055 part 100 [1] and in the DIN 18800 part 1 [2], becomes a central part of the global static analysis. The appropriate safety factors for these structures cannot be determined in advance but only after having analyzed the structural sensitivities in relation to the load parameters, especially those of climatic loads. The present work shows the contribution of the structural analysis to a complex team‐work of wind and snow experts, checking and approving authorities exemplified at the AWD Arena roof.     

Hinweise und Erläuterungen zur Anwendung der neuen Windlastnorm DIN 1055‐4:2005‐03

Notes and Comments on the Application of the New Wind Loading Standard DIN 1055‐4.2005‐03 The final draft of the German Wind loading code DIN 1055‐4 has been published in March 2005. It is scheduled for implementation as a design rule in 2007. The code is basically new in several aspects: the development of a new wind map, the introduction of two wind profiles accounting for changes of surface roughness and the application of the gust response factor to determine equivalent static wind loads for structures and structural elements prone to wind induced vibration. The development of the DIN 1055‐4 has been harmonized during the final drafting process with the Eurocode Draft prEN 1991‐1‐4.6:2002: Actions on Structures – Wind Actions. The following contribution presents a survey of the main features and illustrates the application referring to some typical cases.     

Erfahrungen mit der neuen DIN 1055‐4 im Stahlschornsteinbau

Experiences with the new DIN 1055‐4 in Steel‐Chimney Building. This report summarizes the first experiences of the author with the new wind standard DIN 1055‐4 in the steel chimney building. It compares the calculation of gust wind profiles according to DIN 1055‐4 with those of the current valid standard for steel chimneys DIN 4133 Annex A. Additionally suggestions are made, that could give simplifications to the practictioner in the use of this standard.     

Bemessungsvorschlag für Holz/Beton‐Verbundbalken unter Beachtung abgestufter Verbindungsmittelabstände

Design proposal for timber/concrete composite beams with graded connnector distances. The distance of connections of timber/concrete composite beams is often graded for economical reasons according the shear force distribution. The load‐carrying capacity of composite beams according to DIN 1052 respectively E DIN 1052 with internal forces, which are linearly determined, (γ‐procedure) are clearly reduced compared to beams without graded distances of connectors. The actual load‐bearing behaviour distinctly shows non‐linearities. The influence of the gradations of the connectors on the load‐bearing behaviour of composite beams is investigated, because the influence of the stiffness of connections on the load‐bearing capacity of composite beams is small. The paper presents a comparison between failure loads determined by FE‐analysis and the working loads according to the current design rule. It is shown that the decrease of load‐bearing capacity is smaller than assumed by current code of practice. Structures with several different distances of connections have the largest safety‐factor. These systems can more economically be designed. As the result of the investigations, a new design proposal is presented, which takes non‐linearities into account and guarantees a constant safety‐zone between failure load and working load. These proposal permits an economic design of timber/concrete composite beams.     

Teilsicherheitsfaktoren für die Berechnung von Großkraftwerken

Die Baustrukturen von Großkraftwerken werden in Deutschland u. a. auf Basis der VGB‐Richtlinie R 602 U berechnet und bemessen. In dieser Richtlinie sind unter Berücksichtigung der Besonderheiten des Großkraftwerksbaus Einwirkungen und Teilsicherheitsfaktoren definiert. Während die Lasten auf diese Randbedingungen abgestimmt wurden, hat man die Teilsicherheitsfaktoren auf der Lastseite aus der DIN 1055‐100 entnommen und lediglich die Kombinationsbeiwerte angepasst. Diese Sicherheitsbeiwerte tragen jedoch den speziellen Randbedingungen eines Kraftwerks oder Schwerindustriebaus nur bedingt Rechnung. Im Rahmen des Beitrags werden die Teilsicherheitsbeiwerte auf der Einwirkungsseite – insbesondere für das Konstruktionseigengewicht – für die Bemessung von Stahlbetonteilen vor diesem Hintergrund kritisch diskutiert und ein optimierter, wissenschaftlich abgesicherter Vorschlag unterbreitet. Partial Safety Factors for the Design of Power Plants In Germany power plants are designed in accordance to VGB regulation R 602 U. In this code load actions and partial safety factors are applied taking the special characteristics of power plants into consideration. The actions are defined regarding these circumstances, however the safety coefficients are assumed according to DIN 1055‐100 and only the combination coefficients are adjusted. However it has to be recognized that the partial safety factors in DIN 1055‐100 are calibrated for building constructions and thus do not consider the specialities of power plants in an adequate manner. In this paper the partial safety factors for the design of power plants and other heavy industry buildings are discussed for structural concrete elements and a scientific based optimized approach for the safety factor for dead load is presented.     

Einsparpotentiale beim Bau von Kraftwerken am Beispiel von Windeinwirkungen auf Kühltürme

Financial safety potential of power plant constructions by example of wind loads on cooling towers Wind loads are one of the most dominant loads in power plants. In this paper, the financial benefit of windtechnological analyses on large‐scale power plants is examined exemplarily by means of cooling towers in the context of the new German wind code DIN 1055‐4:2005‐03. The results of the investigations clarify the amount of financially quantifiable savings as a result of windtechnological analyses.     

Zur Traglastermittlung von Druckstäben im Holzbau

Determination of ultimate loads for compression members in timber constructions. The design of compression members in timber constructions has to consider the increasing stress due to the non‐linear behaviour of the members. The determination of the ultimate load of compression members requires the consideration of non‐linear geometric behaviour, if the bending moments increase more than 10% in relation to the linear theory. In the German timber design code, DIN 1052 [1], two methods of calculation are suggested. The second method uses geometric non – linear theory (theory second order) for calculation of the ultimate load. According to DIN 1052 the load carrying capacity can be determined without reducing stiffness parameters using the modification factor. The calculation methods for compression members according to DIN 1052 are compared and differences between them are discussed. A calculation with identical results for the ultimate loads using either the first or the second method is proposed.     

Starr verankerte dünnwandige windbelastete Kreiszylinderschalen mit Dachscheibe

Anchoring forces of cirular cylindrical shells. The wind force distribution according to the new german standard DIN 1055‐4:2005‐03 “Action on structures – Wind loads” is shown and transferred into Fourier series for various values of the Reynolds constant. The values are given in tables. Using a computer program developed by the author anchoring forces of closed circular cylindrical shells are calculated, based on the shell theory, for various non‐dimensional geometries and for rigid anchors. The results of these calculations are presented in tables for easy use by designers. An example shows the influence of elastic anchors.     

Die VGB‐Richtlinie “Bautechnik bei Kühltürmen” und ihre Anpassung an die neue DIN 1045 / DIN 1055

The VGB Guideline “Structural Design of Cooling Towers” and its adjustment to the new DIN 1045 The current VGB guideline for the structural design of cooling towers is based on obsolete versions of the German design standards DIN 1045 and DIN 1055. Corresponding to the new generation of German standards DIN 1045 and DIN 1055 a revision of the VGB guideline has become necessary. Regarding the revision essential topics are given by the consideration of the partial safety concept, the possible application of non‐linear design analyses and the increased requirements with respect to durability. The revised VGB guideline is intended to be published at the beginning of 2005.     

Anpassungsfaktoren für das Lastmodell 1 des DIN‐Fachberichtes 101 für gewichtsbeschränkt beschilderte Straßenbrücken

Correction Factors for the Load Model 1 according to the DIN‐Fachbericht 101 for Weight constricted signposted Road Bridges Since 2003 the DIN‐Fachbericht 101 is the normative basis for the design loads of bridges in Germany. In contrast to the previous code of practice, the DIN 1072, the DIN‐Fachbericht does not include details about bridges, which will be signed with traffic weight limitations. This paper describes the development of reduction factors for the Load Model 1 in the DIN‐Fachbericht and presents the new calculated factors. Therefore the DIN‐Fachbericht Load Model 1 has been extended for the application of traffic weight limitations signed bridges.     

Sonderlösungen bei der Tragwerksplanung auf der Grundlage der neuen Normen – Klimatische Einwirkungen

Special solutions in structural design on the basis of the new design codes – climatic actions. The following contribution deals with climatic actions on large lightweight roofs of stadia. The focus is on the wind loads. In some cases, it becomes necessary or advantageous to provide more precise design wind loads compared to the code provisions. This applies to the local wind climate as well as to the aerodynamic coefficients. The framework for such investigations is established by the requirements set by the code DIN 1055‐100: Basis of design, with regard to structural safety and reliability, and by those basic stipulations in the wind loading code which may not be altered. The author presents and discusses the framework for optimised design wind loads.     

Betrachtungen zur Verkehrslastannahme bei Holzbalken/Beton‐Verbunddecken

Considerations regarding the live‐load of Timber/Concrete‐ Composite Ceilings According to DIN 1055‐T3, the live‐load of ceilings without a sufficient load‐carrying effect perpendicular to the main stress direction in dwellings is 2,0 kN/m². For concrete floors, the serviceload is 1,5 kN/m² because of the sufficient load‐carrying effect perpendicular to span. Timber/concrete‐composite ceilings neither act like timber floors nor like concrete floors. Therefore, the paper investigates the load‐carrying effect of the composite structures perpendicular to the main stress direction, applying different spans, distances between beams and stiffnesses of joints. The aim is a practice‐oriented proposal for determining the standard live‐load assumption of timber/concrete‐composite ceilings.     

Zur Querkraftgefährdung bestehender Spannbetonbrücken

Zur Formulierung einer Handlungsanweisung werden in Teil I die geänderten Lastannahmen für Brücken nach DIN Fachbericht 101 mit den Belastungsklassen nach alten Normen verglichen und gezeigt, wie anhand aktueller Verkehrszahlen die Lastansätze modifiziert werden können. Der aktuelle Brückenbestand in Hessen wird mit der Straßeninformationsbank (Teilprojekt Bauwerksdaten) ausgewertet, um Klassifizierungs‐ und Bewertungskriterien zu erarbeiten. Zur Beurteilung des Querkraftwiderstandes werden die Grundlagen der Querkraftbemessung nach DIN 1045, DIN 4227, DIN Fachbericht 102 und aus der Literatur gegenübergestellt. Shear‐Vulnerability of Existing Pre‐Stressed Concrete Bridges. Part One: Basics In Part I, to formulate an operation directive the revised load assumptions for bridges of DIN Technical Report 101 are compared with the loading classes according to old standards and it is demonstrated, how the loading models can be modified based on actual traffic data. The current bridge asset in the Federal State of Hesse is evaluated using the “Road Information Database (Sub‐Project: Structural Data)” in order to work out classification and evaluation criteria. Regarding the assessment of the shear load‐bearing capacity the fundamentals of the shear load design models of DIN 1045, DIN 4227, DIN TR 102 and from the literature are compared.     

Türme unter Glocken‐ und Erdbebenlast nach alter und neuer DIN 4178 und 4149

Towers under Bell and Earthquake Loads according to the old and new DIN 4178 and 4149 Due to their slenderness and their function bell towers are especially exposed to dynamic loads. These loads are the dynamic loads due to the ringing of the bells (DIN 4178 of 1978) and earthquake loads (DIN 4149 of 1981). The two for these load cases relevant codes have been updated to the current technical state of knowledge and have been published in April 2005. In this article the differences between the old and new versions of the codes are explained by two selected examples. The consequences of rehabilitation measures of the bells are also considered. It was found that the new versions of the codes lead to higher loads of the towers. To design new towers and to investigate existing ones it is therefore required to use the updated versions of the codes to obtain reliable results.     

Probabilistische Modellierung hochfester Stahlbetonstützen in Hochhäusern

Probabilistic Modelling of HPC Slender Columns in High‐Rise Buildings In Germany high strength concrete is used successfully since 1990. The extremely high compressive strength of this material allows considerable reduction in cross‐sectional dimensions of reinforced concrete columns and accordingly accomplishes highest architectural and functional requirements. This leads in many cases to extremely slender structures and therefore increases the risk of failure due to loss of stability. Because of the positive experience with high strength concrete up to now, the current study questions the initial conservative design provisions. In this context code procedures of DIN 1055‐3 and DIN 1045‐1 are compared with the results of probabilistic analysis and potential optimization will be indicated.     

Zur Tragfähigkeit unbewehrter Betonwände

Load Bearing Capacity of Non‐Reinforced Concrete Walls The simplified approach for the design of compression members made of non‐reinforced concrete according to DIN 1045‐1 leads to large cross sections for slender walls with eccentric loading. Based on the principles of DIN 1045‐1 a design method is deduced in this article. The use of this method allows a simple, standardised and economic design of non‐reinforced compression members. A further increase in load bearing capacity can be achieved by taking into account the concrete tensile strength.     

Zur Querkraftgefährdung bestehender Spannbetonbrücken

Zur Formulierung einer Handlungsanweisung wurden in Teil I die geänderten Lastannahmen für Brücken nach DIN Fachbericht 101 mit den Belastungsklassen nach alten Normen verglichen und gezeigt, wie anhand aktueller Verkehrszahlen die Lastansätze modifiziert werden können. Der aktuelle Brückenbestand in Hessen wurde mit der Straßeninformationsbank (Teilprojekt Bauwerksdaten) ausgewertet, um Klassifizierungs‐ und Bewertungskriterien zu erarbeiten. Zur Beurteilung des Querkraftwiderstandes wurden die Grundlagen der Querkraftbemessung nach DIN 1045, DIN 4227, DIN Fachbericht 102 und aus der Literatur gegenübergestellt. In Teil II werden Verfahren zur nachträglichen Verstärkung von Querschnitten und Tragsystemen mit zu geringer Querkrafttragfähigkeit zusammengestellt. Des Weiteren werden verschiedene Varianten der Modellierung verglichen, die bei der linearelastischen Schnittgrößenermittlung nach der Finite‐Elemente‐ Methode verwendet werden. Auf Grundlage der gewonnenen Erkenntnisse werden schließlich Empfehlungen für eine Handlungsanweisung zur Beurteilung querkraftgefährdeter Brückenbauwerke formuliert. Shear‐Vulnerability of Existing Pre‐Stressed Concrete Bridges In Part I, to formulate an operation directive the revised load assumptions for bridges of DIN Technical Report 101 are compared with the loading classes according to old standards and it is demonstrated, how the loading models can be modified based on actual traffic data. The current bridge asset in the Federal State of Hesse is evaluated using the “Road Information Database (Sub‐Project: Structural Data)” in order to work out classification and evaluation criteria. Regarding the assessment of the shear load‐bearing capacity the fundamentals of the shear load design models of DIN 1045, DIN 4227, DIN TR 102 and from the literature are compared. In Part II, the procedures for the subsequent strengthening of cross‐sections and structural systems with a low shear load‐bearing capacity are compiled. In addition, different types of finite element modelling are compared used for the calculation of the linear‐elastic internal forces. Finally, based on the findings recommendations are formulated for an operation directive in regard to the assessment of shear‐vulnerable bridges.