Behebung von Baugebrechen

Die Anlage eines Spielplatzes ist weder bewilligungs-noch anzeigepflichtig. Die Bewilligungs- und Anzeigefreiheit von Spielplatzger?ten ist nicht auf ein einzelnes Ger?t beschr?nkt.     

Querkraftwiderstand von Stahlbetonbauteilen ohne Querkraftbewehrung

Shear Strength of Reinforced Concrete Members without Transverse Reinforcement A new theoretical model concerning the shear strength of reinforced concrete members without transverse reinforcement is presented, considering free‐bodies unilaterally bounded by a fictitious crack, inclined at π/4 to the tension chord and extending from the tension chord to the compression chord. It is assumed that the shear stress that can be transferred across a crack decreases linearly with the crack width and that the crack width at the level of the tension chord is proportional to the product of the tension chord strain at the crack and the chord distance. This results in a linear‐hyperbolic relationship between the shear strength and the (elastic) tension chord force at the crack, allowing to determine the governing crack location and other relevant quantities via equilibrium considerations. Due to potential strut or arch action for the transfer of loads applied in the vicinity of supports the crack location is somewhat restricted; it is assumed that the corresponding length is equal to twice the chord distance.     

Zusammentreffen von nachbarrechtlicher und vertraglicher Haftung

Neben der nachbarrechtlichen Haftung wegen Emissionen bzw Grundstückssetzungen besteht grunds?tzlich auch die Haftung des ausführenden Werkunternehmers aus Vertrag mit Schutzwirkung zugunsten Dritter.     

Behebung von Baugebrechen

Der Anwendungsbereich der Bestimmungen über die "Vermeidung und Behebung von Baugebrechen" (§ 33 n? BauO 1996) bezieht sich auch auf Baugenehmigungen, die vor Inkrafttreten der BauO 1996 erlassen wurden. § 33 n? BauO 1996 bietet keine M?glichkeit, Vorschreibungen zu treffen, welche die einmal erteilte Baubewilligung ab?ndern würden.     

Korrelation von Betondruck‐ und Zugfestigkeit historischer Betone

Correlation between the compressive and tensile strength of old concretes – Applicability of the relationship described by DIN EN 1992‐1‐1 In the design of a new structure, DIN EN 1992‐1‐1 [1] normatively regulates the correlation between the compressive strength and tensile strength of concrete, produced according to DIN EN 206‐1 [2]. However, as there are many different time‐ and load‐dependent impacts on existing structures, the relationship described by DIN EN 1992‐1‐1 [1] can't be assumed without any further observations for existing structures. At the moment, there is no comprehensive investigation on the influences of e.g. subsequent hardening and carbonation on the concrete compressive or tensile strength. The tensile strength of concrete defined in DIN EN 1992‐1‐1 [1] is based on a water storage and a testing age of 28 days. Furthermore, the in‐situ tensile strength is affected by micro‐crack formation cause of internal stresses due to outflow of hydration heat. Generally, there is a different influence of micro‐crack formation on the tensile strength of concrete than on the compressive strength of concrete. The real value of the in‐situ tensile strength of concrete affects the shear force resistance and the load‐bearing capacity of anchors with concrete cone failure as decisive failure mode. Within the framework of a research project, financed by ”Forschungsinitiative Zukunft Bau“, an initiative of the Federal Institute for Research on Building, Urban Affairs and Spatial Development (BBR) structural investigations on the correlation between the compressive and tensile strength of old concretes have been performed. Below, the results of the research project are presented.     

Tragverhalten von geschichteten Deckenelementen aus Normal‐ und Porenleichtbeton

Load bearing behaviour of layered ceiling elements made of regular and porous lightweight concrete Lightweight and efficiently bearing steel reinforced elements may be achieved through the application of regular and porous concrete in a three‐layer cross‐section. While exterior layers of higher strength carry bending moments, a lightweight core layer material holds up to shear stresses. In order to quantify the potential of this construction method, the bearing behaviour of 18 layered ceiling elements with six different geometries was investigated. The goals were both to identify different failure modes, as well as evaluate the suitability of commonly used calculation procedures. The following paper shows that an optimal usage of cross‐sections of ceiling elements can already achieved by using concrete with strengths between 5 MN/m² and 20 MN/m². The efficiently bearing elements are characterized by the fact, that both the concrete, the reinforcing steel and the layer's interface are highly stressed both under pressure and tension. The tested specimens showed both a tensile bending and interface failure with a partly very high utilization of the flexural compressive zone.     

Zum Durchstanzen von Flachdecken nach Eurocode 2

Die Regelungen zur Durchstanzbemessung im Eurocode 2 basieren im Wesentlichen auf den Modellvorstellungen in Model Code 90, der die Durchstanztragfähigkeit auf die Querkrafttragfähigkeit zurückführt. Nach Versuchsauswertungen ist diese Analogie für punktgestützte Platten jedoch nicht in jedem Fall zutreffend. Insbesondere für bügelbewehrte Platten ist bei der Bemessung nach Eurocode 2 ein Sicherheitsdefizit möglich, und es erscheint eine Anpassung der Bemessungsgleichungen zwingend erforderlich. Dieser Beitrag erläutert die Sicherheitsdefizite und schlägt verbesserte Bemessungsgleichungen vor. Punching of Flat Slabs according to Eurocode 2 The punching shear provisions according to Eurocode 2 are based on the design recommendations in Model Code 90 where no differentiation between shear and punching shear design is made. This approach is not fully confirmed by test results for flat slabs. In particular for flat slabs with stirrups as shear reinforcement some design provisions according to Eurocode 2 do not achieve the required safety level. Therefore adjustments to the design equations seem to be necessary. In this paper the Eurocode 2 provisions are critically reviewed and improved design regulations are proposed.     

Auswirkungen der Vorspannung auf das Tragverhalten von SL‐Verbindungen

Der Tragsicherheitsnachweis für Schrauben mit Zug‐ und Querbelastung erfolgt nach DIN 18800‐1 (810) durch die quadratische Interaktion. Dabei stellt sich die Frage, ob bei reiner Querbeanspruchung eine Vorspannkraft als Zuganteil berücksichtigt werden muss. Um diese Frage zu klären, wurden am Fachgebiet Stahlbau der TU Darmstadt Abscherversuche an Schrauben mit unterschiedlichen Vorspanngraden durchgeführt. In diesem Beitrag werden die Versuche vorgestellt und Empfehlungen zur Behandlung der Vorspannkraft ausgesprochen. Influence of the preload on the resistance of bearing‐type connections. The design resistance of bolts under tension and shear is given in DIN 18800‐1 (810) by a quadratic interaction. The question is, whether the tension due to a preload has to be taken into account. The workgroup steel construction of the Technische Universität Darmstadt, Germany, has run tests to assess the influence of the preload in bearing‐type connections. In this paper the tests are presented and recommendations to take the preload into account are given.