Development Of Failure Criteria Research Articles

New steel‐concrete connection for prefabricated composite bridges

AbstractAn investigation of a new type of connection between precast concrete decks and steel girders, for composite steel‐concrete bridges, is being performed by the Steel Structures Laboratory, ICOM, of Ecole Polytechinque Fédéral de Lausanne, EPFL. The connection resists the loads by shear resistance between base materials. Hence, a fundamental part of the research focuses on the behaviour of the different confined interfaces of the connection, subjected to shear, static and fatigue loading. The confinement is a combined outcome of the kinematic law of the interfaces and the section geometry. Experimental investigation through a series of direct shear tests on confined interfaces has resulted in the development of failure criteria and constitutive and kinematic models describing the behaviour of the different interfaces. Those laws are used as an input for a model that simulates the connection behaviour. The model of the connection is validated by push‐out tests on large‐scale specimens. Finally, a composite beam has been tested under constant amplitude for five million cycles. A static test, following the fatigue sequence, has shown that the composite beam reaches its plastic moment capacity due to the sufficient ductility of the connection.Neue Stahl‐Beton‐Verbindung für vorgefertigte StahlverbundbrüKen. Im Labor für Stahlkonstruktionen (ICOM) der Eidgenössischen Polytechnischen Hochschule Lausanne werden Untersuchungen für eine neue Verbindungsart zwischen Betonfertigteil‐Fahrbahn und Stahlträgern bei Stahlverbundbrücken durchgeführt. Die Verbindung nimmt die Beanspruchungen über den Schubwiderstand zwischen den Grundmaterialien auf. Daher konzentriert sich ein wesentlicher Teil der Forschung auf das Verhalten der verschiedenen, eingeschlossenen Verbundfugen, die Schubkräften und statischen und ermüdungswirksamen Beanspruchungen ausgesetzt sind. Die Zwängungsbeanspruchung ist ein kombiniertes Ergebnis der Kinematik der Verbundfugen und der Profilgeometrie. Experimentelle Forschung anhand einer Reihe von direkten Abscherversuchen an eingeschlossenen Verbundfugen führte zur Entwicklung von Versagenskriterien, Materialgesetzen und kinematischen Modellen zur Beschreibung des Verhaltens der verschiedenen Verbundfugen. Diese Gesetze werden als Eingangsgrößen für ein Modell verwendet, welches das Verhalten der unterschiedlichen Verbundfugen simuliert. Das Modell der Verbindung wird durch Push‐ Out‐Versuche an großen Prüfkörpern validiert. Abschließend ist ein Verbundträger unter konstanter Amplitude mit 5 Millionen Lastwechseln geprüft worden. Eine statische Prüfung der Resttragfähigkeit hat gezeigt, dass der Verbundträger die vollplastische Momententragfähigkeit aufgrund einer ausreichenden Duktilität der Verbindung erreicht.

Status of boiling water reactor structural integrity programs at the General Electric Company

The General Electric Company is actively involved in a variety of programs whose objective is to evaluate and improve the technology related to structural integrity of Boiling Water Reactors. This work covers many technical disciplines that fall broadly under the title of Applied Mechanics and includes the technologies of solid mechanics, structural dynamics, elasticity, plasticity, and fluid dynamics. General Electric programs are directed at qualification of the predictive methodology, design bases and criteria used to evaluate and confirm the structural design margins of the Boiling Water Reactor Nuclear Steam Supply System. This includes the reactor pressure vessel, piping, fuel, core structures, and auxiliary equipment within General Electric's scope of supply. Focus of these programs includes identification, measurement and refinement of operational and postulated accident-type loads; prediction of structure and component response; study of damage mechanisms; and development of failure criteria, evaluation methods and design rules. In this report, some specific activities and accomplishments during the last few years are summarized in order to provide a broad overview of the wide range of technical issues and programs undertaken. These activities have been grouped into areas of: I — Dynamic Modeling and Structural Analysis; II — Fatigue and Fracture Evaluations; III — Structural Capability Tests; and IV — Flow Induced Vibration Experiments.

Multiaxial Creep Studies on Inconel at 1500 F

Design engineers have become concerned with the effect of multiaxial stresses on the creep rate and on the rupture life of metals as the demands for higher performance have necessitated the use of higher operating temperatures. The goal of applied research in this field is the development of failure criteria based on properties measured in the conventional uniaxial tension creep test.