End Zone Reinforcement for Pretensioned Concrete Girders
In this study, a literature review was conducted to establish the background of current specifications and to evaluate the applicability of various theories and methods for design of end zone reinforcement. Analytical methods reviewed in this paper include finite element analysis, strut- and-tie modeling, and the Gergely-Sozen equivalent beam method. Previous experimental work combined with work conducted as part of this study were used to correlate between various theoretical and experimental results. This paper illustrates that no single theoretical method adequately represents the complex behavior at the end of a pretensioned concrete member. A general semi-empirical design procedure is proposed here. It is based on theoretical behavior and experimental observation. Standard reinforcement details are given. The proposed procedure could result in reduction in the congestion of reinforcement while maintaining acceptable crack control at the member end. Application of the proposed procedure to highly pretensioned bridge girders is demonstrated.
PRACTICAL ANALYSIS OF THE ANCHORAGE ZONE PROBLEM IN PRESTRESSED BEAMS
THIS TWO-PART PAPER PRESENTS METHODS FOR /A/ THE DETERMINATION OF TRANSVERSE STRESSES AND /B/ THE PROPORTION- ING OF TRANSVERSE REINFORCEMENT IN THE ANCHORAGE ZONE OF PRESTRESSED CONCRETE BEAMS. THE METHODS PRESENTED ARE BASED ON A PHYSICAL ANALOG REPRESENTING THE END OF THE BEAM. PART 1 OF THE PAPER DESCRIBES THE BASIC FEATURES OF THE APPROACH, COMPARES THE RESULTS WITH OTHERS BASED ON THEORY AND EXPERI- MENT, DEVELOPS SIMPLE DESIGN PROCEDURES, AND CONCLUDES WITH NUMERICAL EXAMPLES. PART 2 DISCUSSES IN DETAIL THE DERIVATIONS ASSOCIATED WITH THE DEVELOPMENT OF THE PHYSICAL ANALOG. A CONSIDERABLE AMOUNT OF SIGNIFICANT WORK ON ANCHORAGE ZONE STRESSES HAS PRECEDED THIS PAPER. THE CONTRIBUTION OF THIS EFFORT IS THAT IT PROVIDES AN ANALYTICAL TOOL WHICH CAN BE USED IN DESIGN TO INVESTIGATE MANY DIFFERENT CONDITIONS WITHOUT THE NECESSITY OF LABORIOUS SOLUTIONS. /RRL/A/
An Introduction to Property Theory: Utilitarian Property Theories
As a leading property law casebook puts it, “[u]tilitarian theory is, without doubt, the dominant view of property today, at least among lawyers.” This is certainly true, but the story is also significantly more complicated. Although utilitarian analysis provides tremendous insight into the institution of property, it raises a number of important questions when treated as a comprehensive theory of property. Moreover, the term utilitarian masks a great deal of intellectual and methodological diversity. Rather than a single utilitarian theory, it is more appropriate to speak of a number of utilitarian (or even utilitarian-influenced) property theories . For our purposes, these utilitarian-influenced theories include many contemporary theories that refer to themselves as economic or welfarist . In this chapter, we will explore the broad outlines of these theories, focusing on their points of overlap and also on key areas of disagreement. A BRIEF INTRODUCTION TO UTILITARIANISM Utilitarianism is a consequentialist moral philosophy, that is, one that judges the rightness and wrongness of actions or rules or institutions by the goodness and badness of the consequences they bring about. Utilitarianism assesses the goodness or badness of consequences in terms of their tendency to maximize utility or welfare. Bernard Williams has observed that “[t]he fathers of utilitarianism thought of it principally as a system of social and political decision,” as opposed to “a system of personal morality.” As Williams correctly notes, it is sometimes hard to keep these two domains apart. Nevertheless, it is plainly as a theory of social choice that utilitarianism has been deployed in the context of property theory.