THE ANALYSIS OF TRANSVERSE PRESTRESSING EFFECTS IN BRIDGE DECKS.

摘要

The growing awareness of the high cost of bridge deck repair and replacement has focused recent attention on this critical problem of bridge decks. In addition to other possible protective techniques, it has been suggested that design quality of bridge decks might be improved by utilizing transversely prestressed concrete.;The objective of the overall research study of which this dissertation is a part is to develop design criteria for the application of transverse prestressing in bridge decks. This dissertation study focused on the development of structural analysis procedures to assess the distribution of transverse post-tensioning and their verification. The analysis procedures developed were to be experimentally verified for transverse stress distribution in the deck slab of a slab-girder bridge. A finite element model and an associated computer proram were developed and used to study the effects of lateral stiffness of girders or webs, size of end and interior diaphragms, deck slab thickness, bridge length, bridge skew angle, and prestress profile on changing the transverse stress distribution due to transverse post-tensioning of the deck slab. In the box-girder bridge investigation, the number of the cells, section depth and bottom slab thickness were also studied. The computer program was verified using experimental results and was used to generalize the study.;From the analytical and experimental investigations of girder-slab bridges, it was found that the desired transverse stress distribution in transversely prestressed decks is mainly affected by the restraining actions of the end and interior diaphragms and is influenced by the slab thickness, bridge length, bridge skew angle and prestress profile. Possible measures to counter the reducing effect of diaphragms on slab transverse stresses were suggested.;From the analytical investigation of box-girder bridges, it was found that the transverse stress distribution in transversely prestressed decks is affected by the lateral restraining actions of the webs and is influenced by number of cells, section depth, deck slab thickness, bottom slab thickness, web inclination and prestress profile. . . . (Author's abstract exceeds stipulated maximum length. Discontinued here with permission of author.) UMI.;In contrast to ordinary reinforcing steel, utilizing prestressed reinforcement will definitely introduce stresses in the deck slab (and possibly other members of the bridge as well) because the deck slab undergoes an elastic shortening. Due to the restraining actions of the girders and diaphragms in girder-slab bridges, and of the webs and diaphragms in box-girder bridges, the desired transverse stress distribution in the deck may be altered.