A STUDY OF THE EFFECTS OF PLACING A LIGHTWEIGHT CONCRETE DECK ON PRESTRESSED GIRDERS DESIGNED FOR A NORMAL WEIGHT CONCRETE DECK

摘要

A study was performed to demonstrate the effects of changing the deck concrete type after a new design has been completed using a normal weight concrete deck, and for projects where a normal weight concrete deck is being replaced on an existing bridge. Lightweight concrete decks are usually used to reduce structure weight to improve ratings or structural efficiency, or to allow reuse of existing substructure units when widening a bridge. But lightweight concrete has also recently been considered as a strategy to reduce deck cracking. Therefore, this study is also important for new designs where a deck could be either normal weight concrete or lightweight concrete depending on the crack reduction strategy selected by a contractor.rnThis paper examines the consequences of replacing a normal weight concrete deck with either a sand lightweight concrete deck or an all lightweight concrete deck. The effect of the change in deck type is evaluated for key design parameters, quantities related to service and strength limit state behavior, and rating factors. Typical prestressed concrete girder bridge cross-sections are studied for short, medium and long spans so the effect of the changing dead to live load ratios can be observed.