Influences of the incremental launching construction method on the sizing of prestressed concrete bridge decks

摘要

The construction of a prestressed concrete bridge deck in a fixed formwork placed behind an abutment with incremental launching of the deck as it is gradually built - a process at first sight comparable to a cadenced extrusion - is a very competitive technique for a wide range of deck spans and sizes. During launching, the movement of the support sections produces transitory stresses that affect the sizing of the deck and increase the consumption of materials. Although materials are only one component of the overall cost of the deck, and the costs associated with the particular building technique used are often much more significant when comparing different alternatives, correct pre-estimations of cost cannot fail to take into account this tendency to oversize with respect to service requirements. A comparison of the main dimensions of the cross sections of decks built by incremental launching with those built by alternative techniques provides an opportunity to illustrate the effects on structural sizing, and data interpolation may help in pre-sizing new structures.