Design principles of totally prefabricated counterfort retaining wall system compared with existing cast-in-place concrete structures

摘要

Counterfort retaining walls are usually constructed with cast-in-place concrete, which can be complicated by site preparation, formwork, and traffic congestion. An alternative is the totally prefabricated concrete counterfort retaining wall, which is composed of a wall component (face panel and counterforts) and a base slab connected on-site through headed anchors. The anchors extend downward from the counterforts and are designed to be embedded in shear pockets in the base slab. While the design of totally prefabricated concrete counterfort retaining walls shares some features with cast-in-place concrete systems, it also has specific requirements for anchor connections, strength of shear pockets, and counterfort design. The proposed totally prefabricated concrete counterfort retaining wall design was developed according to the 2012 AASHTO LRFD Bridge Design Specifications and compared with an existing cast-in-place counterfort system in Chicago, Ill., for both structural and economic performance. The totally prefabricated concrete counterfort retaining wall's design strength (moment and shear) surpassed that of the existing system with an overall reduction in concrete volume reaching 57%. A parametric study identified a counterfort spacing-to-base length ratio of 0.35 and a counterfort extension-to-heel length ratio of 0.6 as optimal values. This geometry achieved the highest economic efficiency while meeting all strength requirements of the AASHTO LRFD specifications.