Highly Documented Comparisons and Measurements of...

The comparison of measurement and prediction of prestress losses in prestressed members is highly documented in literature. Hale et al. (2006) studied the prestress losses behavior of girders subjected to increased fiber stresses. They concluded that the previous AASHTO LRFD Specifications equations (2004) overestimated the prestress losses by roughly 50%. It was found that the NCHRP Report 496 (Tadros et al., 2003) equations predicted the losses to within an average of 6%. Currently, there have been quite a few investigations on empirical models for prestress losses for HSC. In a study conducted by Kowalsky et al. (2001) on several HPC bridge girders in North Carolina to determine the prestress losses of HPC girders. The researchers found shrinkage losses were a small component of the overall prestress losses and that the elastic shortening and creep losses were the main contributors. These larger than expected losses from elastic shortening and creep were because of a predicted m odulus of elasticity that was higher than actual. The total prestress losses ranged from 12.9% to 19.1% of the initial jacking stress. In an investigation conducted by Tadros et al. (2003), seven full-scale bridge girders were instrumented in Washington, Texas, Nebraska and New Hampshire to determine the prestress losses of HPC girders. The total prestress losses measured were found to be lower than the AASHTO LRFD (1998) model. Modiï ¬ ed expressions were proposed to AASHTO and later adopted inShow MoreRelatedProject Managment Case Studies214937 Words   |  860 PagesProject, could have been listed under several topics. Several of the cases and situations have seed questions provided to assist the reader in the analysis of the case. An instructor s manual is available from John Wiley Sons, Inc., to faculty members who adopt the book for classroom use. Almost all of the case studies are factual. In most circumstances, the cases and situations have been taken from the author s consulting practice. Some educators prefer not to use case studies dated back to theRead MoreCommunication Management Challenges in Construction Project Execution63139 Words   |  253 Pagesdifferent locations by different individuals and developers at the same time. Because of the relative ease of entry, at least at the lower end of the market, many new builders are attracted to the residential housing construction. Hence, this market is highly competitive, with potentially high risks as well as high rewards. Figure 1-2:   Residential Housing Construction (courtesy of Caterpillar, Inc.) Institutional and Commercial Building Construction Institutional and commercial building construction