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5 CD-ROM). Other bridges beyond the parametric limits include Horizontally curved bridges, for which a system analy- a limited number of prestressed-concrete bridges, two-girder sis is recommended instead of a line-girder approach for bridges with girders spaced as widely as 7.6 m, tub-girder, which effective width is traditionally applied; hybrid, and prestressed-slab bridges. Finite element analy- Segmental bridges; and sis results for these "validation cases" are documented in Tied-arch bridges, with net tension added to flexure on Appendix J (provided on the accompanying CD-ROM). the cross section. Task 7 involved the development of curve-fit expressions for predicting effective width based on the results of the finite element analyses. Development and comparison of various such curve-fit expressions are documented in Appendix K 1.4 ORGANIZATION OF THIS REPORT (provided on the accompanying CD-ROM). This report consists of four chapters as well as the afore- Task 8 addressed evaluating the impact of these candidate beff expressions as compared with the current AASHTO pro- mentioned appendixes (provided on CRP-CD-56). This chap- visions. The basis for this evaluation of impact was taken to ter provides the introduction and research approach, describes be the Rating Factor, considering both service and strength the research objectives, and outlines the scope of the study. limit states, and was documented in Appendix L (provided Chapter 2 describes the findings of the survey and literature on the accompanying CD-ROM). The culmination of this review, new definitions for effective width, verifications of effort was the draft code and commentary language for pro- the FEM (Finite Element Method) modeling approaches posed new effective width provisions, which were docu- employed, highlights of results from the FEM-based para- mented along with their underlying rationale in Appendix M metric study, and insights from the experiments performed. (provided in print herein and on the accompanying CD-ROM). Chapter 3 summarizes the development of candidate design Appendix N (provided on the accompanying CD-ROM) criteria and impact assessment of these criteria using a straight- contains information about the finite element modeling of the forward application of Process 12-50 to show that the subtle prestressed girder bridge structures investigated in this study, differences among the various possible curve-fit expressions while Appendix O (provided in print herein and on the accom- are, for all practical purposes, negligible. This observation panying CD-ROM) presents worked design examples illus- leads to a recommendation of simplified design criteria for trating the use of the new proposed provisions for effective effective width. Highlights of the worked example illustrat- slab width. ing the use of these simplified design criteria are summa- The scope of the investigation excludes consideration of rized. Chapter 4 then summarizes the conclusions of this the following: study and presents suggestions for future research.