ACI 342R-2016
Report on Flexural Live Load Distribution Methods for Evaluating Exisiting Bridges

Standard No.

ACI 342R-2016

Release Date

2016

Published By

ACI - American Concrete Institute

Scope

This report is intended for the bridge engineering community@ particularly engineers responsible for bridge load rating@ to provide basic guidance on the methods and tools available for determining live load distribution behavior of in-service bridges. The objective is to present guidance on available methods for determining live load distribution@ including approximate formulas@ structural analysis@ or load testing. The selection of a particular method of analysis is presented within the context of the intended level of refinement and bridge type@ such as slab@ beam-slab@ and box girder. Included in this report are descriptions@ a brief history@ and background of the flexural load distribution phenomena and a summary of design and analysis methods used to describe the phenomena in practice. This report provides an overview of criteria for transverse load distribution@ including their limitations and acceptability; a summary and description of the use of refined methods of analyses for transverse load distribution; and load test methods. A series of case studies are presented in the latter part of the report to serve as a comparative analysis of commonly used live load distribution methods and their performance in describing the behavior of in-service structures. While this distribution phenomenon is relevant to a variety of force effects@ this report focuses exclusively on flexure. The treatment of shear is a topic of future work by the committee and will be part of a guide on the in-service evaluation of concrete bridges@ but is beyond the scope of this report. For a treatment of shear load distribution@ thereader is encouraged to review existing literature on the topic (Bakht et al. 1983; Ebeido and Kennedy 1995@ 1996; Modjeski and Masters Inc. 2002; Barr and Amin 2006; Suksawang et al. 2013).