NCHRP Report 449, Test Methods for Elastomeric Bridge Bearings, contains the findings of a study undertaken to develop performance-related specifications for elastomeric bridge bearings. The report includes recommended specifications and three new test methods for evaluating essential properties of elastomeric bearings. The material in this report will be of immediate interest to bridge designers and materials engineers.
Elastomeric bridge bearings have generally performed satisfactorily under current AASHTO and state DOT materials-test methods and requirements. Nevertheless, there has been concern that bearings are being unnecessarily rejected because of noncompliance with testing requirements that may not be essential or appropriate. Although specifications exist for the materials, design, and construction of elastomeric bearings, little information has been available on the relationship between test results and field performance. Additionally, some current materials-test requirements are thought to be inappropriate for bearing applications. If tests that are accurate and essential predictors of field performance can be employed, testing requirements and elastomeric bearing costs can be reduced.
Under NCHRP Project 10-51, the University of Texas at Austin addressed these concerns. Through laboratory testing and mathematical analysis, 8 of the 15 existing required tests were demonstrated to be unnecessary. Three new tests were developed to replace existing tests for creep, shear modulus, and compressive strain. This report provides full details of the research methods and the new test methods and presents recommended specifications for the acceptance testing of elastomeric bearings.