The overall objective of this project was to develop specifications for unconfined, plain and reinforced elastomeric bridge bearings.
The findings of Phase I of Project 10-20 were published as: NCHRP Report 248, "Elastomeric Bearings Design, Construction, and Materials," and included recommendations for improved specifications for unconfined, plain and reinforced elastomeric bridge bearings. These recommendations were based on currently existing information. In 1985, AASHTO adopted many of the recommendations of the Phase I research, substantially revising the provisions for elastomeric bearings in the AASHTO Standard Specifications for Highway Bridges.
The objective of the second phase of research was to develop a more sophisticated specification for special applications and to improve the simplified provisions recommended in Phase I. The Phase II research included testing and evaluation of bearing compression, rotation, shear, stability, fatigue, and low temperature behavior. Recommendations for a more rational bearing specification were included in the project report. The findings of Phase II of Project 10-20 were published as NCHRP Report 298, "Performance of Elastomeric Bearings."
The objectives of the third phase of research were to resolve design procedures for special applications of unconfined elastomeric bearings and to provide a critical state-of-the-art review of design and construction procedures for pot bearings. The Phase III research included additional experimental work on the low temperature behavior of unconfined elastomeric bearings in order to assist in the development of recommended manufacturing tolerances, bearing prequalification procedures and tests, and improved design specifications. The findings of the unconfined bearing research are contained in NCHRP Report 325, "Low Temperature Behavior and Acceptance Criteria for Elastomeric Bridge Bearings." The pot bearing state-of-the-art review is summarized in NCHRP Research Results Digest 171, "Pot Bearings and PTFE Surfaces."