Lightweight Concrete: Development of Mild Steel in Tension.

摘要

Much of the fundamental basis for the current lightweight concrete provisions in the AASHTO LRFD Bridge Design Specifications is based on research of lightweight concrete (LWC) from the 1960s. The LWC that was part of this research used traditional mixes of coarse aggregate, fine aggregate, portland cement, and water. Broad-based advancement in concrete technology over the past 50 years has given rise to significant advancements in concrete mechanical and durability performance. This document describes the results of tests on high-strength LWC splice beams that were conducted as part of an overall FHWA research project on LWC. The FHWA test results are included in a database of bond tests with over 200 tests on LWC specimens available in the literature. An analysis of the database was used to develop potential revisions to provisions related to LWC within Chapter 5 of the AASHTO LRFD Specifications. The framework for addressing LWC in the specifications that was proposed previously as a part of this research effort is applied to the design expression for development length of mild steel. The framework includes a proposed revision to the definition of LWC and a proposed modification factor relevant to LWC structural performance.