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Code Provisions for High Strength Concrete Strength-Temperature Relationships at Elevated Temperatures.


pdf icon Code Provisions for High Strength Concrete Strength-Temperature Relationships at Elevated Temperatures. (535 K)
Phan, L. T.; Carino, N. J.

Materials and Structures, Vol. 36, No. 256, 91-98, March 2003.

Keywords:

codes; high strength concrete; concretes; temperature; concrete strength

Abstract:

This paper presents results of experiments, conducted at NIST and elsewhere, to measure compressive strength of concrete at elevated temperature. The paper compares the test data with existing design rules and recommendations to assess their applicability to HSC. Based on the compiled data, the paper proposes new stength-temperature relationship for HSC and discusses the need for standardizing the test procedure for testing concrete at high temperature and for a revision of the current design guides to include new data for properties of concrete at high temperature. Degradation of concrete strength due to short-term exposure to elevated temperature has been studied as early as the 1950s. Among the early studies were those of Abrams [1968, 1971], Malhotra [1956], and Schneider [1983, 1985, 1988]. Results of these studies constituted the technical basis for the provisions and recommendations for determining concrete strength at elevated temperature in many existing codes and authoritative design guides. While these studies provided valuable information on the variation of concrete strength as a function of temperatures, almost all used specimens made with NSC (according to the current ACI definition). Thus, in light of the results of recent studies which have shown that HSC behavior at elevated temperature may be significantly different from that of NSC [Phan (1996); Phan and Carino (1998, 2001)], question may be raised as to whether existing design rules and recommendations are applicable to HSC.