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Journal ArticleDOI

Analysis of the ASTM C512 Spring-Loaded CREEP Frame

01 Oct 2019-Journal of Materials in Civil Engineering (American Society of Civil Engineers (ASCE))-Vol. 31, Iss: 10, pp 04019234

Abstract: The test method of ASTM C512 (ASTM. 2015. Standard test method for creep of concrete in compression. ASTM C512/C512M. West Conshohocken, PA: ASTM) dictates the use of a spring-loaded creep ...
Topics: Creep (51%)
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01 Jan 2020-
Abstract: In this paper, the flexural creep behavior of hooked-end steel fiber reinforced high-strength concrete was evaluated to investigate the steel fiber content influence on long-term behavior of flexural members. An experimental program consisted of nine prismatic beam specimens with dimensions of 150 × 150 × 600mm reinforced with different contents of steel fiber (0, 0.75 and 1.5% at the volume fraction). To introduce flexural creep loading to notched prismatic beam specimens, a four-point bending test setup was used. The sustained load with 40% of the flexural strength was applied by means of a lever system and controlled by a load cell for 90 days. During sustained loading, crack mouth opening displacement (CMOD) was monitored. Conventional flexural test after creep tests were carried out to evaluate the residual capacity of each specimen. Test results showed that steel fiber content has a significant effect on the flexural creep behavior of high-strength concrete and long-term flexural load with 40% of flexural strength doesn’t generate negative effects on the residual capacity of steel fiber reinforced high-strength concrete.

3 citations

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Journal ArticleDOI
Joseph Abate, Ward Whitt1Institutions (1)
TL;DR: A framework for constructing algorithms to invert Laplace transforms numerically and it is shown that it can be advantageous to use different one-dimensional algorithms in the inner and outer loops.
Abstract: We introduce and investigate a framework for constructing algorithms to invert Laplace transforms numerically. Given a Laplace transform \hat{f} of a complex-valued function of a nonnegative real-variable, f, the function f is approximated by a finite linear combination of the transform values; i.e., we use the inversion formula f(t) \approx f_n (t) \equiv \frac{1}{t} \sum_{k = 0}^{n}\omega_{k}\hat{f}\biggl(\frac{\alpha_{k}}{t}\biggr),\quad 0 where the weights ωk and nodes αk are complex numbers, which depend on n, but do not depend on the transform \hat{f} or the time argument t. Many different algorithms can be put into this framework, because it remains to specify the weights and nodes. We examine three one-dimensional inversion routines in this framework: the Gaver-Stehfest algorithm, a version of the Fourier-series method with Euler summation, and a version of the Talbot algorithm, which is based on deforming the contour in the Bromwich inversion integral. We show that these three building blocks can be combined to produce different algorithms for numerically inverting two-dimensional Laplace transforms, again all depending on the single parameter n. We show that it can be advantageous to use different one-dimensional algorithms in the inner and outer loops.

385 citations

Journal ArticleDOI
Abstract: The material properties of high-performance concrete (HPC) directly affect the design and construction of prestressed HPC bridge girders and their cast-in-place deck slabs. This paper discusses research experiments conducted over more than 2 years on material properties such as creep, shrinkage, and modulus of elasticity of 3 HPC mixtures with local materials from Nebraska. Test results from this research show that current ACI equations for shrinkage, creep, and modulus of elasticity of concrete do not accurately predict these material properties for HPC. Revised formulas for shrinkage strain and creep coefficient are proposed. Through this study, it was also indicated that it would be desirable to determine experimentally the shrinkage strain, creep coefficient, and modulus of elasticity using the locally available aggregates for the specified HPC mixture proportions.

94 citations

Journal ArticleDOI
01 Jun 1958-

39 citations

Journal ArticleDOI
01 Feb 1928-

15 citations

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