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International Concrete Abstracts Portal

Showing 1-2 of 2 Abstracts search results

Document: 

17-477

Date: 

September 1, 2018

Author(s):

Yu-Szu Chen, Hayder A. Rasheed, and Robert J. Peterman

Publication:

Materials Journal

Volume:

115

Issue:

5

Abstract:

The development of stress-strain models for prestressing wires has not been performed in earlier studies. The existing modeling approaches (the PCI strand equation and the ACI equation) lack sufficient accuracy when compared to the actual response of prestressing wires. This paper improves the accuracy in predicting fps by modifying the existing “Power Formula” to suit the response of these wires. The newly developed “Wire Specific Formula” was based on using the actual stress-strain curves collected from experimental testing in an analytical modeling process. A total of 13 types of prestressing wires with 5.32 mm (0.2094 in.) diameter were tested and the wires’ geometric properties were measured. The adapted Power Formula captured the accuracy of the actual experimental or design-oriented stress-strain response very well through linear regression of key parameters, showing strong correlation. Then, the same Power equation is redeveloped for design-oriented purposes when the level of ultimate prestressing strength is specified or assumed. The present version of the Power Formula can, accordingly, be used either for specific wire type (Wire Specific Formula) or certain strength grade (Wire Strength Formula).

DOI:

10.14359/51706940


Document: 

16-216

Date: 

March 1, 2017

Author(s):

Metwally Abd Allah Abd Elaty, Mariam Farouk Ghazy, and Mohamed Fattouh Abd El Hameed

Publication:

Materials Journal

Volume:

114

Issue:

2

Abstract:

This paper optimizes the properties of fiber-reinforced geopolymer concrete by principal component analysis. The approach is to first use the Latin Cube Orthogonal Array as an experimental plan to carry out the experiments. Four responses—namely, splitting tensile strength, critical stress intensity factor, fracture energy, and degree of brittleness—were conducted. Sodium hydroxide ratio, polypropylene fiber content, metakaolin replacement by mass of fly ash, and alkaline solution to binder ratio were chosen as control factors at three levels each. The single-response optimization of each response was conducted by the Taguchi method. To transform the correlated concrete properties, a principal component analysis was employed to correspond to multi-response cases. These principal components were accumulated further to calculate the multiple performance characteristic index (MPCI). Finally, a combined quality loss (CQL) was defined as the deviation of MPCI, which serves as the single-objective function for optimization with the aim to minimize it.

DOI:

10.14359/51689563


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