Experimental Study on the Behaviours of Post-tensioned Concrete Members with Unbonded Tendons

Iqbal Peera; Nazar K. Oukaili

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Publication Date

Mon Feb 01 2021

Journal Name

Iop Conference Series: Materials Science And Engineering

Volume

1067

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Experimental Study on the Behaviours of Post-tensioned Concrete Members with Unbonded Tendons

Iqbal Peera

Nazar K. Oukaili

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AbstractThis paper presents experimental results regarding the behaviours of eight simply supported partially prestressed concrete beams with internally unbonded tendons, focusing particularly on the effect of three different variables: concrete compressive strength, <italic>fc </italic>′; jacking stress, <italic>fj </italic>; and the prestressing index, ω. Increasing the concrete compressive strength from 35 MPa to 60 MPa was seen to lead to an increase in load-carrying capacity by about 10%. The load capacity was also affected, though to a lesser extent, by the jacking stress. The failure load of partially prestressed concrete beams with internally unbonded strands was increased by about 2.5%, to 10%, when the jacking stress increased from 0.5 to 0.7 of the strand’s ultimate strength, <italic>fpu </italic>. The test results showed that the prestressing index was the most influential parameter among the examined variables. The experimental results of the stress increase in unbonded strands at failure and the ultimate load resistance of members were also compared to the analytical results of various standards and research methodologies for verification.

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Publication Date

Thu Nov 19 2020

Journal Name

Indonesian Journal Of Chemistry

Determination of Eugenol in Personal-Care Products by Dispersive Liquid-Liquid Microextraction Followed by Spectrophotometry Using p-Amino-N,N-dimethylaniline as a Derivatizing Agent

dispersive liquid-liquid microextraction

derivatizing agent

eugenol

p-amino-N

N-dimethylaniline

Bahaa Malik

Omar

Sarmad Bahjat

Keith Edward

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Two simple methods for the determination of eugenol were developed. The first depends on the oxidative coupling of eugenol with p-amino-N,N-dimethylaniline (PADA) in the presence of K3[Fe(CN)6]. A linear regression calibration plot for eugenol was constructed at 600 nm, within a concentration range of 0.25-2.50 μg.mL–1 and a correlation coefficient (r) value of 0.9988. The limits of detection (LOD) and quantitation (LOQ) were 0.086 and 0.284 μg.mL–1, respectively. The second method is based on the dispersive liquid-liquid microextraction of the derivatized oxidative coupling product of eugenol with PADA. Under the optimized extraction procedure, the extracted colored product was determined spectrophotometrically at 618 nm. A l

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