Experimental evaluation of the mechanical properties of steel reinforcement at elevated temperature

Abstract

This paper describes an experimental investigation into the influence of elevated temperatures on the mechanical properties of steel reinforcement. The study includes tests carried out under ambient temperature as well as steady-state and transient elevated temperature conditions. A complementary study, in which the residual post-cooling properties of reinforcing bars were examined, is also described. The tests focused on assessing the performance of 6 and 8 mm diameters, although 10 mm bars were also considered in some cases. The specimens included both plain and deformed bars. After providing an outline of the experimental set-up and loading procedures, a detailed account of the test results is presented and discussed. Apart from the evaluation of stress-strain response and the degradation of stiffness and strength properties, particular emphasis is given to assessing the influence of temperature on enhancing the ductility of reinforcement. The findings of this study have direct implications on procedures used for predicting the ultimate behaviour of structural floor elements and assemblages during, and following, exposure to elevated temperatures.

Failure Assessment of Lightly Reinforced Floor Slabs. II: Analytical Studies

“…All of the eighteen slab tests described previously are used for calibration and validation. As shown before (Cashell, 2009;Cashell et al, 2010), within realistic limits, the bond strength has a relatively small effect on the load-deflection response whereas it has a pronounced influence on the failure level. It is therefore essential that a realistic representation of the idealised effective bond strength is employed for an accurate failure assessment.…”

“…On the other hand, the concrete is rigid in compression and does not contribute to the behaviour in tension. Furthermore, the bond-slip relationship is represented as a rigid-plastic idealisation which was previously validated (Cashell, 2009;Cashell et al, 2010) and is expressed as the total bond force per unit length per unit width (τ b ).…”

“…The analytical approaches are calibrated and validated with reference to available experimental results. The information acquired in another experimental programme (Elghazouli et al, 2009) is utilised within the various models in order to provide an accurate representation of the temperature-dependant material properties.…”

Pengaruh Suhu Tinggi Terhadap Lendutan dan Kekakuan Balok Beton Bertulang

“…Kekuatan sisa baja tulangan jenis hot rolled dan cold worked yang telah mengalami pemanasan pada suhu 600 ˚C hanya menunjukkan penurunan kekuatan sebesar 10% -15% meskipun regangan ultimate mengalami kenaikan sebesar 50% pada jenis hot rolled dan 150% pada jenis cold worked [4].…”

“…Reduksi nilai kuat tekan dan kuat tarik yang terjadi pada beton serta peningkatan intensitas retak pada zona transisi antara agregat dengan pasta semen akan membuat balok beton bertulang mengalami reduksi besarnya nilai beban yang mengakibatkan balok retak pertama, leleh pertama maupun besarnya beban maksimum, disamping itu penurunan kuat tarik yang terjadi pada baja tulangan [4] juga akan mengakibatkan nilai kapasitas lentur penampang untuk balok yang telah mendapatkan pengaruh suhu tinggi mengalami penurunan.…”