The effect of traditional reinforcement – prestressed reinforcement ratio on the behaviour of concrete beams

Abstract

Firstly, the effect of traditional reinforcementprestressed reinforcement ratio on the behaviour of concrete beams up to failure was experimentally investigated. The beams were 10 m long and 0.5 m high, with different ratios of traditional and prestressed reinforcement. The total quantity of reinforcement in each beam was selected to provide their equal ultimate bending bearing capacity. Deflections, stresses in concrete, traditional and prestressed reinforcement, as well as concrete cracks, were monitored until the beams failure. Using the previously developed numerical model of authors of this paper for static analysis of spatial frame structures, which can simulate main nonlinear effects of their behaviour, then numerical analysis of tested beams was performed. Good agreement was obtained between the experimental and the numerical results, which confirms the possibility of practical application of the adopted numerical model. Main conclusions and recommendations for practical applications according to results of performed tests are given at the end. Keywords: Experimental test / traditional reinforcement / prestressed reinforcement / beam failure / numerical model Zuerst wurde der Effekt der Verhältniszahl (traditionelle Verstärkungvorgespannte Verstärkung) auf das Verhalten von Betonträgern bis zum Bruch experimentell untersucht. Die Träger waren 10 m lang und 0,5 m hoch mit verschiedenem Verhältnis von traditioneller und vorgespannter Verstärkung. Die gesamte Verstärkung in jedem Balken wurde ausgewählt, um ihre Lasttragfähigkeit zu erhalten. Durchbiegung, Betonspannung, traditionelle und vorgespannte Verstärkung, aber auch Risse im Beton wurden bis zum Versagen aufgezeichnet. Basierend auf dem von den Autoren dieses Beitrags entwickelten numerischen Modells zur statischen Analyse von räumlichen Tragwerken, das die wichtigsten nichlinearen Effekte beinhaltet, wurde das Verhalten der getesteten Balken simuliert. Die gute Übereinstimmung zwichen den experimentellen und numerischen Ergebnissen bestätigt, dass das numerische Modell in der Praxis eingesetzt werden kann. Die wesentlichen Schlussfolgerungen und Empfehlungen für praktische Anwendungen, basierend auf den Ergebnissen der Untersuchungen, werden am Ende angeführt.

Modelling of Steel Creep at High Temperatures Using an Implicit Creep Model

“…The numerical model for the behaviour of structures exposed to fire must be able to describe, beside the nonlinear behaviour of structures under load, the development of the temperature inside the structure and changes of material parameters at high temperatures as well. A complete non-linear calculation must include the geometry of the cross-sections, the type and distribution of reinforcement (for reinforced concrete structures) and loading conditions, as well as the non-linear constitutive stress-strain material relationship [6][7][8][9][10][11][12]. The results obtained by a nonlinear calculation are more realistic, especially in predicting the state of stresses and strains in a particular structural element.…”

“…Model description. FIRE STASUS is generally based on a spatial beam-column element analysis (spatial frame structures), which has a detailed description in [6,7,11,12]. The model consists of three submodels: a model for structural analysis (Bernoulli beam elements with six degrees of freedom), a model for calculation of the nonlinear stress-strain distribution in the crosssection and a 3D transient nonlinear heat transfer model (eight node cube element) [13].…”

Experimental testing of concrete beams with different levels of prestressing

“…These studies can be found in various studies. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] Aparicio et al 1 tested externally prestressed monolithic and segmental concrete beams in bending, combined bending and shear. Ashour et al 2 tested 27 reinforced concrete beams to study the effects of steel fibres, longitudinal tensile reinforcement ratios and concrete compressive strengths on the flexural behaviour of reinforced concrete beams.…”

“…Ombres 10 researched (i) the strengthening effect of the FRCM system on the flexural behaviour of reinforced concrete beams in terms of ultimate capacity, deflections and ductility and (ii) the influence of the fibre reinforcement ratio on the occurrence of premature failure modes. Radnic´et al 11 studied the effect of the degree of prestressing on the behaviour of concrete beams. Rashid 12 tested 16 reinforced concrete beams to evaluate the implications of using highstrength concrete.…”

“…Radnić et al. 11 studied the effect of the degree of prestressing on the behaviour of concrete beams. Rashid 12 tested 16 reinforced concrete beams to evaluate the implications of using high-strength concrete.…”