Influence of the Percentage of Reinforcement on the Compressive Forces Loss in Pre-stressed RC Beams Strengthened with a Package of Steel Bars

Production Engineering Archives

Selejdak

Bobalo

et al. 2021

Self Cite

This article presents the materials of deformability studies of pre-stressed steel-concrete beams reinforced with a package of reinforcement with different ratio of tape and rebar in the pure bending moment zone. The aim of the research was determination of the reinforcement percentage influence, for pre-stressed reinforced concrete beams reinforced with a package of reinforcement on their deformability. Also, the aim was to evaluate the effectiveness of using pre-stressed rebar in combined reinforcement. The practical significance of the experimental research is to study the deformability in pre-stressed bending elements with external tape and rebar reinforcement, taking into account the influence of different ratios of reinforcement areas within the combined reinforcement and development of proposals for such structures` calculation and design. The scientific novelty of the research is in obtaining the deformability characteristics of reinforced concrete beams reinforced with a package of reinforcement (tape and steel bars with periodic profile) with different ratios in the case of static loads` action.

Section: Methodsmentioning

confidence: 99%

Influence of the percentage of reinforcement by unstressed rebar on the deformability of pre-stressed RC beams

Production Engineering Archives

Selejdak

Bobalo

et al. 2021

Self Cite

“…Studying building structures always begins with the study of their design features [1]. This is the first step in the development of a new structure, or the detection of features in the known one.…”

Section: Introductionmentioning

confidence: 99%

Development methodology of determinating residual carrying capacity of reinforced concrete beams with damages tensile reinforcement which occurred during loading

Vegera

Vashkevych

et al. 2021

EEJET

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This paper reports the improved and verified procedure for calculating reinforced concrete beams affected by damage to stretched reinforcement when loaded. The main results from testing the reinforced concrete beams with damage in the stretched zone in the form of one hole in the reinforcement in the middle of the beam are given. The variable parameter of the study was the level of load resulting in the damage. It acquired values of 0, 30 %, 50 %, 70 % of the bearing capacity of control undamaged samples. Overall, the results of testing 12 samples are given. A new procedure has been proposed for taking into consideration changes in the mechanical characteristics of stretched reinforcement arising from its damage. This makes it possible to more accurately establish the bearing capacity of reinforced concrete bended elements affected by damage to their reinforcement during operation. The analysis of the calculation, compared with experimental quantities, led to a conclusion that the strain model could determine when the bearing capacity of reinforced concrete beams without damage and with damage to working reinforcement is exhausted. Based on the improved algorithm, the principle of using a strain model was proposed to establish when the bearing capacity of damaged samples, taking into consideration the effect of the load level, is exhausted. The theoretical estimation, considering when the bearing capacity is exhausted, showed results that are 3...21 % less than the experimental values, which ensures reliability of calculation of such structures. The proposed calculation provides a new approach to determining the bearing capacity of reinforced concrete beams damaged during operation. That, in turn, makes it possible to more accurately determine the residual bearing capacity of structures and increases the safety of their operation.

“…The calculation was carried out according to the deformation model with embedded theoretical nonlinear curves of concrete destruction. For the experimental studies of reinforced concrete beams with pre-strained working reinforcement [6,7], the limit deformation and concrete stress are relevant, since this is one of the criteria for such structures in terms of exhaustion of their bearing capacity. The use of downward concrete deformation curve is relevant for the calculation of reinforced concrete structures damaged during operation [8,9].…”

Section: Introductionmentioning

confidence: 99%

Formation of a complete stress-strain curve of concrete using digital image corellation

Pavliv

2021

EEJET

Self Cite

This paper reports the development and verification of a new procedure for formation of a complete stress-strain curve of concrete with a downward region of strain by using a digital image correlation method. A new technique to build spectle patterns on the surface of concrete is described. That makes it possible to accurately enough reproduce the spectle patterns on the surface of concrete and perform a high-quality analysis of strains involving digital image correlation. The advantages of this research technique have been established when predicting the formation of internal cracks in concrete followed by their propagation. In addition, using the digital image correlation methodology makes it possible to obtain strains of the entire studied plane of the sample at each stage of loading. This procedure provides an opportunity to investigate a change in strains and the movement of individual points or areas when studying concrete surfaces. That is a relevant issue as it enables more detailed diagnostics of existing reinforced concrete structures. To check the accuracy of this procedure application, a mechanical gauge with an accuracy of 0.001 mm was additionally installed. 2 high-speed monochrome CCD cameras with different lenses were used in determining concrete strains involving the digital image correlation technique. The deformations were controlled with a period of time every 250 ms. The load was controlled by an additional third camera with a speed of 50 frames/second. The result of the experimental study is the formed full concrete destruction diagram with a downward region of strain. The deviation of the results of strains based on the mechanical gauge with an accuracy of 0.001 mm with a base of 200 mm from those acquired by the digital image correlation procedure was mainly up to 10 %, which confirms the reliability of the results. The results of this work allow a more accurate calculation of reinforced concrete structures in the practice of design, inspection, or reinforcement of existing structures