scholarly journals Calculation of damage RC constructions according to deformation model

2020 ◽  
Vol 2020 (2) ◽  
pp. 99-106
Author(s):  
Yaroslav Blikharskyy ◽  

This article presents results of a theoretical study of reinforced concrete beams with damaged reinforcement. The change of micro-hardness of a reinforcing rebar’s with a diameter of 20 mm of A500C steel in the radial direction is investigated and the thickness of the heat-strengthened layer is established. It is established that the thickness of the thermo-strengthened steel layer of the reinforcing bar with a diameter of 20 mm of A500C is approximately 3 mm. It is shown that the strength characteristics of this layer are on 50% higher compared to the core material of the rebar, while the plasticity characteristics are lower. The aim of the work is to determine the strength and deformability of reinforced concrete structures without damaging the reinforcement and in case of damage. Determining the impact of changes in the physical characteristics of reinforcement on the damage of reinforced concrete structures, according to the calculation to the valid norms, in accordance with the deformation model. To achieve the goal of the work, theoretical calculations of reinforced concrete beams were performed according to the deformation model, according to valid norms. This technique uses nonlinear strain diagrams of concrete and rebar and is based on an iterative method. According to the research program 3 beam samples were calculated. Among them were undamaged control sample with single load bearing reinforcement of ∅20 mm diameter – BC-1; sample with ∅20 mm reinforcement with damages about 40% without changes in the physical and mechanical properties of reinforcement – BD-2 and sample with ∅20 mm reinforcement with damages about 40% with changes in the physical and mechanical properties of reinforcement – BD-3. The influence of change of physical and mechanical characteristics of rebar’s on bearing capacity of the damaged reinforced concrete beams is established.

2015 ◽  
Vol 660 ◽  
pp. 186-191 ◽  
Author(s):  
Marina Lute

The purpose of this paper is looking at the dynamic response of existing reinforced concrete structures which have possibly sustained various levels of damage, a set of tests need to be identified that will be able to detect damage and quantify the damage if damage exists. In this work it is presented a further study on the effect of damage on the behavior of reinforced concrete beams. In particular, the non-linear behavior of these beams is considered once significant cracking has been introduced, outlining the stage of testing carried out in dynamic field.


Author(s):  
Дронов ◽  
Andrey Dronov

Two types of steel reinforcement depassivation process: carbonation of concrete and chloride penetration are considered in the article. The comparison between the corrosion due to carbonation of concrete and the chloride-induced corrosion was carried out. It was found out, that chlorides induced corrosion is potentially more dangerous than that resulting from carbonation. Method of durable tests of reinforced concrete structures under the action of the gravitational load and the corrosive chloride environment is described in the article. The results of experimental research on reinforced concrete structures with corrosive damages to steel reinforcement are given in the article. The properties of corrosion cracking in the case of the pitting corrosion were determined. The character of corrosive damage distribution along the reinforcement bars and its effect on the strength of reinforced concrete beams were determined.


2013 ◽  
Vol 712-715 ◽  
pp. 966-969 ◽  
Author(s):  
Ze Bao Kan ◽  
Yan Ru Li

The present status of reinforced concrete structure confined by FRP is introduced, and the recent technical researches of reinforced concrete beams and columns confined by BFRP are summarized. Based on those researches, the mechanical properties and calculation models are analyzed. At the same time, the seismic performance of reinforced concrete beams and columns confined by BFRP is also explored.


2002 ◽  
Vol 8 (3) ◽  
pp. 164-168
Author(s):  
Juozas Valivonis

In many cases concrete structures with prestressed steel being sufficiently strong do not meet requirements for stiffness. It is possible to avoid steel prestressing in concrete structures by means of providing additional non-metallic reinforcement, which gives opportunity to increase stiffness of beams significantly. Experimental investigations of reinforced concrete beams with external non-metallic reinforcement were made. Method for calculation of deflection of beams with external non-metallic reinforcement is presented in this article. Theoretical calculations of deflections using the proposed method were performed. Sufficiently good agreement with experimental deflection values was obtained.


2021 ◽  
Vol 13 (9) ◽  
pp. 168781402110449
Author(s):  
Xiwu Zhou ◽  
Wen Zhang ◽  
Xiangyu Wang

In the present study, based on the previous impact resistance test study results regarding stainless steel reinforced concrete beams, six steel fiber stainless-steel reinforced concrete (SFSRC) beams were subjected to drop-hammer impact tests using an advanced ultra-high heavy multi-function drop hammer impact test system. The goal was to further investigate the mechanical properties of SFSRC beams under impact load conditions. The influencing effects of the steel fiber content and impact velocity levels on the impact resistance mechanical properties of SFSRC beams were analyzed. A digital image correlation method (DIC) was used to analyze the full-field strain and displacement values of the specimens. The results revealed that the steel fibers had significantly enhanced the overall energy dissipation and crack resistance capacities of the specimens, and also improved the brittleness of the stainless steel reinforced concrete beams. In addition, the addition of steel fibers effectively inhibited the local damages of the beam-hammer contact areas. In this study’s experiments, the impact resistance of the beams was observed to be the highest when the fiber content was 2.0%. The internal force formula of the local response stage of the beams showed that the shearing effects had significant impacts on the overall failure modes of the specimens. It was found that with the increases in impact velocity, the failure mode of the SFSRC beams transitioned from bending failure to shear failure, and then to a punching shear failure mode. The DIC results indicated that the addition of steel fiber improved the bonding performances between the concrete matrixes, along with inhibiting the crack development rates through the bond force between the fiber and the concrete.


Author(s):  
Dong-Jin Yoon ◽  
W. Jason Weiss ◽  
Surendra P. Shah

Reinforced concrete beams were tested in flexure, and their acoustic emission (AE) response was recorded. This research was performed to investigate the characteristic AE response that is associated with microcrack development, localized crack propagation, corrosion, and debonding of the reinforcing steel in an attempt to use AE to characterize the source of damage. Concrete beams were prepared to isolate these damage mechanisms by using unreinforced, notched-unreinforced, reinforced, and corroded-reinforced specimens. The AE response was analyzed to obtain key parameters such as the total number and rate of AE events, the amplitude and duration of the events, and the characteristic features of the waveform. Initial analysis of the AE signal has shown that a difference in the AE response can be observed depending on the source of the damage. By plotting the AE signal amplitude versus duration (cross-plot), it can be seen that distributed microcracking is typically characterized by a relatively low amplitude and short duration, whereas debonding cracks have a higher amplitude and longer duration. The Felicity ratio (ratio of the load level at which AE activity begins to occur and the previous loading level) exhibits a favorable correlation with the overall damage level, and the total number of AE events that occur during unloading may provide an effective criterion for estimating the level of corrosion distress in reinforced concrete structures. Based on these results, AE parameter analysis may provide a promising approach for estimating the level of damage and corrosion distress in reinforced concrete structures.


2018 ◽  
Vol 7 (3.2) ◽  
pp. 236
Author(s):  
Grigoriy Masiuk ◽  
Oleksandr Yushchuk ◽  
Andrii Paschenko

The article is devoted to the experimental studies of the stress and strain state of the two-pass reinforced concrete beams under the influence of low-cyclic repeated and alternating loads. Based on the results of experimental studies, the effect of low-cyclic repeated and alternating loads on the change of the stress and strain state of continuous reinforced concrete beams has been established. In the course of testing the sample, it was found that the stress and strain state of the beams under the action of the above mentioned loads is significantly different from the stress and strain state of the beams under the action of nonalternating static loads, namely, the decrease of the bearing capacity, the increase of the deflections and the width of the cracking. All this is due to the change in the physical and mechanical properties of concrete in response to the above-mentioned loads on experimental.  


Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3043
Author(s):  
Barbara Goszczyńska ◽  
Wiesław Trąmpczyński ◽  
Justyna Tworzewska

The reliability and durability of reinforced concrete structures depend on the amount of concrete cracking. The risk associated with cracks generates a need for diagnostic methods for the evaluation of reinforced concrete structures. This paper presents the results of a study of 10 single-span reinforced concrete beams to follow the process of crack formation and changes in their width. The beams were loaded to failure with two forces in a monotonic manner with unloading and in a cyclic manner. Continuous observation of the crack formation process was provided by the digital image correlation system. The simplified method for estimating the maximum crack width is proposed. The presented results confirmed the stochastic character of the process of crack formation and development. The maximum crack widths calculated on the basis of the proposed formula were on the safe side in relation to those calculated according to Eurocode 2. It was also confirmed that the distances between cracks do not depend on the loading manner. Hence the density function describing the distribution of distances between cracks can be used to assess the condition of reinforced concrete elements. The research has also shown the suitability of the DIC system (ARAMIS) for testing concrete elements.


2020 ◽  
Vol 14 (54) ◽  
Author(s):  
Thalyson Brito ◽  
Danilo Santos ◽  
Fabio Santos ◽  
Rafael Cunha ◽  
David Amorim

The analysis of reinforced concrete structures can be performed by means of experiments or numerical studies. The first way is usually quite expensive, so the second one sometimes is a good option to understand the physical behaviour of actual structures. Lumped damage mechanics appears as one of the latest nonlinear theories and presents itself as an interesting alternative to analyse the mechanical behaviour of reinforced concrete structures. The lumped damage mechanic applies concepts of the classic fracture and damage mechanics in plastic hinges for nonlinear analysis of reinforced concrete structures. Therefore, this paper deals with a novel physical definition of the correction factor γ for cracking evolution that ensures the presented lumped damage model depicts accuracy when it is compared to experimental observations of reinforced concrete beams and arches. Based on such experiments, the numerical analysis showed that γ value has upper and lower thresholds, depending on the physical and geometric properties of the reinforced concrete element. Notwithstanding, for γ values inside of the proposed interval, there is a best value of γ.


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