scholarly journals RA V9 N1, Mensaje del Editor en Jefe (Enero - Abril 2019)

2018 ◽  
Vol 9 (1) ◽  
Author(s):  
Pedro Castro Borges

Journal of the Latin-American association of quality control, pathology and recovery of constructionhttp://www.revistaalconpat.orgWith great satisfaction, we present the first issue of the ninth year of the ALCONPAT journal.The aim of the journal is to publish case studies within the scope of the Association, namely quality control, pathology and recovery of constructions, including basic and applied research, reviews and documentary research.The V9 N1 issue begins with a work where Nicolle Christine Sotsek and colleagues provide, through a systematic review of the literature and focused on the quality control of buildings, a consistent database to present the most used criteria by the Building Performance Evaluation (BPE). It was possible to define 9 dimensions of analysis that are presented and discussed in this document.In the second work, Cristiano Corrêa et. al. present the computational simulation of a fire previously carried out as an experiment in a room that reproduced a single-family residence room, typically burnt down in the city of Recife (Pernambuco, Brazil). The objective of the article is to compare the results of the development of the temperatures of the gases obtained through computer simulation with the Fire Dynamics Simulator software (FDS) through the measurements obtained in the experiment. It was verified that the results obtained through the model developed in the FDS were coherent with those obtained experimentally.In the third article, Mauricio de Pina Ferreira et. al. evaluate the influence of anchoring on the flexural strength of beams reinforced with Carbon Fiber Reinforced Polymer (PRFC) blankets. The parameters affecting the performance and strength of the beams are evaluated, and the sizing criteria of FIB Bulletin 14 (2001) and ACI 440-2R (2008) are discussed. It was observed that, even with auxiliary devices in the anchoring of the PRFC, there is the possibility of premature failures, and that both recommendations lead to safe, but overly conservative estimates in cases where the anchoring of the PRFC blanket is carried out properly.In the fourth article, by Yagho de Souza Simões and Carol Ferreira Rezende Santos, we compare two techniques of structural reinforcement, carbon fiber and metal foil, used for the recovery of reinforced concrete structures degraded by fire. A deterioration of a beam in a fire situation is simulated from a thermal numerical modeling and, next, the reinforcements are calculated. It is concluded that carbon fiber has greater advantages regarding the reinforcement of beams.The fifth work in this issue is written by Ricardo José Carvalho Silva and colleagues, who analyze the efficiency of reinforcement in reinforced concrete beams by adding steel bars and epoxy adhesive. The tests showed that the clamps reduced the strength of the beams, compared to those that did not. The reinforced beams without clamps obtained better results, but the most important limiting factor was the adhesion between the epoxy and the beam. The use of clamps to try to solve the problem of adherence gave originality to this investigation.In the sixth work, Marcela Tavares de Araujo Silva and colleagues evaluate an ultrasound test to estimate the depth of cracks in the concrete, using a mathematical model of the literature, in addition to checking the depth with better results. The results show that the test is sensitive to detect the presence of cracks in the concrete. The mathematical model used allowed to estimate the most depths of fissures; but the results are scattered and with a high margin of error for the depths of 5 cm and 15 cm, since for 10 cm better results were observed.The seventh work in this issue is written by Renato Guilherme Pereira and colleagues, who present an experimental program to determine the residual strength of bi-supported reinforced concrete beams subjected to pure bending after fires. The beams presented, up to 120 minutes of exposure to fire, a good performance after the fire, not showing a significant reduction in their residual strength, and the numerical model was accurate in forecasting the temperatures and the residual rupture load when the experimental results were compared.The article that closes this edition is by Erick Maldonado et. al. they present the results of concrete manufactured with supersulfated cements (SSC) volcanic material bases. After 180 days, the concrete with a cementitious compound of 5% An-10% CP-10% CaO-75% PM exposed to the CaSO4 solution reached a compressive strength of 46 MPa and 44 MPa in dry conditions. laboratory. The microstructure was analyzed by scanning electron microscopy, energy dispersion spectroscopy and XRD, showed that the main hydration products are C-S-H and ettringite.We are confident that the articles in this issue will be an important reference for those readers involved with issues of modeling applications and service life, as well as inspections with modern and / or improved methodologies. We thank the authors participating in this issue for their willingness and effort to present quality articles and meet the established times.On behalf of the Editorial Board  Pedro Castro Borges          Editor in Chief                     

2013 ◽  
Vol 756-759 ◽  
pp. 25-28 ◽  
Author(s):  
Chun Xia Li ◽  
Zhi Sheng Ding ◽  
Shi Lin Yan ◽  
Jun Ming Chen

Based on the experimental result of the flexure capability of reinforced concrete beams strengthened by carbon fiber sheets, the stress distribution changes only after steel yielding and carbon fiber sheets function better. However serious the extent of the damage is before strengthened, the tensile strain of main steel reaches about 1.6 times of the yield strain for the secondary grade of steel as failure happens. To satisfy the object reliability indicator, reliability is analyzed using the ratio of the steel strain at the balanced failure to the yield strain as variable to obtain its optimum value, which is coincide with the experimental result, and makes better consistency between calculated reliability indicator and object reliability indicator.


2018 ◽  
Vol 931 ◽  
pp. 379-384
Author(s):  
Yuri V. Ivanov ◽  
Yuri F. Rogatnev ◽  
Igor I. Ushakov

The paper considers the results of the experimental study of the reinforced concrete beams strengthened by carbon fiber reinforced plastics (the CFRP). Eight reinforced concrete beams of the 80x160 mm section and 1500 mm designed span have been manufactured and tested. The influence of the number of the CFRP layers (strengthening power) on bearing capacity and rigidity under the static loading of beams in the thirds of the span has been studied. The results obtained indicate the increase in bearing capacity of the reinforced beams from 24% up to 55% and the increase in rigidity by 45% for the commonly adopted limiting state, i.e. achieving ultimate deformations in concrete of the compressed zone). The paper underlines the need for using anchor devices in the form of U-shaped binders to ensure the efficiency of the given method of strengthening.


Author(s):  
Aaron Kadima Lukanu Lwa Nzambi ◽  
Dênio Ramam Carvalho de Oliveira ◽  
Marcus Vinicius dos Santos Monteiro ◽  
Luiz Felipe Albuquerque da Silva

Abstract Some normative recommendations are conservative in relation to the shear strength of reinforced concrete beams, not directly considering the longitudinal reinforcement rate. An experimental program containing 8 beams of (100 x 250) mm2 and a length of 1,200 mm was carried out. The concrete compression strength was 20 MPa with and without 1.00% of steel fiber addition, without stirrups and varying the longitudinal reinforcement ratio. Comparisons between experimental failure loads and main design codes estimates were assessed. The results showed that the increase of the longitudinal reinforcement ratio from 0.87% to 2.14% in beams without steel fiber led to an improvement of 59% in shear strength caused by the dowel effect, while the corresponding improvement was of only 22% in fibered concrete beams. A maximum gain of 109% in shear strength was observed with the addition of 1% of steel fibers comparing beams with the same longitudinal reinforcement ratio (1.2%). A significant amount of shear strength was provided by the inclusion of the steel fibers and allowed controlling the propagation of cracks by the effect of stress transfer bridges, transforming the brittle shear mechanism into a ductile flexural one. From this, it is clear the shear benefit of the steel fiber addition when associated to the longitudinal reinforcement and optimal values for this relationship would improve results.


Reinforced concrete structures are subjected to deterioration due to many factors such as corrosion of reinforcing steel. Ultimate strengths of structural elements can be greatly affected by these deteriorating factors. There are numerous methods and techniques used to protect these structural elements. The mortar layer (Plastering) is considered the first defense line against all the deteriorating factors. The main goal of this research is to investigate to what extent the plastering layer can protect reinforced concrete beams against corrosion. The aim of the experimental program is to study the effect of plastering layer on corrosion resistance of reinforced concrete beams. Four reinforced concrete beams (1002001100 mms) and four Lollypop specimens (cylinders 100200 mms) were tested and described as follows: • A beam and a lollypop specimen without any plastering layer (control). • A beam and a lollypop specimen with traditional plastering layer (cement + sand + water). • A beam and a lollypop specimen with modified plastering (traditional plastering + waterproof admixtures). • A beam and a lollypop specimen with painted and modified plastering layer (traditional plastering + waterproof admixtures + external waterproof paint). These eight specimens were subjected to corrosion using accelerated corrosion technique, after that the four beams were tested in flexure under three point load arrangement while the four lollypops were used to calculate the total mass loss due to accelerated corrosion. The test results were used to figure out the effect of plastering layer on corrosion resistance of RC beams.


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