scholarly journals Diagnóstico patológico y propuesta de intervención de los cimientos y de los muros de contención de derrames de dos tanques de almacenamiento de ácido sulfúrico para usos industriales

2013 ◽  
Vol 3 (3) ◽  
pp. 177-187 ◽  
Author(s):  
M.Y. Dikdan ◽  
R. M. De Corrales ◽  
D. Avon
Keyword(s):  
Concrete Cover ◽  
The Other ◽  
Reinforcing Bars ◽  
Industrial Facility ◽  
Concrete Walls ◽  
Floor Slab ◽  
Structural Capacity ◽  
Epoxy Material ◽  
Concrete Tank ◽  
Cover Thickness

RESUMENEn los muros y la losa de piso de una piscina de contención de derrames de tanques metálicos de ácido sulfúrico se evidenciaron sintomatologías de fallas. Se observó desagregación en las bases de los tanques y en la losa de piso. En la parte inferior de los muros se evidenció pérdida de conexión con la losa de piso. Mediante la extracción de núcleos al concreto se determinó: carbonatación, porosidad, penetración de sulfatos y resistencia a compresión. Al acero se le midió: espesor de recubrimiento, diámetro, potenciales y velocidad de corrosión. Se determinó la capacidad remanente del muro mediante cálculo estructural. Como conclusión la estructura se apreció muy afectada. Se recomienda el diseño especial de concreto con revestimiento antiácido y dos acciones, una inmediata mediante la construcción de tacos que garanticen apoyo y estabilidad a los tanques, y otra definitiva, reubicación del sistema de los tanques y la piscina.Palabras clave: Tanques; Ácido sulfúrico; Desagregación; Corrosión; Muros.ABSTRACTIn an industrial facility, several failure symptoms were found on walls, floor slab, and foundations of concrete tanks designed to contain eventual spilling from two metallic containers of sulfur acid (one at 11% concentration, and the other at 98%). Loss of connection between lateral walls and floor slab was observed. Interior wall areas and foundations of tanks were covered with epoxy material which was mostly peeled off. By extraction of concrete nucleus samples, the following parameters were determined: carbonation, porosity, sulfate penetration, and compressive strength. Reinforcing bars were tested for: concrete cover thickness, diameter, potential measurements (Cu/SO4Cu), and corrosion rate. Remaining structural capacity of concrete walls was calculated, concluding that the structure is severely affected by sulfur acid. Two actions are suggested: a provisional one by constructing big reinforced concrete cubes around the tank to make it stable; the other, a final solution, replacing the sulfur acid containers and the concrete tank for possible sulfur infiltration to the ground underneath them.Keywords: Tanks; Sulfur acid; disaggregation; corrosion; walls.

scholarly journals Condition assessment of selected reinforced concrete structural elements of the bus station in Kielce

2019 ◽  
Vol 284 ◽  
pp. 06007
Author(s):  
Paweł Tworzewski ◽  
Wioletta Raczkiewicz ◽  
Wioletta Grzmil ◽  
Przemysław Czapik
Keyword(s):  
Detection System ◽  
Thickness Distribution ◽  
Concrete Cover ◽  
Composition Analysis ◽  
Reinforcing Bars ◽  
X Ray Diffraction ◽  
Phenolphthalein Solution ◽  
Corrosion Risk ◽  
Cover Thickness ◽  
Non Destructive

The paper presents the results of the research aimed at assessing the condition of reinforcement and concrete cover in selected elements of the structure of the most recognizable structure in Kielce, i.e. PKS station, located at Czarnowska Street. Currently, demolition works are underway resulting from the planned modernization. The assessment of the corrosion risk of the reinforcement in the construction elements was carried out with the use of a semi-non-destructive electrochemical method. The use of this method made it possible to determine the probability of reinforcement corrosion in the selected areas and to estimate its rate. The protective properties of concrete cover were checked by the carbonation test (test using a 1% phenolphthalein solution) and phase composition analysis (X-ray diffraction analysis). In order to determine the position of the reinforcing bars and to estimate the concrete cover thickness distribution in the areas corresponding to the aforementioned measurements, ferromagnetic detection system was used.

scholarly journals Modelling of Corrosion-Induced Concrete Cover Cracking Due to Chloride Attacking

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1440
Author(s):  
Pei-Yuan Lun ◽  
Xiao-Gang Zhang ◽  
Ce Jiang ◽  
Yi-Fei Ma ◽  
Lei Fu
Keyword(s):  
Service Life ◽  
Corrosion Current ◽  
Practical Experience ◽  
Concrete Cover ◽  
Premature Failure ◽  
Rc Structures ◽  
Structural Capacity ◽  
Cover Cracking ◽  
Deterioration Process ◽  
Cracking Process

The premature failure of reinforced concrete (RC) structures is significantly affected by chloride-induced corrosion of reinforcing steel. Although researchers have achieved many outstanding results in the structural capacity of RC structures in the past few decades, the topic of service life has gradually attracted researchers’ attention. In this work, based on the stress intensity, two models are developed to predict the threshold expansive pressure, corrosion rate and cover cracking time of the corrosion-induced cracking process for RC structures. Specifically, in the proposed models, both the influence of initial defects and modified corrosion current density are taken into account. The results given by these models are in a good agreement with practical experience and laboratory studies, and the influence of each parameter on cover cracking is analyzed. In addition, considering the uncertainty existing in the deterioration process of RC structures, a methodology based on the third-moment method in regard to the stochastic process is proposed, which is able to evaluate the cracking risk of RC structures quantitatively and predict their service life. This method provides a good means to solve relevant problems and can prolong the service life of concrete infrastructures subjected to corrosion by applying timely inspection and repairs.

scholarly journals Determination of reinforcing bars for tests of hollow core slabs with continuity

2013 ◽  
Vol 6 (6) ◽  
pp. 903-932
Author(s):  
A. P. Santos ◽  
M. A. Ferreira ◽  
R. C. Carvalho ◽  
L. M. Pinheiro
Keyword(s):  
Shear Strength ◽  
The Other ◽  
Hollow Core ◽  
Reinforcing Bars ◽  
Simply Supported ◽  
Resistance Moment ◽  
Hollow Core Slab ◽  
Maximum Shear Strength

The structural designs of floors formed by hollow core slabs usually consider these as simply-supported slabs. In recent years there have been project changes and hollow core slabs with continuity are widely used. The objective of this study is to suggest a way to calculate the reinforcement bars to be used in tests with continuity provided by a structural topping. Thus, this paper presents a method based on the maximum positive resistance moment and maximum shear strength of a hollow core slab. The method is applied to a test in hollow core slab specimens which have the following dimensions: 2 m width, 6 m long, and 21 cm high. The results indicated that the method was satisfactory to the performed test, and can therefore be applied to the other test configurations or even designs.

Seismic Rehabilitation of a School Building in Cephalonia, Greece

2020 ◽  
pp. 1-20
Author(s):  
Christos Giarlelis ◽  
Evlalia Lamprinou ◽  
Constantinos Repapis
Keyword(s):  
Reinforced Concrete ◽  
Response Spectrum ◽  
Earthquake Sequence ◽  
School Building ◽  
Structural Walls ◽  
Concrete Walls ◽  
Seismic Rehabilitation ◽  
Reinforced Concrete Walls ◽  
Structural Capacity ◽  
Structural Failures

<p>The 2014 earthquake sequence in Cephalonia, Greece, resulted in a number of structural failures. In Argostoli, the capital of the island, a school building suffered light damage; however, the structural assessment following the analysis procedures of the recently published Greek Code for Structural Interventions, showed that seismic strengthening is required. The structure was built on the aftermath of the catastrophic 1953 Ionian earthquake sequence based on older code requirements, which are much outdated, as indicated from the results of both modal response spectrum analyses and non-linear static analyses. The retrofit aims to increase the very low structural capacity of the building and as a means for that the use of concrete jackets is selected. Based on the results of the assessment, it was decided that concrete jackets should be applied to all columns, while large structural walls running along the transversal direction were strengthened with single-sided reinforced concrete jacketing. The interventions are limited by architectural demands and cost considerations. However, analyses of the strengthened structure show that the interventions improve its seismic behaviour adequately. The detailing of interventions is thoroughly presented. What makes this case study interesting is the unusual structural system of the building, which is an ingenious combination of frame elements and lightly reinforced concrete walls and its behaviour to one of the strongest recent Greek earthquakes. The rehabilitation study had to model correctly the structure and propose interventions that were in agreement with the architectural demands and the cost consideration.</p>

scholarly journals Experimental Study on Bond Performance and Damage Detection of Corroded Reinforced Concrete Specimens

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Yubin Tian ◽  
Junran Liu ◽  
Hengheng Xiao ◽  
Yi Zhang ◽  
Qingcheng Mo ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Nonlinear Coefficient ◽  
Concrete Cover ◽  
Empirical Formulas ◽  
Accelerated Corrosion ◽  
Bond Slip ◽  
Passivation Film ◽  
Bond Performance ◽  
Damage Degree ◽  
Cover Thickness

This paper presents the results of an experimental research designed to investigate the combined effects of corrosion rate, concrete cover thickness, and stirrup spacing on the bond performance between reinforcement and concrete of reinforced concrete (RC) specimens. The RC specimens were immersed into sodium chloride solution to eliminate the passivation film on reinforcement. Then, an accelerated corrosion method was applied to corrode reinforcement embedded in concrete specimens. Pullout test was carried out to establish empirical formulas for ultimate slip and ultimate bond strength of RC specimens with three different corrosion rates, different concrete cover thicknesses, and different stirrup spacings. In addition, the bond-slip relation model was developed to predict and evaluate the bond performance of RC specimens. Finally, the ultrasonic technology was used to detect the damage of RC specimens, and the corresponding nonlinear coefficient β was proposed to characterize the damage degree of RC specimens. The susceptibility of β on the damage of specimens was compared with that of ultrasonic velocity, indicating β was more appropriate to evaluate the damage of RC specimens.

scholarly journals Experimental analysis of the spalling phenomenon in precast reinforced concrete columns exposed to high temperatures

2018 ◽  
Vol 11 (4) ◽  
pp. 856-875 ◽  
Author(s):  
A. M. GIL ◽  
B. FERNANDES ◽  
F. L. BOLINA ◽  
B. F. TUTIKIAN
Keyword(s):  
High Temperatures ◽  
Concrete Columns ◽  
Concrete Cover ◽  
Concrete Compressive Strength ◽  
Concrete Mixtures ◽  
Strength Tests ◽  
Fire Curve ◽  
Cover Thickness ◽  
Real Scale

Abstract Among the processes that involve the degradation of concrete structures subject to the high temperatures of a fire there is the spalling phenomenon. Its mechanisms are related to the thermal stress of the materials dilatations and pore pressure the process of vaporization of water during heating. The factors that influences in its occurrence are related to concrete properties, structural member characteristics or the exposure conditions, and their parameters are not clearly known yet. This paper aimed to study the influence of three concrete mixtures, four coating thicknesses and two bars diameters of longitudinal reinforcement in the spalling phenomena exposed to ISO 834 fire curve. The characterization of concrete were performed either of the axial compression strength tests, water absorption by capillary and mercury intrusion porosimetry, besides the fire resistance tests in real-scale specimens. It was concluded that the diameter of the bar does not have influence, while the mixture and the concrete cover thickness does. More spalling was recorded for the columns with thicker concrete cover and concrete compressive strength at 61,9 MPa, and although higher strength concrete have less permeability, this characteristic can be balanced with the higher tensile strength of this type of concrete.

Analysis on Fire Resistance of Reinforced Concrete Beams Base on the Failure Probability

2010 ◽  
Vol 452-453 ◽  
pp. 197-200 ◽  
Author(s):  
Zhen Qing Wang ◽  
Zhi Cheng Xue ◽  
Mu Qiao
Keyword(s):  
Reinforced Concrete ◽  
High Temperature ◽  
Fire Resistance ◽  
Failure Probability ◽  
Reliability Index ◽  
Concrete Beams ◽  
Reinforced Concrete Beam ◽  
Concrete Cover ◽  
Reinforced Concrete Beams ◽  
Cover Thickness

For the mechanical properties of reinforced concrete under high temperature with large deterioration, the reliability of reinforced concrete beams have been largely discounted. A calculation of fire resistance based on failure probability is given by this paper. Reinforced concrete beam is usually working with cracks. Since each section with cracks has possibility of destruction, the reliability of the beam is calculated by the minimum value of n crack-sections’ resistance. The plastic zone resistance of concrete under high temperature is considered in this paper. A simple and feasible time-variant model of the resistance of reinforced concrete beams under fire and a reliability index analysis method of reinforced concrete beams under fire has been given. The action of ISO834 temperature rising curve on the reliability index of different specifications of concrete beams at different time is analyzed. The action of main parameters on the reliability index changes with time is shown. The fire resistance considers the failure probability is given. The results show that increase the reinforcement ratio and concrete cover thickness appropriately are effective measures to improve the fire resistance limit of reinforced concrete beams.

Sign in / Sign up

Export Citation Format

Share Document