Reinforced concrete Research Papers - Academia.edu (original) (raw)

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- Structural Engineering, Measurement, High-Rise Buildings, Reinforced concrete
- by Aeid Abdulrazeg
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- Materials Science, Finite Element, Multidisciplinary, Finite Element Analysis

Concrete in farm buildings is subjected to severe corrosion if manure is stored below slatted floors. Many chemicals associated with manure are identified as having a detrimental effect on concrete and the reinforcing steel embedded in the concrete. Of these, hydrogen sulfide is the most corrosive agent that leads to the rapid deterioration of concrete in barns. As well, manure has high concentrations of sulfates. In the present study, 48 concrete cylinders, 100 mm diameter and 100 mm high, were made with Portland cement, and various combinations of slag, fly ash and silica fume. Each has a reinforcing steel bar embedded in it. 24 cylinders are half immersed in sodium sulfate (20,000 ppm SO4 2- ) and also subjected to hydrogen sulfide gas (1,000 ppm H2S). The second set of 24 is subjected only to hydrogen sulfide gas. In each set, there are 8 different treatments. The specimens results indicate that after 16 cycles (each cycle is about five weeks long) of testing over 28 months, spe...

- by Vivian Abdelmseeh
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- Agricultural Engineering, Materials Science, Fly Ash, Agricultural

The opportunities provided by the use of Carbon Fiber Reinforced Polymer (CFRP) composites for the seismic repair of reinforced concrete (RC) structures were assessed on a full-scale dual system subjected to pseudodynamic tests in the... more

- by Gaetano Manfredi
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- Engineering, Civil Engineering, Structures and Fire Engineering, FRP

The purpose of this research is to evaluate and compare the relative merits of the two coating systems for reinforcing bars in concrete. A review is given of the nature and characteristics of both epoxy coated and galvanized steel for use as reinforcement in concrete. Also presented is an overview of the results from recent experimental work on the comparative corrosion behavior of uncoated black steel, epoxy coated steel, and galvanized steel in concrete.

- by Gokhan Gelisen
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- Bridge Engineering, Structural Designs in Bridges, Reinforcement, Epoxy

Story-high, prefabricated concrete façade elements with 6-8 cm thick outer layers were frequently used in building construction in the 1960/70s. In current construction and rehabilitation, they are much thicker (12-15 cm) or economically non-competitive, due to significantly increased concrete cover or the required use of stainless steel reinforcement, respectively, for durability. Additionally, these elements are placed further away from the support structure, owing to significantly increased requirement in thermal insulation. The outer shell of a façade element of the late 1960s was 4-8 cm away from the support structure while today, it is placed at a distance of 16-32 cm. The potential of replacing steel bars in prefabricated concrete façade elements by non-metallic glass-fiber reinforced polymer (GFRP) reinforcement was explored experimentally in a collaborative research project, targeting 5 cm thin elements and also requiring to test an associated new anchor system.

- by Hans-Rudolf Bärtschi
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- Engineering, Prefabrication, Conceptual Design, Polymer Composites

In recent decades, shear walls and tube structures have been the most appropriate structural forms for the construction of high-rise concrete buildings. Thus, recent Reinforced Concrete (RC) tall buildings have more complicated structural behaviour than before. Therefore, studying the structural systems and associated behaviour of these types of structures is very important. The main objective of this paper is to study the linear and nonlinear behaviour of one of the tallest RC buildings, a 56-storey structure, located in a high seismic zone in Iran. In this tower, shear wall systems with irregular openings are utilized under both gravity and lateral loads and may result in some especial issues in the behaviour of structural elements such as shear walls and coupling beams. The analytical methodologies and the results obtained in the evaluation of life-safety and collapse prevention of the building are also discussed. The weak zones of the structure based on the results are introduced, and a detailed discussion of some important structural aspects of the high-rise shear wall system with consideration of the concrete time dependency and constructional sequence effects is also included. Copyright © 2010 John Wiley & Sons, Ltd.

- by siamak epackachi
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- Civil Engineering, Nonlinear dynamics, Structural Design, Reinforced concrete

The earthquake of the 9th of July 1998 that hit in the central group of the Azores archipelago greatly affected the islands of Faial, Pico and São Jorge, reaching a magnitude of Mw 6.2 with the epicentre located about 15km northeast of the Faial Island. This earthquake allowed the collection of an unprecedented quantity of data concerning the characterisation of the building stock and the damage suffered by construction. This is the main purpose of this research, consisting essentially of three main aspects: (i) A detailed characterisation of the building stock, assigning a five category classification, from old traditional rubble stone masonry to reinforced concrete moment framed buildings; (ii) A detailed damage grade classification based on the different damage mechanisms observed; and, (iii) A seismic vulnerability assessment of the building stock. The results of the vulnerability assessment together with the building stock database and damage classification were integrated into a GIS tool, allowing the spatial visualation of damage scenarios, which is potentially useful for the planning of emergency response strategies and retrofitting priorities to mitigate and manage seismic risk.

- by Anibal Costa
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- Civil Engineering, Geology, Damage Mechanics, Emergency Response
- by Mohammed Alamoudi
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- Trace Metals, Structural Stability, Biological Sciences, Nondestructive testing

Modelling of existing reinforced concrete (r.c.) frames designed without specific seismic rules is a key problem for maintenance, structural upgrading and seismic assessment. In many European countries a very large percentage of reinforced concrete buildings are 40 years old, or even older; thus reinforcement consists of smooth rebars, since only in the 1970’s did early applications of deformed rebars appear. Technical literature on mechanical performances of anchored smooth rebars is non-comprehensive, mainly from the deformation standpoint, despite the relevance of this aspect to the response of critical regions, i.e. beam to column joints and column bases. In the present paper a series of experimental tests on smooth rebars are presented; they are aimed at describing in detail the force–slip relation for the bond mechanism for straight rebars and for anchoring end details, i.e. circular hooks with a 180∘ opening angle.

- by Giovanni Fabbrocino
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- Civil Engineering, Behavior, Structures and Fire Engineering, Anchoring

Secondary elements such as barriers, sidewalks, and diaphragms may increase the load carrying capacity of girder bridges. This in turn affects reliability. The objective of this study is to evaluate the potential benefit of secondary elements on the system reliability of girder bridges, if these elements are designed with the structural system to participate resisting vehicular live loads. Simple span,

- by Andrzej Nowak
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- Engineering, Civil Engineering, Finite element method, Finite Element
- by E. Spacone
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- Civil Engineering, Structures and Fire Engineering, Reinforced concrete
- by Kazimierz Darowicki
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- Civil Engineering, Materials Science, Cathodic Protection, Building
- by cris domingues
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- Engineering, Software Engineering, Knowledge Based System, Computer Model

The electrochemical behaviour of reinforcing steel in plain and blended cement concrete specimens placed in sulphate, chloride and sulphate-chloride environments was investigated. The effect of cement composition and the exposure condition on the corrosion behaviour of reinforcing steel was evaluated by measuring corrosion potentials at periodic intervals and conducting potentio-dynamic scans after two and half years of exposure. The corrosion potential data indicated passive corrosion in plain and blended cement concrete specimens placed in the pure sulphate environment. The time to initiation of reinforcement corrosion, however, was higher in blended cements than plain cements in all chloride and chloride-sulphate environments. The concomitant presence of suphate and chloride salts did not significantly influence the time to corrosion initiation. The corrosion rate, however, was significantly influenced by the quantum of sulphate ions associated with the chloride salts. The superior performance of silica fume blended cement, in terms of longer time to corrosion initiation and lower corrosion rate, indicates its potential in enhancing the useful service life of reinforced concrete structures placed in the chloride-sulphate environments.

- by Mourad Abdessemed
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- Civil Engineering, Finite element method, Numerical Modelling, Finite Element
- by Mark Adom-Asamoah
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- Crack propagation, Developing Country, Materials Design, Cyclic Loading
- by Bibiana Maria Luccioni
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- Civil Engineering, Structural Engineering, Stress, Reinforced concrete

Стаття присвячена методиці розрахунку стиснутих залізобетонних елементів на основі деформаційної моделі за національними нормами з урахуванням впливів першого і другого порядку. Наведено алгоритм розрахунку стиснутих елементів за другою... more

- by Olha Uzhehova
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- Deformation and strain, Reinforced concrete
- by Murat Dicleli
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- Civil Engineering, Earthquake Engineering, Energy, Stress
- by Dylan Burns and +1
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- Civil Engineering, Ground Penetrating Radar, Ultrasound, Reinforced concrete
- by Julian Alcala
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- Civil Engineering, Heuristics, Simulated Annealing, Optimization techniques

Deterioration of reinforced concrete and the reliability of deteriorating structures have been, and still are, widely researched fields. A critical aspect of this research effort is the integration of deterioration modelling with reliability assessment. This paper focuses on this issue and illustrates how the integration of these techniques can lead towards more realistic predictions of the time dependent performance of reinforced concrete bridge structures. The introduction of spatial random fields into the proposed approach facilitates the identification of the type and quantity of data required to update models and improve predictions. This is an essential step in the rational prioritisation of maintenance actions for such structures. However, there are still important gaps both in understanding and modelling the deterioration process, as well as in assessing its influence on bridge performance. In this respect, the methodology presented in the paper can be developed further, and...

- by Marios Chryssanthopoulos
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- Reliability, Spatial Variability, Bridges, Reinforced concrete
- by Nick Buenfeld
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- Civil Engineering, Cathodic Protection, Building, Current Density
- by Frank Foulkes
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- Civil Engineering, Building, Iron, Reinforced concrete

The procedures to do response analysis of a seismically isolated building are summarized based on

- by Demin Feng and +1
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- Structural Engineering, Base Isolation, Building Codes, Reinforced concrete
- by Mark Alexander
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- Construction Industry, Case Study, South African, Reinforced concrete

Computers are an integral part of day to day activities in engineering design and engineers have utilised various applications to assist them improve their design. Although computers are used to model a variety of engineering activities, currently the main focus of computer applications are areas with well defined rules. Activities related to the conceptual stage of the design process are generally untouched by computers.Artificial neural networks (ANN) have recently been widely used to model some of the human activities in many areas of science and engineering. Early applications of NN in civil engineering occurred the late eighties. One of the distinct characteristics of the ANN is its ability to learn from experience and examples and then to adapt with changing situations. Engineers often deal with incomplete and noisy data, which is one area where NN are most applicable. This is particularly the case at the conceptual stage of the design process.This paper presents practical guidelines for designing ANN for engineering applications.A brief introduction to NN is given; major aspects of three types of NN, multi-layer perceptron (MLP), radial basis network (RBF) and normalised RBF (NRBF) are discussed; new methods for selection and normalisation of training data are introduced and a practical example of a reinforced concrete slab design is presented.

- by SUMIT BHATI
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- Engineering, Engineering Design, Neural Network, Design process

This paper reports on the experimental assessment of the punching shear behaviour of reinforced recycled concrete slabs characterized by fine natural aggregates and coarse recycled aggregates. In particular, the latter were obtained only from demolished concrete. The experimental campaign has been carried out on 12 specimens. Moreover, three reinforced natural aggregate concrete slabs have been casted and tested as benchmarks. Four replacement percentages (30, 50, 80 and 100%) of coarse recycled aggregates in place of coarse natural aggregates have been considered. The punching shear behaviour of simply supported reinforced recycled concrete slabs under a central patch load has been investigated by means of failure patterns, ultimate loads and deflection–load curves.
Moreover, comparisons and a review of international code models for slabs under punching shear have been developed. The results show a reduction in recycled concrete mechanical performance with increasing replacement percentage of natural aggregate with coarse recycled aggregates. However, the reduced recycled concrete performance does not translate directly to the punching shear strength of reinforced recycled concrete slabs; indeed, the punching forces of all recycled concrete slabs tested are very similar to those of slabs realized with ordinary reinforced concrete. Actually, although the theoretical models on the punching shear are based on the characteristics of the concrete, this study indicates that the reinforcement role is of paramount relevance.

- by Lorena Francesconi and +1
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- Civil Engineering, Structural Engineering, Recycled Construction Materials, Concrete Technology

This paper presents a novel analytical formulation of an element removal algorithm based on dynamic equilibrium and the resulting transient change in system kinematics, by applying imposed accelerations instead of external forces at a node where an element was once connected. The algorithm is implemented into an open-source finite element code, numerically tested using a benchmark structural system with simplified element removal criteria, and able to capture the effect of uncertainty in member capacity. Realistic element removal criteria are introduced for mode-dependent gravity load collapse of seismically deficient and retrofitted reinforced concrete (RC) columns and unreinforced masonry (URM) infill walls. Two applications are conducted using structural systems of RC frames with URM infill walls. The first is a probabilistic study of a one-story model subjected to an ensemble of 14 ground motion recordings from similar neighboring sites during an earthquake event. The study produces empirical probability curves for partial and complete collapse conditioned on different hazard levels, and concludes that the intra-event variability is a major source of uncertainty affecting the outcome of progressive collapse simulations. The second application is a deterministic sensitivity study of progressive collapse response in a five-story structural model to uncertainty in live load, stiffness, damping, and seismic hazard level, subjected to one ground motion record. The analysis identifies the time at incipient collapse as an adequate sensitivity measure, and the uncertainty in ground motion intensity as the most important, followed by the stiffness of the URM infill wall. Copyright © 2009 John Wiley & Sons, Ltd.

- by Mohamed Talaat
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- Civil Engineering, Algorithms, Earthquake Engineering, Finite Element
- by Gaetano Manfredi
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- Civil Engineering, Monte Carlo Simulation, Risk assessment, Structural Stability

Most codes of practice, like ACI 318-14, 9.9.1.3, require the use of strut-and-tie modeling (STM) to deal with reinforced concrete continuous deep beams (rc-cdbs). Though, investigations that conducted on rc-cdbs did not include all the most influential parameters. This work presents an analytical parametric study using STM stated by ACI 318-14 to calculate load capacity of 20 rc-cdbs with different parameters. The parameters took into consideration in the current work are shear span to overall depth ratio (a/h), width of beam (bw), width of bearing plate (BP), concrete compressive strength (f'c) and amount of vertical shear web reinforcement (pv). It is seen that the load capacity decreases by about 14% to 37% when a/h increases by about 33% to 100%. It is also seen that load capacity increases by about 33% to 100% when bw increases by about 33% to 100%, while the load capacity increases by about 10% to 30% when BP increases by about 33% to 100%. Finally, it is found that load capacity increases by about 35% to 100% when compressive strength increases by about 35% to 100%, while the load capacity increases by about 0% to 25% when pv increases by about 33% to 100%.

- by Khattab S Abdul-Razzaq and +1
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- Reinforced concrete, Continuous deep beams

Reinforced concrete poles are very popular in transmission lines due to their economic efficiency. However, these poles have structural safety issues in their service terms that are caused by cracks, corrosion, deterioration, and short-circuiting of internal reinforcing steel wires. Therefore, they must be periodically inspected to evaluate their structural safety. There are many methods of performing external inspection after installation at an actual site. However, on-site nondestructive safety inspection of steel reinforcement wires inside poles is very difficult. In this study, we developed an application that classifies the magnetic field signals of multiple channels, as measured from the actual poles. Initially, the signal data were gathered by inserting sensors into the poles, and these data were then used to learn the patterns of safe and damaged features. These features were then processed with the isometric feature mapping (ISOMAP) dimensionality reduction algorithm. Subsequently, the resulting reduced data were processed with a random forest classification algorithm. The proposed method could elucidate whether the internal wires of the poles were broken or not according to actual sensor data. This method can be applied for evaluating the structural integrity of concrete poles in combination with portable devices for signal measurement (under development).

- by tuan anh Nguyen
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- Materials Engineering, Corrosion, Design Methodology, Knowledge base
- by Oscar Gonzalez
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- Physics, Mexico City, Reinforced concrete

Addressing the use of reinforced concrete for restoration at archaeological sites, Paola Pesaresi, the conservation architect with the Herculaneum Conservation Project, reviews how concrete was employed at Herculaneum during the first half of the twentieth century, and how the subsequent deterioration of the concrete elements incorporated into the site is now being handled by authorities there.

- by Adolfo Matamoros
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- Civil Engineering, Reinforced concrete
- by Manuel Romero
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- Civil Engineering, High Strength Concrete, High Temperature, Reinforced concrete

A new method is described for thein-situ measurement of electrical resistivity of concrete structures. The method is based on the early work of J. Newman who calculated the electrolyte resistivity between a disk and a counter electrode located at infinity. This method has the advantage compared with Wenner's of using a single small electrode for the measurements. In this paper, results are presented comparing this method with Wenner's and with results carried out using a conductivity cell in electrolytes. Finally, values of resistivity are compared to corrosion intensity, and a threshold for active corrosion is suggested. On décrit une nouvelle méthode de mesure de la résistivité électrique du béton dont la technique est basée sur un travail ancien de J. Newman qui avait calculé la résistivité entre un disque et une électrode auxiliaire placée à l'infini. Comparée à la méthode de Wenner, cette méthode présente l'avantage de n'utiliser, pour les mesures, qu'une petite électrode. Dans cet article, on présente les résultats de la comparaison établie avec la méthode de Wenner et avec les résultats obtenus avec une cellule de conductivité placée dans les électrolytes. Enfin, on compare les valeurs de la résistivité du béton avec celles de l'intensité de la corrosion et on suggère un seuil de corrosion active.

- by Pedro Hidalgo
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- Compressive Strength, Reinforced concrete, Aspect Ratio