scholarly journals Multi-scale and multi-physics deterioration modelling for design and assessment of reinforced concrete structures

2017 ◽  
Vol 2 ◽  
pp. 119-128 ◽  
Author(s):  
Mette Geiker ◽  
Alexander Michel ◽  
Michel D. Lepech ◽  
Jie Wu ◽  
Henrik Stang
Keyword(s):  
Reinforced Concrete ◽  
Prediction Models ◽  
Functional Performance ◽  
Concrete Structures ◽  
In Situ Monitoring ◽  
Reinforced Concrete Structures ◽  
Multi Scale ◽  
Ongoing Work ◽  
Interface Characteristics ◽  
The Impact

This paper discusses the need for reliable and valid multi-scale and multi-physics prediction models to support the design of new as well as the assessment, maintenance, and repair of existing reinforced concrete structures. A multi-physics and multi-scale deterioration model for chloride-induced corrosion of reinforced concrete has been established. Ongoing work includes extension of the model to 3D as well as modelling of the impact of the steel-concrete interface characteristics and electrochemical potential on chloride thresholds. Identified challenges include, among others, the improved understanding and modelling of single- and multi-deterioration mechanisms, environmental exposure, and data for validation. We envision that next generation maintenance and management of reinforced concrete infrastructure will combine numerical simulations based on multi-scale and multi-physics principles and extensive in-situ monitoring, allowing continuous Bayesian updating of 4D simulations of functional performance.

A Study for Evaluating Local Damage to RC Panels Subjected to Oblique Impact: Part 1 — A Study for Evaluating Local Damage Caused by Oblique Impact of Rigid Projectiles

2017 ◽  
Author(s):  
Yoshimi Ohta ◽  
Akemi Nishida ◽  
Haruji Tsubota ◽  
Yinsheng Li
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Oblique Impact ◽  
Reinforced Concrete Structures ◽  
Local Damage ◽  
Normal Impact ◽  
Impact Tests ◽  
Oblique Impacts ◽  
New Formula ◽  
The Impact

Many empirical formulae have been proposed to evaluate the local damage to reinforced concrete structures caused by the impact of rigid projectiles. Most of these formulae have been derived based on impact tests perpendicular to the target structures. To date, few impact tests oblique to the target structures have been conducted. The purpose of this study is to propose a new formula for evaluating the local damage caused by oblique impacts based on experiments and simulations. The new formula is derived by modifying an empirical formulation for normal impact and the agreement with results of past oblique impact tests is discussed.

Multiprobe chloride sensor for in situ monitoring of reinforced concrete structures

2006 ◽  
Vol 28 (3) ◽  
pp. 233-236 ◽  
Author(s):  
M.F. Montemor ◽  
J.H. Alves ◽  
A.M. Simões ◽  
J.C.S. Fernandes ◽  
Z. Lourenço ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
In Situ Monitoring ◽  
Reinforced Concrete Structures

scholarly journals Calculation of damage RC constructions according to deformation model

2020 ◽  
Vol 2020 (2) ◽  
pp. 99-106
Author(s):  
Yaroslav Blikharskyy ◽  
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Concrete Structures ◽  
Physical And Mechanical Properties ◽  
Reinforced Concrete Beams ◽  
Core Material ◽  
Deformation Model ◽  
Reinforced Concrete Structures ◽  
The Impact

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.

scholarly journals Impact of impurities of local construction materials on the bearing capacity of the concrete used in structures in Burundi

Vestnik MGSU ◽  
2021 ◽  
pp. 1357-1362
Author(s):  
Emmanuel Mikerego ◽  
Nestor Niyonzima ◽  
Jean Claude Ntirampeba
Keyword(s):  
Compressive Strength ◽  
Reinforced Concrete ◽  
Concrete Structures ◽  
Construction Materials ◽  
Reinforced Concrete Structures ◽  
Ordinary Concrete ◽  
Average Decrease ◽  
Local Construction ◽  
The Impact ◽  
Mixing Water

Introduction. The article is about an assessment of the impact of impurities contained in the local construction materials on the mechanical characteristics of the concrete used in reinforced concrete structures in Burundi. Materials and methods. The methodology of the study consisted in varying the quantity of impurities for the manufactu­ring of the concrete experimental cubic samples. The grain sizes of the studied ordinary concrete were in the favourable zones according to the recommended granulometry for standard concretes. Simulation of impurities was made by adding in the mixing water solid particles taken from a local rock called “red earth”. The particles were composed by (24 %) of clays, (38 %) of silts and (38 %) of sands. As for the used cement in this study, it was the type CEM I (32.5). The quantities of impurities were expressed in grams per litre of mixing water (g/l) and were varying from (0 g/l) to (100 g/l) with a step of (20 g/l). The prepared experimental concrete samples were stored in the laboratory of materials at the University of Burundi and were subjected to compression testing under hydraulic press after 28 days. Results. The impact of impurities consisting of (24 %) of clays, (38 %) of silts and (38 %) of sands is identified. Each increase of (20 g) of impurities in a litre of mixing water induces an average decrease of (4 %) on the compressive strength and the Young’s modulus for an ordinary concrete. Conclusions. The impact of impurities contained in the local construction materials used in the manufacturing of the concrete for reinforced concrete structures in Burundi is studied. Each increase of (20 g) of impurities in a litre of mixing water induces an average decrease of (4 %) on the compressive strength and the Young’s modulus of an ordinary concrete. For Burundi, a curve for the approximation of the bearing capacity of the concrete used in reinforced concrete structures according to the quantity of impurities contained in the local construction materials was established. Hence, it is advisable to start by the specification of the quantity of impurities contained in the construction materials before making the concrete for reinforced concrete structures in order to predict the mechanical performances of the concrete used in reinforced concrete structures.

ANALYSIS OF DURABILITY OF REINFORCED CONCRETE STRUCTURES OF BRIDGES ACCORDING TO THEIR TYPICAL DESIGNS

2020 ◽  
Vol 264 (4) ◽  
pp. 58-63
Author(s):  
Larysa Bodnar ◽  
◽  
Serhii Zavhorodnii ◽  
Serhii Stepanov ◽  
Vitalii Yastrubinetskyi
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Highway Bridges ◽  
Reinforced Concrete Structures ◽  
Bridge Management ◽  
Bridge Span ◽  
Standard Design ◽  
Standard Designs ◽  
Bridge Spans ◽  
The Impact

Thousands of bridges built in the 20th century are operated on Ukrainian roads. In the limited funding of the road industry of Ukraine, the age of highway bridges is constantly increasing, the number of defects in structures is growing. The largest number of defects is concentrated in the bridge spans. The main part of the bridge spans consists of prefabricated reinforced concrete beams, manufactured in factories of reinforced concrete structures according to standard designs developed in the middle of the last century. As a result of long-term operation of bridges, the shortcomings of these designs which reduce the service life of bridge spans and bridges in general are revealed. The systematic approach is required to study this process. The Analytical Expert Bridge Management System (AESUM) operates in the Ukravtodor system. This software complex accumulates all the information on the results of inspections (certification) of bridges on public roads. The special module AESUM – a database of standard designs of bridge spans which is constantly updated was developed to make decisions on repair works taking into account the features of structures on standard designs, to store this information in a single complex, in electronic form. Standard designs of reinforced concrete bridge spans built and operated on the roads of Ukraine are considered, and a comparative analysis of the features of these designs is performed taking into account the impact on the safety of bridge operation, their main features and shortcomings are given. The concept of rank of the standard design on durability is entered. A formula for estimating the durability of bridge span of a standard design using this concept is proposed. The analysis of durability of bridge span is performed. A number of problematic standard designs have been identified. Keywords: road bridge, standard designs, durability.

CONCRETING AND EARLY HARDENING PROCESSES IN MONOLITHIC REINFORCED CONCRETE STRUCTURES / PROCESAI, VYKSTANTYS BETONAVIMO IR PRADINIO KIETĖJIMO METU GELŽBETONINĖSE MONOLITINĖSE KONSTRUKCIJOSE

2012 ◽  
Vol 4 (2) ◽  
pp. 67-75
Author(s):  
Vigantas Antanas Žiogas ◽  
Svajūnas Juočiūnas ◽  
Violeta Medelienė ◽  
Giedrius Žiogas
Keyword(s):  
Reinforced Concrete ◽  
Structure Formation ◽  
Structural Strength ◽  
Concrete Strength ◽  
Time Moment ◽  
Concrete Structures ◽  
Concrete Mixture ◽  
Industrial Building ◽  
Reinforced Concrete Structures ◽  
The Impact

The exploitation time and reliability of monolithic reinforced concrete structures largely depend on concreting technology and process influence during concreting and early setting stages. Different types of cracks in monolithic reinforced concrete structures appear due to internal and external effects. Cracks appear when the technology of structure concreting is damaged, when formwork is removed during the further setting and structures loaded period. In order to avoid micro and macro cracks in monolithic structures, it is important to measure the particular setting time moment and technological process moment when stresses that exceed the permissible values appear in concrete. The article analyses the processes that appear when horizontal, sloping and vertical monolithic reinforced concrete structures are concreted. The analysis of concrete mixture pressure on formwork is performed. The pressure which is calculated according to different countries’ methodology is different: the smallest pressure is obtained calculating according to the British recommendations, and the largest pressure is obtained according to French CIB recommendations. In Lithuania, it is recommended to follow the German DIN 18218 standard. The balance conditions of concrete mixture concreting on slope surface are described. The main concreting technology parameters and their interaction are analysed; the speed, intensity and time of continuous concreting technology are presented. When the process of continuous concreting is performed, it is necessary to evaluate the interaction and values of parameters properly. Methodical theoretical calculation is presented. Practical solutions for industrial building construction applying the modern sliding formwork technology are presented. The impact of cement type, superplasticizers and temperature over the concrete mixture mobility, changes, fresh concrete structural strength and concrete setting kinetics are analysed. The main characteristics of the initial setting — the beginning of structure formation, when concrete mixture turns into concrete state — is analysed applying the ultrasonic method. The beginning of structure formation influences the regulated time of concrete mixture laying and compaction. The requirements for structural strength (permissible strength limits) and concreting rate (formwork movement) of freshly formed concrete are set when the construction is performed applying the continuous concreting technology method. The analysis is implemented performing the construction of cylindrical sludge tank with slipping formwork. While performing the analysis during concreting, it was stated that the concrete setting kinetics corresponds to the sludge tank concreting rate. The analysis performed after concreting and in 28 days of hardening revealed that there are no surface defects or cracks, and concrete strength exceeds the required sludge tank design strength. Santrauka Monolitinių gelžbetoninių statinių konstrukcijų eksploatacijos trukmė ir patikimumas daugiausia priklauso nuo betonavimo technologijos ir procesų poveikių betonavimo bei pradinio kietėjimo metu. Straipsnyje nagrinėjami procesai, vykstantys betonuojant horizontaliąsias, nuožulniąsias ir vertikaliąsias monolitines gelžbetonines konstrukcijas. Atlikta betono mišinio slėgio į formas analizė. Tiriami pagrindiniai betonavimo technologijos parametrai, analizuojamas jų ryšys, pateikiamas nepertraukiamo betonavimo technologijos betonavimo greitis, intensyvumas, trukmė. Atlikti teoriniai skaičiavimai ir siūlomi praktiniai sprendimai pramoninių statinių statybai, naudojant šiuolaikinę slankiųjų klojinių technologiją. Ištirta cemento tipo, superplastiklių, temperatūros įtaka šviežiai suformuoto betono struktūriniam stipriui ir betono kietėjimo kinetikai. Nustatyti reikalavimai šviežiai suformuoto betono struktūriniam stipriui, betonavimo greičiui (klojinių kėlimui), vykdant statybą nepertraukiamos betonavimo technologijos metodu. Tyrimai pritaikyti vykdant cilindrinio dumblo pūdytuvo statybą slankiaisiais klojiniais.

scholarly journals Nonlinear calculation of reinforced concrete structures to the impact of the air shock wave

Vestnik MGSU ◽  
2019 ◽  
pp. 33-45 ◽  
Author(s):  
Anton Y. Savenkov ◽  
Oleg V. Mkrtychev
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Reinforced Concrete ◽  
Nonlinear Dynamic ◽  
Software Package ◽  
Crack Opening ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Advantages And Disadvantages ◽  
The Impact

Introduction. Researched methods of accounting for the nonlinear operation of reinforced concrete structures on the example of an industrial structure, when exposed to an air shock wave using modern software systems based on the finite element method. The calculation of reinforced concrete construction to the impact of an air shock wave, if no increased requirements for tightness are presented to it, in accordance with current regulatory documents, must be carried out taking into account the elastic-plastic work, crack opening in the stretched zone of concrete and plastic deformations of reinforcement are allowed. Reviewed by new coupling approach to determining the dynamic loads of a shock wave, implemented in the LS-DYNA software package, which allows to take into account the effects of a long-range explosion and wave-wrapping around a structure. Materials and methods. The study of the stress-strain state of the structures was carried out using numerical simulation. For the nonlinear equivalent-static method, a step-by-step calculation algorithm is used, with gradual accumulation and distribution of stresses, implemented in the LIRA-SAPR software package. For the nonlinear dynamic method, the Lagrangian-Eulerian formulation is used using the methods of gas dynamics in the LS-DYNA software package. Results. As a result of numerical simulation, the following was done analysis of existing methods of nonlinear calculations; analysis of the existing loads during the flow of shock waves around the structure; analysis of the forces and movements in the bearing elements, as well as pictures of the destruction of concrete and reinforcement. Conclusions. According to the results of the comparison of the two approaches, conclusions are drawn about the advantages and disadvantages of the methods. Advantages of nonlinear dynamic calculation methods are noted compared to the equivalent-static ones. Use of the combined approach to the description of the shock wave front gives a reduction in time and allows us to describe the interaction of the wave with the structure with sufficient accuracy. The findings indicate the relevance of the study and provide an opportunity to move to more reasonable computational models.

scholarly journals Case study: influence of performance levels of ABNT NBR 15575 without consumption of materials used in reinforced concrete structures

2019 ◽  
Vol 12 (4) ◽  
pp. 956-971
Author(s):  
F. S. CUNHA ◽  
K. A. L. COLLA ◽  
H. EHRENBRING ◽  
F. L. BOLINA ◽  
B. TUTIKIAN
Keyword(s):  
Reinforced Concrete ◽  
Residential Buildings ◽  
Concrete Structures ◽  
Performance Level ◽  
Superior Performance ◽  
Performance Standard ◽  
Reinforced Concrete Structures ◽  
Performance Levels ◽  
The Impact ◽  
Minimum Performance

Abstract The Brazilian construction industry still discusses the consequence of the Performance Standard on housing developments. According to ABNT NBR 15575 [1], the systems that compose residential buildings need to meet minimum performance requirements. Among the systems, the structural must reach a minimum Service Life (SL) of 50 years, or intermediate or higher that corresponds to 63 and 75 years, respectively. The industry also debates the impact and viability of increasing the SL of reinforced concrete structures. Therefore, this article aimed to analyze a single reinforced concrete building designed for the 3 SL specified by ABNT NBR 15575 [1]. The study focused on the total consumption of steel and concrete. The structure’s designed conditions of exposure were varied for each performance level, based on the 4 environmental exposure classes (EEC) of ABNT NBR 6118 [3] and ABNT NBR 12655 [11], totalizing 12 situations. It was noted that the increased performance level increases consumption of materials, and the designs made for EEC IV consumed 12.3% and 16.2% more steel and concrete at the intermediate and superior performance levels respectively, when compared to the minimum performance level.

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