Service Life of Concrete Structures

2020 ◽  
Vol 309 ◽  
pp. 267-271
Author(s):  
Milan Holicky ◽  
Jiří Kolísko
Keyword(s):  
Service Life ◽  
Concrete Structure ◽  
Limit State ◽  
Concrete Structures ◽  
Technical Specification ◽  
Working Life ◽  
Degradation Process ◽  
International Standards ◽  
Limit States ◽  
Existing Structures

The concept of service life of structures is included in international standards ISO (under the term Design Working Life), in the European document EN 1990 (Design Service Life) and in the upcoming document CEN for assessment of existing structures - Technical Specification TS (Remaining Working Life). The mentioned documents contain mainly material-independent provisions for the design and assessment of all types of structures and for any category of actions. The submitted paper includes the definition of service life (performance time) tser, which is extended for any concrete structure, considering the resistance of a structure R(t) and the effect of action S(t). Both the aggregate variables R(t) and S(t) are usually random variables significantly dependent on time t. Due to the random variability of the variables R(t) and S(t), the service life tser, needs to be related to the probability that the performance of the structure is weakened or completely eliminated. Basically, serviceability limit states (SLS) and ultimate limit states (ULS) should be considered. In the case of concrete structures another limit state corresponding to the beginning of a specific degradation process (corrosion of reinforcement), denoted tinit, may be important. In specific cases of buildings and bridges a functional (moral) service life may be taken into account. The paper includes also a practical example of assessing the remaining working life of a concrete structure.

Prediction of durability of structural concrete in aggressive exposures

2018 ◽  
Author(s):  
Сергей Леонович ◽  
Sergey Leonovich ◽  
Валентин Доркин ◽  
Valentin Dorkin ◽  
Оксана Чернякевич ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Service Life ◽  
Building Materials ◽  
Limit State ◽  
Concrete Structures ◽  
Life Cycles ◽  
Reinforced Concrete Structures ◽  
Concrete Durability ◽  
Concrete Carbonation ◽  
Corrosion Of Steel

The monograph is devoted to the prediction of the longevity of reinforced concrete structures, the destruction of which is associated with corrosion of steel reinforcement caused by chloride aggression or concrete carbonation. On the basis of a comprehensive analysis of models for calculating the service life of structures and experimental data, preference is given to the mathematical model Dura Crete. Life cycles for the main degradation processes in concrete and reinforcement, periods of initiation and propagation of corrosion are considered. Particular attention is paid to the influence of environmental factors and the quality of concrete on the kinetics of chloride penetration and movement of the carbonization front. Formulated limit state design reinforced concrete durability in chloride attacks and carbonation. The basic provisions of the method of calculating the durability of reinforced concrete structures, based on the use of the reliability coefficient for the service life. The practical assessment of service life of reinforced concrete elements taking into account stochastic processes in concrete and reinforcement is made. Verification of the model reliability is performed. For all those interested in the issues of building materials and processes occurring in them.

Experimental Study of Concrete Class Influence on Cracks Spacing

2014 ◽  
Vol 600 ◽  
pp. 558-568
Author(s):  
Omar Zorkane ◽  
Farid Chalah ◽  
Lila Chalah-Rezgui ◽  
Abderrahim Bali ◽  
Mohamed Nadib Oudjit
Keyword(s):  
Experimental Study ◽  
Reinforced Concrete ◽  
Phase Ii ◽  
Normal State ◽  
Limit State ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Limit States ◽  
Continuous Beams ◽  
Real Size

The aim of this work is to study the cracking of reinforced concrete continuous beams by considering different classes of concrete. It is well known that the design of reinforced concrete structures includes three limit states (limit state of collapse, limit state of strain and limit state of cracking). The cracks in reinforced concrete structures are admitted in the phase II (cracked sections). Thus, the phenomenon of cracks formation can be treated as a normal state only when their openings are limited to avoid a permanent risk of collapse and ensure durability for the civil engineering concrete structures. The importance of this work is described by the tests made on reinforced concrete continuous beams in real size, under concentrated loads increasing from zero up to collapse, where the concrete class influence on the cracks spacing has been studied. As this wasnt theoretically investigated, the used references for an aim comparison were relative to experimentations made by Monnier and Kuczynski on an only one concrete class to the cracks openings and the spacing evaluation analysis The findings of the research reported in this paper show that there is no effect of the concrete class on the cracks spacing.

Study and Application of Permeability Formwork to Marine Concrete

2013 ◽  
Vol 438-439 ◽  
pp. 333-337
Author(s):  
Qi Feng ◽  
Xiao Guang Wu ◽  
Ben Dong Zhao
Keyword(s):  
Concrete Structure ◽  
Concrete Structures ◽  
Working Life ◽  
Construction Process ◽  
Marine Structures ◽  
Working Mechanism ◽  
Development History ◽  
Research Status ◽  
Marine Concrete ◽  
Durability Of Concrete

During the construction of concrete structure, laying controlled permeability formwork within the traditional formwork can effectively improve the durability of concrete for marine structures and prolong the working life of concrete structures. This paper discusses the working mechanism of controlled permeability formwork, introduces its development history and research status, summarizes the construction process and matters needing attention of controlled permeability formwork, and puts forward the problems remaining to be solved at present.

scholarly journals Durability design of concrete structures, Part 1: Analysis fundamentals

2009 ◽  
Vol 7 (1) ◽  
pp. 1-18 ◽  
Author(s):  
Radomir Folic
Keyword(s):  
Service Life ◽  
Limit State ◽  
Natural Extension ◽  
Concrete Structures ◽  
International Committee ◽  
Chloride Ingress ◽  
Freezing And Thawing ◽  
Model Code ◽  
Design Service Life ◽  
Present Design

Concrete structures (CS) are designed so that they can satisfy requirements regarding safety, serviceability, durability and aesthetics throughout their design service life. Present design procedures regarding CS required by national or international codes and standards such as Model Code Euro International Committee of Concrete (1993) now Federation Internationale du Beton (FIB), Eurocodes, ACI, RILEM, etc. are predominantly based on strength principles and limit state formulation. The durability aspect is a natural extension of the classical resistance verification where deterioration effects are normally neglected. The reliability is assessed through the given performance that must be delivered within the design service life, the so-called performance-based design. This approach can be adopted for a performance based on service life design. In the recent years design is related to durability through the analysis of carbonation, resistance to chloride ingress, improved freezing and thawing resistance, etc. The review of literature and some recommendations are presented referring to the design of structures aiming to attain greater durability of CS. The accent is put on the theory of reliability, failure probability and service life probability. The basics of this analysis are given through the principles of performances and service life, and deterministic and scholastic methods using the lifetime safety factor.

Special Limit Condition Of Reinforced Concrete Structures And Its Normalization

2020 ◽  
pp. 4-9
Keyword(s):  
Reinforced Concrete ◽  
Limit State ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Functional Requirements ◽  
Limit States ◽  
Limit Condition ◽  
Load Bearing ◽  
Significant Strength ◽  
Special Limit

One of the ways to improve the resilience of buildings in the event of failure of the bearing structure or emergency, seismic effects is a more complete account of the behavior of elements and their mates at short-term action of loads and dynamics of change of the scheme of the bearing system of the building. To do this, it is advisable to allow more cracks to open, the development of deflections and partial destruction of some sections, which contradicts the current criteria for the first and second limit states that ensure the operational suitability of structures and buildings. Therefore, it is necessary to introduce specific standards of a special limit state for structures. A special limit state is the stage of operation of the structure after reaching the load-bearing capacity for the first and the deformation limits for the second limit states. Exceeding this state, in which the structures do not fully meet the functional requirements, leads to their collapse. The implementation of this limit state is most appropriate in load-bearing systems with a high degree of static indeterminability and constructive interaction of all bearing elements. The introduction and consideration of a special limit stress-strain state of reinforced concrete structures make it possible to detect significant strength and deformation reserves, even after significant fragmentation of the compressed concrete zone and, as a result, reducing the working section of the structure. As the main criteria of a particular limit state for reinforced concrete structures, it is recommended to adopt: the ultimate deformations of compressed concrete and tensile reinforcement with higher values than permissible under normal conditions; as well as the deflections of elements, provided that the minimum allowable length of the zone of bearing and anchorage of reinforcement.

IMPACT OF PREDICTING BRITTLE FAILURE MODES ON SELECTION OF LIMIT STATES OF VERTICALLY-IRREGULAR TALL BUILDINGS

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Aman Mwafy ◽  
Sayed Khalifa ◽  
Bilal El-Ariss
Keyword(s):  
Failure Modes ◽  
Limit State ◽  
Tall Buildings ◽  
International Standards ◽  
Performance Criteria ◽  
Far Field ◽  
Limit States ◽  
Earthquake Records ◽  
Irregular Buildings ◽  
Definition Of

The proper definition of structural failure of irregular structures is a critical element in building vulnerability assessment. Shear force demands may be the main cause of failure under earthquake loading. This increases the uncertainty related to the definition of the limit states of irregular buildings. The present study thus focuses on the assessment of brittle shear failure on the performance criteria of vertically irregular tall buildings. Five 50-story structures are designed using international standards to represent code-conforming tall buildings with main vertical irregularities. Detailed simulation models are used to assess the failure modes of the buildings under the effect of far-field and near-source earthquake records. Experimentally verified shear strength models are adopted to monitor the shear supply-demand response of the reference structures. Based on the comprehensive results obtained from incremental dynamic analyses, it is concluded that shear modeling is essential for the reliable assessment of vertically irregular buildings. The characteristics of earthquake records and the irregularity type significantly influence the limit states of the reference buildings. Unlike the behavior of the buildings under the far-field earthquake scenario, which is controlled by flexure, the collapse prevention limit state is significantly influenced by the member shear response under the effect of near-field earthquakes. Accordingly, improved limit state criteria are proposed, which supports the reliable earthquake loss estimation of tall buildings with different vertical irregularities.

Evolution of design standards and recorded failures of guyed towers in Canada

1989 ◽  
Vol 16 (5) ◽  
pp. 725-732 ◽  
Author(s):  
Mohammed H. Magued ◽  
Michel Bruneau ◽  
Robert B. Dryburgh
Keyword(s):  
Failure Rate ◽  
Limit State ◽  
Companion Paper ◽  
International Standards ◽  
Rational Approach ◽  
Design Standards ◽  
Existing Structures ◽  
Working Stress ◽  
Recent Edition ◽  
Guyed Towers

The information contained herein constitutes the foundations for a companion paper in which a set of guidelines for the upgrading of existing guyed towers is developed, following a rational approach. Large increases in strength requirements for guyed towers have been introduced by successive revisions of the CAN-CSA-S37 Standard "Antennas, Towers and Antenna-Supporting Structures" (S37). Up to now, there has been a perception among tower owners that tower failures were few and, in consequence, that the added strength requirements are not needed, and further, that existing towers should not be forced to comply with the latest edition of the S37 standard. This paper demonstrates that the failure rate for guyed towers designed to earlier versions of S37 is generally unacceptably high. General comments on standard developments and various design philosophies are presented. The evolution of the Canadian standard for the design of guyed towers is also examined, as deficiencies in earlier versions of S37 are partly accountable for the high observed failure rate. Other international standards for the design and analysis of guyed towers are also reviewed for their approach towards the upgrading of existing towers. Since guyed telecommunication towers are often reviewed for addition of new antennas, upgrading to the strength levels of the most recent edition of the standard — as required in many cases — can be very expensive. Yet, in many cases, much of this expense is unjustified for a variety of reasons. This paper proposes the need for the development of upgrading guidelines and further development work on S37. Key words: guyed towers, failure, failure rate, working stress design, limit state design, environmental loading, existing structures, strength upgrading.

scholarly journals Service Life Prediction of Concrete Structure Using Life-365 Software

2021 ◽  
Vol 12 (2) ◽  
pp. 1816-1826
Author(s):  
A. Deiveegan, Et. al.
Keyword(s):  
Service Life ◽  
Concrete Structure ◽  
Concrete Structures ◽  
High Strength ◽  
Vital Role ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Global Concern ◽  
Peak Value

The performances of repaired concrete structures continue to be a major global concern. This is the improvement in repairing materials and method, several repaired concrete structures still fail, leading to costly and time-consuming. This study was conducted to assess the effect of long-term chloride penetration as well as the effect of fly ash, water-cement ratio, and inhibitor on concrete structures to predict its Service life to obtained high strength durable concrete. The water-cement ratio played a vital role, as the water-cement ratio is reducing to get more service life of the concrete and at the value of 0.5, it seems that the peak value of service life of the concrete structure. In this paper, it is generally finding the service life of a concrete structure by reviewing the previous researches and by using Software Life-365.

Experimental studies on the development of a self-healing cementitious matrix for repair and retrofitting of concrete structures

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Dibyendu Adak ◽  
Donkupar Francis Marbaniang ◽  
Subhrajit Dutta
Keyword(s):  
Service Life ◽  
Mechanical Strength ◽  
Concrete Structure ◽  
Concrete Structures ◽  
The Self ◽  
Self Healing ◽  
Content Type ◽  
Cementitious Matrix ◽  
Healing Period ◽  
Strength And Durability

PurposeSelf-healing concrete is a revolutionary building material that will generally reduce the maintenance cost of concrete constructions. Self-healing of cracks in concrete structure would contribute to a longer service life of the concrete and would make the material more durable and more sustainable. The cementitious mortar with/without incorporating encapsulates at different percentages of slag replacement with the cement mix improves autogenous healing at different ages. Therefore, this study’s aim is to develop a self-healing cementitious matrix for repair and retrofitting of concrete structures.Design/methodology/approachIn the present work, waste straw pipes are used as a capsule, filled with the solution of sodium hydroxide (NaOH), sodium silicate (Na2SiO3) and colloidal nano-silica as self-healing activators. An artificial micro-crack on the control and blended mortar specimens at different percentages of slag replacement with cement (with/without encapsulation) is developed by applying a compressive load of 50% of its ultimate load-carrying capacity. The mechanical strength and ultrasonic pulse velocity, water absorption and chloride ion penetration test are conducted on the concrete specimen before and after the healing period. Finally, the self-healing activity of mortar mixes with/without encapsulation is analysed at different ages.FindingsThe encapsulated mortar mix with 10% of slag content has better self-healing potential than all other mixes considering mechanical strength and durability. The enhancement of the self-healing potential of such mortar mix is mainly due to hydration of anhydrous slag on the crack surface and transformation of amorphous slag to the crystalline phase in presence of encapsulated fluid.Research limitations/implicationsThe self-healing activities of the slag-based cementitious composite are studied for a healing period of 90 days only. The strength and durability performance of the cracked specimen may be increased after a long healing period.Practical implicationsThe outcome of the work will help repair the cracks in the concrete structure and enhances the service life.Originality/valueThis study identifies the addition encapsulates with a self-healing activator fluid that can recover its strength after minor damage.

Non-Destructive Inspection Method and Application Research of Steel Corrosion in Concrete Structures

2013 ◽  
Vol 438-439 ◽  
pp. 497-500 ◽  
Author(s):  
Xiao Na Zhang ◽  
Ming Xiao Jia
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structure ◽  
Concrete Structures ◽  
Steel Corrosion ◽  
Reinforced Concrete Structure ◽  
Application Research ◽  
Inspection Method ◽  
Existing Structures ◽  
Non Destructive ◽  
Physical Quantities

In the reinforced concrete structure, steel corrosion is a major factor affecting the durability of existing structures, it is necessary to explore the extent of steel corrosion in order to take the necessary measures. Based on non-damaged concrete components or structures, by measuring the performance of concrete-related physical quantities, non-destructive inspection could presume strength, compactness, uniformity and defects of concrete components or structure. Combined with engineering example, non-destructive inspection technique and its application in the degree of steel corrosions inspection have great prospects through further validation.

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