scholarly journals Prevention of Structural Damage of Reinforced Concrete Structures during Construction : Reliability construction method based on variation of concrete strength

1989 ◽  
Vol 403 (0) ◽  
pp. 1-11
Author(s):  
Toshihiko Yamamoto
Keyword(s):  
Reinforced Concrete ◽  
Structural Damage ◽  
Concrete Strength ◽  
Concrete Structures ◽  
Construction Method ◽  
Reinforced Concrete Structures

The Lima earthquake of October 3, 1974: Damage distribution

1977 ◽  
Vol 67 (5) ◽  
pp. 1441-1472
Author(s):  
R. Husid ◽  
A. F. Espinosa ◽  
J. de las Casas
Keyword(s):  
Reinforced Concrete ◽  
Structural Damage ◽  
Concrete Structures ◽  
Effective Length ◽  
Reinforced Concrete Structures ◽  
Severe Damage ◽  
Original Design ◽  
Reinforced Masonry ◽  
Water Tanks ◽  
Story Building

abstract The October 3, 1974, earthquake caused severe damage to buildings of adobe and quincha construction, and also to masonry, reinforced masonry, and reinforced-concrete structures in Lima and vicinity. Most of the damage to well-built structures was due, in part, to the lack of lateral resistance in the original design and to the fact that this earthquake had more energy around 0.4 seconds period than prior destructive earthquakes. Water tanks on the roofs of structures with four or five stories were damaged. Well-engineered single-story buildings were less affected than taller structures. Considerable structural damage to reinforced-concrete structures occurred in the districts of Barranco, La Campiña Molina, and Callao. In La Campiña three-story building partly collapsed and other buildings sustained considerable damage. In La Molina, the buildings of the Agrarian University sustained severe damage, and some collapsed. In Surco, the district adjacent to La Molina, there was no appreciable damage. In Callao, a four-story building collapsed, and the upper half of a concrete silo collapsed. In reinforced-concrete structures, column ties were frequently small in diameter, widely spaced, and not well connected. Usually, the reinforcement of resisting elements had no relation to their stiffnesses. Front columns in school buildings were restrained by high brick walls and had rather short effective lengths to allow building displacement in that direction. The windows in the rear walls gave the rear columns a much greater effective length. Therefore, a longitudinal displacement induces large shear forces in the front columns where most of the severe damage occurred. This problem was not considered in the design of these structures.

scholarly journals Damage Assessment of Reinforced Concrete Structures: A Review

2022 ◽  
pp. 1-7
Author(s):  
Gomasa Ramesh ◽  
Keyword(s):  
Reinforced Concrete ◽  
Damage Assessment ◽  
Structural Damage ◽  
Concrete Structures ◽  
Practical Method ◽  
Assessment Method ◽  
Reinforced Concrete Structures ◽  
Current Response ◽  
Damage Indices ◽  
Seismic Damage Assessment

Damage may be assessed using several damage indices with values associated with different structural damage states. The usefulness of a variety of current response-based damage indices in seismic damage assessment is addressed and critically assessed. A novel rational damage assessment method is provided, which measures the structure’s physical reaction characteristics. A practical method based on various analyses is given to evaluate the damaged structures in earthquakes of different intensities. This paper provides an overview of previous research works on the damage assessment of the reinforced concrete structures. This study may be helpful for easy understanding about the damage assessment of reinforced concrete structures and reduce the impacts of disaster and surrounding structures.

DAMAGE DETECTION OF RC SLABS USING NONLINEAR VIBRATION FEATURES

2009 ◽  
Vol 09 (04) ◽  
pp. 687-709 ◽  
Author(s):  
XINQUN ZHU ◽  
HONG HAO
Keyword(s):  
Reinforced Concrete ◽  
Nonlinear Vibration ◽  
Structural Damage ◽  
Concrete Structures ◽  
Dynamic Responses ◽  
Mode Shapes ◽  
Reinforced Concrete Structures ◽  
Vibration Frequencies ◽  
Skeleton Curve ◽  
Time Frequency

Studied herein are the signatures of nonlinear vibration characteristics of damaged reinforced concrete structures using the wavelet transform (WT). A two-span RC slab built in 2003 was tested to failure in the laboratory. Vibration measurements were carried out at various stages of structural damage. The vibration frequencies, mode shapes, and damping ratios at each loading stage were extracted and analyzed. It is found that the vibration frequencies are not sensitive to small damages, but are good indicators when damage is severe. The dynamic responses are also analyzed in the time–frequency domain by WT and the skeleton curve is constructed to describe the nonlinear characteristics in the reinforced concrete structures. The results show that the skeleton curves are good indicators of damage in the reinforced concrete structures because they are more sensitive to small damages than vibration frequencies.

scholarly journals Experimental study of the influence of crack width due to corrosion behaviour using different measurement methods and different exposures

2019 ◽  
Vol 289 ◽  
pp. 08005
Author(s):  
Martin Schneider ◽  
Georg Gardener
Keyword(s):  
Reinforced Concrete ◽  
Crack Width ◽  
Corrosion Behaviour ◽  
Concrete Strength ◽  
Concrete Structures ◽  
Chloride Ions ◽  
Reinforced Concrete Structures ◽  
Reinforcing Steel ◽  
Surface Corrosion ◽  
Potential Mapping

Corrosion of reinforcing steel has a great influence in reducing the lifetime of concrete structures; Carbonation of the concrete pore solution causes surface corrosion on the steel and diffusion of chloride ions through the capillary system of the concrete cover causes pitting corrosion on the steel surface. Corrosion of metals is highly dependent on the environmental conditions. Exposure to chloride ions can be critical to the service life of reinforced concrete structures. The durability of reinforced concrete structures exposed to deicing salt or marine environments can be affected by impact of chloride ions. Detection methods for the rate of corrosion of non-destructive and destructive procedures were analysed. The potential mapping applied on the concrete surface was discussed as a standard method for corrosion detection and will be explained in detail including the application boundaries of the method. It is assumed that the corrosion behaviour of reinforcing steel depends on crack widths. To analyse that, 8 coated and 8 uncoated test samples with different concrete strength classes were used. The concrete objects were exposed to a 3% sodium chloride solution. The corrosion behaviour of reinforcing steel is analysed by using potential mapping with different reference electrodes (Ag/AgCl and Cu/CuSO4). The results show a significant correlation between crack size and protection system on the surface. The maximum crack width with a low indication of corrosion was found to be 0.1 mm.

Research on Corrosion of Reinforced Concrete Structures by Chloridion in Port Engineering Construction

2011 ◽  
Vol 90-93 ◽  
pp. 2483-2486 ◽  
Author(s):  
Yan Ying Dong ◽  
Li Shan Zhang ◽  
Ming Zhang ◽  
Tian Zhi Zhu
Keyword(s):  
Reinforced Concrete ◽  
Structural Damage ◽  
Raw Materials ◽  
Concrete Structures ◽  
Raw Material ◽  
Reinforced Concrete Structures ◽  
Engineering Construction ◽  
Rebar Corrosion ◽  
The Right ◽  
Port Engineering

In port engineering construction, the source of chloridion is concrete raw materials, admixtures and the penetration of seawater. Chloridion makes rebar corrosion, and makes the expansion and crack of reinforcement concrete, leading to concrete structural damage. By selecting the right concrete raw material, appropriate admixtures and to ensure concrete construction quality, in order to effectively avoid chloridion to the damage of reinforced concrete structures in construction.

How does concrete strength affect the fire resistance?

2020 ◽  
Vol 11 (3) ◽  
pp. 311-324
Author(s):  
Eva Lubloy
Keyword(s):  
Reinforced Concrete ◽  
Fire Resistance ◽  
Fire Safety ◽  
Strength Class ◽  
Concrete Strength ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Building Structures ◽  
Content Type ◽  
Upper Limit

Purpose The aim of the research was to investigate the effect of concrete strength on the fire resistance of structures. At first, it may seem contradictory that higher concrete strengths can decrease the fire resistance of building structures. However, if the strength of the concrete exceeds a maximum value, the risk of spalling (the detachment of the concrete surface) significantly. Design/methodology/approach Prefabricated structural elements are often produced with higher strength. The higher concrete strengths generally do not cause a reduction in the load bearing capacity, but it can have serious consequences in case of structural fire design. Results of two prefabricated elements, namely, one slab (TT shaped panel) and one single layer wall panel, were examined. Results of the specimen with the originally designed composition and a specimen with modified concrete composition were examined, were polymer fibres were added to prevent spalling. Findings As a result of the experiments, more strict regulations in the standards the author is suggested including more strict regulations in the standards. It has been proved that to ensure the fire safety of the reinforced concrete structures, it is required after polymer fibres even in lower concrete strength class than prescribed by the standard. In addition, during the classification and evaluation of structures, it is advisable to introduce an upper limit of allowed concrete strength for fire safety reasons. Originality/value As a result of the experiments, the author suggests including more strict regulations in the standards. It has been proved that to ensure the fire safety of the reinforced concrete structures, it is necessary to require the addition of polymer fibres even in lower concrete strength class than prescribed by the standard. In addition, during the classification and evaluation of structures, it is advisable to introduce an upper limit of allowed concrete strength for fire safety reasons.

scholarly journals The Mechanical Properties of Centrifuged Concrete in Reinforced Concrete Structures

2020 ◽  
Vol 10 (10) ◽  
pp. 3570
Author(s):  
Romualdas Kliukas ◽  
Ona Lukoševičienė ◽  
Arūnas Jaras ◽  
Bronius Jonaitis
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
Concrete Strength ◽  
Concrete Structures ◽  
High Strength ◽  
Reinforcement Ratio ◽  
Transverse Reinforcement ◽  
Reinforced Concrete Structures ◽  
Test Results ◽  
Moduli Of Elasticity

This article explores the influence of transverse reinforcement (spiral) and high-strength longitudinal reinforcements on the physical-mechanical properties of centrifuged annular cross-section elements of concrete. The test results of almost 200 reinforced, and over 100 control elements are summarizing in this article. The longitudinal reinforcement ratio of samples produced in the laboratory and factory varied from 1.0% to 6.0%; the transverse reinforcement ratio varied from 0.25% to 1.25%; the pitch of spirals varied from 100 mm to 40 mm and the concrete strength varied from 25 MPa to 60 MPa. Experimental relationships of coefficients for concrete strength, moduli of elasticity and limits of the longitudinal strain of centrifuged concrete in reinforced concrete structures in short-term concentrically compression were proposed.

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.

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