Damage evaluation of a PCCP joint with a localized soil void and broken wires

2021 ◽  
pp. 136943322110204
Author(s):  
Haizhen Li ◽  
Xin Feng ◽  
Bozhi Chen ◽  
Lin Zhao
Keyword(s):  
Structural Damage ◽  
Elastic Limit ◽  
Limit State ◽  
Concrete Core ◽  
Finite Element Software ◽  
Micro Cracks ◽  
Breakage Rate ◽  
Preliminary Study ◽  
Surrounding Soil ◽  
Pipe Joint

During the service life of a pipeline, the surrounding soil may erode locally around the pipe due to seepage and leakage, making the pipe partially unsupported and weakening the pipe–soil interaction. The presence of soil voids provides the possibility for broken wires and further accelerates damage. In this paper, the stress and strain of PCCP joint in service under a localized soil void and with broken wires were investigated using the general finite element software ABAQUS, and the structural damage of the pipe joint under superimposed defects was evaluated. The numerical model contained two PCCP segments, a flexible joint and the surrounding soil. The preliminary study suggests that the superimposed defects of a soil void and broken wires can cause increased damage to the PCCP joint. With the addition of the soil void, the micro cracks of both the concrete core and mortar coating transform into visible cracks, and the relative wire breakage rate with coupling defects is reduced by approximately 36% to reach the elastic limit state of the pipe. The findings of this research highlight the importance of good pipe–soil interactions and could provide a theoretical reference for damage assessment and further repair strategies.

Combined Reinforced Concrete Columns Strengthening with Steel Clipping and Concrete Surfacing

2021 ◽  
pp. 11-22
Author(s):  
Ю. Г. Москалькова ◽  
С. В. Данилов ◽  
В. А. Ржевуцкая
Keyword(s):  
Reinforced Concrete ◽  
Load Transfer ◽  
Limit State ◽  
Concrete Columns ◽  
Ultimate Limit State ◽  
Concrete Core ◽  
Reinforced Concrete Columns ◽  
Entire Height ◽  
Complex Structural ◽  
Ultimate Limit

Постановка задачи. Исследуется метод усиления железобетонных колонн устройством стальной обоймы с обетонированием, который позволяет восстанавливать эксплуатационные показатели колонн, имеющих значительные дефекты и повреждения. Предпосылкой настоящих исследований явилось предположение о том, что усиление стальной обоймой с обетонированием является эффективным способом повышения несущей способности железобетонных колонн, причем вариант приложения нагрузки - только на бетонное ядро или ко всему сечению - существенно на эффективность усиления не влияет. В связи с этим целью исследования является определение необходимости устройства стального оголовка и включения в работу ветвей стальной обоймы при условии обетонирования стержня колонны по всей высоте. Результаты и выводы. Рациональным признан способ передачи нагрузки только на бетонное ядро усиленных колонн, поскольку устройство оголовка стальной обоймы требует применения сложных конструктивно-технологических решений, но при этом дополнительно увеличивает несущую способность незначительно (согласно проведенным исследованиям менее чем на 10 %). Ввиду отсутствия необходимости устройства конструкций стального оголовка снижаются трудоемкость и сроки производства работ по усилению колонн. Statement of the problem. The method of strengthening reinforced concrete columns with a steel clipping and the concrete surfacing is investigated. This method allows one to repair the columns with significant defects and damage. The prerequisite for this study was the assumption of strengthening with a steel clipping and the concrete surfacing is an effective way to increase the ultimate limit state of reinforced concrete columns, furthermore, the option of applying the load (only to the concrete core or to the entire section) does not significantly affect the strengthening effectiveness. In this regard, the purpose of the investigation was to identify the need to include the steel jacketing in the work, on the condition the column is coated with concrete along with the entire height. Results and conclusions. The load transfer method only to the concrete core of the strengthened columns is recognized as rational since the device of the steel clipping head requires the use of complex structural and technological solutions, but at the same time additionally increases the ultimate limit state insignificantly (according to the studies by less than 10 %). Due to the absence of the need to establish structures of the steel jacketing head, the labor intensiveness and terms of work production on strengthening the columns are reduced.

scholarly journals Behavioural Study of Shear Wall with Correlational to Bracing under Seismic Loading

2018 ◽  
Vol 65 ◽  
pp. 08008
Author(s):  
Syed Muhammad Bilal Haider ◽  
Zafarullah Nizamani ◽  
Chun Chieh Yip
Keyword(s):  
Reinforced Concrete ◽  
Lateral Displacement ◽  
Limit State ◽  
Shear Wall ◽  
Design Tool ◽  
Base Shear ◽  
Building Model ◽  
High Rise ◽  
Finite Element Software ◽  
Seismic Vibrations

The reinforced concrete structures, not designed for seismic conditions, amid the past earthquakes have shown us the significance of assessment of the seismic limit state of the current structures. During seismic vibrations, every structure encountered seismic loads. Seismic vibrations in high rise building structure subjects horizontal and torsional deflections which consequently develop extensive reactions in the buildings. Subsequently, horizontal stiffness can produce firmness in the high rise structures and it resists all the horizontal and torsional movements of the building. Therefore, bracing and shear wall are the mainstream strategies for reinforcing the structures against their poor seismic behaviours. It is seen before that shear wall gives higher horizontal firmness to the structure when coupled with bracing however it will be another finding that in building model, which location is most suitable for shear wall and bracing to get better horizontal stability. In this study, a 15 story residential reinforced concrete building is assessed and analyzed using building code ACI 318-14 for bracing and shear wall placed at several different locations of the building model. The technique used for analysis is Equivalent Static Method by utilizing a design tool, finite element software named ETABS. The significant parameters examined are lateral displacement, base shear, story drift, and overturning moment.

An Evaluation of Two-Level Seismic Design Procedure

1993 ◽  
Vol 9 (1) ◽  
pp. 121-135 ◽  
Author(s):  
Chia-Ming Uang
Keyword(s):  
Structural Damage ◽  
Limit State ◽  
Design Procedure ◽  
Reduction Factor ◽  
Performance Criteria ◽  
Ultimate Limit State ◽  
Seismic Codes ◽  
Seismic Force ◽  
Force Reduction Factor ◽  
Force Reduction

The two-level design philosophy is recognized by modern seismic codes. When this philosophy is implemented in the code, the intensities of the two design earthquakes, the structural performance criteria, explicit versus implicit design approach, and the effectiveness to achieve the performance criteria vary considerably from one code to the other. For the ultimate limit state, the UBC was compared with seismic codes of Canada, Japan, and Eurocode. It was found that a trend to deviate from the UBC approach of using a single seismic force reduction factor (i.e., Rw) is apparent. Instead, an approach using a compound force reduction factor which considers the contribution of structural ductility and structural overstrength is preferred. For the serviceability limit state, a comparison of the level of design earthquakes and performance criteria of the UBC, Tri-Services Manual, and the Japanese code indicates that the UBC produces the most flexible structure, and that UBC does not control structural damage. It is suggested that the UBC adopts an explicit serviceability design procedure.

Evaluation on Safety of In-Service Structures Concerning Earthquake Resistance Based on Fourth-Order Moment of Limit State Function

2014 ◽  
Vol 1065-1069 ◽  
pp. 2319-2322
Author(s):  
Yu Ying Wang ◽  
Ya Zhou Sun ◽  
Le Yang Feng
Keyword(s):  
Bearing Capacity ◽  
Fourth Order ◽  
Structural Damage ◽  
Limit State ◽  
Decisive Role ◽  
Order Moment ◽  
State Function ◽  
Limit State Function ◽  
Engineering Structures ◽  
Internal Factors

During the process of being used, engineering structures will undergo material aging and structural damage with time passing by under the combined influence of internal factors including load, environment and structural material[1], and accumulation of such damages will cause decrease of bearing capacity, durability and reliability. Among various factors influencing the reliability of in-service structures, ultimate bearing capacity plays the decisive role in safety. In this paper, the fourth-order moment of limit state function is inferred through calculation of failure probability of in-service structures, and thus safety and durability of in-service structures can be ensured.

scholarly journals Dynamic Damage Mechanism and Seismic Fragility Analysis of an Aqueduct Structure

2021 ◽  
Vol 11 (24) ◽  
pp. 11709
Author(s):  
Xinyong Xu ◽  
Xuhui Liu ◽  
Li Jiang ◽  
Mohd Yawar Ali Khan
Keyword(s):  
Ground Motion ◽  
Structural Damage ◽  
Large Scale ◽  
Seismic Analysis ◽  
Fragility Curves ◽  
Limit State ◽  
Fragility Analysis ◽  
Seismic Fragility ◽  
Exceedance Probability ◽  
Computation Efficiency

The Concrete Damaged Plasticity (CDP) constitutive is introduced to study the dynamic failure mechanism and the law of damage development to the aqueduct structure during the seismic duration using a large-scale aqueduct structure from the South-to-North Water Division Project (SNWDP) as a research object. Incremental dynamic analysis (IDA) and multiple stripe analysis (MSA) seismic fragility methods are introduced. The spectral acceleration is used as the scale of ground motion record intensity measure (IM), and the aqueduct pier top offset ratio quantifies the limit of structural damage measure (DM). The aqueduct structure’s seismic fragility evaluation curves are constructed with indicators of different seismic intensity measures to depict the damage characteristics of aqueduct structures under different seismic intensities through probability. The results show that penetrating damage is most likely to occur on both sides of the pier cap and around the pier shaft in the event of a rare earthquake, followed by the top of the aqueduct body, which requires the greatest care during an earthquake. The results of two fragility analysis methodologies reveal that the fragility curves are very similar. The aqueduct structure’s first limit state level (LS1) is quite steep and near the vertical line, indicating that maintaining the excellent condition without damage in the seismic analysis will be challenging. Except for individual results, the overall fragility results are in good agreement, and the curve change rule is the same. The exceedance probability in the case of any ground motion record IM may be estimated using only two factors when using the MSA approach, and the computation efficiency is higher. The study of seismic fragility analysis methods in this paper can provide a reference for the seismic safety evaluation of aqueducts and similar structures.

scholarly journals Strengthening of Concrete Column by Using the Wrapper Layer of Fibre Reinforced Concrete

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5432
Author(s):  
Peter Koteš ◽  
Martin Vavruš ◽  
Jozef Jošt ◽  
Jozef Prokop
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Limit State ◽  
Fibre Reinforced Concrete ◽  
Limit States ◽  
Load Bearing Capacity ◽  
Concrete Core ◽  
Fibre Concrete ◽  
Special Cases ◽  
Ultimate Limit

Structures and bridges are being designed on the proposed and requested design lifetime of 50 to 100 years. In practice, one can see that the real lifetime of structures and bridges is shorter in many cases, in some special cases extremely shorter. The reasons for the lifetime shortening can be increased of the load cases (e.g., due to traffic on bridges, or due to other uses of a structure), using the material of lower quality, implementation of new standards and codes according to Eurocode replacing older ones. During the whole lifetime the structures must be maintained to fulfil the code requests. If the constructions are not able to fulfil the Ultimate Limit States (ULS) and the Serviceability Limit State (SLS), the structures or bridges have to be strengthened (whole or its elements). The purpose of the paper is the presentation of using a layer of the fibre concrete for a columns’ strengthening. Using the fibre reinforced concrete (FRC) of higher tensile strength makes it possible to increase the load-bearing capacity of the cross-section the column. The contact between the old concrete (core of column) and newly added layer (around column) is very important for using that method of strengthening. In the article, there is also a comparison of the surface modification methods.

scholarly journals Mechanical Response of Gasketed Bell-and-Spigot Joint of Concrete Pipeline under Multifield Coupling

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Hang He ◽  
Hongyuan Fang ◽  
Xueming Du ◽  
Bin Li
Keyword(s):  
Flow Field ◽  
Mechanical Response ◽  
Coupling Effect ◽  
Circumferential Stress ◽  
Traffic Load ◽  
Vertical Deformation ◽  
Finite Element Software ◽  
Concrete Pipe ◽  
Internal Fluid ◽  
Pipe Joint

Concrete pipe may suffer joint failure under the coupling effect of internal fluid and overlying load, which may lead to pipe leakage. Based on Abaqus and Fluent finite element software, a three-dimensional refined model of drainage pipeline with gasketed bell-and-spigot joints and flow field model inside the pipeline was established. Fully considering the compression of the gasket during pipeline assembly and pipe-soil interaction, the fluid-structure coupling numerical simulation was carried out by using the MpCCI (Mesh-based parallel Code Coupling Interface) platform, and the mechanical response of the concrete pipe joint under the multifield loads coupling effects of burial condition, traffic load, and internal fluid was studied. The accuracy of the coupling model was verified through the full-scale tests that have been carried out. The influences of various factors on the circumferential stress and vertical deformation of the joint were mainly studied. The result reveals that the influence of different working conditions on the circumferential stress of the pipe joint is mainly concentrated on the crown and the invert of the joint, the areas vulnerable to tensile damage. The change of flow field leads to a slight difference in the vertical deformation of the joint, while variation in gasket hardness and cushion compactness has a certain influence on the vertical deformation of the joint. The change of buried depth has a negative correlation to the vertical deformation of the joint, and the change of load position has a significant nonlinear effect. The result provides a theoretical basis for further research on the mechanical mechanism of the pipeline joints during operation.

scholarly journals Some considerations on shear and torsion in R/C structural members in fire

2018 ◽  
Vol 9 (2) ◽  
pp. 94-107 ◽  
Author(s):  
Patrick Bamonte ◽  
Pietro G. Gambarova ◽  
Nataša Kalaba ◽  
Sergio Tattoni
Keyword(s):  
Limit State ◽  
Ultimate Limit State ◽  
Structural Members ◽  
Zone Method ◽  
Concrete Core ◽  
Content Type ◽  
Dowel Action ◽  
In Fire ◽  
Ultimate Limit ◽  
Fire Conditions

Purpose This study aims to provide a factual justification of the extension to fire conditions of the well-known design models for the calculations of R/C members at the ultimate limit state in shear and torsion. Both solid and thin-walled sections are considered. In the latter case, the little-known topic of shear-transfer mechanisms at high temperature is introduced and discussed. Design/methodology/approach Both the effective-section method and the zone method are treated, as well as the strut-and-tie models required by the analysis of the so-called D zones (discontinuity zones), where heat-enhanced cracking further bears out the phenomenological basis of the models. Findings The increasing role played by the stirrups in shear and by the rather cold concrete core in torsion stand out clearly in fire, while high temperatures rapidly reduce the contributions of such resisting mechanisms as concrete-teeth bending, aggregate interlock and dowel action. Originality/value On the whole, beside quantifying the side contributions of web mechanisms and section core in fire conditions, this study indicates a possible approach to extend to fire the available models on the coupling of shear and bending, and shear and torsion in R/C members.

The study of regularities of changes in acoustic characteristics depending on microstructure parameters and development of acoustic limit state criterion

2020 ◽  
pp. 32-42
Author(s):  
V. N. Gadalov ◽  
S. V. Safonov ◽  
E. A. Filatov ◽  
O. N. Boldyreva ◽  
I. A. Makarova
Keyword(s):  
Structural Damage ◽  
Limit State ◽  
Acoustic Characteristics ◽  
Term Operation ◽  
Long Run ◽  
Microstructure Parameters ◽  
State Criterion ◽  
Good Agreement

The studies of the dependence of acoustic characteristics on the microstructure of chromium-molybdenum-vanadium steels in various structural states after long term operation are presented. The meaning of the acoustic limit state criterion, which represents a relative assessment of accumulated structural damage of the long run metal for the time delay of ultrasonic Rayleigh waves and determination of the limit state of the material, is revealed. It is established that at the acoustic criterion of the limit state of ≥0.7, the metal is in the state of avalanche creep and reaches the limit state. Measurements of acoustic characteristics gave a good agreement with the results of metallographic studies conducted on sections of metal cuttings. In addition, the criterion was tested when diagnosing technical devices made of steel 15X1M1F, 12X2MFSR, 17GS, 09G2S.

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