scholarly journals Experimental Study of the Fatigue Performance of the Bonding Surfaces and Load-Bearing Capacity of a Large-Scale Severely Damaged Hollow Slab Strengthened by CFRP

2021 ◽  
Vol 13 (21) ◽  
pp. 12179
Author(s):  
Hao Hu ◽  
Chuan-Zhi Dong ◽  
Jiji Wang ◽  
Jiaqi Chen
Keyword(s):  
Bearing Capacity ◽  
Large Scale ◽  
Single Point ◽  
Experimental Studies ◽  
Real Life ◽  
Load Test ◽  
Strengthening Effect ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Destructive Test

In recent years, carbon fiber reinforced polymer (CFRP) has been widely used in bridge repair, retrofitting, rehabilitation and strengthening to improve the bearing capacity. Although many studies have been conducted to explore the strengthening efficiencies of CFRP, the test specimens were small and the results were difficult to apply to full-scale bridges. Investigations into the strengthening effects of CFRP on real life structures rely on field load tests (without damaging the structures), making it difficult to understand actual improvements in load carrying capacity and strengthening effect. Moreover, there have been few experimental studies on the fatigue performances of CFRP-strengthened structures, especially on the large-scale structures with real wheel moving loads. In this study, the feasibility and efficiency of CFRP strengthening and repair was investigated on a large-scale, prestressed concrete hollow slab decommissioned from a real-life concrete bridge. The hollow slab was first put through a destructive test to test the ultimate load-bearing capacity. Then, CFRP strips were installed on the surface of the severely damaged slab to repair and strengthen it. Fatigue load test—including the moving load test and single point sinusoidal load—and load-bearing capacity tests were conducted on the CFRP-strengthened hollow slab after the destructive test to evaluate the strengthening performance. This study could help us to understand the actual load-bearing capacities of severe damaged concrete structures strengthened by CFRP, reduce waste, save resources and improve the utilization of our infrastructures.

scholarly journals Axial Behaviour of Slender RC Circular Columns Strengthened with Circular CFST Jackets

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Yiyan Lu ◽  
Tao Zhu ◽  
Shan Li ◽  
Weijie Li ◽  
Na Li
Keyword(s):  
Bearing Capacity ◽  
Ductile Failure ◽  
Steel Tube ◽  
Experimental Results ◽  
Strengthening Effect ◽  
Load Bearing Capacity ◽  
Rc Columns ◽  
Load Bearing ◽  
Cfst Columns ◽  
Material Utilization

This paper investigates the axial behavior of slender reinforced concrete (RC) columns strengthened with concrete filled steel tube (CFST) jacketing technique. It is realized by pouring self-compacting concrete (SCC) into the gap between inner original slender RC columns and outer steel tubes. Nine specimens were prepared and tested to failure under axial compression: a control specimen without strengthening and eight specimens with heights ranging between 1240 and 2140 mm strengthened with CFST jacketing. Experimental variables included four different length-to-diameter (L/D) ratios, three different diameter-to-thickness (D/t) ratios, and three different SCC strengths. The experimental results showed that the outer steel tube provided confinement to the SCC and original slender RC columns and thus effectively improved the behavior of slender RC columns. The failure mode of slender RC columns was changed from brittle failure (concrete peel-off) into ductile failure (global bending) after strengthening. And, the load-bearing capacity, material utilization, and ductility of slender RC columns were significantly enhanced. The strengthening effect of CFST jacketing decreased with the increase of L/D ratio and D/t ratio but showed little variation with higher SCC strength. An existing expression of load-bearing capacity for traditional CFST columns was extended to propose a formula for the load-bearing capacity of CFST jacketed columns, and the predictions showed good agreement with the experimental results.

scholarly journals Analysis of Tribological Behavior of Carbon Nanotube Based Industrial Mineral Gear Oil 250 cSt Viscosity

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Shubrajit Bhaumik ◽  
S. Prabhu ◽  
Kingsly Jeba Singh
Keyword(s):  
Carbon Nanotube ◽  
Bearing Capacity ◽  
Wear Test ◽  
Mineral Oil ◽  
Load Test ◽  
Multiwalled Carbon Nanotube ◽  
Load Bearing Capacity ◽  
Multiwalled Carbon ◽  
Sem Images ◽  
Load Bearing

The paper investigates the exceptional antiwear and extreme pressure properties of multiwalled carbon nanotube based mineral oil. Different samples of oil containing varying proportions of MWNT (MWNT) and graphite were prepared. The samples were tested for their antiwear and load bearing capacity according to ASTM G99 and ASTM D-2783 standards. After pass load test in four ball tester the rubbed surfaces were investigated with Scanning Electron Microscope (SEM) images. The wear test results show a decrease wear by 70–75% in case of multiwalled nanotube based mineral oil as compared with pure mineral oil. Furthermore, it has been observed that the load bearing capacity in case of multiwalled carbon nanotube based mineral oil increases by 20% as compared to pure mineral oil. A comparison in the antiwear and load bearing capacity properties of graphite and nanotube based mineral oil was studied which showed the inefficiency of graphite based lubricant over MWNT based oil. Thus, the finding would be helpful in developing new nanoparticle based lubricants.

scholarly journals DETERMINATION OF THE AMOUNT OF ADHESION OF BASALT-PLASTIC REINFORCEMENT TO CONCRETE

2020 ◽  
Vol 8 (3) ◽  
pp. 36-39
Author(s):  
Yulia Kustikova
Keyword(s):  
Bearing Capacity ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Load Bearing Capacity ◽  
Load Bearing

The results of experimental studies and tests of concrete structures with basalt-plastic reinforcement to determine the load-bearing capacity, as well as the mechanism of adhesion of basalt-plastic rods to concrete are considered.

The assessment of the level of local strengthening of pipe steel welded connections

2020 ◽  
Vol 10 (3) ◽  
pp. 252-262
Author(s):  
Marat Z. Yamilev ◽  
◽  
Egor А. Tigulev ◽  
Andrey А. Raspopov ◽  
◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Numerical Model ◽  
Bearing Capacity ◽  
Pipe Steel ◽  
Carbon Steels ◽  
Strengthening Effect ◽  
Low Carbon ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Welded Connection

The metal welding is accompanied by the formation of mechanically non-homogenous sections of welded connection. The pipeline welded connections also have sections, which are different in structure, chemical composition and mechanical properties. The mechanical inhomogeneity affects the load bearing capacity of welded connection and the structure as a whole, which is necessary to take into consideration when performing calculation analysis. So far, the specialists have established the dependencies in assessment of welded connection strength with various types of heterogeneous sections. However, this phenomenon has received little attention in case of pipeline welded connections made of low carbon steels. The existing theoretical models do not reflect actual anisotropy of mechanical properties of the welded connections and weld adjacent zone. The present study considers the model of welded connections of K56 pipe steels with various strength characteristics of sections of welded seam and weld adjacent zone, without defects. The assessment of mechanical inhomogeneity influence on load bearing capacity of welded connections was performed by applying the finite-element modelling of its stress-strain state. The developed numerical model helps to determine and optimize the criteria of testing of full scale samples of pipe steel welded connections with regards to the implementation of local strengthening effect. The research results demonstrated that the degree of contact strengthening in welded connections with X-shape grooving is higher than in welded connections with V-shaped grooving by 8 % at similar relative thickness of soft interlayer. The suggested numerical model can be applied for detailed calculations of pipelines with regards to the mechanical inhomogeneity of its welded connections.

Role of Collagen Content and Architecture in the Load Bearing Capabilities of Tissue-Engineered Cartilage

2011 ◽  
Author(s):  
M. Khoshgoftar ◽  
C. C. van Donkelaar ◽  
K. Ito
Keyword(s):  
Bearing Capacity ◽  
Network Architecture ◽  
Mechanical Performance ◽  
Experimental Studies ◽  
Limiting Factor ◽  
Collagen Network ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Native Cartilage ◽  
Engineer Cartilage

A promising treatment for damaged cartilage is to replace it with tissue-engineered (TE) cartilage. However, the insufficient load-bearing capacity of today’s TE cartilage is an important limiting factor in its clinical application. In native cartilage, collagen fibers resist tension and proteoglycans (PG’s) attract water through osmotic pressure and resist its flow, which allows cartilage to withstand high compressive forces. One of the main challenges for tissue engineering of mechanically stable cartilage is therefore to find the cues to create an engineered tissue with an ultrastructure similar to that of native tissue. Currently, it is possible to tissue engineer cartilage with almost native PG content but collagen reaches only 1/4 of the native content [1]. Furthermore, the specific depth dependent arcade-like organization of collagen in native cartilage (i.e. vertical fibers in the deep zone and horizontal fibers in the superficial zone), which is optimized for distributing loads, has not been addressed in TE’d cartilage. However, the relative importance of matrix component content and collagen network architecture to the mechanical performance of TE cartilage is poorly understood, perhaps because this would require substantial effort on time consuming and labor-intensive experimental studies. The aim of this study is to explore if it is sufficient to produce a tissue with abundant proteoglycans and/or collagen, or whether reproducing the specific arcade-like collagen network in the implant is essential to develop sufficient load-bearing capacity, using a numerical approach.

scholarly journals Determination of the load-bearing capacity of «steel-wood» connections of LVL structures under tension

2021 ◽  
Vol 18 (1) ◽  
pp. 60-69
Author(s):  
Quoc Phong Tran ◽  
Keyword(s):  
Bearing Capacity ◽  
Cross Section ◽  
Steel Plate ◽  
Experimental Studies ◽  
Steel Plates ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Dowel Connections ◽  
Wooden Structures

The article presents the results of calculation of the load-bearing capacity of connections of LVL structures under tension using cylindrical dowels in trusses and frames. The description of calculation schemes for determining the load-bearing capacity of connections with different location and sizes of steel plates in the connection is given. The influence of steel plate placement on the distribution of forces in the cross-section of samples is investigated. Based on the results of analytical and experimental studies, the load-bearing capacity of dowels during bending is considered, as well as the mechanism of wooden structures` fracture during chipping. A comparative analysis of the effectiveness of different schemes of dowel connections with three steel plates under tension is carried out.

scholarly journals OTIMIZAÇÃO DO CÁLCULO DA CAPACIDADE DE CARGA E TENSÃO ADMISSÍVEL DO SOLO PARA SAPATAS ISOLADAS

2016 ◽  
Vol 12 (2) ◽  
Author(s):  
Bruna Leal Melo de Oliveira ◽  
Luciana Barbosa Amancio
Keyword(s):  
Bearing Capacity ◽  
Human Error ◽  
Specific Weight ◽  
Load Test ◽  
Allowable Stress ◽  
Microsoft Excel ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Plate Load Test ◽  
Short Period

RESUMO: Para o dimensionamento geotécnico de fundações superficiais é necessário conhecer a tensão admissível do solo, obtida indiretamente a partir da capacidade de carga; ou diretamente aplicando-se os métodos semiempíricos. Uma alternativa para automatizar esses cálculos é a utilização de planilha eletrônica, uma ferramenta simples, com o intuito de otimizar o tempo e reduzir as falhas humanas. Para demonstrar a aplicabilidade e a eficiência desta ferramenta, desenvolveu-se uma planilha eletrônica através do software Microsoft Excel que, a partir de variáveis como: coesão, ângulo de atrito, peso específico e nível freático; dentre outras, é capaz de estimar a capacidade de carga e a tensão admissível para sapata isolada, em diferentes ocasiões, por diversas metodologias consagradas e, além disso, exibir graficamente a comparação entre os resultados obtidos. Por fim, a ferramenta foi aplicada em três cenários fictícios: (1) sapata quadrada com variação da cota de assentamento; (2) sapata retangular com variação do nível freático e (3) sapata circular com realização de ensaio de placa, comprovando que é possível testar várias hipóteses para um mesmo problema em um curto período de tempo. ABSTRACT: For geotechnical design of shallow foundations it is necessary to know the allowable stress of the soil, obtained indirectly from the load bearing capacity; or directly, applying the semi-empirical methods. An alternative to automate these calculations is the use of spreadsheet, a simple tool, aiming to optimize time and reduce human error. To demonstrate the applicability and effectiveness of this tool, a spreadsheet was developed using the Microsoft Excel software, based on some variables such as: cohesion; friction angle; specific weight; groundwater level; among others, to estimate the load bearing capacity and the allowable stress for isolated footing on different occasions, by several methodologies, and in addition, to show graphically the comparison between the results obtained. Finally, the tool was applied on three fictitious scenarios: (1) Square isolated footing with variation of the settlement quota; (2) rectangular isolated footing with variation of the water level and (3) circular isolated footing with execution of the Plate Load Test, proving that it is possible to test several hypotheses for the same problem in a short period of time.

scholarly journals FLEXURAL CAPACITY OF CORRODED POST-TENSIONED CONCRETE BEAMS: LARGE SCALE TESTS AND NUMERICAL SIMULATION

2020 ◽  
Author(s):  
Antonino Recupero ◽  
Nino Spinella ◽  
Antonio Marì ◽  
Jesús Miguel Bairan
Keyword(s):  
Numerical Model ◽  
Bearing Capacity ◽  
Large Scale ◽  
Concrete Beams ◽  
Structural Response ◽  
Experimental Results ◽  
Analysis Model ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Post Tensioned

An experimental campaign on corroded post-tensioned concrete beams is being carried out at the University of Messina (Italy). The main goal of the research project is to study the influence of the tendon corrosion on the response behaviour of post-tensioned concrete beams subjected to a transversal load. In 2006, six beams were cast with a tendon placed at the centroid of the cross-section. Corrosion of the tendons was artificially induced in each specimen by injecting a chemical solution or an acid in some parts of the duct. The experimental results have showed how external causes, reproduced by artificial defects, can induce several critical issues, and undermine both the durability and the load bearing capacity of the beams. The load bearing capacity of the beam with defects was reduced until half of the one recorded for the specimen with not corroded tendon. In addition, a non-linear and time dependent analysis model, developed at UPC in Barcelona, was used to simulate the response of the tested beams, with the purpose of experimentally verifying the capacity of the model to capture the effects of corrosion along the time. A parametric study was performed with the numerical model to capture the influence of the degree of corrosion, (defined as the % loss of steel mass) on the serviceability response and on the ultimate capacity. By comparing the theoretical and the experimental results, the degree of corrosion was estimated and compared with that observed subsequently on the tested beams. Good correlation was obtained, thus allowing the numerical model to be used as a “virtual lab” to study the influence of several parameters on the structural response of corroded post-tensioned beams.

scholarly journals Methods of Calculation the Increased Reinforced Concrete Elements by Carrying Capacity of Slope Sections

2021 ◽  
Vol 1203 (2) ◽  
pp. 022051
Author(s):  
Andrii Mazurak ◽  
Roman Kinasz ◽  
Ivan Kovalyk ◽  
Rostyslav Mazurak ◽  
Vitaliy Kalchenko
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Experimental Studies ◽  
Longitudinal Axis ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Theoretical Approaches ◽  
Reinforced Beams ◽  
Eurocode 2 ◽  
Concrete Elements

Abstract Reinforcement bending reinforced concrete structures by increasing the cross section and assessing the load-bearing capacity of the inclined section such elements is an urgent problem, as not yet accumulated adequate research data on the stress-strain state such structures in the span, which works on shear and shear bending moment and transverse force. Analyzing the development theories calculation reinforced concrete elements inclined to the longitudinal axis, we can identify many areas, the main approach of which was based on the calculation using the bases of material resistance, and the use of empirical dependencies. Theoretical approaches calculation the European construction magazine RILEM TC, SNiP 2.03.01.-84* are considered, DBN B.2.6-98 2009 (Eurocode 2), US ACI 318-19. Experimental studies reinforced concrete elements to determine the load-bearing capacity inclined sections were performed on the basis of 5 samples reinforced concrete beams, 14 reinforced samples of reinforced concrete and shotcrete a total of 19 pieces in four series. Beams were made of concrete in each series fck = 19.08 MPa; fck = 27.74 MPa; fck = 20.48 MPa; fck = 20.48 MPa, respectively, reinforced samples with concrete fck = 17.95 MPa; fck = 19.5 MPa (shotcrete fck = 31.00 MPa); shotcrete fck = 19.9 MPa; fck = 19.9 MPa. Also for the manufacture and reinforcement beams used flat and U-shaped frames with working longitudinal reinforcement Ø22, Ø16, Ø12, Ø10, Ø6 A400C, and transverse reinforcement Ø6 A240C (step 120 mm). Reinforcement inclined sections of the experimental beams was performed on one, two or three sides, depending on the variant of the sample and the type of frame flat or U-shaped. Investigations of beams were performed according to the static scheme - a beam on two supports, span L=2100 mm. Deformations of concrete and reinforcement in the samples when determining the bearing capacity of inclined sections were measured using microindicators of the clock type, strain gauges. According to the results theoretical and experimental studies the bearing capacity inclined sections to the longitudinal axis, we can see a significant reassessment between the theoretical values inclined sections according to the new DBN B.2.6.-98: 2009 (Eurocode 2) over the actual results obtained during testing samples 53-67% for conventional beams, and 27-50% for reinforced beams. The results US regulations ACI 318-19 showed convergence of results in the range of 2-9% for samples without reinforcement and 1-7% for samples with reinforcement, but the values show the excess of experimental data over theoretical, indicating the impossibility of accurately determining the actual final bearing capacity. The results the calculation obtained by the method of SNiP 2.03.01-84*, both unreinforced and reinforced beams has a satisfactory agreement with the experimental values in the range of 6-10%.

scholarly journals Investigation of Mechanical and Hydrologic Characteristics of Porous Asphalt Pavement with a Geocell Composite

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3165
Author(s):  
Jaehun Ahn ◽  
Tan Hung Nguyen ◽  
In Kyoon Yoo ◽  
Jeongho Oh
Keyword(s):  
Bearing Capacity ◽  
Hydrological Cycle ◽  
Asphalt Pavement ◽  
Load Test ◽  
Rainfall Simulation ◽  
Base Layer ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Plate Load Test ◽  
Porous Asphalt

Porous asphalt pavement is a part of the permeable pavement system, which can be used to mitigate the negative impacts of urbanisation on the water hydrological cycle and environment. This study aims to assess the mechanical and hydrologic characteristics of porous asphalt pavements, with and without geocell composites, using a plate load test, falling weight deflectometer test, and rainfall simulation test. The corresponding results indicate that the elastic modulus of the unreinforced pavement is lower than that of the reinforced pavement. The analysis demonstrates that the use of geocell composites effectively increases the load-bearing capacity of the pavement. When the base layer is reinforced with geocells, its load-bearing capacity increases. Observation of the rainfall simulation tests on the reinforced pavement indicates that the reinforced pavement effectively handles the surface runoff.

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