scholarly journals Load-bearing capacity of concrete elements reinforced with steel and composite coatings

2019 ◽  
Vol 97 ◽  
pp. 06043
Author(s):  
Marta Pomada ◽  
Tadeusz Czarniawski

In the article, the compressive strength of steel-concrete structures defined as CFST (Concrete Filled Steel Tubular) has been checked. The steel elements used in CFST columns have high tensile strength and ductility while the concrete elements have high compressive strength and stiffness. Therefore, CFST elements have a large range of applications in construction. The analysis included 8 examples of elements consisting of a steel tube filled with a concrete core. The examples differed in the thickness of the steel coating and the compressive strength of the concrete core. Analytical calculations and experimental studies for them were carried out. The analytical calculations were based on the author’s method of assessing the load-bearing capacity of concrete-filled steel tubes. In experimental verification, CFST samples were subjected to a static compression test. The calculation method was also used to calculate the load capacity when composites reinforcement is the outer coating for the concrete core. Three types of composites were analysed. The obtained results show a large influence of the steel coating thickness on the compressive strength for the CFST elements. The load-bearing capacity of the elements depends on the appropriate ratio of the surface of the steel coating to the concrete coating.

2019 ◽  
Vol 8 (1) ◽  
pp. 523-538 ◽  
Author(s):  
Kang He ◽  
Yu Chen ◽  
Wentao Xie

AbstractThis paper attempts to investigate the effect of various parameters on the axial compressive behavior of nano-silica concrete-filled angle steel reinforced GFRP tubular columns. The proposed new composite column consists of three parts: the outer GFRP tube, the inner angle section steel and the nano-silica concrete filled between GFRP tube and angle section steel. Twenty-seven specimens with different nano-silica concrete compressive strength (20MPa, 30MPa and 40MPa), diameter-to-thickness ratio of GFRP tube (20, 25 and 40) and steel ratio (0.008, 0.022 and 0.034) were tested under axial load. The main purpose of this study is to examine the effect of the three parameters on the following: failure modes, deformation capacity, load bearing capacity, ductility and initial stiffness of the new composite column under axial load. It was found that the load bearing capacity and initial stiffness increased as the nano-silica concrete compressive strength of the specimens increased. But the specimens with higher nano-silica concrete compressive strength showed lower deformation capacity than that of the specimens with lower nano-silica concrete compressive strength. The varieties of the steel ratio have no significant effect on the specimens’ axial deformation behavior. Experimental results also showed that both load bearing capacity and deformation capacity increased with the decrease of diameter-to-thickness ratio of GFRP tube. However, diameter-to-thickness ratio of GFRP tube has no significant effect on the initial stiffness of specimens. The confinement coefficient was proposed to better evaluate the confinement effect of GFRP tube on the inner angle section steel reinforced core nano-silica concrete. The confinement effect of GFRP tube on lower strength concrete was better, and the confinement effect reduced as the diameter-to-thickness ratio of GFRP tube increased. The design formulas for the load bearing capacity of the nano-silica concrete-filled angle steel reinforced GFRP tubular columns under axial load were proposed.


2009 ◽  
Vol 15 (1) ◽  
pp. 21-33 ◽  
Author(s):  
Artiomas Kuranovas ◽  
Douglas Goode ◽  
Audronis Kazimieras Kvedaras ◽  
Shantong Zhong

This paper represents the analysis of 1303 specimens of CFST experimental data. Test results are compared with EC4 provided method for determining the load‐bearing capacity of these composite elements. Several types of CFSTs were tested: both circular and rectangular cross‐sections with solid and hollow concrete core with axial load applied without and with moment, with sustained load and preloading. For circular cross‐section columns there is a good agreement between the test failure load and the EC4 calculation for both short and long columns with and without moment. For rectangular cross‐section columns the agreement is good except when the concrete cylinder strength was greater than 75 MPa, when many tests failed below the strength predicted by EC4. Preloading the steel tube before filling with concrete seems to have no effect on the strength. This paper also presents the stress distribution, confinement distribution and complete average longitudinal stress‐strain curves for concrete‐filled steel tubular elements. Based on the definition of the “Unified Theory”, the CFST is looked upon as an entity of a new composite material. In this paper, the research achievement of the strength and stability for centrifugal‐hollow and solid concrete filled steel tube are introduced. These behaviours relate to the hollowness ratio and the confining indexes of corresponding solid CFST. If the hollow ratio equals to 0,4–0,5 and over, the N‐ϵ relationship exists in steady descending stage. The critical stress of CFST elements stability is determined as an eccentric member with the initial eccentricity by use of finite element method. Santrauka Straipsnyje analizuojami 1303 betonšerdžių plieninių strypų bandinių eksperimentiniai duomenys. Duomenys lyginami su eurokode 4 pateiktais kompozitinių elementų laikomosios galios nustatymo metodais. Analizuojami šie betonšerdžių plieninių strypų bandinių tipai: pilnaviduriai ir tuščiaviduriai, apskrito ir stačiakampio skerspjūvio kolonos, kurių galuose veikia arba neveikia momentas, su iš anksto pridėta arba ilgalaike apkrova. Apskrito skerspjūvio kolonų laikomosios galios bandymų rezultatai atitinka skaičiavimų reikšmes, apskaičiuotas pagal eurokode 4 pateiktu metodu. Stačiakampio skerspjūvio elementų laikomosios galios reikšmių bandymo rezultatai puikiai atitinka teorines reikšmes, kai betono ritininis stipris nesiekia 75 MPa. Išankstinis elementų apkrovimas poveikio elementų laikomajai galiai beveik neturi. Taip pat nagrinėjami betonšerdžių elementų įtempių būvių pasiskirstymas, betono apspaudimo poveikis ir išilginių deformacijų ir įtempių kreivės. Pateikiama S. T. Zhong „Unifikuota teorija“, kuri nagrinėja kompozitinį elementą kaip visumą. Straipsnyje nagrinėjamos kompozitinio plieninio ir betoninio elemento stiprumo ir pastovumo sąlygos. Tokių elementų reikšmėmis. Jeigu tuštumos santykis lygus 0,4–0,5 ir daugiau, N-ε sąryšis yra kritimo stadijoje. Elgsenos stadijos keičiasi pagal tuštumos koeficientą.


2019 ◽  
Vol 106 ◽  
pp. 38-48
Author(s):  
Maciej Sydor ◽  
PIOTR POHL

Load-bearing capacity and characteristic forms of destruction of furniture joints made with rastex 15 and P-10 clamex fasteners. The study tested the relationship between the load and angular deflection in furniture joints. The tests were carried out for two types of fasteners and five types of materials: chipboard, MDF, hardwood plywood, glued pine boards and glued oak boards. The furniture joint samples contained two fasteners preloaded only with a bending moment (without application of shear forces). The results were converted per single fastener specifying: its maximal load capacity, 50 mrad (2.9°) limit deflection and rigidity coefficient. It was found that rigidity is a better structural property of the tested joint types than their load capacity. As far as rigidity is concerned, the most durable is the combination of oak glued board – rastex 15 fastener (13.2 Nm bending moment per fastener), while the least durable combination is chipboard – clamex P-10 fastener (4.8 Nm bending moment per fastener). Photographic documentation of damaged furniture joint samples was prepared and analysed. In case of chipboard and MDF combinations (where the load is determined by the combined material), the combined boards suffer a disastrous damage, while in combinations of plywood boards and pine or oak glued boards, (where the capacity is determined by the fastener), both clamex P10 and rastex 15 fasteners are damaged.


Author(s):  
D. Dowson ◽  
C. M. Taylor

A preliminary examination of the bearing indicates that it is not capable of hydrodynamic action as the fluid film is parallel in the direction of motion. However, in practice it has been found that the bearing can support considerable loads. Earlier papers by the authors have examined the proposal of Shaw and Strang that the inertia of the lubricant could account for the load capacity of the bearing. This contention was rejected by the authors, and after other possible explanations had been investigated it was concluded that thermal distortion was the most likely cause of the load-bearing capacity. In this paper recent work will be reported which supports this proposal. The analysis of fluid inertia effects is summarized for a continuous hemispherical seat whose surface is disturbed only by the central lubricant supply hole (the grooveless case). The paper also presents experimental results and an approximate analysis of the thermal distortion for a hydrosphere seat with four lubricant grooves running from the supply hole to the equator along longitudinal lines.


2021 ◽  
Vol 11 (23) ◽  
pp. 11428
Author(s):  
Jerzy Madej ◽  
Mateusz Śliwka

Interference fit joints have been widely used in many engineering constructions, in particular in electric motors. It is of particular importance to calculate the load capacity of press-fit joints, especially in the overload ranges of construction to estimate the safety factor. The article presents a FEM numerical simulation of pressing the shaft into the hub, taking into account various types of fits. The results of numerical simulations presented in the article were positively verified with the MTS measuring device, which confirmed the correctness of the numerical model. So far, the load-bearing capacity of press-fit joints has been calculated from Lame’s formulas. The results of the load capacity of the joints obtained by the FEM simulation were compared with the results obtained from Lame’s formula. The comparison shows that when designing interference fit joints, attention should be paid to the fact that the press-in process, depending on the type of fit, may be elastic-plastic. Plastic deformations in the contact zone of the joint affect its load-bearing capacity. Therefore, the design of press-fit joints should not be based on Lame’s formulas, which do not take into account the range of plastic work of the material.


2010 ◽  
Vol 42 ◽  
pp. 255-258
Author(s):  
Hong Chao Fan ◽  
Jing Lin Tong ◽  
Xin Hua Yi ◽  
Jin Bao He ◽  
Jian Xi Yang

The oil film have many excellences such as bigger load bearing capacity, longer life, wider velocity range, lower friction etc. The traditional design method is experience test. Even the design parameters could meet the application requirements, but they can not exert the best performance of the oil film bearing. The relationship between load bearing capacity and materials, lubricants, design parameters and structural characteristics of oil film bearing was analysed. To improve the load capacity and run at the optimal state, the objective function was built to optimize the main parameters. Optimization results showed that the load bearing capacity has been greatly improved.


2021 ◽  
Vol 1203 (2) ◽  
pp. 022051
Author(s):  
Andrii Mazurak ◽  
Roman Kinasz ◽  
Ivan Kovalyk ◽  
Rostyslav Mazurak ◽  
Vitaliy Kalchenko

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%.


2020 ◽  
Vol 1 (154) ◽  
pp. 50-56
Author(s):  
О. Kuznetzov ◽  
О. Rubanenko ◽  
О. Khrenov ◽  
E. Rafalskiy

Priority directions and measures among the main branches of urban electric transport are resource saving in the subway transportation system during its operation. First of all, this problem must be solved by scientific support, that is, at the stage of designing parts and components of vehicles. One of the main tasks that are solved at the design stage is to increase the load-bearing capacity of the parts by analyzing their stress-strain state. The article is devoted to the calculation of the load capacity reserve of the longitudinal beam of the front subway trolley under the action of evenly distributed over the entire length of the load without taking into account the transverse forces. The priority of the research topic is substantiated, the purpose and tasks are formulated. Two approaches to the power calculation of the bearing capacity of the longitudinal beam are introduced: the calculation of the permissible stresses and the limit state. In both cases elastic models of beams are considered. In the case of calculation on the limit state, the mechanics of the occurrence of plastic hinges at the places of rigid fixing of the ends of the beam are first substantiated. The beam still retains its load capacity. With the further growth of the external load, the emergence of a plastic hinge is justified even in the middle of the beam with the simultaneous loss of the beam of the bearing capacity. To simulate the behavior of the beam according to its characteristics, including the stress and the degradation condition of its load capacity, the mathematical formulation of the problem of calculating the load capacity of the longitudinal beam when calculating the permissible stresses and the limit state without taking into account the transverse force. The load-bearing capacity of the longitudinal beam in the calculation of permissible stresses and the limit state is analyzed. The analysis of the obtained results allows us to judge the effectiveness of the proposed mathematical model as a whole. The obtained equations for the maximum allowable load when calculating the limit state and the allowable stresses allow us to reliably estimate the bearing capacity of the longitudinal beam in both cases. The increase in the bearing capacity of the beam in the case of calculation on the limit is three times. The conclusions about the adequacy of the analysis of the bearing capacity of the longitudinal beam bearing capacity were made. Keywords: resource saving, beam, bearing capacity, allowable stresses, limit state.


2020 ◽  
Vol 60 (3) ◽  
pp. 259-267
Author(s):  
Yoginibahen Devendrasinh Vashi ◽  
Rakesh Manilal Patel ◽  
Gunamani Biswanath Deheri

This study intents to scrutinize the impact of ferrofluid in the presence of couple stress for longitudinally rough porous circular stepped plates. The influence of longitudinal surface roughness is developed using the stochastic model of Christensen and Tonder for nonzero mean, variance and skewness. Neuringer-Roseinweig model is adopted for the influence of ferrofluid. The couple stress effect is characterized by Stoke’s micro continuum theory. The modified Reynolds’ type equation is stochastically averaged and solved by no-slip boundary conditions. The closed form solutions for load bearing capacity and film pressure are obtained as a function of different parameters and plotted graphically. It is perceived that the load capacity gets elevated owing to the combined influence of magnetization and couple stress when the proper choice of roughness parameters (negatively skewed, standard deviation) is in place. Porosity and roughness (positively skewed) adversely affect bearing’s performance. The graphical and tabular analysis shows that there is a significant growth in load bearing capacity compared to the conventional lubricant case.


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