scholarly journals РАСЧЕТ НЕСУЩЕЙ СПОСОБНОСТИ И УСТОЙЧИВОСТИ ОСНОВАНИЯ ВЕРТИКАЛЬНО НАГРУЖЕННОЙ ОДИНОЧНОЙ СВАИ ВДАВЛИВАЮЩЕЙ (ВЫДЕРГИВАЮЩЕЙ) СИЛОЙ ПО РЕЗУЛЬТАТАМ ИСПЫТАНИЙ ГРУНТОВ

2020 ◽  
Author(s):  
V. Kravtsov
Keyword(s):  
Experimental Data ◽  
Bearing Capacity ◽  
Limit Equilibrium ◽  
Theoretical Solution ◽  
Actual State ◽  
Loss Of Stability ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Manufacturing Method ◽  
The Difference

The article discusses modern practical approaches to the calculation of pile bases, gives the actual picture of their deformation and loss of stability under the influence of vertical pressing/ pulling loads. It is stated that the currently used methods for assessing the load-bearing capacity and stability of the pile base (theoretical, engineering-practical, numerical), based on simplified idealized models, the theory of solid body elasticity, do not correspond to the actual state, properties and behaviour of dispersed soils under load. This greatly reduces the reliability of the results obtained for them (the difference between the calculated and experimental data reaches 100 %), and therefore they need to be clarified. Therefore, the aim of this work is to improve the accuracy and reliability of calculation methods by taking into account the actual operation of piles in the ground and its properties. Analysis of experimental data showed that the loss of stability of the pile base at the stage of exhaustion of its load-bearing capacity well corresponds to the assumptions and principles adopted in the theory of ultimate soil equilibrium. In this regard, the article offers a theoretical solution that develops the provisions of the theory of the ultimate stress state of soils in relation to the assessment of the bearing capacity and stability of the Foundation of piles. The solution is obtained for the condition of a flat problem when loading a multi-layer base of a pile with a vertical pressing force. In the design scheme, the following basic assumptions are made: - the loss of stability of the pile base occurs as a result of shifts on the sliding surface of an undisturbed volume of soil in the form of a truncated cone, including the pile, relative to stationary soil; - sliding surfaces have constant faces close to rectilinear, which are rigidly oriented in space by angles of inclination to the vertical-βi, along the length of the trunk, and αi-to the horizontal, at the level of the end of the pile; - the maximum normative load on the pile is determined under the condition of the maximum ordinate of the development of the limit equilibrium region zmax = 0.25d, which corresponds to the critical draft sкр ≤ ξ su.. The proposed theoretical solution can be used to develop methods for assessing the load-bearing capacity and stability of both finished and Packed piles of various types, for which partial coefficients of the working condition are established, depending on their parameters, soil properties and manufacturing method. В статье рассматриваются современные практические подходы к расчету оснований свай, даны фактическая картина их деформирования и потери устойчивости при воздействии вертикальной вдавливающей/выдергивающей нагрузки. Констатируется, что используемые в настоящее время методы оценки несущей способности и устойчивости основания свай (теоретические, инженерно-практические, численные), построенные на упрощенных идеализированных моделях, теории упругости твердого тела, не соответствуют фактическому состоянию, свойствам и поведению дисперсных грунтов под нагрузкой. Это сильно снижает достоверность полученных по ним результатов (разница между рассчитанными и опытными данными достигает 100 %), в связи с чем они требуют уточнения. Поэтому целью работы является повышение точности и надежности расчетных методов посредством учета фактической работы свай в грунте и его свойств. Анализ опытных данных показал, что потеря устойчивости основания свай на стадии исчерпания его несущей способности хорошо соответствует допущениям и принципам, принятым в теории предельного равновесия грунтов. В связи с этим в статье предложено теоретическое решение, развивающее положения теории предельного напряженного состояния грунтов применительно к оценке несущей способности и устойчивости основания свай. Решение получено для условия плоской задачи при нагружении многослойного основания сваи вертикальной вдавливающей силой. В расчетной схеме приняты следующие основные допущения: - потеря устойчивости основания сваи происходит в результате сдвигов по поверхности скольжения ненарушенного объема грунта в форме усеченного конуса, включающего сваю, относительно неподвижного грунта; - поверхности скольжения имеют постоянные близкие к прямолинейным грани, жестко ориентированные в пространстве углами наклона к вертикали – βi, по длине ствола, и αi – к горизонтали, в уровне конца сваи; - предельная нормативная нагрузка на сваю определяется при максимальной ординате развития области предельного равновесия zmax = 0,25d, что соответствует критической осадке sкр ≤ ξ su. Предложенное теоретическое решение может быть применено для разработки методов оценки несущей способности и устойчивости как готовых, так и набивных свай различных типов, для которых установлены частные коэффициенты условия работы, зависящие от их параметров свойств грунтов и способа изготовления.

scholarly journals Experimental Investigation and Modelling of the Layered Concrete with Different Concentration of Short Fibers in the Layers

Fibers ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 76
Author(s):  
Vitalijs Lusis ◽  
Olga Kononova ◽  
Arturs Macanovskis ◽  
Rimvydas Stonys ◽  
Inga Lasenko ◽  
...  
Keyword(s):  
Experimental Data ◽  
Bearing Capacity ◽  
Fracture Process ◽  
Fiber Reinforced Concrete ◽  
Short Fibers ◽  
Steel Fiber Reinforced Concrete ◽  
Load Bearing Capacity ◽  
Fiber Concentration ◽  
Load Bearing ◽  
Pull Out

The use of steel fiber reinforced concrete (SFRC) in structures with high physical-mechanical characteristics allows engineers to reduce the weight and costs of the structures, to simplify the technology of their production, to reduce or completely eliminate the manual labor needed for reinforcement, at the same time increasing reliability and durability. Commonly accepted technology is exploiting randomly distributed in the concrete volume fibers with random each fiber orientation. In structural members subjected to bending, major loads are bearing fibers located close to outer member surfaces. The majority of fibers are slightly loaded. The aim of the present research is to create an SFRC construction with non-homogeneously distributed fibers. We prepared layered SFRC prismatic specimens. Each layer had different amount of short fibers. Specimens were tested by four point bending till the rupture. Material fracture process was modelled based on the single fiber pull-out test results. Modelling results were compared with the experimental curves for beams. Predictions generated by the model were validated by 4PBT of 100 × 100 × 400 mm prisms. Investigation had shown higher load-bearing capacity of layered concrete plates comparing with plate having homogeneously distributed the same amount of fibers. This mechanism is strongly dependent on fiber concentration. A high amount of fibers is leading to new failure mechanisms—pull-out of FRC blocks and decrease of load-bearing capacity. Fracture surface analysis was realized for broken prisms with the goal to analyze fracture process and to improve accuracy of the elaborated model. The general conclusion with regard to modelling results is that the agreement with experimental data is good, numeric modelling results successfully align with the experimental data. Modelling has indicated the existence of additional failure processes besides simple fiber pull-out, which could be expected when fiber concentration exceeds the critical value.

Verankerung der Stützmauer Entschigtal / Anchorage of the Sustaining Wall Entschigtal

1997 ◽  
Vol 3 (6) ◽  
pp. 619-632
Author(s):  
M. Schmid
Keyword(s):  
Service Life ◽  
Bearing Capacity ◽  
Structural Design ◽  
Test Methods ◽  
Actual State ◽  
Complex Task ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Required Service

Abstract Structural design and the position of the sustaining wall Entschigtal were at the origin of corrosion of the back layer of reinforcement. A drecrease of the load bearing section was observed in 1995. The assessment of the actual state of the reinforcement turned out to be a complex task in the context of the inspection of the structure. It was the combination of different test methods which finally led to reliable results concerning the extent and the position of corrosion of reinforcement. In order to restore the load bearing capacity for the remaining required service- life consolidation measures werde necessary. Permanent strand anchors have been placed to strengthen the wall.

scholarly journals The influence of the moisture content in historical masonry walls on the load bearing capacity

2018 ◽  
Vol 49 ◽  
pp. 00100
Author(s):  
Monika Siewczynska ◽  
Barbara Ksit
Keyword(s):  
Moisture Content ◽  
Bearing Capacity ◽  
Actual State ◽  
Masonry Walls ◽  
Historical Buildings ◽  
Load Bearing Capacity ◽  
Reliable Determination ◽  
Load Bearing ◽  
Historical Masonry

The moisture content in historical masonry walls, particularly on the ground floor, caused by i.e. lack of damp insulation, is a phenomenon of common occurrence. It is usually analysed in terms of mycological changes, thermal insulation and frost damage. The paper discusses the influence of the increased moisture content on the weight and load bearing capacity of the structure. The determination of moisture content in masonry elements, performed during the inspection of the building, provides information from which an increase in the structure's weight can be defined. Reliable tests for the moisture content and compressive strength of masonry and mortar components are invasive, and the number of testing in historical buildings should be limited to the minimum necessary to preserve their vintage nature. As a result, the received overall picture of the work of masonry may not be consistent with its actual state since historical buildings could have been rebuilt or repaired, and consequently, contain masonry conversions made of various materials with different properties. Absorbability can serve here as an example as it is a factor that disrupts a reliable determination of load bearing capacity values of masonry structures. The article attempts to determine the change in load bearing capacity of a moist masonry structure compared to the original - in the air-dry state - for various types of historical masonry and mortar components. The main influence analysed was due to capillary action, whereas the effect of other sources of moisture, i.e. salinity, was excluded.

scholarly journals Numerical limit analysis of the ultimate load bearing capacity of a pier foundation under complex load

2019 ◽  
Vol 277 ◽  
pp. 02018
Author(s):  
H F Wang ◽  
X H Cheng
Keyword(s):  
Bearing Capacity ◽  
Limit Analysis ◽  
Design Theory ◽  
Ultimate Load ◽  
Limit Equilibrium ◽  
Gobi Desert ◽  
Load Bearing Capacity ◽  
Complex Load ◽  
Load Bearing ◽  
Collapsible Loess

A pier foundation has plenty of advantages as the foundation form for large onshore wind turbines in the terrain of the Gobi desert and collapsible loess areas. The ultimate load bearing capacity design, as an important part in the design phase of this foundation form, is not sufficiently in terms of design theory and the checking method, especially for application in collapsible loess areas. In this paper, numerical limit analysis has been employed to analyze the load bearing capacity for the scheme of selection of a pier foundation of a 100 MW wind farm in certain collapsible loess geology in Ningxia. The results were then compared with the empirical formulas, the limit equilibrium solutions and the finite element solutions to verify the accuracy of the results. It has been demonstrated that under the ultimate engineering load, the pier foundation can meet the stability requirement. In the ultimate state, whether the surrounding soil of the foundation falls in plasticity is associated with the ratio of the depth to the diameter of the foundation. The numerical limit analysis method can automatically determine the failure surface.

Nonlinear modelling and finite element analysis on the load-bearing capacity of RC beams with considering the bond–slip effect

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Pandimani Pandimani ◽  
Markandeya Raju Ponnada ◽  
Yesuratnam Geddada
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Bearing Capacity ◽  
Experimental Program ◽  
Nonlinear Behaviour ◽  
Rc Beams ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Content Type ◽  
Bond Slip

Purpose This paper aims to present nonlinear numerical simulations using the versatile finite element (FE) analysis tool ANSYS and theoretical analysis based on code provisions to assess the load-carrying capacity of reinforced concrete (RC) beams under two-point monotonic static loadings. Design/methodology/approach Four quarter-size FE models with load and geometry symmetry conditions were constructed, the load-bearing capacity and associated mid-span deflections at critical points are verified against the full-scale experimental RC beams available in the literature. These developed FE models incorporated the tension stiffening effects and bond–slip behaviour. Theoretical analyses based on Indian standard code IS: 456–2000 and ACI 318–19 were also carried to verify the experimental and numerical predicted moments at critical loading points. Findings The load-deflection curves predicted through FE models exhibit closer corroboration with the experimental curves throughout the loading history. The contour plots for deflections, concrete principal stresses, reinforcement yield stresses are satisfactorily predicted by the FE models, which reveal the complete information of nonlinear behaviour of RC beams. The developed model well captured the initial and progressive crack patterns at each load increments. Practical implications The FE modelling is an efficient, valid and economical tool that is an alternative to the expensive experimental program and can be used to explore, analyse and fully understand the nonlinear response of RC beams under static loadings. Originality/value The ultimate moment capacity evaluated based on ACI 318–19 code provision show a better correlation with the experimental data as compared to the IS: 456–2000 code provision. The ultimate loads and associated centre-span deflections predicted by RN-2, RN-3, RB-12 and RB-16 FE model show a discrepancy of 1.66 and –0.49%, –4.68 and –0.60%, –9.38 and –14.53% and –4.37 and 4.21%, respectively, against the experimental results, which reveals that the developed ANSYS FE models predict consistent results and achieved a reasonable agreement with the experimental data.

scholarly journals ENGINEERING METHOD FOR CALCULATING STEEL-REINFORCED CONCRETE ELEMENTS WITH FLEXIBILITY

2019 ◽  
Vol 2 (53) ◽  
pp. 85-89
Author(s):  
Olena Yefimenko
Keyword(s):  
Experimental Data ◽  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Cross Section ◽  
Engineering Method ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Steel Reinforced Concrete ◽  
Concrete Elements

In the article presents an engineering method for calculating compressed flexible reinforced concrete elements with sheet reinforcement over a steel cross section. The results of the calculation are compared with the experimental data. Calculation ofload-bearing capacity of reinforced concrete flexible elements with sheet reinforcement is based on the method of boundarystates. The work of specimens under load and the nature of the load-bearing capacity depending on the height and eccentricity of the effort were investigated. The proposed method of calculating compressed elements with sheet reinforcement on asteel-cross-section allows to take into account their flexibility in both axial and out-of-center application of load.

Increased load bearing capacity of mechanically joined FRP/metal joints using a pin structured auxiliary joining element

2020 ◽  
Vol 62 (1) ◽  
pp. 55-60
Author(s):  
Per Heyser ◽  
Vadim Sartisson ◽  
Gerson Meschut ◽  
Marcel Droß ◽  
Klaus Dröder
Keyword(s):  
Bearing Capacity ◽  
Load Bearing Capacity ◽  
Load Bearing

Load-Bearing Capacity of Direct Inlay-Retained Fibre-reinforced Composite Fixed Partial Dentures with Different Cross-Sectional Pontic Design

2017 ◽  
Vol 68 (1) ◽  
pp. 94-100
Author(s):  
Oana Tanculescu ◽  
Adrian Doloca ◽  
Raluca Maria Vieriu ◽  
Florentina Mocanu ◽  
Gabriela Ifteni ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Fracture Pattern ◽  
Load Bearing Capacity ◽  
Cross Sectional ◽  
Load Bearing ◽  
Reinforced Composite ◽  
Polyethylene Fibre

The load-bearing capacity and fracture pattern of direct inlay-retained FRC FDPs with two different cross-sectional designs of the ponticwere tested. The aim of the study was to evaluate a new fibre disposition. Two types of composites, Filtek Bulk Fill Posterior Restorative and Filtek Z250 (3M/ESPE, St. Paul, MN, USA), and one braided polyethylene fibre, Construct (Kerr, USA) were used. The results of the study suggested that the new tested disposition of the fibres prevented in some extend the delamination of the composite on buccal and facial sides of the pontic and increased the load-bearing capacity of the bridges.

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