Estimation Of Load Capacity Research Articles

Estimation of load capacity of driven piles by COA–MLP and COA–SVR models: a comparative study

Estimation of load capacity of driven piles by COA–MLP and COA–SVR models: a comparative study

Driven piles’ load capacity estimation by applying comparative regression methods

Driven piles’ load capacity estimation by applying comparative regression methods

Applicability of new regression model for determining axial load capacity of concrete filled double steel tubular composite columns

Using various composite materials and components as a replacement for conventional materials and components has various structural benefits in the construction field. Concrete Filled Double Steel Tubular Composite Columns (CFDST) are composite components consisting of two concentric metal (steel) tubes and a gap between them filled with concrete. These are composed of three constituent materials that exhibit higher structural performance than constituent materials. This study aims to propose a new regression model for determining the axial load capacity of CFDST columns. For this purpose, one twenty-four data collected from various experimental studies referred to literature. The model represented here was developed using the statistical tool Minitab. Length, yield strengths, diameters and thicknesses of both external and internal tubes of CFDST columns, compressive strength of in-filled concrete and experimental ultimate axial strength of CFDST columns are considered for model development. The model's applicability is confirmed when the developed model's results are compared to earlier researchers' models and the equations provided in the design guidelines. The suggested model achieves an R2 value close to one hundred percent and ultimate axial load capacity estimation with the least error.

Finite Element Model-Based Weight-Over Process Philosophy for Bridge Loading Capacity Evaluation and Rating Factor Estimation

Existing rating methods estimate bridge loading capacity and demand from secondary actions due to live loads in the primary structural components. In these methods, uniaxial yielding stress is traditionally used to detect component capacity using either stress quantities or shear-moment actions to compute the capacity demand of the bridge. These approximations can lead to uncertainties in load capacity estimation. This article presents the weight-over process (WOP), a novel computer-aided approach to bridge loading capacity evaluation based on tonnage and rating factor estimation. WOP is expected to capture different forms of failure in a more general manner than existing methods. In WOP, a bridge finite element model (FEM) is discretized into many sections and element sets, each containing a single material type, and each assigned a suitable 3D failure criterion. Then, factored gross vehicle weights (GVWs) are incrementally imposed on the bridge FEM with those predefined ultimate unfavored loading scenarios in a manner similar to proof load testing. WOP code runs nonlinear analysis at each increment until a stopping criterion is met. Two representative bridges were selected to confirm WOP’s feasibility and efficacy. The results showed that WOP-predicted values at the interior girders were between those of the conventional AASHTO and the nondestructive testing (NDT) strain measurement methods. That may put WOP in a favorable zone as a new method that is less conservative than AASHTO but more conservative than real NDT testing.

Lattice modeling and testing of aerated autoclaved concrete infilled frames

Significant infill wall damage in reinforced concrete frame buildings was observed in the past earthquakes. A vast number of numerical approaches have been proposed to estimate the non-linear behavior of infilled frames at different scales. Mesoscale lattice models were successfully used in the past to simulate the behavior of reinforced concrete member response. In this study, two-dimensional mesoscale lattice approach with an extended calibration technique was consistently applied to simulate the response of unreinforced Aerated Autoclaved Concrete (AAC) masonry infilled reinforced concrete frames. Two AAC infilled walls were tested for the purposes of this study. The objective of the tests were to investigate the effect of infilled wall-frame interaction with and without openings and validate the proposed numerical approach. In addition to the tests conducted, two tests were used from the literature for further validation. The maximum error of load capacity estimation from the simulations was less than 15% for all the examined tests. The proposed lattice model was capable of estimating crack propagation in the infill walls with reasonable accuracy. The frame-infill wall interaction was successfully simulated with providing a realistic representation of strut formation. Finally, a parametric study was conducted to examine contact length and strut width as a function of lateral deformation. The results show that the infill wall-frame contact length is significantly dependent on the lateral deformation demand levels and properties of interaction region.

EVALUATION OF LOAD-BEARING CAPACITY OF THE STEEL CONSTRUCTION JOINTS ON THE BASIS OF COMPONENT METHOD

Connections are essential in every kind of steel constructions. Structure is a constructed assembly of joints separated by members which implies the importance of connections. Three basic parameters describe the behavior of connections: strength, stiffness and ductility, and the mechanical behavior of steel joint in those terms are complex phenomena. It must be said that absence in current Ukrainian design codes rules for the load capacity calculation of steel constructions connections led to some difficulties in project decisions. On the basis of component method, which lay in the EC3 design codes load capacity estimation of beam to column connection was made. According to component method beam to column connection divided into basic components. EN 1993 -1-8 provides a good overview of different components. Most important components for bolted steel joints are the plates and bolts which both are considered by the design of a T-stub through the “Equivalent T-stub in tension”. The procedure of load capacity calculation used yield line formulations to determine resistance of the following basic components: column flange in bending, end plate in bending, column flange in bending, column web in tension, column web in compression, beam flange in compression. Failure by this method is described by yield-line models depending on geometry of plates and bolts. Obtained analytical results were compared with the results obtained by means of specialized software and it shown their adequacy. It must be noted that presented in EC3 calculation algorithm of beam to column connection is time consumable for domestic designer also designer must have knowledge about features of connection design in countries of EC. The choice of design procedure depends on the time effort and thereby to the designer preferences.

Deep learning for bridge load capacity estimation in post-disaster and -conflict zones.

Many post-disaster and post-conflict regions do not have sufficient data on their transportation infrastructure assets, hindering both mobility and reconstruction. In particular, as the number of ageing and deteriorating bridges increases, it is necessary to quantify their load characteristics in order to inform maintenance and asset databases. The load carrying capacity and the design load are considered as the main aspects of any civil structures. Human examination can be costly and slow when expertise is lacking in challenging scenarios. In this paper, we propose to employ deep learning as a method to estimate the load carrying capacity from crowdsourced images. A convolutional neural network architecture is trained on data from over 6000 bridges, which will benefit future research and applications. We observe significant variations in the dataset (e.g. class interval, image completion, image colour) and quantify their impact on the prediction accuracy, precision, recall and F1 score. Finally, practical optimization is performed by converting multiclass classification into binary classification to achieve a promising field use performance.

Crack tip constraint analysis in welded joints with pronounced strength and toughness heterogeneity

Application of standardized fracture testing methods in heterogeneous welded joints might lead to overestimation or underestimation of fracture toughness and consequentially to inaccurate estimation of loading capacity of welded structure. Combining experimental testing and numerical modelling of double mismatched welded joints provided a view on influence of pronounced strength heterogeneity on fracture behaviour under monotonous loading. Investigated double mismatched welded joints had a fatigue crack located in one mismatched weld material region. The fatigue crack plane was perpendicular to the interface of two distinctive mismatched weld material regions, while the stable crack extension was estimated to be from one weld material region to other, crossing the interface. Single edge notched bend (SE(B)) specimens were used to investigate double mismatched welded joint fracture behaviour under high constraint conditions. Crack extension has been evaluated using normalization data reduction technique and crack driving force has been evaluated as specified in ASTM E1820 standard. Stress triaxiality has been implemented as a second fracture parameter, evaluating level of constraint. Obtained results show that combination of strength overmatched and undermatched weld material has a significant effect on the weld load capacity and stress triaxiality ahead of the crack tip. The latter leads to reduced or increased fracture toughness of the weld as the crack tip is closer to the fusion line between overmatched and undermatched weld material. Finally, computational simulations revealed how double mismatched weld configuration alters the stress field near the crack tip and corresponding values of J-integral. This implies that standard fracture test overestimate or underestimate fracture toughness of the double mismatched welded joint.

A comparison between performances of the behavioral models in evaluating load-bearing capacity of piles in fine-grained unsaturated soil

<p>Virtually all structural piles are installed on the top of groundwater level, and these piles are located on unsaturated soils. In this case, the negative orifice water pressure caused by capillarity significantly influences the mechanical behavior of unsaturated soils. Consequently, structural suction is highly important to load-bearing capacity of loads. In this paper, an evaluation was drawn between the Mohr-Coulomb, modified Cam-Clay, and Barcelona behavioral models using the finite-difference method, and results of studies conducted to estimate load-bearing capacity in the static state were provided. The behavioral model guidelines matched the laboratory models. To estimate soil vividness on the suction level of concern, the water-soil curve (showing suction patterns in relation to moisture) utilized. The general tendencies of settlement gotten by the numerical examination are reliable with pile insert test results. Results suggest that the Barcelona personality model (BBM) yields more realistic estimates of load capacity as it looks at the effect of unsaturated soil suction.</p>

Load capacity probabilistic sensitivity analysis of thin-walled beams

The paper deals with the load carrying capacity probabilistic variance-based sensitivity analysis of thin-walled box-section girders subjected to pure bending. The lower- and upper-bound load capacity estimation is performed using two different analytical methods. The sensitivity analysis performed is based on the methodology of the Monte-Carlo method. The analysis is carried out using the polynomial decomposition and multi-dimensional linear regression. The sample results obtained are presented in diagrams and pie charts showing the sensitivity of load capacity to different random input variables (material properties and geometrical parameters). The variance-based analysis (Anova) of lower-bound and upper-bound load capacity estimation is carried out, from which some conclusions are derived, if (and how) assumed changes in standard deviations of input variables influence the magnitude of the load capacity and differences in upper-bound and lower-bound load capacity estimations. The results of Anova tests are shown in sample histograms. Some final conclusions concerning the efficiency of the applied models and the statistically significant influence of input random variables (yield stress, wall thickness, height and length of the beam) upon the upper-bound and lower bound estimation of the load capacity as well as the difference of these two estimations, are presented.

Undrained Sliding Resistance of Shallow Foundations Subject to Torsion

Although the behavior of shallow foundations under vertical load combinations has been the subject of numerous studies, the response of shallow foundations subjected to combined horizontal and torsional loading has received considerably less attention. New offshore applications of shallow foundations for liquid natural gas facilities and other subsea structures have underscored the importance of the behavior of shallow embedded foundations subjected to combined in-plane translation and torsion. This study investigates the undrained bearing capacity of rectangular and square shallow foundations under eccentric horizontal loads through comparisons of various limit-equilibrium and plastic-limit analysis solutions to three-dimensional finite-element (FE) solutions. In general, the plastic-limit approach considered in this paper agrees well with the FE solutions, although it has some tendency to overpredict capacity at greater embedment depths. The studies revealed a general insensitivity in the shape of the yield envelope to variations in embedment depth, which permits a simplified analysis suitable for first-order estimates of load capacity. The variables considered in this study include footing aspect ratio, embedment depth, and load direction in addition to eccentricity.

Estimation of Axial Load Capacity for Bored Tapered Piles Using CPT Results in Sand

Tapered piles in comparison to cylindrical piles can be beneficial in terms of the load capacity. In this paper, estimation of the load capacity for tapered piles using cone penetration test (CPT) resistance was investigated. Fourteen calibration chamber load tests using different pile types and six CPTs were conducted under various soil conditions. From the calibration chamber test results, the total, base, and shaft load capacities were analyzed in terms of soil conditions and taper angle. To evaluate CPT-based load capacity of tapered piles, normalized base and shaft resistances were obtained from normalized unit load-settlement curves. Based on the normalized base and shaft resistances, design equations that can be used to evaluate the base and shaft resistances of tapered piles were proposed. The proposed method is valid for sands of medium to dense conditions, while it may result in unconservative predictions for loose sands. To check the accuracy of the proposed method, field load tests using both cylindrical and tapered piles were conducted and compared with the predictions using the proposed method. A simplified approach using an equivalent cylindrical pile was also investigated and compared.

Load-capacity estimation and collapse analysis of thin-walled beams and columns—recent advances

The present paper is devoted to the recent results of research in the area of load-capacity and post-failure behaviour of thin-walled beams and columns (among them thin-walled cold-formed profiles). It deals with ultimate load and collapse of box-section girders (tubes) of different cross-sections under bending, as well as of lipped and plain channel-section beam-columns. The paper contains the presentation of theoretical analysis and experimental investigation of plastic mechanisms of failure and collapse behaviour of these thin-walled sections. The short review of results obtained in recent years in general precedes those obtained by the Department of Strength of Materials and Structures, TUL. The problem of post-failure behaviour is solved using the rigid-plastic theory adopted and modified for the purposes of the solution taking into consideration strain-hardening of the member’s material. On the basis of experimental investigations theoretical models of plastic mechanisms of failure are produced for different sections. Theoretical analysis is based on the principle of virtual velocities. The problem is solved in an analytical–numerical way. The particular attention has been paid to the influence of the strain-hardening of the material after yielding upon the collapse structural behaviour and also to the influence of cross-section shape and dimensions on the character of collapse. The upper-bound estimation of the load-carrying capacity of analysed thin-walled sections by combining results of non-linear, elastic post-buckling analysis with the results of plastic mechanism analysis is carried out. Results are presented in diagrams showing post-failure curves as well as curves representing structural behaviour in the whole range of loading up to and beyond the ultimate load. Some results are compared with experimental results and those obtained from FE analysis. A comparison of lower- and upper-bound estimation of the load-carrying capacity is discussed and illustrated in diagrams. Conclusions dealing with the influence of strain-hardening phenomenon displayed by the material upon the load-carrying capacity and collapse behaviour of examined sections are derived. Also conclusions concerning different upper- and lower-bound estimations of the load-carrying capacity of analysed sections are presented.

Estimation of Load Capacity of Pipe Piles in Sand Based on Cone Penetration Test Results

Pipe piles can be classified as either closed- or open-ended piles. In the present paper, the load capacity of both closed- and open-ended piles is related to cone penetration resistance qc through an experimental program using calibration chamber model pile load tests and field pile load tests. A total of 36 calibration chamber pile load tests and two full-scale field pile load tests were analyzed. All the test piles were instrumented for separate measurement of each component of pile load capacity. Based on the test results, the normalized base resistance qb/qc was obtained as a function of the relative density DR for closed-ended piles, and of both the relative density DR and the incremental filling ratio (IFR) for open-ended piles. A relationship between the IFR and the relative density DR is proposed as a function of the pile diameter and driving depth. The relationship between IFR and DR allows the estimation of IFR and thus of the pile load capacity of open-ended piles at the design stage, before pile driving operations.

Estimation of Load Capacity of Pipe Piles in Sand Based on Cone Penetration Test Results

Estimation of Load Capacity of Pipe Piles in Sand Based on Cone Penetration Test Results

Load Capacity Estimation of Foil Air Journal Bearings for Oil-Free Turbomachinery Applications

This paper introduces a simple “Rule of Thumb” (ROT) method to estimate the load capacity of foil air journal bearings, which are self-acting compliant-surface hydrodynamic bearings being considered for Oil-Free turbomachinery applications such as gas turbine engines. The ROT is based on first principles and data available in the literature and it relates bearing load capacity to the bearing size and speed through an empirically based load capacity coefficient, D. It is shown that load capacity is a linear function of bearing surface velocity and bearing projected area. Furthermore, it was found that the load capacity coefficient, D, is related to the design features of the bearing compliant members and operating conditions (speed and ambient temperature). Early bearing designs with basic or “first generation” compliant support elements have relatively low load capacity. More advanced bearings, in which the compliance of the support structure is tailored, have load capacities up to five times those of simpler designs. The ROT enables simplified load capacity estimation for foil air journal bearings and can guide development of new Oil-Free turbomachinery systems. Presented as a Society of Tribologists and Lubrication Engineers Paper at the ASME/STLE Tribology Conference in Seattle, Washington, October 1–4, 2000

Shear Strain Effects in Lateral Stability of Thin-Walled Fibrous Composite Beams

An analytical study of the transverse shear strain effect on the lateral buckling of thin-walled, open-section fibrous composite beams is presented in order to derive a better estimate of load capacity. Uniformly distributed and transverse central point loads are applied, being two popular loading systems, on simply and clamped supported I-section beams. An analytic-numerical moment method is used as an effective approach for solving the coupled system of differential equations. The present study highlights the insensitivity of the shear factor for UDL (uniformly distributed load) systems in lateral buckling. However, the results show, in short-span composite beams under concentrated central loads, the shear factor causes a considerable drop in the buckling load.