Estimation Of Bearing Capacity Research Articles

Bearing Capacity Estimation of Ring Footing on Layered Sand with Geogrid at the Interface Using FELA and MARS

Bearing Capacity Estimation of Ring Footing on Layered Sand with Geogrid at the Interface Using FELA and MARS

Influence of Spring Stiffness on the Loading Speed of the Falling Weight Deflectometer (FWD) in Bearing Capacity Evaluation of Cement Concrete Pavement

Introduction: The bearing capacity evaluation of cement concrete runway pavement is one of the most important contents in the airfield operation. Among the methods for estimating bearing capacity, the Falling Weight Deflectometer (FWD) is the most widely used method because it does not damage the pavement structure and spends so much time. The equipment for evaluation should have suitable parameters, such as. magnitude and loading speed, to the actual operating loads. Aims and Objectives: Currently, the equipment to assess the bearing capacity of cement concrete pavements of highways and airports by falling weight has been widely used in the world and is being applied in Vietnam. The loading system consists of a falling block through a spring system acting on the pressure plate under the pavement with a certain falling height. In particular, the spring system plays an important role in controlling the speed of the load on the pavement. In Vietnam, the test standards (Industry Standard 22TCN335-06, Vietnamese Standard TCVN 11365-2016) for assessing the pavement bearing capacity by FWD equipment do not specify the selection of spring stiffness corresponding to different operating speeds of the vehicle. Therefore, it is difficult to use the equipment for pavements with operating speeds different from the standard. In this paper, we study the effect of spring stiffness on the loading speed when considering different loading speeds corresponding to different speeds of vehicles moving in reality. This research is only limited to laboratory experiments. This study aims to determine the dependence of the loading magnitude and loading time on the damping spring stiffness of the dynamic loading equipment, that is, used as a basis for choosing the appropriate damping stiffness of FWD corresponding to actual vehicles. Methods: Among the methods for estimating the bearing capacity, the Falling Weight Deflectometer (FWD) is the most widely used method as it does not cause any damage to the pavement structure and spends much time. The equipment for evaluation should have suitable parameters, such as magnitude and loading speed, to the actual operating loads. Results: This paper presents the results of experimental research that determines the influence of the damping spring stiffness on the loading speed of the dynamic loading equipment on the model of the concrete slab in the laboratory. Conclusion: Based on the comparison of the FWD loading speed when using 02 damping springs with different stiffness, we propose the basis for choosing the damping system that conforms to the evaluation needs of different types of vehicles.

Second-Order Generalized Plastic Hinge Method for Ultimate Bearing Capacity Estimation of Unbraced Steel Frames

The traditional first-order plastic hinge method (FPHM) utilizes the proportionality property to rapidly estimate the external load increment between any two adjacent plastic hinges, with superior computational efficiency. However, the FPHM cannot consider the influence of second-order effects and residual stresses. Although the refined plastic hinge method (RPHM) overcomes these problems, it must solve the nonlinear structural stiffness equation, resulting in low computational efficiency. In this paper, the second-order generalized plastic hinge method (sGPHM) is proposed to evaluate the ultimate bearing capacity of unbraced steel frames on the basis of using the proportionality property to estimate the external load increment. First, the element bearing ratio (EBR) that considers second-order effects and residual stresses is defined. Since the EBR and the external load are proportional, the plastic yield degree of the cross-section can be easily obtained. Then, the displacement increment and the load increment between any two adjacent plastic hinges can be rapidly estimated through the proportionality property between the EBR and the external load. Accumulating all load increments can determine the ultimate bearing capacity of frames. Finally, several benchmark frameworks in the literature are compared and analyzed with different methods to verify the superior calculation accuracy and efficiency of the proposed sGPHM.

Performance assessment of borehole arrangements for the design of rectangular shallow foundation systems

This study proposes a framework to evaluate the performance of borehole arrangements for the design of rectangular shallow foundation systems under spatially variable soil conditions. Performance measures are introduced to quantify, for a fixed foundation layout and given soil sounding locations, the variability level of the foundation system bearing capacities in terms of their mean values and standard deviations. To estimate these measures, the recently proposed random failure mechanism method (RFMM) has been adopted and extended to consider any arrangement of rectangular foundations and boreholes. Hence, three-dimensional bearing capacity estimation under spatially variable soil can be efficiently performed. Several numerical examples are presented to illustrate the applicability of the proposed framework, including diverse foundation arrangements and different soil correlation structures. Overall, the proposed framework represents a potentially useful tool to support the design of geotechnical site investigation programs, especially in situations where very limited prior knowledge about the soil properties is available.

Bearing Capacity of Karst Cave Roof under Pile Foundation Load Using Limit Analysis

Reducing the computational workload by simplifying the analysis of karst foundations into a plane strain problem can yield significant advantages. Yet, such an approach fails in reproducing the engineering situation in a rigorous manner. In this regard, this paper proposes an upper-bound method that can effectively analyze the bearing capacity of three-dimensional karst foundations. This method is utilized to investigate the impact of various pile diameters, the ratio of roof thickness to pile diameter, and the ratio of cave width to pile diameter on the stability of karst foundations. The validity of this method is established through an illustrative example. The outcomes illustrate that when subjected to both tensile and compressive horizontal stresses if the maximum horizontal stress surpasses the tensile strength of the rock mass, the roof rock mass may suffer damage. Increasing the ratio of roof thickness to pile diameter can bring down the horizontal stress value. The stability factor is largely influenced by the ratio of roof thickness to pile diameter. The most prominent growth trend of the stability factor is observed when the ratio is less than 3. If the ratio of the roof thickness to pile diameter exceeds 3, the prediction of the bearing capacity estimation for the karst foundation in three-dimensional circumstances is more conservative than that in two-dimensional circumstances.

PERBANDINGAN DAYA DUKUNG FONDASI TIANG BOR MENGGUNAKAN METODE REESE & WRIGHT DAN MEYERHOF

The Serang-Panimbang Toll Road Construction Project is one of the National Strategic Projects (PSN) with a total length of 83,677 km. The main bridge 18, which is one of the projects on the toll road section, has a drill pile foundation for its substructure. The drill pile foundation is a pile foundation that is installed by drilling the ground first, then filling it with reinforcement that has been assembled and cast in concrete. The foundation has a slope that is less than the permitted slope to support the load above it and is built to withstand both vertical and horizontal stresses. This study compared the Reese & Wright method with the Meyerhof method, two bearing capacity estimation techniques. The comparison aims to determine whether the outcomes of the two approaches utilized significantly differ from one another. The findings of the SPT test were used to conduct the analysis of bearing capacity. In this work, drill piles with a 1 m diameter and 15 m depth were used. According to the analysis's findings, the permit's bearing capacity using the Reese & Wright approach was 246.20 tons, however the permit's bearing capacity using the Meyerhof method was found to be 541.87 tons. For the Reese & Wright approach, the single drill pile decreased by 9,07 mm, and the group pile decreased by 25,7 mm; for the Meyerhof method, the single drill pile decreased by 9,17 mm, and the group pile decreased by 25,34 mm. Furthermore, it was found from both methods of calculating the bearing capacity that both stable static loads and dynamic loads work so that the foundation can be categorized (P max < Q single permit). The ratio of the bearing capacity of the single mast permit on the Reese & Wright method compared to the Meyerhof method is 0.478:1. Keywords: Bearing Capacity, Drilled Pile, Stability.

Experimental determination of the tightening coefficient of bolts according to the din standard

The use of slip-critical connections is very common in the design of critical steel structures and is seen as an effective way to transfer the force in conditions of dynamic loading. The limit state of the connection occurs when the calculated shear stress is reached, which depends on the friction coefficient of the contact planes and the value of the clamping force, equal to the bolt tension stress. In order to ensure the necessary bolt tensioning force, it is necessary to know the bolt tightening coefficient, because according to the current understanding of the slip-critical connection performance, the designed functioning of the bolt connection is ensured when the bolt tensioning force arising at the necessary torque value is achieved. Otherwise, the actual work of the connection will be different from the calculated, because only a given tension force provides the estimated bearing capacity of the bolted connection with friction planes. This article focuses on tensile testing of a bolt and determining the tightening factor of a bolt made of high-strength10.9 M14 steel. The tightening factor is determined with strain gauges by measuring the relative strain of the bolt when the nut is tightened. This method requires specialized equipment and a test bench and can be used in the study of bolt performance in the absence of a certificate or the need to verify or clarify the available data. The results show that the proposed method can provide a stable determination of the coefficient value. The examined bolts were made according to the German standard DIN931, strength 10.9 size M14x220, nuts according to the German standard DIN934, strength 10 size M14. An Instron 1000HDX tensile testing machine was used to plot the performance of the bolt steel. Nut tension control was determined with the use of NOGRAU NTW24-034R torque wrench, and bolt elongation control with FLA 5-11 strain gauges and National Instruments data acquisition system. On the basis of the conducted research, a method for determining the tightening factor of high-strength bolts has been tested and proposed. The proposed method of determining the tightening factor of a high-strength bolt can be used in research work and allows to determine the coefficient in the absence of an appropriate certificate or the need to clarify (verify) the stated value of the coefficient.

Model and field tests of drilled displacement system piles

Drilled Displacement System (DDS) and Continuous Flight Auger (CFA) piles are two popular techniques used for building pile foundations that offer advantages over traditional pile systems, including improved load-carrying capacity, reduced installation time, and less spoil generation. This article presents laboratory-scaled model tests conducted on model piles installed using the Drilled Displacement System (DDS) and Continuous Flight Auger (CFA) technologies on a test tank setup filled with soil. Model piles considering a scaling factor of 1/20 with a diameter of 20 mm and a length of 300 mm were adopted for the study. Static loading is applied to the model piles and the corresponding displacements are measured during each loading phase. The results of the analysis were compared for load-settlement curves and ultimate bearing capacity estimates for both DDS and CFA piles. Based on the study, the DDS piles were observed to perform well in terms of load-carrying capacity compared to the CFA piles. Further, full-scale field tests under static load conditions were carried out on DDS-drilled piles of diameter 400 mm and length 6 m. The load-settlement response from the field test shows good agreement with the model tests. Overall, the results of the study provide valuable insights into the behavior and performance of DDS piles that can be used to optimize their design and installation in different soil types.

Bearing capacity prediction of strip and ring footings embedded in layered sand

A prediction model for the bearing capacity estimation of strip and ring footing embedded in layered sand is proposed using soft computing approaches, namely, artificial neural network (ANN) and random forest regression (RFR). The required data for the model preparation were generated by performing lower- and upper-bound finite-elements limit analysis by varying the properties of the top and bottom layers. Two types of layered sand conditions are considered in the study: (a) dense on loose sand; (b) loose on dense sand. The investigation for strip footing was carried out by varying the thickness of the top layer, embedment depth of the foundation and friction angles of top and bottom layers. For a ring footing, the internal-to-external diameter ratio forms an additional variable. In total, 1222 and 4204 data sets were generated for strip and ring footings, respectively. The performance measures obtained during the training and testing phase suggest that the RFR model outperforms the ANN. Also, following the literature, an analytical model was developed to predict the bearing capacity of strip footing on layered sand. The ANN and the generated analytical model predictions agreed with the published experimental data in the literature.

Local buckling in cold-formed steel built-up I-section columns: Experiments, numerical validations and design considerations

A series of axial compression tests were conducted on cold-formed steel built-up I-section columns consisting of two identical lipped channel sections connected by self-drilling screws at the web. At first, the buckling behavior, failure mode, and ultimate bearing capacity of columns with lipped channels and built-up sections were investigated. A nonlinear finite element model that can predict the built-up I-section column was established, and the model’s accuracy was validated against experimental results. Then, a method for estimating local buckling bearing capacity for built-up I-section columns under axial compression was proposed based on the local buckling critical stress calculation formula (Eq. (3)) in this paper, as well as the local buckling bearing capacity curve (Eq. (2)) of the current direct strength method. In order to simplify the calculation, based on revealing the mechanism of instability, two sets of simplified calculation formulas for local buckling critical stress suitable for different ranges of geometric parameters were given, namely Eqs. (23) and (24). Finally, the predicted capacity obtained using the proposed bearing capacity estimation method was compared with the experimental and supplementary finite element results. The comparison results show that the predicted bearing capacity of the built-up I-section column affected by the pure local buckling mode is in good agreement with the experimental or finite element results. However, this method leads to unsafe design predictions for columns with local-distortional interaction buckling.

Finite element and empirical solutions for estimating bearing capacity and settlement of a jointed, multi-layered dam rock foundation

Finite element and empirical solutions for estimating bearing capacity and settlement of a jointed, multi-layered dam rock foundation

A novel whale optimization algorithm optimized XGBoost regression for estimating bearing capacity of concrete piles

A novel whale optimization algorithm optimized XGBoost regression for estimating bearing capacity of concrete piles

EVALUATION OF THE PILE BEARING CAPACITY IN ROCK INTERBEDDED BY COHESION SOILS UNDER VERTICAL LOADING

Introduction . The current regulatory calculation procedure for piles in rocks provides a means to determine the bearing capacity of a pile embedded in a solid rock mass containing no weak interlayers. However, it is not uncommon in actual design practice for rocky soils to be interbedded with softer and less stiff dispersive soils, whose presence affects pile performance. In this case, a summation of estimated resistances along the pile length and at its foot overestimates its estimated bearing capacity, which does not correspond to the actual work due to the different rates of friction force generation in soils of varying formations. Aim . To develop a procedure for determining the bearing capacity of a single bored cast in place pile interacting with rock mass interbedded with cohision soils under vertical indentation loading. Materials and Methods . The procedure for estimating the skin friction resistance of a pile penetrating rocky and dispersive soils is based on the analysis of static pile tests and numerical simulation, taking into account tabulated and analytical solutions given in regulatory literature. Results . A procedure for determining the bearing capacity of a single pile interacting with a rock mass interbedded with cohision soils was developed using tabulated solutions given in regulatory literature, empirical dependencies, and numerical simulation. As a criterion for the ultimate shear resistance of bearing soil, a formula for reference settlement S ref is proposed, which factors in pile dimensions and the characteristics of the pile shaft material. The extent to which the pile bearing capacity is sensitive to the parameters of the model and computational assumptions of numerical modeling is analyzed. The presented examples of determining the design pile bearing capacity via the proposed procedure show results similar to experimental data obtained in the field tests. Conclusions . The presented method allows engineers to factor in the skin friction resistance of cohision soil interbedding in the rock mass to increase its design bearing capacity.

Calculation Model for Estimation of Residual Bearing Capacity of Damaged Reinforced Concrete Slender Columns

This work is devoted to the study of the influences of various parameters on the bearing capacities of compressed reinforced concrete columns of varying flexibilities damaged during operation. Experimental tests of pilot samples were carried out, and results were analyzed on the basis of which it was established that significant longitudinal bending was observed in the direction of the x-axis. By analyzing the influences of the angle and depth of damage on the behavior and nature of the destruction in the experimental samples, three main destruction patterns were identified. An analysis of the experimental and statistical models showed that the greatest influences on the bearing capacity of the samples were the depth of the damage and the angle of the cut, and the effect of the height of the samples was virtually negligible. A model of calculation for the residual bearing capacities of compressed damaged reinforced concrete elements of different flexibilities was developed. The results of the comparison testify to the good coincidence of the theoretical values with the values obtained from the actual experiment (the difference of an average of no more than 29.8%), indicating that the proposed method can be applied in building practice.

Estimation of horizontal bearing capacity of mat foundation on structured and over-consolidated clays under cyclic wave loads

Bottom-supported platform with mat foundations is considered as a cost-effective option for offshore wind power installations due to its rapid installation and extraction period. However, the contact interface between mat foundation and soft seabed may undergo softening due to cyclic wave loads in operation, leading to bearing capacity losses especially in horizontal direction. In this study, the behavior of mat foundation on clay seabed under cyclic wave loads is investigated and the weakening effect on bearing capacity is presented. A unified elastoplastic constitutive model is adopted to consider the soil structure and over-consolidation in natural clay. Responses of excess pore water pressure, effective stress and horizontal bearing capacity for clays with various degrees of clay structures and over-consolidation ratios (OCR) are studied. Effects of wave frequencies and amplitudes on weakening effect of the interface are presented and discussed. Results indicate that the degrees of weakening effects of the normalized horizontal bearing capacity decrease with the increase of the degree of clays structure and OCR value. The clays structure is not easily damaged under the action of cyclic wave loads. The clay's over-consolidation state can be easily dissipated and transformed into normally consolidated clays under the action of wave loads with frequency equal to 0.4/s. The horizontal bearing capacity is basically consistent with the evolution tendency of the vertical effective stress at the interface of mat foundation and clay seabed, and it can be considered that the weakening effect of the horizontal bearing capacity is controlled by the interface.

Regional-scale investigation of pile bearing capacity for Canadian permafrost regions in a warmer climate

Climate change is being experienced particularly intensely in the Arctic and therefore adaptation of engineering systems for this region cannot be further delayed. However, one of the major barriers to studies focused on adapting northern engineering systems is the lack of information at the spatial and temporal scales required for engineering applications. This study investigates pile bearing capacity for selected pile configurations for the Canadian permafrost regions (Nunavut and Northwest Territories), for current and future climates, using the very first ultra-high resolution (4 km) climate change simulation developed for the region using the Global Environmental Multiscale (GEM) model, for a high emission scenario.Comparison of the ultra-high-resolution GEM simulation, driven by reanalysis, with available observations confirms the model's ability in representing near-surface permafrost and related climate variables. The estimated adfreeze contribution to the total bearing capacity, for current climate, informed by the reanalysis-driven GEM simulation, for a 5-m cement pile, is found to be of the order of 15% for regions with shallow bedrock and 80% for regions with deeper bedrock. Application of the GEM climate change simulation outputs, for RCP8.5 scenario, suggest decreases to adfreeze contribution in the 5–30% range by 2040, with the largest differences noted for regions with deeper bedrock. For steel piles of same configuration, although the adfreeze contributions are only about 70% of that for cement piles, the projected relative changes are of similar magnitude.Further downscaling to 250 m resolution using the land model of GEM for the Slave Geological-Grays Bay corridor, where future developments are planned, including an all-season road, enables better estimation of bearing capacity for realistic pile scenarios such as those for bridges (in thick layer of sediments) used for river crossings. Due to the wide variation of pile materials, lengths and installation methods, site specific information can be developed from the framework developed in this study. The results of this study, including the ultra-high resolution climate change information, will thus form the basis for additional detailed investigations on climate-infrastructure interactions and climate resiliency studies.

Estimation of ultimate bearing capacity of bored piles using machine learning models

The ultimate bearing capacity of bored piles is an essential parameter in foundation design of structure. In the present study, three Machine Learning (ML) methods namely Adaptive Neuro-Fuzzy Inference System (ANFIS), Support Vector Machine (SVM) and Artificial Neural Network (ANN) were utilized to estimate bearing capacity of bored piles based on limited engineering parameters of pile and soil obtained from 75 test sites in Vietnam. These parameters include pile diameter, pile length, tensile strength of main longitudinal steel bar, compressive strength of concrete, average SPT index at the tip of the pile, average SPT index at the pile body. Validation of the methods was verified using standard statistical metrics namely Root Mean Square Error (RMSE) and Correlation coefficient (R). The results show that all the proposed models have good potential in predicting correctly bearing capacity of bored piles on training data (R>0.93) and on testing data (R>0.88) but performance of the SVM model is the best (R:0.985 (training) and R:0.958 (testing). Thus SVM model can be used for the accurate prediction of ultimate bearing capacity of bored piles for proper designing of the civil engineering structure foundation.

Foundation bearing capacity estimation on unsaturated soil slope under transient flow condition using slip line method

In this paper, an analytical method is proposed for estimating the bearing capacity of soil within the framework of slip line theory. The method incorporates a closed-form solution taking account the transient unsaturated vertical flow conditions. The proposed framework is validated for both level and sloping ground scenarios considering saturated and unsaturated soil conditions. More specifically, the bearing capacity of a strip foundation located on an unsaturated soil slope under the influence of different rainfall infiltration conditions is evaluated. A comprehensive parametric study is also conducted taking account the influence of the rainfall influx, rainfall duration, slope angle, foundation setback distance, soil type, and the depth of the ground water table. In addition, the contribution of matric suction towards the bearing capacity under transient flow conditions is evaluated. Results of this study provide a rigorous understanding of the performance of foundations on sloping ground extending the mechanics of unsaturated soils.

Hysteresis behavior of 3D RC exterior beam-column joints strengthened with CFRP sheets and spike anchors

Full-scale 3D exterior beam-column joints lacking shear reinforcement but externally shear-strengthened with carbon fiber reinforced polymer (CFRP) sheets were investigated with respect to their behavior under both gravity and lateral cyclic loadings. For this purpose, three such joints including one control and two experimental ones (strengthened either with CFRP sheets or with both CFRP sheets and spike anchors) were subjected to relevant tests. Prior to CFRP installation, all the externally strengthened specimens were subjected to surface preparation and grooving in order to prevent possible CFRP debonding. The flexural capacity of both the non-strengthened and strengthened joints were estimated using a specially-developed analytical method. Comparisons of the lateral load–displacement hysteresis curves and in the test results revealed that, compared to the control, the externally strengthened joints showed enhancements of 30, 222, and 200% in lateral load-bearing capacity, energy dissipation, and secant stiffness, respectively. It was further found that despite the efficacy of the shear retrofit design proposed for 3D exterior connections, those strengthened with the combined CFRP sheets and spike anchors outperformed the ones solely strengthened with CFRP sheets. The sectional analysis results also revealed that the simple method proposed in this study is well capable of estimating bearing capacity in both the control and strengthened connections with reasonable accuracy.

Quantitative Estimation of Ecocultural Bearing Capacity of Urban Agglomerations in Britain

Aiming at the imbalance of urban ecological carrying capacity, this paper proposes a method to estimate the ecological and cultural carrying capacity of British urban agglomeration. The difference method and standardization method are used for positive combination and dimensionless processing of the indicators to realize the data preprocessing of the indicators. Through questionnaire survey, consulting relevant scholars and experts, and referring to the specified values in relevant British policies, determine the ideal value of the index. The index weight is determined by the open-scoring method. According to the index weight, the ecological and cultural carrying capacity of British urban agglomeration is calculated by vector model method. Calculate the index weight according to the ideal value of the index and the ecological text. The strength of ecological culture carrying capacity is calculated by the actual value of carrying capacity. Taking London urban agglomeration as the experimental object, this paper calculates the ecological and cultural carrying capacity and analyzes the ecological and cultural carrying capacity of three subsystems. The results show that this method can effectively estimate the ecological and cultural carrying capacity of British urban agglomeration.