Calculation Of Bearing Capacity Research Articles

Axial compressive performance of RC columns strengthened with prestressed CFRP fabric and UHPC jacket with spiral stirrups

AbstractTo address the issue of easy shearing damage of Carbon Fiber Reinforced Polymer (CFRP) in enhancing the axial compressive performance of CFRP and Ultra‐High‐Performance Concrete (UHPC) strengthened concrete columns, two methods, prestressed CFRP and UHPC with spiral stirrups, were employed for composite strengthening of reinforced concrete (RC) columns. A total of one unstrengthened column and eight strengthened columns were designed and fabricated to validate the effectiveness of the proposed methods. The axial compressive performance and bearing capacity of each specimen were analyzed by considering parameters such as single or composite strengthening method, presence of spiral stirrups in UHPC, and application of pre‐stressed CFRP. The results show that, compared with any single strengthened specimen, the ultimate bearing capacity of the composite strengthened specimen is greater than the sum of the corresponding single strengthened specimens, and the bearing capacity of the prestressed CFRP with spiral stirrup UHPC composite strengthened specimen is the most significant, reaching 235.63%. By incorporating spiral stirrups in the UHPC jacket, the phenomenon of uneven fragmentation during the failure of the strengthened column is improved. This helps prevent premature shearing damage of CFRP and enhances the fracture strain and effective utilization of CFRP. Additionally, prestressed CFRP effectively restrains the lateral deformation and crack development of the core concrete in the UHPC jacket, fully utilizing the high compressive strength of UHPC. This further enhances the ultimate bearing capacity and ductility of the specimens. Based on the experimental phenomena and strain of each material, the failure mechanism of prestressed CFRP‐spiral reinforced UHPC composite‐strengthened columns is proposed. Finally, a unified bearing capacity calculation formula for single and composite strengthened columns is established, based on the theory of confined concrete strength and the assumption of strength increment superposition. The formula is validated with experimental results from relevant literature, showing small errors in the calculated results and indicating good applicability of the formula.

Axial compressive performance and finite element analysis on spirally reinforced seawater sea-sand concrete-filled aluminum alloy tube columns

Axial compression experiment and finite element analysis were used in this research to explain the mechanical properties of spirally reinforced seawater sea-sand concrete-filled aluminum alloy tube (SR-CFAT) columns. The diameter and spacing of the spiral stirrup, the quantity and diameter of the longitudinal reinforcement, and the ratio of the spiral stirrup to longitudinal reinforcement (rhv) were used as the variation parameters in the design of 16 SR-CFAT columns and 1 seawater sea-sand concrete-filled aluminum alloy tube (CFAT) column. The results demonstrated that both the SR-CFAT columns and the CFAT column experience shear failure, while the former exhibited greater axial compression bearing capacity and deformation capacity. The ultimate bearing capacity, ductility, and energy absorption value of this composite column increase with an increase in rhv, then decrease under the same reinforcement content. The specimens perform best under axial compression when rhv is 2.20. Among the others, specimens with "fine and dense" spiral stirrups and "less and coarse" longitudinal reinforcement have higher ultimate bearing capacities, ductility, and energy absorption values. An FE model is created for the SR-CFAT columns, followed by a parameter extension analysis. Based on test and finite element results, a high-accuracy axial compression bearing capacity calculation algorithm is provided using cylinder theory.

Bearing Capacity Equations for Intact Argillaceous and Arenaceous Rocks in Malaysia Derived from P-Wave Velocity

This paper presents the derivation of the bearing capacity equation of shallow foundations using P-wave velocity based on the seismic refraction method on argillaceous rocks (shale) and arenaceous rocks (sandstone). Various theories of bearing capacity equations were developed over the years for the calculation of bearing capacity under vertical central loading. But, the most widely used on rock is the Mohr-Coulomb failure criterion given by Meyerhof (1963). Based on this theoretical development, the empirical equation of ultimate bearing capacity was obtained. The detailed derivation of these parameters is comprised of the results from Uniaxial Compressive Strength (UCS) and P-wave velocity values. The proposed empirical equation of bearing capacity derived from P-wave velocity herewith can be used as an alternative method in designing shallow foundations. There is a good agreement on the bearing capacity determination from P-wave velocities.

Research on seismic performance of prefabricated composite shear wall with end steel plate connection

Chinese construction industry is gradually transforming to industrialization, which promotes the development of prefabricated buildings. As an efficient lateral force resisting system, prefabricated steel-plate concrete composite shear wall structure has become a research hotspot in the field of architecture at home and abroad. Based on the mechanical characteristics of the shear wall, this paper proposes a end steel plate connection prefabricated composite shear wall structure. Through numerical simulation and analysis of the prefabricated composite shear wall with different connection areas and the cast-in-place composite shear wall, which verified the feasibility and reliability of end steel plate connection. Based on the above verification, the influence of different parameters on the seismic performance of the prefabricated composite shear wall with end steel plate connection has been further studied, and the theoretical calculation of bearing capacity is carried out. The results show that the length of the connector should be controlled within a reasonable range. The tie bars in the node connection area can improve the strength and ductility of the prefabricated composite shear wall. The aspect ratio and axial pressure ratio have obvious influence on the seismic performance of the wall, which should be reasonably selected in design.

Study on mechanical properties and bearing capacity calculation of eccentric compression of RC columns reinforced with prestressed lattice steel

The external steel structure and RC column under eccentric compression have a reduced ability to work together, and using prestressing technology can significantly improve their ability to work together. Therefore, the paper proposes a new prestressed column reinforcement technology by adopting a space profile steel structure instead of angle steel and combining prestressing technology with the bolted connection. By conducting eccentric compression test studies on 11 specimens with different reinforcement methods, prestressing and eccentricity, load-displacement curves, stress distribution laws, ultimate bearing capacity, damage modes and prestressing influence rules were obtained. The main conclusions are as follows: prestressing can significantly improve the ability of external reinforcement steel structure and core column to work together and inhibit the development of concrete cracks. Compared with the traditional angle steel reinforcement, the bearing capacity is increased by 17.5 %, the stiffness is increased by 26.6 %, and the ductility is increased by 12.3 %. However, the reinforcement effect will be reduced if the prestressing is too large. It is recommended that the prestressing should be applied according to the size of 0.09 fc of the unilateral area of the core column. According to the prestressed lattice steel constraint mechanism, a mechanical analysis model of the reinforced member was established. Finally, based on the cross-section equilibrium method, a calculation method of eccentric compressive ultimate bearing capacity was proposed, and the research results can provide a basis for the engineering application of the new reinforcement method.

Behaviour of concrete-filled circular steel tubular K-joints in wind turbine towers

The advantages of concrete-filled steel tubular lattice towers in stress efficiency, material consumption, and industrial construction are significant for the future development of ultra-long blades, ultra-high towers, and large-capacity units. The stress state of the joints is a key component of a wind tower structure. Therefore, experiments were conducted on four concrete-filled circular steel tubular (CFCST) K-joints in a lattice wind turbine tower, along with one hollow circular steel tubular (HCST) K-joint for comparison. The test results revealed that the CFCST K-joints failed due to local and overall buckling of the compression web, whereas no plastic deformation occurred on the chord. The stiffness of the CFCST K-joints significantly improved, and the stress concentration around the intersecting line was significantly reduced. Existing structural codes, both domestic and international, underestimate the bearing capacity of CFCST K-joints because the contribution of the core concrete cannot be accounted for. Finite element analyses indicate that the bearing capacity of the CFCST K-joints is dependent on the failure mode, primarily influenced by the thickness ratio τ and the angle θ. To prevent joint failure in the CFCST lattice wind turbine towers, specifically suggest τ ≤ 1 and θ ≤ 45°. Based on the bearing capacity calculation method proposed by CIDECT for HCST K-joints, design equations were obtained to predict the punching shear bearing capacity of CFCST K-joints using the least-squares method. The established formula exhibited high accuracy through regression verification.

Model uncertainties in action effects and load bearing capacity calculation in statically indeterminate reinforced concrete structures

AbstractFor the dimensioning and assessment of structures, it is common practice to compare action effects with sectional resistances. Extensive studies have been performed to quantify the model uncertainty on the resistance side. However, for statically indeterminate systems, the model uncertainty in the calculation of action effects has not been properly investigated yet. The aim of this article is to contribute in quantifying the model uncertainty in action effects and load bearing capacity calculations for reinforced concrete structures, accounting for the type of mechanical model used and for various failure modes. To collect a sufficient amount of data and perform statistical analyses, the experimental response of statically indeterminate systems is obtained with a simple and effective technique which allows using experimental results available in literature. Finally, on the basis of a parametric analysis and case studies, practical implications are discussed and recommendations are given concerning the implementation in the partial safety factor format.

Predicting the ultimate bearing capacity of spudcan in stiff-over-soft clay based on a failure model varying with soil parameter

A jack-up platform is prone to a ‘punch-through’ accident when working on the stiff-over-soft clay foundation. To assess the risk of punch-through, it is necessary to plot the bearing capacity-penetration curve for evaluating the penetration depth of the pile leg or to calculate the ultimate bearing capacity of the spudcan and compare it with the preload. However, accurate prediction of spudcan bearing capacity is not easy. In this paper, the failure mode about the stiff-over-soft clay under different geological conditions when punch-through occurs is discussed using coupled Eulerian lagrangian (CEL) method, varying the strength ratio between soft and stiff soil layers, the thickness of stiff soil relative to the spudcan diameter, and the non-homogeneity factor of soil strength. Based on the soil failure model with varying soil parameters, a new calculation method for ultimate bearing capacity of spudcan is proposed and then verified against existing centrifuge test results. The results show that the shape of soil shear plane in stiff clay is significantly affected by the strength ratio of soil layer and the non-homogeneity factor of soil strength. And the presented new method whose prediction errors compared with centrifuge test results are less than 5%, has better calculation accuracy than the ISO (International Organization for Standardization) method, which is valuable in guiding the calculation of the ultimate bearing capacity of the spudcan and ensuring the safe operation of the jack-up drilling units on stiff-over-soft clay.

Experimental and simulative study on seismic performance of stiffener‐plate PEC beam‐column joint

AbstractAn innovative assembled stiffener‐plate PEC beam‐column joint (SP‐PEC) is proposed to improve better constructability. In this paper, 12 PEC beam‐column joint specimens were subjected to quasi‐static cyclic tests. The design parameters included the thickness of the stiffener‐plate (equal‐stiffness thickness at load standard combination, full‐stiffness thickness of the cross‐section, and 120% of full‐stiffness thickness of the cross‐section) and the beam‐column connection with or without the stub beam. The results revealed that the assembled SP‐PEC beam‐column joint exhibited better seismic performance than the conventional PEC beam‐column concrete joint. The strength degradation coefficients of SP‐PEC beam‐column nodes are all greater than 0.92, and the stiffness decreases slowly. The specimens had good bearing capacity, deformation ability, energy dissipation capacity, and stiffness under a reasonable stiffener‐plate thickness. Then, the bearing capacity calculation formulae of the novel joint with certain prediction accuracy were proposed. Besides, the finite element models of the test specimens were established in ABAQUS and validated against the test results. Finally, further investigations of the SP‐PEC joint configuration by finite element analysis and engineering design recommendations for the assembled SP‐PEC beam‐column joint were provided.

Calculation of second-order bearing capacity of members subjected to axial load and biaxial bending

The second-order effects of biaxial bending members involve dual non-linear problems, namely material nonlinearity and geometric nonlinearity. These problems typically require iterative calculations and cannot be solved manually. To address this issue, this paper founded upon the strain-based resolution of stress and internal forces, deduces the formula for calculating the load-bearing capacity of the cross-section. The elastoplastic second-order deformation is then calculated at the member level, and the final result is presented in the form of a dimensionless nomogram for calculating the second-order biaxial bending members. In this paper, the limit range of section strain is determined based on the constitutive relationship of concrete and reinforcement. This range is divided into three limited strain areas, which enable the calculation of section bearing capacity and limit curvature, and subsequently the second-order bearing capacity of the member. The results are in good agreement with experimental data. The dimensionless nomogram in this paper considers the complete parabolic and rectangular of concrete stress-strain relationship and the ideal elastoplastic constitutive relationship of reinforcement and the second-order effect. It does not require iteration. It can quickly calculate the reinforcement or check the section bearing capacity by hand. It can be used to check the calculation results of engineering software and provides ideas for the design method of member subjected to axial load and biaxial bending based on seismic restoring force.

Study on failure modes and calculation method of the cast steel joint with branches in treelike structure

The treelike structure links members and transfers loads via its solitary cast steel joint with branches. Therefore, the joint’s bearing capacity significantly affects the treelike structure’s stability, security, and economics. This paper utilized experimental verification and numerical modeling to examine the mechanical behavior of cast-steel joints with branches in the treelike structure under various loading conditions. Then, researchers investigated the failure process and mechanism of joints, and the three most common failure modes were outlined. Furthermore, the researchers proposed the bearing capacity calculation formula based on the common failure modes. The results show that the three common failure modes of the cast-steel joints with branches under different loading conditions are the failure in the joint core area under the axial load, the failure in the main pipe compression side under eccentric load, and the failure in the compression side of the single branch pipe root when the single branch pipe is under the uneven load. The suggested empirical calculation method can serve as a reference point for similar engineering practices design.

Finite element analysis and bearing capacity calculation of cross-shaped CFST columns under compressive load

The study investigated the load capacity of cross-shaped concrete-filled steel tubular (CFST) columns under axial and eccentric compression using finite element software ABAQUS. It analyzed six specimens with measured data and an additional 26 specimens with varied parameters, including eccentricity, slenderness ratio, section steel ratio and material properties such as concrete strength and steel yield strength.The objective was to understand how these parameters affect the load capacity of cross-shaped CFST columns. The research findings suggest that as eccentricity and slenderness ratio increase, the ultimate capacity decreases. Conversely, it increases with higher steel content, concrete strength and steel yield strength. Moreover, the bearing capacity deteriorates more rapidly with reduced eccentricity and concrete strength, while it demonstrates a nearly linear increase with greater steel content. Additionally, the study found that enhancing the resilience of the channel steel significantly boosts the load-bearing capacity of the column. Based on these findings, practical design equations were developed to determine the maximum bearing capacity of cross-shaped CFST columns under axial and eccentric compression. These equations are grounded in confined concrete theory and demonstrate robust applicability for practical design purposes.

Theoretical study of bearing capacity calculation model for multi-segment confined concrete arch and design method in underground engineering

Theoretical study of bearing capacity calculation model for multi-segment confined concrete arch and design method in underground engineering

Experimental study and optimal design of UHPC T‐shaped beam

AbstractIn this paper, the ordinary reinforced UHPC T‐shaped beam, steel plate reinforced UHPC T‐shaped beam and prestressed UHPC T‐shaped beam were compared by conducting the flexure test. The vertical displacement, crack development, strain change, and crack resistance were discussed. The steel plate reinforced UHPC T‐shaped beam shown better cracking resistance and mechanical properties. Based on the research, the multi‐scale finite element model of the steel plate reinforced UHPC T‐shaped beam was established, and the influence parameters were analyzed. The beam height, steel plate thickness and web thickness shown great influence on the ultimate bearing capacity of the beam. The bearing capacity calculation formulas of the steel plate reinforced UHPC T‐shaped beam based on the plastic strengthening model of the steel were proposed. The calculation results shown good agreement with the test value.

Research on the Design and Application of Anti-wind devices for Seismically Isolated Buildings

Specialized anti-wind devices were designed and applied to seismically isolated buildings to solve the problem that seismic isolation buildings in areas with high wind loads could not simultaneously meet the requirements of the seismic damping objectives and the wind bearing capacity calculation. Taking an actual project as an example, anti-wind devices are added to the seismic isolation interface, a finite element analysis model of the structure is established and a time-distance analysis calculation is performed, and a synergistic design is carried out for the seismic damping effect and wind-resistant calculation. The results of the study show that the addition of anti-wind devices to reduce the number of lead rubber bearings can simultaneously satisfy the expected seismic damping effect and wind bearing capacity requirements; Numerical analysis of static loading verifies the effectiveness of anti-wind devices; This anti-wind device can be popularized for use in seismically isolated buildings in areas with high wind loads.

ПРОЕКТИРОВАНИЕ ГРУНТОВЫХ АНКЕРОВ. УЧЕТ ТОРЦЕВОГО СОПРОТИВЛЕНИЯ УШИРЕНИЯ ГРУНТОВОГО АНКЕРА ПРИ РАСЧЕТЕ ЕГО НЕСУЩЕЙ СПОСОБНОСТИ ПО ГРУНТУ.

Currently, ground grouted anchor systems are widespread in geotechnical construction. One of the stages of anchor system designs is ultimate load-holding (bearing) capacity calculation. To date, a clear methodology for calculation the bearing capacity of a ground anchor is not presented by the current regulatory documents. On the other hand, the existing calculation methods for determining the bearing capacity of the anchor (which are presented in SP 381.1325800, VSN 506-88, TSN-50-302-2004 and others) do not take into account all geometric parameters and technological factors. Therefore, the results of determination bearing capacity are significantly lower than the actual ones. Also, the calculation of the bearing capacity is reduced to determination the lateral surface resistance of the anchor’s cylindrical body only. An end-bearing resistance component of the fixed anchor is not taken into account by calculation. This article raises the issue of reliable determination of the ground grouted anchor’s calculated bearing capacity, taking into account all geometric and technological factors, and also considers the stress-strain state of soil and the destruction mechanics.

Experimental Study and Bearing Capacity Calculation of Compression-Reinforced Concrete Columns Strengthened with Ultra-High-Performance Concrete

A total of five ultra-high-performance concrete (UHPC)-strengthened reinforced concrete (RC) columns and one RC column were built and subjected to eccentric compression testing to examine the force performance of UHPC-strengthened eccentrically compressed plain RC columns. This experimental study examined the crack progression, the damage morphology, the deformation ability, the maximum load-carrying capacity, and the ductile properties of the eccentrically compressed columns. It also investigated the impacts of eccentricity, the reinforcement thickness, and the addition of steel fibers on the effectiveness of reinforcement. The cracking load, peak load, and ductility coefficient of the UHPC-reinforced specimens were increased by 100.28%, 172.30%, and 56.30%, respectively, compared with the RC column at an initial eccentricity of 50 mm. As the eccentricity distance increased, the bearing capacity of the UHPC eccentrically compressed specimens decreased, and the deformation capacity increased. Increasing the steel fiber dosage within the appropriate range decreased the crack width of the specimen. The addition of 2% steel fiber resulted in a 24.8% increase in cracking load, an 8.96% increase in peak load, and a 2.60% increase in ductility coefficient compared to the addition of 1% steel fiber. However, the reinforcing effect of UHPC was weakened under high eccentric pressures. Based on the theory of concrete structure and mechanical principles, the formula for calculating the compressive bearing capacity of RC columns strengthened with high-performance concrete was proposed. The results of calculating the positive section bearing capacity of eccentrically compressed RC columns reinforced with high-performance concrete are in good agreement with the test values. The results of this paper provide an experimental basis and theoretical foundation for the cross-sectional design of UHPC eccentrically compressed columns.

Study on the Influence of Water Erosion on the Bearing Capacity and Function of the High Pile Foundation of the Wharf

High-pile foundation is a common form of deep foundation commonly used in ocean environments, such as docks and bridge sites. Aiming at the problem of bearing capacity of high pile foundations, this paper proposes the calculation of bearing capacity and the analysis of scour depth of high pile foundations under the action of scour based on the modified p-y curve. In this paper, three kinds of scour mechanisms—natural evolution scour, general scour, and local scour—are described; and the calculation methods of scour widely used at present are compared and analyzed. The solution of the vertical stress of soil around the pile under local scour is solved and applied to the β method to solve the lateral resistance of the pile under local scour. The local erosion is equivalent to the whole erosion, and the expression of the ultimate soil resistance before and after the equivalent is calculated, respectively, according to the principle that the ultimate soil resistance at a certain point above the equivalent pile end remains unchanged. The distance from the equivalent soil surface to the pile end can be obtained simultaneously, and then the equivalent erosion depth, p-y curve of sand at different depths, and high pile bearing capacity can be obtained. Finally, it is found that the bending moment of a single pile body varies along the pile body in the form of a parabola, and the maximum bending moment of the pile body is below the mud surface and increases with the increase in horizontal load. When the scouring depth is 30 m, the horizontal load is 25 KN, and the maximum bending moment of the pile body is about 150 N·m. The data with a relative error greater than 10% accounted for only 16.6% of the total data, and the error between the calculated value and the measured value was small. The formula can predict the erosion depth more accurately.

Axial Compression Bearing Capacity of Bolted Drum-Shaped Spherical Shell Joints: Experimental and Numerical Analysis

Bolted drum-shaped spherical shell joints (BDSSJs) represent a type of joint applicable to space grid structures. These joints merge the benefits of both bolted spherical joints and welded hollow spherical joints, embodying features such as a compact size, favorable centerline alignment with members, a high degree of adjustability, and high installation efficiency. Through unidirectional axial compression tests on specimens of BDSSJs, this study examines the stress distribution, force transmission pathways, ultimate bearing capacity, and failure modes of the joint, thereby determining its bearing capacity and presenting a bearing capacity calculation formula for such joints. By establishing a finite element model with parameters identical to the experimental specimens, this study analyzes the force and deformation of BDSSJs under unidirectional compression, identifying the high-stress areas during the compression process of BDSSJs. The findings of this study provide a basis for the practical engineering application of such joints, as well as theoretical support for subsequent dynamic performance into BDSSJs.

Stochastic analysis for bearing capacity computation of twin strip footings on geogrid-reinforced sands

ABSTRACT The interaction of closely-spaced footings on soils is of concern for recent decades. The inherent variability of soil makes the topic more challenging. This study investigates the behaviour of twin strip foundations on both unreinforced and geogrid-reinforced spatially random sands. The Random Finite Difference is performed by coupling Matlab and FLAC2D in each Monte Carlo simulation. Two types of sands, dense and loose, are assumed as the spatially correlated log-normal random fields and the friction angle is considered a random parameter. This study discusses how much the bearing capacity of twin footings is impressed by the heterogeneity of random sands. The unreinforced soil results show that when the uncertainty of φ is high, the homogeneous soil assumption could overestimate the interference effect by about 18% and 9% in the dense and loose sands, respectively. While soil reinforcement reduces the difference between results obtained from probabilistic analysis with those calculated with deterministic analysis. Moreover, the isotropic random fields with rapid fluctuation of φ yield the greatest interference influence in the unreinforced and reinforced dense sands. The combined impact of interference and reinforcement is greater in loose sand than in dense sand, regardless of whether the soil is heterogeneous or homogeneous. HIGHLIGHT Random heterogeneous variability of φ on the interaction of the twin foundations on both unreinforced and geogrid-reinforced sand was investigated. For twin footings on unreinforced dense sand, Scr/B changes from 1.25 to somewhere between 1.25 and 1.5 by increasing COV φ , while on the unreinforced loose sand, Scr/B = 1 remains constant, irrespective of COV φ values. For high variability of φ, the assumption of soil without variability results in overestimation of twin footings interference effect by about 18% and 9%, which means the risk acceptance yields irrevocable damages. Increasing the number of geogrid layers, N, declines the risk of estimating the analysis with homogeneous soil, especially for high variability of φ. By all means, the footing interference and geogrid effects become lower when N is added. The interference effect is usually higher for twin footings on unreinforced sand than on the same reinforced sand. Overall, the integrated influence of interference and reinforcement in loose sand is more than that in dense sand The combined influence of interference and the first geogrid layer is the most in the isotropic random field (θ x = θ y = 1 m) for both sand since the rapid variation of φ in both directions increases the influence and reinforcement effects. The deterministic analysis underestimates the interaction of twin foundations on the reinforced loose sand compared to the anisotropic random fields.