Ultimate Bearing Capacity Analysis Research Articles

Experimental Study on a New Connection Method of Latticed Shell Joint

In this research, the axial and eccentric pressure tests and finite element analysis (FEA) of a latticed shell joint with different parameters were carried out. The experimental and FEA results showed that the annular plate yielded first, followed by steel tube 1, and then steel tube 2 under the axial pressure and eccentric pressure. The ultimate bearing capacities of connection method II under axial pressure and eccentric pressure were 15% and 11% higher than that of connection method I, respectively. The wall thickness of steel tube 2 was reduced by 2 mm, and the ultimate bearing capacities under axial pressure and eccentric pressure is reduced by 15% and 11%, respectively. The wall thickness of steel tube 1 was reduced by 2 mm, and the ultimate bearing capacities under axial pressure and eccentric pressure is reduced by 6% and 9%, respectively. With the decrease of the concrete thickness, the ultimate bearing capacity under axial pressure and eccentric pressure reduced by 18% and 17%, respectively. The ultimate bearing capacity analysis showed that the height of the concrete and the thickness of steel tube 2 had a greater effect on the ultimate bearing capacity than the thickness of steel tube 1.

Prediction and Analysis of Ultimate Bearing Capacity of Square CFST Long Column under Eccentric Compression after Acid Rain Corrosion.

This paper adopts the method of steel tube wall thickness and strength reduction to simulate corrosion damage. The numerical model of the square concrete-filled steel tube long column (SCFST-LC) under eccentric compression after acid rain corrosion is established in the finite element software, ABAQUS. The reliability and accuracy of the model are verified by comparing it with published relevant experimental results. The failure mode, load-deformation curve, and ultimate compressive load were analysed. Following that, the impacts of section size, yield strength of the steel tube, axial compressive strength of concrete, steel ratio, slenderness ratio, and load eccentricity on its ultimate compressive load are comprehensively investigated. The results demonstrate that the ultimate compressive load of the SCFST-LC decreases significantly with the increase in corrosion rate. The corrosion rate increases from 10 to 40%, and the ultimate bearing capacity decreases by 37.6%. Its ultimate bearing capacity can be enhanced due to the increase in section size, material strength, and steel ratio. In contrast, the ascending slenderness ratio and load eccentricity has harmful effects on the ultimate compressive load of the specimens. Finally, a simplified formula for the axial compressive load of the SCFST-LC under eccentric compression after acid rain corrosion is proposed. The calculation accuracy is high and the deviation of the results is basically within 15%, which is in good agreement with the numerical simulation results.

Bearing Capacity Analysis of Spun Pile Foundation in Gas Engine for Electrical Power Plant Project of Selayar

Gas Engine for Electrical Power Plant Project of Selayar is a power plant which will be built in Selayar Regency. This plant uses gas and biodiesel as a fuel. The facilities needed in the power plant construction includes a Gas Engine, Service Water Tank and Biosolar Tank. This study aims to obtain the allowable bearing capacity of the prestressed spun pile foundation for the three buildings based on soil investigation data of SPT (Standard Penetration Test) at BH-1 (gas engine), BH-2 (service water tank) and BH-3 (biosolar tank). The Meyerhof formula is used for the calculation of ultimate bearing capacity analysis on prestressed spun piles with various diameters for each depth. Calculation of the allowable bearing capacity (Qa) of the foundation at a depth of 19 meters, using a spun pile with a diameter of 300 cm, obtained a Qa value of 94.17 tons at BH-1, 94.20 tons at BH-2, and 74.65 tons at BH-3. Using a spun pile with a diameter of 400 cm, the Qa values were 116.71 tons on BH-1, 117.64 tons on BH-2, and 91.92 tons on BH-3. Using a spun pile with a diameter of 500 cm, the Qa values were 168.67 tons on BH-1, 172.09 tons on BH-2, and 131.49 tons on BH-3. Meanwhile, the values of Qa obtained were 229.85 tons on BH-1, 236.66 tons on BH-2, and 177.79 tons on BH-3 with the use of a spun pile with a diameter of 600 cm.

Elastoplastic Analysis of Ultimate Bearing Capacity for Multilayered Thick-Walled Cylinders Under Internal Pressure

The elastoplastic analysis based on the unified strength theory was performed to evaluate the ultimate bearing capacity of double- and multilayered thick-walled cylinders. The theory provides a new concept and method for the analysis of thick-walled cylinders. The solutions derived herein are widely applicable and can quantitatively account for different tension-compression strength values and mean principal stress. The fundamental solutions for single radii, assemblage pressure, and shrink range are derived with the yield condition of the theory. The traditional existing elastoplastic results by the Tresca or von Mises yield criteria can be seen as a particular case of the new solutions that can overcome shortcomings. The strength parameter, tension-compression strength ratio, radii ratio, and combined cylinder layers were taken as major theory variables for the unified solutions. The new solutions are versatile and can be adapted to the existing formulas, to more accurately calculate the structural stress conditions. The strength theory effect due to adopting different yield criteria is quite significant, which cannot be underestimated.

Analysis of ultimate bearing capacity of pressure spherical shell with openings

As the main pressure bearing structure of the deep submerger, it is inevitable to open manholes and observation holes on the pressure spherical shell, and the openings will affect the ultimate bearing capacity of the pressure spherical shell. In this paper, 7000m pressure spherical shell is taken as the research object, the finite element model of the spherical shell is established based on ANSYS, and the influence of the opening size on the ultimate bearing capacity of the spherical shell is calculated. At the same time, the trunk bulkhead strengthening method is adopted, and the thickness and height are taken as variables to calculate the change of the ultimate bearing capacity under different working conditions. The results show that the wall strengthening can significantly reduce the influence of opening on the pressure spherical shell, and the appropriate increase of thickness or decrease of height can increase the ultimate bearing capacity of the structure.

Analysis of Ultimate Bearing Capacity of Large Span Continuous Rigid Frame Curved Bridge

In order to study the ultimate bearing capacity of the large span continuous rigid frame curved bridge, a three-dimensional solid finite element model of a curved bridge was established based on ANSYS software. Different load cases were considered in analysing the ultimate bearing capacity. The results show that the loading process of the selected background curved bridge can be divided into elastic, elastoplastic and failure stages. Besides, under the most unfavourable load case, the living load coefficient and the safety factor is are 20.40 and 2.94, respectively. This indicates that the calculation formula of ultimate bearing capacity provided by the current standard has enough safety degree. In addition, because of the coupling effect of bending and torsion, the tensile stress and compressive stress on the outside of girder are larger than those on the inner part. Moreover, the ultimate bearing capacity of vehicle eccentric loading is lower than that of medium load, which should be considered in the design.

Elastic Modulus Reduction Method Based Ultimate Bearing Capacity Analysis of CFST Truss Arch

In order to evaluate the application of elastic modulus reduction method on the ultimate bearing capacity analysis of CFST truss arch, the elastic modulus reduction method was compared with the test data and the increment nonlinear finite element method. Firstly, the element bearing ratio was defined according to the homogeneous generalized yield function, and the principle of deformation energy conservation was adopted to derive the elastic modulus adjustment strategy, based on which the modulus reduction method was developed for the ultimate bearing capacity analysis of CFST structures. Then, combined with the incorporated strength capacity technique, the section strength was modified to consider the structural constant load effect. Finally, the ultimate bearing capacity of a CFST truss girder and 136m span truss arch was obtained on the basis of the proposed method, and the results were compared with the test data and the incremental nonlinear finite element method. The results show that the elastic modulus reduction method can achieve high calculation accuracy and wide application for the ultimate bearing capacity analysis of CFST truss arch.

Ultimate pressure bearing capacity analysis for the prestressed concrete containment

PWR nuclear power technology has been developed in China according to the experience feedback of the Fukushima accident and the global latest safety requirements, in which the double-containment design with hemisphere dome having larger free space is adopted. Ultimate pressure bearing capacity of the Prestressed Concrete Containment Vessel (PCCV) is analyzed in this study to provide technical support for development of Severe Accident Management Guidelines (SAMG) in nuclear power plants. Firstly, the finite element model of the PCCV is built, including the concrete, the rebars, the prestressed tendons, the steel liner, and penetrations. Combining of free-sweep mesh is adopted according to the characteristics of the containment structure. Proper mesh size is determined through mesh sensitivity analysis. Prestressing loss is calculated for four types of prestressed tendons, and decreasing temperature method is adopted in prestressing simulation. Temperature field of the containment is calculated, and stratified temperature method is adopted in temperature simulation. Ultimate pressure bearing analysis results show that, with the increase of internal pressure, the containment gradually expands outward, and the maximum stress and maximum radial deformation of the containment appear near the equipment hatch. When the internal pressure load reaches 1.26 MPa (g), the equivalent plastic strain of the steel liner in the right area of the equipment hatch is 0.15%. At this time, the concrete cracks on a large area, and the prestressed tendons do not yield.

Probabilistic analysis of ultimate seismic bearing capacity of strip foundations

This paper presents a reliability analysis of the pseudo-static seismic bearing capacity of a strip foundation using the limit equilibrium theory. The first-order reliability method (FORM) is employed to calculate the reliability index. The response surface methodology (RSM) is used to assess the Hasofer–Lind reliability index and then it is optimized using a genetic algorithm (GA). The random variables used are the soil shear strength parameters and the seismic coefficients (kh and kv). Two assumptions (normal and non-normal distribution) are used for the random variables. The assumption of uncorrelated variables was found to be conservative in comparison to that of negatively correlated soil shear strength parameters. The assumption of non-normal distribution for the random variables can induce a negative effect on the reliability index of the practical range of the seismic bearing capacity.

Reliability analysis of seismic bearing capacity of strip footing by stochastic slip lines method

In this research, the reliability analysis of seismic ultimate bearing capacity of strip footing is assessed with implementing slip lines method coupled with random field theory. The probability density functions of seismic and static bearing capacities which are log-normal and nearly normal distribution respectively are compared to each other. The predicted Probability Density Function (PDF) of the seismic bearing capacity by slip line method is verified, with those of the Terzaghi equation and Monte Carlo simulation (MCs). For uncertainties analysis by Terzaghi equation the Nc, Nq and Nγ are assessed stochastically.

Ultimate Bearing Capacity Analysis and Sizing Optimization of a Cracked Reactor Pressure Vessel in the Coupled Thermo-Mechanical Field

Pressurized thermal shock (PTS) can subject a crack surface to a very high tensile stress. Also the material toughness is obviously decreased in the cooling process, so it is necessary to study the influence of PTS on the ultimate bearing capacity of a reactor pressure vessel with defects. A 3-D finite element model is established for the beltline region around an inner crack. The FEM is used to reveal the transient temperature field and stress field, and the XFEM is adopted to simulate the ductile crack propagation. To ensure that the strength requirement is satisfied, the ultimate internal pressures of vessels with different crack sizes and different wall thicknesses are obtained. The result shows that the ultimate bearing capacity of the base wall with shallow surface cracks at high temperature is mainly controlled by tensile strength, while it is also affected by the fracture toughness of the material under the severe PTS. The stress in the early stage of the PTS is mainly the thermal stress, and later is the thermo-mechanical coupling stress. The impact of the crack depth on the bearing capacity of the structure is much greater than that of the crack length.

Ultimate bearing capacity analysis of a reactor pressure vessel subjected to pressurized thermal shock with XFEM

Abstract Under pressurized thermal shock (PTS), the structure integrity of reactor pressure vessel (RPV) meets a potential challenge. The vicinity of inlet nozzle is the weak link and hazardous area of the vessel. Once crack initiation occurs here, the stress concentration around the crack tip would lead to plastic deformation, crack propagation, and even the failure of the whole structure. Based on ABAQUS, the beltline region around the inlet nozzle was modeled to calculate the response of the transient temperature field and stress strain field. In order to demonstrate the ultimate bearing capacity of the RPV with the critical crack sizes, the dynamic process of crack propagation was simulated with the XFEM. Through the quantitative analysis of the Mises stress and circumferential stress through the wall thickness, the crack propagation paths in different directions were confirmed. The above analysis and calculation provide an important reference for the safety and reliability assessment of RPV.

Effects of central column aspect ratio on seismic performances of subway station structures

The subway station structures have a contradiction in its design of the cross section of the central columns: larger aspect ratio increases the longitudinal traffic capacity, yet decreases the lateral seismic capacity. However, both capacities are important. Thus, finding a reasonable aspect ratio has become a significant problem to be studied in depth. In this article, a series of time history analyses are carried out on a typical two-story three-span subway station structure, and ultimate bearing capacity analysis of isolated columns of various sizes is performed. The static axial compression ratio (ranging from 0.13 to 0.68) and the aspect ratio (ranging from 0.04 to 26.67) are taken as parameters, and their influence on internal force and damage to the structure are explored. It is found that the increase in axial compression ratio of the columns increases both the compression and tension damage and reduces the seismic performance of the station structure. However, the influence of increasing the aspect ratio of columns on the seismic performance of structures is more complicated. The compression and tension damage rises first (ranging from 0.04 to 1.67) and then decreases (greater than 6.67), while the tension damage of the structure increases monotonously. Finally, (0.15, 0.6) is given as the recommended aspect ratio range.

Incorporated Strength Capacity Technique for Limit Load Evaluation of Trusses and Framed Structures under Constant Loading

AbstractTo overcome the difficulties encountered by the elastic modulus adjustment procedures applied to the ultimate bearing capacity analysis of framed structures under combined action of both constant and varying live loads, an efficient incorporated strength capacity technique is proposed in this work. A new structural analysis model is developed with totally different distributions of loads and resistance from the original model by incorporating the constant load effects into the sectional strength capacity of components in framed structures. The element bearing ratio (EBR) is defined according to the modified structural model on the basis of the generalized yield function of spatial beam element. The uniformity of the EBR is presented in terms of the EBR distribution characteristics, on the basis of which the reference EBR (REBR) is defined as a dynamic threshold to identify the highly stressed elements with the EBR greater than the REBR. Subsequently, an adaptive strategy of elastic modulus adjustm...

Ultimate bearing capacity analysis of strip footings on reinforced soil foundation

Reinforced soil foundations (RSFs) have been employed in engineering practice to increase the soil bearing capacity and to reduce the potential footing settlement. The aim of this study is to develop analytical solutions for estimating the ultimate bearing capacity of strip footings on RSFs. A general failure mode for RSFs was first proposed based on previous studies conducted by the authors and test results from literature study. A limit equilibrium stability analysis of RSFs was performed based on the proposed failure mechanism. New bearing capacity formulas, which consider both the confinement and the membrane effects of reinforcements on the increase in ultimate bearing capacity, were then developed for strip footings on RSFs. Several special cases of RSFs were presented and discussed. The proposed model was verified by the experimental data reported in the published literature. The predicted ultimate bearing capacity was in good agreement with the results of model tests reported in the literature. The study showed that the depth of the punching shear failure zone (DP) depends on the relative strength of the reinforced soil layer and the underlying unreinforced soil layer, and is directly related to the reinforced ratio (Rr).

Ultimate Bearing Capacity Analysis of Oblique Beam System Supported by Knee Brace

This article established the oblique beam system supported by knee brace in portal frame by using finite element software ANSYS. We analysed the ultimate bearing capacity of the system, and discussed the effects of purlin stiffness and knee brace layout on the bearing capacity of the structure. Preliminary analysis shows that, increasing the number of knee brace or improving purlin stiffness can improve ultimate bearing capacity of the system.

Stochastic analysis of ultimate bearing capacity of strip footing considering spatial variability of undrained shear strength

Stochastic analysis of ultimate bearing capacity of strip footing considering spatial variability of undrained shear strength

Analysis of Ultimate Bearing Capacity of Shallow Circular Foundation

AbstractThis study derives the equation for the bearing capacity of shallow circular foundation on the basis of the upper bound theorem of limit analysis method. The equation is derived by considering the work of soil weight and by assuming that the foundation failure mode obeys Prandtl sliding mechanism, which consists of ABC, ADE rigid body, and ACD logarithmic spiral deformable—body. Using the equation, we determine the internal energy dissipation rate, gravity work, energy dissipation rate of overlaying soil, the total power of the force are obtained respectively. The solution for ultimate bearing capacity has been realized by analyzing the external power and internal energy dissipation rate of the soil under unrestricted plastic flow. The results calculated in this study are found to be higher than those reported in previous references. However, the error between the measured value and calculated value is in the range of 20%. The analytical solution deduced in this study can be used as a reference fo...

Nonlinear Finite Element Analysis of the Ultimate Bearing Capacity of the Arch Plate Based on the ABAQUS

In this paper, nonlinear analysis of arch plate ultimate bearing capacity and the process of nonlinear ultimate failure were conducted by ABAQUS finite element software. The numerical failure simulation of steels, arch plate under different external loads and the separation of concrete as well as the whole slippage of concrete were operated. A reference for the further design calculations of reinforced concrete arch plate structure is provided as well.

The Ultimate Bearing Capacity Analysis of RC Beams Strengthened by Externally Bonded and Anchored I-Section Steel

At first, mechanical behaviour and failure pattern are analyzed in the condition of full bond (with no relative deformation) with I-section and RC beam, and influence of unloading degree in this text, the theory formula of bearing capacity correspondence to failure pattern is erected, the appropriate simple calculate in engineering employ are submitted. In the condition of large the initial reinforcement ratio and the advice is given that strengthening by externally bonded and anchored I-section steel is avoided. Besides, in the condition of considering of bold-slid, the formula of interface stress is erected. Base on the relative slipping effect, the theory formula of additional moment that is derivable from slid action, and the influence of the thickness of glue, unloading degree the ratio of I-section steel to additional moment is discussed.