Solutions Of Ultimate Bearing Capacity Research Articles

An Investigation on the Estimation Methods for the Equivalent Mohr-Coulomb Strength Parameters of Generalized Hoek-Brown Rock Mass

Many practical engineers are often accustomed to understanding the strength of the rock mass in terms of friction angle and cohesion. Therefore, it is necessary to provide a resonable tool implementing the Generalized Hoek-Brown (GHB) failure condition in the framework of the Mohr-Coulomb (M-C) criterion. In this study, the features of Lee (2015) and Hoek et al. (2002) methods for calculating the equivalent friction angle and cohesion of GHB rock masses were briefly reviewed. Subsequently, in order to compare the accuracy of the two methods, the ultimate bearing capacity of strip footing resting on the M-C rock mass was assessed by performing the 2D FE analysis incorporating the equivalent M-C strength constants from both approaches. The results show that Lee (2015)’s method, which exploits the upper bound solution of ultimate bearing capacity, is superior to that of Hoek et al. (2002)’s approach.

Study on Buckling of Two Kinds of Thin-Walled Steel Members with Imperfection

Based on Ježek method of computing the elastic-plastic buckling of the members under the axial compressive load and the bending moment, considering the initial imperfection, the analytical expressions of calculating the ultimate load of buckling about the neutral axis with the maximum moment of inertia for an H-shaped member and a square steel tube member are derived. Using the elastic-plastic finite element method and the theory of nonlinear buckling, the impact by initial geometric imperfections on the H-shaped steel member and the square steel tube member under the axial compressive load and the bending moment are analyzed and the numerical solutions of ultimate bearing capacity are obtained. By compared with the values of the finite element method (FEM), it shows that the analytical method in this paper is valid. The results of the example show that the presence of initial imperfections reduces the ultimate bearing capacity of the two kinds of steel members to a great extent. It is also found that the influence of the initial geometric imperfection on the ultimate bearing capacity of members is smaller when the bending moment increases.

Discussion on Application of Empirical Formulas for Ultimate Bearing Capacity

Terzaghi equation is widely used in practice to determine Ultimate Bearing Capacity (UBC). Recent research indicates that exact solution of UBC could be got with the slip line method if the soil is ideal elastic-plastic material. In this paper, dimensionless UBC is gained using ABC software based on the slip line method and is compared with that by Terzagh equation with based on empirical formula. It shows that error of UBC is caused by empirical formula. However, the accuracy of UBC relates to safety and economy of the engineering. Given empirical formulas have a wide application in practice, the scope of application of the four classic empirical formulas is discussed in different range of allowable error. The applicable scope of the four classic empirical formulas within the margin of error is discussed and the results can facilitate the application of classic empirical formulas in practice.

Theory Analysis on Buckling of a Square Steel Tube Member Strengthened by CFRP with the Initial Imperfection

Based on Ježek method of computing the elastic-plastic buckling of the member under the axial compressive load and the bending moment, considering the initial geometric imperfection, the analytical expressions of calculating the ultimate load of buckling about the neutral axis with the maximum moment of inertia for a square steel tube member with flange outsides wrapped by carbon fibre are derived. Using the elastic-plastic finite element method and the theory of nonlinear buckling, the impact of the initial geometric imperfection on the square steel tube steel member wrapped by carbon fibre under the axial compressive load and the bending moment are analyzed and the numerical solutions of ultimate bearing capacity are obtained. By compared with the values of the finite element method (FEM), it shows that the analytical method in this paper is valid. Compared the reinforced effect of the carbon fibrer to the perfection member with the defect member, we find that the former is higher than the latter. The results of the example also show that the presence of initial geometric imperfection reduces the ultimate bearing capacity of the steel member to a great extent. The influence of defect member gradually decreases when the given moment rises.

Buckling Analysis Method and Application of a Square Steel Tube Member with Initial Geometric Imperfection under Axial Compressive Load and Bending Moment

Based on Ježek method of computing the elastic-plastic buckling of the member under the axial compressive load and the bending moment, considering the initial imperfection, the analytical expressions of calculating the ultimate load of buckling about the neutral axis with the maximum moment of inertia for a square steel tube member are derived. Using the elastic-plastic finite element method and the theory of nonlinear buckling, the impact by initial geometric imperfections on the square steel tube member under the axial compressive load and the bending moment are analyzed and the numerical solutions of ultimate bearing capacity are obtained. By compared with the values of the finite element method (FEM), it shows that the analytical method in this paper is valid. The results of the example show that the presence of initial imperfections reduces the ultimate bearing capacity of the steel member to a great extent. It is also found that the influence of the initial geometric imperfection on the ultimate bearing capacity of member is smaller when the M increases.

Study on Buckling of an H-Shaped Steel Member with Initial Geometric Imperfection

Based on Ježek method of computing the elastic-plastic buckling of the member under the axial compressive load and the bending moment, considering the initial imperfection, the analytical expressions of calculating the ultimate load of buckling about the neutral axis with the maximum moment of inertia for an H-shaped member are derived. Using the elastic-plastic finite element method and the theory of nonlinear buckling, the impact by initial geometric imperfections on the H-shaped steel member under the axial compressive load and the bending moment are analyzed and the numerical solutions of ultimate bearing capacity are obtained. By compared with the values of the finite element method (FEM), it shows that the analytical method in this paper is valid. The results of the example show that the presence of initial imperfections reduces the ultimate bearing capacity of the steel member to a great extent. It is also found that the influence of the initial geometric imperfection on the ultimate bearing capacity of member is smaller when the bending moment increases.

Influence of the Initial Imperfection on the Buckling of Steel Member Wrapped by Carbon Fibre

Based on Ježek method of computing the elastic-plastic buckling of the member under the axial compressive load and the bending moment, considering the initial geometric imperfection, the analytical expressions of calculating the ultimate load of buckling about the neutral axis with the maximum moment of inertia for an H-shaped member with flange outsides wrapped by carbon fibre are derived. Using the elastic-plastic finite element method and the theory of nonlinear buckling, the impact of the initial geometric imperfection on the H-shaped steel member wrapped by carbon fibre under the axial compressive load and the bending moment are analyzed and the numerical solutions of ultimate bearing capacity are obtained. By compared with the values of the finite element method (FEM), it shows that the analytical method in this paper is valid. Compared the reinforced effect of the carbon fibrer to the perfection member with the defect member, we find that the former is higher than the latter. The results of the example also show that the presence of initial geometric imperfection reduces the ultimate bearing capacity of the steel member to a great extent. The influence of defect member gradually decreases when the given moment rises.