Papers by Keyword: Unified Strength Theory

Abstract: In order to make the new composite wall structure the group developed to adapt different regional natural conditions, and along with the demand of gradually in-depth study the damage characteristics of the new composite wall, need to research the mechanical properties of the wall filling materials. In this paper, the ZG-CSS Electronic Universal Testing Machine was used on the uniaxial compressive test of the three blocks(the mud billet block, the cotton stalk block, the recycled EPS lightweight concrete block), to analyze the failure characteristics of the blocks and the other mechanical properties, such as Poisson’s ratio, elastic modulus, then the full compressive stress-strain curves are given, and at last fitting the mathematical expression of the uniaxial compressive stress - strain curves. And this paper also gives the yield criterion based on the unified strength theory of the three ecological filling blocks.

Abstract: The ultimate load calculation formula for the solid multi barrel tube-confined concrete columns (CHS inner and SHS outer) was derived based on the Unified Strength Theory (UST) in this paper. The influence of intermediate principal stress and the double restriction effect and the decrease of longitudinal stress were considered in the formula. Based on the axial compression load and consider the eccentricity ratio and slenderness ratio, by introducing the reduction factor of concrete strength and the equivalent restriction reduction factor, based on unified strength theory solutions of thick tube, combined with concrete filled skin tube unified theory, deduce the calculation formula of eccentric compression bearing capacity of concrete filled steel tubular columns and analysis the influence complication.

Abstract: New progress of research and applications of CFRP at home and abroad are introduced in this paper. The circular concrete-filled tubular CFRP-steel stub column under axial loads is studied based on the unified strength theory in the paper. The effect of intermediate principal stress on the ultimate strength for the concrete-filled tubular CFRP-steel stub column have been investigated. The ultimate load calculation formula for the concrete-filled tubular CFRP-steel stub column is derived in this paper, and can be simplified for cases without CFRP. Compared with the solution obtained in this paper and the experimental results, the good agreement can be found. The effects of the intermediate shear stress, the cross-section deformation ratio and also the inner friction angle of the concrete are all considered in the theory analysis. The analysis result further tests the applicability of the unified strength theory in the field of concrete-filled CFRP-steel tube. It has an important theory value for engineering application.

Abstract: Aiming at the specific concrete filled square steel tubular short column stiffened with PBL under axial compression load, considering about the useful effect of the PBL shear connectors, the mechanical behavior of PBL stiffening ribs was analyzed. Through the analysis of the effective restriction-area and ineffective restriction-area of core-concrete, introduce into the effective constraint coefficient of concrete. The ultimate bearing capacity was deduced based on the unified strength theory, with some influencing factors analyzed as well. Compared with the test results in relevant documents, they coincided well with each other. The result shows that the formula which is deducted from the unified strength theory has good applicability and the solution will show its positive impact in the related fields.

Abstract: The plastic ultimate moment of concrete-filled steel tubular and the ultimate displacement of the simply supported beam under uniformly distributed load is established based on unified strength theory. Considered nonlinear impact of mass and stiffness changed in the process of the reaction, the dynamic response of concrete-filled steel tubular columns under blast load were analyzed by the equivalent single degree of freedom model and step by step integration method. Compared the results of this method with relevant literatures, the consequence is good. It can be seen that from the results, this method was satisfied for the requirement of the analytical precision, it can be referred for the research and the safety of concrete-filled steel tubular columns under blast load.

Abstract: Based on the mechanism of punching shear and patterns of failure of Specimen,using the unified strength theory and rigid-plastic models,the punching strength of reinforced concrete slabs supported on four sides is obtained.The theoretical formula of punching shear strength for concrete slab is given.The calculated results are in good agreement with the experimental results.

Abstract: Based on the compaction effect of the gravel pile, the thick-walled tube model is established. Considering the gravel pile and pile materials with different properties of tension and compression of soil pile in the process of expansion, the influence of intermediate principal stress to improving the bearing capacity of foundation in the process of expansion, we use the planar axisymmetric double shear unified strength theory and present a gravel pile ultimate bearing capacity of single pile composite foundation unified expression. The theory study of gravel pile composite foundation and engineering practice has a certain guiding significance.

Abstract: In the ultimate bearing capacity formulas, the factor N_γ has not been given a definite expression, so the calculation diagrams are not serious and the hypothesis can’t match the reality. Most of the ultimate bearing capacity factors are received from the results of Prandtl theory, but the theoretic models they used are not the same. And most of the ultimate bearing capacity theories are based on Mohr-Coulomb theory, the effects of intermediate principle stress are ignored. To solve these problems, according to ultimate balance theory and unified strength theory, the analytical formulas of ultimate bearing capacity and N_γ are received when foundation is completely smooth. The results show that the ultimate bearing capacity will increase when considering the effects of intermediate principle stress and the formulas from practical experiences can make the ultimate bearing capacity unsteady.

Abstract: Based on the unified solution of shear strength in terms of double stress state variables for unsaturated soils, the unified formula of stability coefficient for unsaturated soil slopes under the plane strain condition is derived by Sweden slice method, which considers the effect of the intermediate principal stress rationally. Combining with engineering example, the proposed formula is compared with the one that is on the basis of Fredlund unsaturated soil theory and the influencing characteristics of factors including intermediate principal stress, matric suction, effective internal friction angle and matric suction angle is obtained. The research result indicates that: intermediate principal stress and matric suction have obvious impacts on the stability coefficient for unsaturated soil slopes; the stability coefficient has been increasing with the increase of unified strength theory parameter and matric suction, which proves that the consideration of intermediate principal stress and matric suction can make slopes give full play to their self-stabilities and strength potential, and the yield criterion has great impact on the judgment of slope stability; the stability coefficient also increases nonlinearly with the increase of effective internal friction angle and matric suction angle. The proposed unified formula of stability coefficient for unsaturated soil slopes enjoys a wider application. The stability coefficient for unsaturated soil slopes according to the Fredlund unsaturated soil theory and that for saturated soil slopes are just the special cases. The research result can provide theoretical basis for stability analysis and reinforce design of the unsaturated soil slopes, and it is of great significance to the slope management.

Abstract: With consideration of the intermediate principal stress,the calculation formula of bearing capacity of RPC filled steel tube columns under axial compression is deduced based on the twin shear unified strength theory. Combining with the bond-slip theory,new ultimate bearing capacity formula is derived with the highest regard for bond stress. Compared with the theoretical result and the experimental data,good agreement can be found. The results show that unified strength theory and the bond-slip theory are versatile in theoretical analysis of the column. The analysis results can be provided for the optimum design of RPC filled steel tube and the solution has an important practical value for engineering application.