The paper presents the results of solving the problem of identifying the equivalent depth of the linkage of the frame -pile structural system. The computational model of the problem is a frame -pile structural system in the form of three-dimensional frame, linear elastic deformation, pile -soil link is replaced by a hard restraint (fixed) with equivalent restraint depth. The problem is solved by the method of penalty function to combine with the finite element method. Examples of numerical calculations show that models, algorithms and calculation programs can be trusted and acceptable.

The paper presents the method of the refined second-order plastic hinge analysis for planar steel frames subjected to dynamic loads. The material model used is the generalized Clough model in consideration of effects of axial and shear force on plastic limit state of cross-sections. Geometric nonlinearities of member and frame are taken into account by the use of stability functions in framed stiffness matrix formulation. Non-linear motional equation of structures was established by finite element method and solved by Newmark method combined with the modified Newton-Raphson method. Based on the obtained algorithms, the author has programmed a computational program and calculated the planar steel frames. From the calculated results, discussions and conclusions are presented.

This paper calculates the penetration depth of 85 mm projectile in concrete block B20 by Abaqus software, with the concrete in simplified concrete damage plasticity (SCDP) model. Comparing the results calculated by Abaqus software with the Berezan formula and the improved Petry formula to check the reliability of the computational model and material model. From there, studying the effect of projectile velocity on penetration depth in concrete B20.

This paper, with the simplified concrete damage plasticity (SCDP) model, studying the penetration depth of steel projectile in the concrete block by Abaqus software. Comparing the results calculated by Abaqus software with the Modified NDRC formula to check the reliability of the computational model and material model. From there, studying the effect of concrete strength on penetration depth in concrete B20, B30, B40, B50.

This paper studies a method to identify the elastic fixed stiffness of the frame structure. The model of the problem is three dimensionals structure, linear elastic deformation, pile - soil link is replaced by elastic fixed with stiffness. The problem will be solved by the penalty function method - the minimum of the objective function (which is the total squared error between the measured value and the calculated values particular) - combined with the finite element method. The numerical calculations show that the model, algorithm and calculation program are reliable. The program can be used to identify the elastic fixed stiffness of the frame structure in three dimensions, serving to determine the actual working state of the structure, to propose solutions for reinforcement, repairing, improving bearing capacity, prolonging the life of the structure.