The paper presents the original concept of description and analysis of buildings (wall and floor structures), corresponding to the natural components of construction, quasi finite elements (QWSFS). This concept constitutes one of the component of the developed, interactive model of deep foundation buildings. The presented modelling method enables a significant reduction of the number of unknowns, which in the case of interaction building – subsoil, gives a possibility of including the factual geometry and building development stiffness into the FEM model. Therefore the true representation of static operation of the objects can be analysed. The paper gives basic assumptions to the construction of the QWSF-superelements as well as the results of numerical tests conducted. The potential of using the developed modelling concept in the analysis of the structural elements and deep foundation problems, in a three-dimensional system: subsoil – new building – potential neighbouring building development (at each stage of erection of investment, using a structural statics stage analysis) was presented.

Buckling restrained brace is an important structure for improving the seismic resistance of structures. Conducting research on new types of buckling restrained brace can improve the seismic performance and reliability of buckling resistant support. Four different types of buckling restrained braces specimens were designed and manufactured: cross-shaped square steel pipe members, cross-shaped round steel pipe members, cross-shaped carbon fiber members, and in-line carbon fiber members. By conducting quasi-static tests, the force displacement hysteresis curves, skeleton curves, stiffness degradation, equivalent viscous damping coefficient, and energy dissipation ratio of four different types of buckling restrained brace were analyzed. The research results showed that all four buckling restrained brace specimens have good hysteresis performance. The load-bearing capacity and energy consumption performance of the three specimens of square steel pipe, round steel pipe and carbon fiber with the same core unit are the same, but the inline type is worse than the cross type. The core unit specimen with a width of 80 mm is about 60% higher in bearing capacity and energy consumption than a specimen with a width of 50 mm. The core unit of some specimens undergoes multi-wave buckling. For carbon fiber specimens, the CFRP is prone to breakage due to the lateral thrust of the restraining unit. Therefore, steel hoop or stirrup should be added to the end to improve the restraint effect when designing and manufacturing.