Undermined areas as a factor influencing on the forces of ferroconcrete elements of a wireframe building

Abstract

Objective. To investigate the influence of base pliability on the distribution of additional forces in ferroconcrete elements of the wireframe buildings from a  ground deformation on the undermined areas. The usage of reinforced concrete in almost all areas of construction has taken a vast scale. This is due to its durability, the ability to make extensive use of local construction materials, and to apply profit-proved constructions with low consumption of the metal. Tecnique. The accounting algorithm is based on the basement prototyping of the core elements with the rigid characteristics, depending on the stiffness factor of the base. Stiffness characteristics of the bar section, which simulate the buildings' constructions were made in accordance with educational supplies and were not changed in the accounting process. The accounting was performed using the software package LIRA based on the finite element method. The accountings were performed on the main (constant + temporary + wind left) and a special combination of loads (undermining impact). Results. The application to the descent of the base rigidity can be used in combination with the application to stiffening of the constructive building elements or additional elements, which allow to take the undermining forces, e.g. in combination with tie elements and distance bars. The amplification of a basement suppleness is efficient to effect by applying self-regulating foundations with limited rainfall by maximum allowable value.  In a view of this the essential base stiffness decline may occur through the formation under the bottom of a self-regulating sole foundations of temporary, local sliding areas  of the soil. Scientific novelty. An improved method of wireframe buildings accounting on undermined areas, unlike the previous ones, which were based only on a linear accountings. The practical significance. The usage of the non-linear accounting method will allow to account the ferroconcrete elements of wireframe buildings more accurate. Additional forces in the fabric elements from the undermining influence  may be substantially higher than the forces of the main load combinations, and lead to the destruction and loss of stability of individual structures as well as buildings in general. Maximum further efforts from the undermining effects will appear mainly from the horizontal ground deformation. The maximum additional bending moments and transversal forces arise in end columns and beams of the first floor and the maximum axial forces in the secondary beams of the first and second floors.