Method of calculating multi-storey buildings with account for the design model changes in different operating modes
The methods and techniques used to estimate calculations can give us quite an adequate prediction of stress-and-strain state of load-bearing structures of traditional buildings with simple architectural forms.Traditional calculation methods take the basic parameters of a designe model as constant: a set of elements of a model, their geometry and stiffness properties, external relations with the environment. Loads upon the model are also taken as constant. However, the creation of even relatively simple structures is not a single-stage process. Building is a multistage process, where one may single out separate stages of "closing" a local subsystem of a structure. Each of the operations determines a certain stage of the building process characterized by a definite design model that differs from the design model of a complete structure.Consideration of stagewise changes in the design model parameters is especially necessary in the process of designing high-rise buildings with reinforced concrete framing. The thing is that while constructing each floor the formwork is put in the position predetermined by the design, thus ignoring deformations of the lower structures. The calculation technology is based on the principles of stagewise change tracking in the basic parameters of the design model with the subsystem closing at each stage of construction. All the calculations are made presuming validity of common assumptions in the linear structural mechanics for each stage. Generally, that problem becomes non-linear at the expense of changing the design model in the course of transition from one stage to another. Typically, a special case of operating period begins after some time of normal operation. Hence, the stress-and-strain state of load-bearing structure system that appeared during the main operating period was an initial condition for the next stage of analysis. The problem of an accurate prediction of stress-and-strain state for buildings and structures during different operating periods may be solved only by applying a calculation technology based on the history of erecting, loading and deforming of load-bearing structures of a building. It is necessary to take into account the history of erecting, loading and deforming of the structure elements including variations in structural behavior of the elements during operational period.