With sufficient reserves of the strength of the skeleton, it is advisable to use the simplest and economical type of superstructure without changing the structural scheme, t. e. building the building. This type of superstructure allows you to increase the volume and useful area of the building without a device of new foundations. With insufficient bearing capacity of individual elements of the skeleton, it is necessary to study the possibility of transferring additional load to underloaded elements of the existing building. Indicators of the efficiency and complexity of such superstructures with a changing constructive scheme can be comparable with similar indicators of the above -mentioned protozoa.
If you change the constructive scheme is impossible or inappropriate, it is necessary to strengthen overloaded elements. Strengthening both aboveground structures and foundations significantly complicates the production of work, increases the cost of superstructures and can reduce the advantages of superstructures to zero. An alternative in these conditions may be superstructures on independent supports that do not transfer the load on the existing building, t. e. Not loading superstructures. Structural solutions of non -loading superstructures. The supporting skeleton of non -loading superstructures has one characteristic feature – the presence of an intermediate element between the superstructure itself and the foundations. According to the functional purpose, the supporting structures of superstructures can be divided into three main groups: the upper part of the skeleton, which includes all the supporting structures that are located above the existing building; intended for direct perception of the payload; supporting aboveground structures in the form of columns or racks exceeding the height of the existing building are used to transfer the load from the upper part of the skeleton to the foundations and through them to the base; foundations placed, as usual, below ground level. Thus, the main difference in the design schemes of loading (traditional) superstructures and non -loading (on independent supports) can be noted; Traditional superstructures have only the first group of supporting elements, t. e. the upper part of the skeleton; non -loading have all three groups of supporting elements.