Sliding installation method can be divided into two kinds: structural sliding method and supporting slip method.The construction characteristics of the two methods are described below.
Structure sliding method: the basic idea is to structure the overall (or local) at first for assembling site assembly molding, reused slip system as a whole a method of installation of the shift to design position.Adopt this technology of installation, assembling site and assembled with mechanical equipment can be concentrated in a relatively fixed venues, compared with in situ installation method, can reduce the temporary supporting measures and operation platform, dosage, saving the cost of ground handling and management.The key consideration is the difficulty of construction directly in the design position. For example, the construction site outside the field is limited, and the normal walking of the hoisting equipment can not be satisfied.The method of the basic elements is "the ascent method" in the ground assembly, counterforce support, overall ascension replacement for the lateral movement, so essentially the same as the ascending method.
At the same time, we should pay attention to the following points: the structural support is conducive to the laying of the sliding track, the length of the slip line is longer and the efficiency is higher.The sliding unit should be a geometric invariant system, which has sufficient rigidity and stability in the process of slippage, so as to minimize the resistance of sliding.When more traction to slip is used, to avoid structure in the process of sliding shift, traction synchronicity should be under control, if it is difficult to guarantee, should be fully calculated estimate the effects of the sliding unit due to traction of sync, temporary reinforcement for sliding unit when necessary.Sliding unit, before finally fixed structure exists in the direction of movement and its orthogonal direction "easily slip tendency, because unlike design support conditions, to prevent design (that is, the slip plane), the deformation of the countermeasures to prevent the" down "are necessary, such as near two side bearing set up since the balance of the rigid rod or flexible cable.
In addition, the structural slip method also includes two different processes: one is to slide and the other is accumulated slip.
Slide forward: a truss or a sliding unit consisting of a number of trusses from one end to the design position. Each sliding unit is connected at high altitude and directly forms the overall structure.
Accumulating sliding: the slip unit on the slippery course just slip a moving to design position (no), staying connected to the next unit slip again after a period of distance, so repeatedly, by nature, accumulate, until each common unit to design the position.
In general, in large span and space steel structure installation method, when unable to set up temporary support or use crane installation condition is bad, have a problem, namely direct position in building construction structure sliding method can be used as one of the solutions.
Slip method: supporting sliding method is in erection of supporting frame structure design group, to provide support to structure in situ installation and operation platform, for the part of the structure after the installation is complete, bearing structure slip that never put off till tomorrow what you can and has been shipped out.This creates the conditions for the in-situ installation of the adjacent structures, which loops until the structure completes the overall installation.Therefore, the supporting slip method can be summarized as "structural non-slip and supporting mechanism sliding", while the principle of structural sliding is "structural sliding and supporting mechanism is not slippery".When bearing sliding method is adopted, the design of the supporting frame in addition to satisfying the general overall and local stability, consider the level of dynamic load (starting and braking effect caused by the horizontal inertia force), add big brace when necessary to improve its lateral stiffness.To sum up, the supporting slip method can be used as one of the solutions when the surrounding environment is difficult to provide the structure of the site.It is worth noting that, whether the structural slip or the support slip method, its slip trajectory is not only regular linear translation, but also the curve slip is not uncommon, frequently applied in engineering practice.
Overall ascension installation method: the overall structure of the installation method of ascension is to be installed on the ground or appropriate floor projection position assembly molding, reuse "lift system" will be molding structure overall upward to the design elevation of a kind of installation method.When the large span steel structure is high, it is not conducive to the erection of supporting frame, and when the steel structure shape rule is raised, the overall improvement of the construction method can be used as one of the selection schemes.
Large span cantilever steel structure support free installation method: unsupported so-called long-span cantilever steel structure installation method, which is under the condition of not built for supporting institutions, with cantilever steel structure is based on the stiffness of the ontology, use of hoisting machinery for high-altitude bulk, installation, use gradually extend, phase installation process for the construction.Relative high in situ installation method, while the implementation method is also near the high altitude in situ installation, but because no temporary supporting institutions, less construction measures, construction technology is simple (no unloading).It is suitable for the structure with large rigidity, good stability and high height.By using this technique, influenced by gravity, cantilever segments will downwarping, resulting is component installation coordinates of the unknown, when it encounters the installation configuration there is a requirement or closure, in the process of the construction of the structure of the configuration control is one of the biggest technical challenge, upon the completion of this is directly related to the structure of the configuration can meet the requirements, as well as joining cantilever segments is success.
For large span steel structure building, high-altitude installed the original empty cell method, slip method and integral lifting method and large span cantilever support free installation method is one of the several typical and common construction methods, but must master its application condition and key technical points, in engineering practice, a reasonable choice.Especially in recent years, most projects have unique architectural modeling, which brings many difficulties to the construction, especially the installation work.Deep understanding of the engineering structure, and the load transfer path, familiar with engineering areas surrounding environmental conditions and project specific requirements, and the application of available resources and their own proprietary technology, adjust measures to local conditions to design the most appropriate, the installation of the new scheme, it is the pursuit of the highest state of construction technology.