Analysis of imperfections in the interfloor joints of prefabricated reinforced concrete columns of multi-storey frame buildings
Students Name: Hladyshev Roman Dmytrovych
Qualification Level: master (ESP)
Speciality: Building and Civil Engineering
Institute: Institute of Civil Engineering and Building Systems
Mode of Study: full
Academic Year: 2020-2021 н.р.
Language of Defence: ukrainian
Abstract: Hladyshev R.D., Demchyna B.H. (supervisor). Analysis of imperfections in the interfloor joints of prefabricated reinforced concrete columns of multi-storey frame buildings. Master’s thesis. – Lviv Politechnic National University, Lviv, 2021. Extended abstract. In reinforced concrete construction, the use of column joints by welding their reinforcement outlets has been one of the most common methods of rigid horizontal joint joints between columns since 1978. Therefore, this type of connection is classified as a responsible structural element. First of all, the bearing capacity, rigidity, reliability and durability of reinforced concrete structures of prefabricated columns within the frame depend on its efficiency. Interfloor joints of prefabricated reinforced concrete columns, within multi-storey frame buildings, are elements that are responsible for ensuring the structural safety of the frame building as a whole, and their defects can lead to the failure of both individual structures and the whole building. These data are necessary to consider the design situation, within which, according to verified calculations, should take into account a set of conditions to ensure the reliability of the structure, in this case the joints of prefabricated columns of multi-storey industrial buildings. The set of conditions means the allowable dimensions of the actual deviations of the elements in the structures of the joints of prefabricated columns from the standard [2] or design solutions. In the recommendations [1, 2] and examples of joint calculations based on regulations [3, 4], which were in force at the time of design of the surveyed buildings, the limit and intermediate values of deviations from the vertical reinforcement in the joints of precast concrete columns took into account. All authors [5, 6], who record defects in the joints of columns, argue that such joints require additional verification calculations. But they do not offer methods for calculating the impact of these defects on the actual bearing capacity of the joints, except for their continuous reinforcement by external embraces of various types. The study of defects of interfloor joints of columns of multi-storey industrial frame buildings is an urgent task due to the fact that current regulations [7, 8] do not allow to take into account the features of design deviations - manufacturing and installation defects in column joints, which differ significantly from ideal standard [9] solutions and exceed the allowable standard deviations. When developing projects for the reconstruction of multi-storey prefabricated buildings, it is necessary to revise the joints of prefabricated reinforced concrete columns to collect the necessary data of imperfections. Statistical processing of this data will make it possible to determine the range of changes in the recorded imperfections. The analysis of their range of changes according to the developed check calculations will give the chance to define influence of the revealed imperfections on character of work of joints. Verified calculations of joints for the current effort provide guarantees for the adoption of appropriate design decisions to ensure the required load-bearing capacity. The object of the study is the reinforcement and other imperfections in the horizontal joints of precast concrete columns within the multi-storey frame frames of old industrial buildings. The scope of research is the state of horizontal joints in the structures of prefabricated reinforced concrete columns in the frame frames of industrial buildings after their long-term operation to ensure the reliability of the joints in the implementation of building reconstruction projects. The purpose of research: Fixation in the course of inspection of defects in the executed standard interfloor joints of prefabricated reinforced concrete columns of the existing frame multi-storey industrial buildings. Analysis of the developed test calculations of the impact of the identified imperfections on the nature of the joints. Analysis of reserves of bearing capacity of joints for making constructive decisions on strengthening of defective elements in joints, joints, columns or making constructive decisions of increase of rigidity of elements of a framework. Briefly put research results: The technique is developed and measurements of deviations of axes of reinforcing releases from vertical planes and other imperfections in interfloor joints of prefabricated reinforced concrete columns in multistory frame frameworks of buildings, at their inspection are executed. The actual geometric calculated spatial schemes of the general deviations from vertical planes of armature releases within the inspected joints of columns are constructed. The statistical analysis of the data received as a result of measurements is executed. The comparison of actual deviations with their normalized tolerances is performed. 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