ANALYSIS OF THE STRESS-STRAIN STATE OF THE JOINT OPERATION OF THE SPAN STRUCTURE OF THE BRIDGE AND THE CEMENT-CONCRETE COATING OF THE CARRIAGEWAY, TAKING INTO ACCOUNT LONG-TERM PROCESSES

Abstract

Introduction. The statement of the problem, the relevance of the chosen topic, an analysis of the latest research, and the purpose and tasks of the work are outlined. Taking into account the effect of shrinkage and creep of concrete nowadays is a mandatory component calculation of reinforced concrete bridge structures. In prestressed structures, the main part prestressing losses are losses caused by shrinkage and creep of concrete. According to the current norms [1], in prestressed reinforced concrete structures of bridges, losses from concrete creep are taken into account only from the action of prestressing forces. In fact, the creep of concrete should be taken into account from the long-term action of the first and second part of the constant load and shrinkage of concrete. A methodology for determining the stress-strain state of a reinforced concrete beam of a span structure of a bridge, taking into account long-term processes, is proposed. The results. In the presentation main material of the study, a methodology for calculating the stress-strain state reinforced concrete beam span structure of the bridge is proposed, taking into account the shrinkage and creep of concrete. The formulas used to determine the stress in concrete and reinforcement at an arbitrary moment of time t are given. The results study operation temperature-unbroken reinforced concrete beam span structure of the road bridge according to the scheme 3x21.0 m, taking into account the long-term processes according to the given methodology, were analyzed. Conclusions. The proposed method of calculating the reinforced concrete beam span structure of the bridge taking into account the shrinkage and creep of concrete under the action of the bending moment M and the normal force N is based on the apparatus construction mechanics of elastic systems and can be used for the calculation of other building structures. The study work temperature-unbroken reinforced concrete span structure of the bridge made of i-like prestressed beams according to the 21.0+21.0+21.0 m scheme showed that the stress from the creep concrete from the action prestressing forces of the reinforcement in relation to the initial stresses are from 23% to 30%. The stress from concrete shrinkage in relation to the allowable calculated values was from 2% to 6.5%.