Improvement directions of technical regulations in the field of reinforced cellular concrete structures

Abstract

Effective management of real estate complexes, which determines the rational capital intensity of ownership of buildings and structures, largely depends on the consumer qualities of building materials and products included in the investment and construction project at the design stage. The implementation of the principles of rational design, which are regulated in unique and technically complex and responsible structures, is still not properly reflected in the design of second-class objects of responsibility, which, however, make up more than 70% of the capital intensity of the construction market, mainly housing. Complex composite materials that combine innovative and energy-efficient components and technologies, as well as structures made from them that contain significant reserves of load-bearing capacity, which are opened and implemented by improving design standards and rational technical solutions, have the greatest potential for rationalization. Reinforced cellular concrete, which effectively combines load-bearing and enclosing functions, is one of the most popular construction technologies in the perspective practice of low-rise construction. Currently, however, the design of reinforced structures made of cellular concrete in Russia, abroad, mainly performed according to the normative documents, often not taking into account the significant differences in physical and mechanical properties, material structure, principles and working mechanisms of various types of concrete under load, as well as the uniqueness of plastic properties of cellular concrete when assigning the form and composition of discrete reinforcement. In this regard, there is a need to revise and systematize existing standards that contain requirements for the design of directly reinforced structures made of cellular concrete, generalize European experience and these standards, update information in them, as well as develop modern national standards in this area. In addition, the practice of designing bent cellular concrete structures has revealed a significant reserve for increasing the load-bearing capacity of these elements, associated with insufficient inclusion of the material of the traditionally used rod reinforcement due to the primary destruction of the contact layer (pulling the reinforcement). In order to increase the durability and reduce the resource intensity of national cellular concrete structures, the adopted methodology for their design needs to improve both the regulations that establish the principles and rules for calculating reinforcement elements of structures, and structural elements used in precast and in-situ practice of discrete reinforcement.

Theoretical Justification of Increasing the Efficiency of Reinforcement of Flexible Cellular Concrete Structures

“…Правила проектирования и строительства», СП 63.13330.2018 и СП 351.1325800.2017. Прочностные и деформативные свойства ячеистого бетона задавались трехлинейной диаграммой с начальным модулем деформации Eb = 1300 МПа, прочностями бетона Rb,n = 1,4 МПа (Rb = 0,95 МПа) и Rbt,n = 0,22 МПа (Rbt = 0,09 МПа), коэффициентом ползучести b,cr = 3,9 (для бетонов класса ниже В10), относительными деформациями бетона при продолжительном действии нагрузки при сжатии (1) и при растяжении (2). b1 = 0,6Rb/Eb, (1) b1 = 0,0021, b0 = 0,0034,b2 = 0,0048, b1 = 0,6Rbt/Eb, (2) b1 = 0,0002, b0 = 0,00024,b2 = 0,00031.…”

“…6. Продольные усилия в стержневых элементах балки, армированной ими, составили 4,6 кН растяжения/сжатия, что при площади арматурного стержня d10 As = 79 мм 2 Выводы. Результаты численного эксперимента исследования параметров напряженно-деформированного состояния моделей армированных ячеистобетонных балок прямоугольного сечения армированных инновационной ленточной арматурой, позволяют установить не менее, чем двукратно более равномерное и эффективное распределение напряжений в бетоне у ленточных арматурных элементов, существенно меньшую опасность продергивания арматуры, и, как следствие, большую включенность арматуры в работу балки на предельных нагрузках, обеспечивающей ей большую несущую способность по обоим группам предельных состояний [13].…”