Огнестойкость железобетонной конструкции с деформационным швом при знакопеременных нагрузках
Authors: Prusakov Vasily , Gravit Marina , Pekhotikov Andrey , Pavlov Vladimir 
Published: April 2020

Правильное проектирование, устройство и монтаж деформационных швов дают возможность обеспечить длительный срок службы основных несущих и ограждающих конструкций зданий, а также элементов внутренней и внешней отделки. Огнестойкие заполнения устанавливают для компенсации возможных изменений ширины шва от первоначальной ширины в горизонтальные и вертикальные деформационные швы монолитных и сборных железобетонных конструкций зданий и сооружений различного назначения, а также в зазоры между торцом вертикальных стен и межэтажных перекрытий. Для защиты деформационных швов в конструкциях зданий и сооружений от воздействия пожара применяются огнестойкие заделки. В европейских нормативных документах такие противопожарные барьеры специально разрабатываются для применения в деформационных швах и работают при сжатии, растяжении и сдвиге шва. В России изделия и материалы, выполняющие функцию противопожарного барьера, не испытываются в условиях знакопеременной нагрузки. В статье приведена методика испытаний на огнестойкость для деформационного шва в железобетонной конструкции. Получены результаты по параметрам целостности и теплоизолирующей способности для железобетонных плит с последующим в сторону увеличения ширины зазора между плитами и сдвига их относительно друг друга на +25 % составляет не менее 245 мин.

Buildings and structures of complex architectural forms and large extent are subject to deformations under the influence of fluctuations in the temperature of the outside air, uneven sedimentation of the soil base, seismic phenomena and other causes. To prevent cracks in bearing and fencing structures, expansion joints are provided that cut the building into compartments. Proper design, construction and execution of expansion joints are of great importance in construction, as they provide the opportunity to provide long service life and fire resistance of the main load-bearing and enclosing structures of buildings, internal and external finishes. Normative requirements for the device and technical parameters of fire protection of expansion joints do not currently exist, and since the expansion joints are elements of load-bearing and enclosing structures, their fire resistance is determined in conjunction with the rest of the elements of fire protection barriers, use and application is regulated by the norms of Russian federal legislation. To increase the overall fire resistance of the construction, special fire barriers are used, which are installed inside the expansion joints. The article presents an overview of the fire barriers of expansion joints of both foreign and domestic producers. It is shown that for the protection of expansion joints in a fire, fire barriers are used, specially designed for use in expansion joints, which are guaranteed to work with compression, stretching and shear. It has been established that the production of innovative fire-retardant materials is one of the main tasks of fire safety. This is also the way of the consistent transformation of the idea into a product that passes through the stages of research, design development, production and realization in civil and industrial buildings. It is necessary to choose a comprehensive solution that ensures the maximum satisfaction of the requirements when performing fire protection work to protect the expansion joint when exposed to a fire. The authors declare that the structures (products) intended for fire protection of the expansion joint should provide a stable own mechanical tensile strength of at least 40%; at least 50% compression; for a shift of not less than 20%, the retention of elastic properties at the manufacturer’s declared maximum tensile-compressive stress per product of not less than 100 cycles. After the test, the structure (article) should not have mechanical damages and deformation of the filler, as well as the manufacturer’s declared fire resistance tested with at least 20% expansion from the design width of the expansion joint. When using other fillers for the fire barrier, it is recommended that the above requirements should be met using material that provides deformation characteristics, both in the compression of the joint and during its stretching, and in the shear, during the entire period of the intended use. Particular attention should be paid to the technology of interfacing the structures (products) of fire barriers when they are installed in expansion joints along the entire length, which is guaranteed to prevent the appearance of technological gaps and voids.