Square-Section Tube-Concrete Structures Studying Under Axial Compression Both with Spiral Reinforcement of the Concrete Core and Without Reinforcement

The article contains a research methodology and the experiments results on samples of square-section tube-concrete structures, both with spiral reinforcement of the concrete core, and without reinforcement, which perceive a short-term compressive load. The aim was studying the strength and features of the stress–strain state of square-section tube-concrete structures samples, made of concrete of classes B40 and B80, taking into account their flexibility. The experimental part of the work was carried out using modern equipment and devices certified and metrologically certified. Probabilistic-statistical calculation methods were used to process the array of experimental data obtained. According to the requirements of the current regulatory documents, before the tests, the measurement error assessment by the tensoresistive method was carried out. The features of force resistance revealed in experiments testify to the operation of a concrete core and a steel tube under conditions of a volumetric stress state. The deformation nature of the steel tube suggests that its walls experience not only compression in the axial direction. Stretching and bending of the walls from the lateral pressure of the concrete core is also observed. Thus, the tube contribution to the perception of the force Nuexp is significantly less than it would be in the assumption of its operation in uniaxial compression. It indicates a noticeably greater contribution of concrete to the perception of the force Nuexp in comparison with the conditions of uniaxial compression. The main conclusion of the experiments follows from it. It is advisable to increase the strength of square-section tube-concrete structures by using high-strength concrete and providing more effective indirect reinforcement for it. The power resistance features of square-section tube-concrete structures revealed in the experiments must be taken into account when calculating their strength.