Methods for assessing the impact of partial restraint of hollow core slabs in platform joints on the strength of standard slab cross-sections

Introduction. Currently, hollow core slabs are widely used in large-panel construction, including slabs of formwork-free shaping. Structurally, the presence of voids in slabs has both advantages and disadvantages. One of the drawbacks of hollow precast elements in slabs consists in the reduced load-bearing capacity of the support section compared to solid slabs. This issue is most pronounced when considering the effect of partial restraint in the support zone of the slab in platform joints in large-panel buildings. According to the current design standards for large-panel buildings (SP 335.1325800.2017), the strength of support sections under partial restraint depends on the value of the elastoplastic moment, which is determined empirically and requires verification. The value of the support moment under partial restraint also requires verification due to some current theoretical grounds suggesting its underestimation. Therefore, it seems reasonable to analyze existing approaches to calculating the impact of partial restraint of hollow core slabs on the strength of support sections in platform joints in large-panel buildings and, if necessary, to conduct additional experimental and numerical studies on this issue. Aim. To analyze the current practice of designing nodes of large-panel buildings using hollow-core slabs, as well as the available experimental studies of the bearing capacity of platform joints with various structural solutions. Materials and methods. The analysis was conducted by reviewing Russian and foreign regulatory and technical documentation, as well as publicly available results of experimental studies. Results. The authors have systematized the data on existing methodologies for assessing the strength of hollow core slabs in platform joints in large-panel buildings. Conclusions. The study analyzed existing methodologies for calculating the strength of hollow core slabs considering their partial restraint in platform joints in large-panel buildings. The authors examined methodologies adopted in Russian and foreign regulatory documents, as well as experimental studies on the topic. The analysis indicated that current calculation methods may neglect the main factors affecting the load-bearing capacity of support sections in joints in large-panel buildings and require further development. Additional research aimed at analyzing the stress-strain state of support sections of hollow core slabs with partial restraint in platform joints will be instrumental in developing a refined physical multifactor model of joint behavior and optimizing structural solutions in certain cases.