Reliability of multi-story buildings with load-bearing structures of cast reinforced concrete during the construction period

Abstract

Reinforced concrete is considered to be one of the most reliable structural materials. For this reason, it is widely used for mass construction of buildings and structures in Russia and other countries. In particular, reinforced concrete is predominantly used in the construction of multi-story buildings of any design in all Russian regions at any time of the year. Improvements in technologies, construction management and mechanical aids increase the industrialization of construction. Although this fact is generally regarded as extremely positive, it reduces the time allowed for concrete to gain the required strength characteristics. Sometimes, loads from upper structures of buildings are applied to fresh, immature concrete. Obviously, specific technical decisions are required to intensify the concrete hardening process and create favorable temperature and humidity conditions for its curing. Russian science and practical experience have a large arsenal of effective technical means for solving these problems. However, these means are reluctantly applied in practice, since this entails a rise in construction costs, even though slight. This creates a situation when unacceptable loads from the higher floors are applied to the lower floors of the building. The structures perceive static loads rather than dynamic ones, including seismic loads, with an inertial mass of tens of tons, thereby causing a risky situation at the site. This happens en masse. The problem is even more complicated in winter time. During the period of concrete thawing in spring, the entire facility can be classified as being in a metastable state. The paper considers the production circumstances associated with the above situations and proposes recommendations for their prevention.