Probabilistic expression of the function of the change in prestressing force of timber elements depending on climatic conditions in situ

Today demand for sustainability forces us to use an ever-increasing share of renewable materials in construction and the associated increase in their mechanical resistance is related to this. The application of transverse prestress in timber structures will increase the overall stiffness and load-bearing capacity of the structural system. However, the prestressing force and subsequent rectification of the system depends on the relative environmental conditions for the specific location of the construction site. The climatic conditions have a significant impact on changes in the size of the prestressing force. Into the experimental sample, transverse prestressed was introduced by means of prestressing elements. The values of prestressing force and climatic conditions to which the sample was exposed were monitored and recorded. Based on experimentally obtained data, mathematical models were created and evaluated using methods such as principal component method and cross-validation method. The result of the analysis is the function for determining changes in the size of the prestressing force over time depending on the climatic conditions. Using this function, it is possible to determine the time when it is necessary to manually increase the amount of preload in the structure so that it correctly fulfils the purpose for which it was designed.