# Prediction of Thermal Cracking During Construction of Massive Monolithic Structures
## 4 Conclusions  
The three-dimensional calculation model has been proposed and software has been developed to predict the risk of thermal cracking during the construction of massive monolithic reinforced concrete structures. This model takes into account the dependence of the concrete elastic modulus and strength on the time and temperature of hardening. The developed program also has the possibility to take into account the shrinkage deformations of concrete. Verification of the developed software was performed using the example of calculating the massive monolithic dock wall, for which we had the data from field surveys. For the special case when the concrete elastic modulus does not change over time, a comparison was made with the calculation results in the ANSYS software package. The greatest discrepancy in the results for maximum stresses was 2.5%. It has been established that the final thermal stress values are most significantly influenced by how the elastic modulus of concrete changed during the early period of hardening. Most of the existing dependencies give reliable results at the age of concrete of at least 1-3 days. To improve the calculation of the thermal stress state at the construction stage, further studies of the change in the deformation characteristics of concrete at the age of up to 3 days are necessary. For the considered example of the dock wall, the maximum tensile stresses exceed the tensile strength of concrete regardless of the used dependence of  
Figure 15: Comparison of experimental stress values with calculation results. the elastic modulus on time. Thus, cracking is inevitable, which is confirmed by the results of field surveys. The authors' solution is compared with the results of calculation using a simplified method, when the finite element analysis is initially performed with a constant elastic modulus over time, and then the stresses are recalculated to true ones. The discrepancy between the results for maximum stresses is 8%. An analysis was made of the possibility to reduce the probability of early cracking during the construction of a massive monolithic dock wall. The following methods were considered: reducing the length of the concrete block, regulating the heat exchange parameters on the surfaces, and reducing the heat release of concrete. Reducing the block length by 2 times leads to a decrease in maximum stresses by 45%. When the block length is reduced by 4 times compared to the original, the maximum stresses are reduced by 1.8 times. Reducing heat transfer coefficients on wall surfaces by insulating does not lead to a reduction in maximum stresses. Reduction in the heat release of concrete results in an approximately proportional reduction in maximum stresses. The authors' methodology was validated by comparison with experimental data for a massive monolithic foundation slab. When specifying the dependence of the elastic modulus of concrete according to one of the options, good agreement with the experimental data was observed at the moment from the occurrence of tensile stresses to the formation of a crack. The proposed model is only suitable for estimating the probability of cracking, since concrete in this model is taken as a linearly elastic material with time-dependent elastic modulus. Further research may be aimed at developing non-linear models that will allow tracking changes in the stress-strain state after crack formation. Conceptualization, A.C. and V.A. ; methodology, A.C.; software, V.T. ; validation, A.C. and V.A. ; formal analysis, A.C.; investigation, A.C.; resources, V.A. ; data curation, V.T. ; writing--original draft preparation, A.C.; writing--review and editing, V.T. ; visualization, A.C.; supervision, A.C.; project administration, A.C.; funding acquisition, A.C. All authors have read and agreed to the published version of the manuscript. This research received no external funding. Not applicable. The study did not report any data.