MODELING THE THERMAL STRESS STATE OF THE FOUNDATION AND DEVELOPMENT OF MEASURES

The modeling of the thermal stress state of the foundation slab of the building of a general educational institution is considered. The performed calculations took into account the occurrence of stresses as a result of heating of the concrete mass during cement hydration. To simulate the thermal stress state, the specialized Midas Fea software package is used. At control points, diagrams of changes in temperatures, stresses, and crack formation coefficients depending on the periods of curing are obtained. The isopoles of temperature distribution and crack formation coefficients over the volume of the studied array were obtained. Measures have been developed to improve the operational properties of concrete, including engineering and technical recommendations to reduce the negative impact of temperature differences on the manufacturing process of concrete mixtures and foundations.

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MODELING OF TEMPERATURE STRESSES IN THE FOUNDATION SLABS OF A BUILDING

Modeling of systems and processes ◽

10.12737/2219-0767-2020-13-1-54-60 ◽

2020 ◽

Vol 13 (1) ◽

pp. 54-60

Author(s):

Sergey Korablin ◽

S. Nikolenko ◽

Svetlana Sazonova

Keyword(s):

Thermal Stress ◽

Stress State ◽

Educational Institution ◽

Concrete Surface ◽

Institution Building ◽

Thermal Stress State ◽

Temperature Stresses ◽

Foundation Slab ◽

Equivalent Age ◽

Destructive Processes

Computer modeling of the thermal stress state of a concrete foundation slab of an educational institution building is considered. To simulate the thermal stress state, the specialized Midas Fea software package is used. The actual tensile stresses in concrete are compared with the maximum allowable values taking into account the equivalent age. It was established that the likelihood of cracking due to sudden changes in temperature is high, which entails the likelihood of destructive processes in concrete. Based on the calculations and modeling of temperature processes in concrete, it is proposed to use surface thermal insulation or to reduce the initial temperature of the concrete mixture in order to reduce the heat transfer rate of the concrete surface.

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The problem of temperature cracking in concrete gravity dams

Vestnik MGSU ◽

10.22227/1997-0935.2020.3.380-398 ◽

2020 ◽

pp. 380-398

Author(s):

Nikolay A. Aniskin ◽

Nguyen Trong Chuc

Keyword(s):

Thermal Stress ◽

Stress State ◽

Crack Formation ◽

Thermal Cracking ◽

Mass Concrete ◽

Thermal Stress State ◽

Research Projects ◽

Thermal Crack ◽

Gravity Dams ◽

Concrete Gravity Dams

Introduction. The concreting of solid structures, such as concrete dams, bridge constructions, foundations of buildings and structures, is accompanied by exothermic heating, caused by cement hydration. Heat, emitted by mass concrete blocks, slowly leaves constructions. A substantial temperature difference frequently arises between the solid concrete centre and its surface. If this temperature difference reaches a critical value, thermal cracking occurs, which destroys structural continuity. Temperature problems and those associated with thermal stress state should be resolved to pre-assess and prevent potential cracking. This problem has enjoyed the attention of specialists, and it has been the subject of numerous research projects. Materials and methods. The overview is based on the information about implemented research projects focused on the thermal cracking of mass concrete dams and its prevention. Computer modeling techniques were applied to develop a mathematical model capable of projecting and assessing the potential cracking of mass concrete. Results. The co-authors have compiled an overview of advanced approaches to the assessment of potential thermal crack formation, contemporary problem-solving methods and selected research findings obtained using the finite element method. The co-authors offer a thermal behaviour/thermal stress state projection methodology for solid concrete, as well as a thermal crack formation assessment methodology. Conclusions. The thermal cracking problem has not been solved yet. The proposed methodology and a projection-oriented numerical model can be used as a reference by civil engineers in the process of designing and constructing concrete gravity dams. It may help to reduce cracking probability caused by heat evolution in cement.

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