Thermal Stressed State in Massive Concrete Structures in the Winter Building Period

Abstract

Abstract. The article deals with issues of the thermal cracking resistance in massive concrete and reinforced concrete structures during the building period. The paper gives the calculation results of thermal stressed state in massive foundation slabs with different time organization of the thermal protection. It was found that the thermal crack resistance is fully guaranteed when the insulation is installed immediately after concrete has been placed or it has been placed with short delay. The delay can be allowed if the relative tensile strain of the concrete does not exceed the tensility limit. The acceptable delay ranges from 8 to 30% of time it takes to reach the maximum temperature in the concrete block. The surface insulation installation at the time of the temperature peak inevitably leads to the formation and development of cracks.

Mathematical modeling of temperature fields and concrete strength during winter concreting of building structures

“…By analogy with (17) we write: +1/3 = −1, , −1, , +1/3 + −1, , , −1, +2/3 = , −1, , −1, +2/3 + , −1, , , −1 +1 = , , −1 , , +1 + , , −1 (18) Solving together the corresponding equations (17) and 18, we find: After substitution the corresponding expressions (19) into (14), (15) and (16) we have:…”

“…An important task is to provide the thermal stress state of the structure, in which no destructive processes occur in concrete. The recommendations of the Russian and foreign researchers [7][8][9][10][11][12][13][14][15][16] on this issue are insufficiently justified and present restrictions on temperature variations within the cross section of the structure, which are difficult to implement practically. To prevent unacceptable thermal stresses in concrete during its heat treatment one must avoid its overheating or underheating.…”

Phased evacuation algorithm for high–rise buildings

“…Such buildings are subject to special requirements for ensuring fire safety, especially in terms of the construction material quality control and the organization of effective evacuation measures [1][2][3][4]. Particular attention is also paid to space-planning solutions [5], the flame effects on the structures operation [6][7][8][9] and the need for additional fire protection [10][11][12][13][14][15]. The evacuation process analysis from high-rise buildings considers the space of streams crossing between descending people the stairs and people leaving the floor as one of the most problematic areas [16].…”

Increase of fire resistance of reinforced concrete structures with polypropylene microfiber

“…Therefore, in the number of emergency influences [6] fire effects arising from a fire must be included. For example, the fire effect significantly changes the parameters of creep of concrete [7], thermo-stressed state in massive concrete structures in a fire is equivalent to that arising during setting of concrete [8], which causes cracks formations. In this way, the design of fire protection is a mandatory requirement in the design of structures [9][10][11].…”