Concrete heat liberation in thermal stressed state analysis

This paper presents the results of numerical studies of the temperature regime and the thermal stressed state of the reinforced concrete wall of the nuclear power plant foundation block during the construction period with continuous concreting at full height. Calculations were done both using the dependence of the change in heat liberation over time on the hardening temperature, according to the theory of I.D. Zaporozhets, as well as the experimental data. It is established that if Zaporozhets equation is used in calculations, the correction of heat release values should be performed in the first 45 hours of concrete hardening. In order to correct the theoretical values of the specific heat, the last one should be multiplied by the correction factor. The dependence of the factor on the time within the range of 4 to 45 hours is approximated with sufficient accuracy by the obtained fifth degree polynomial. The crack resistance of the structure was determined using a deformation criterion, taking into account the change in the ultimate elongation of concrete over time. In this particular case of concreting a structure it is shown that when the correction function is introduced into the calculation program there is no need to use thermal insulation. The direct economic effect, as well as the indirect one associated with the decrease in the construction period, allow avoiding the rise of the construction costs. It is proposed to use the developed methodology in practical calculations of thermal crack resistance of massive concrete and reinforced concrete structures during the construction period

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements