Prediction of the Remaining Service Life of Reinforced Concrete Structures

The main indicators of durability, which characterize the time of operation of the structure before the onset of an emergency condition, are the total service life and the remaining service life, the determination of which allows a more reasonable approach to the issue of planning current or major repairs in the building. The most common engineering techniques that allow predicting the remaining service life for reinforced concrete structures are considered: according to standard terms and analogous objects, according to external signs, based on changes in reserve coefficients and strength criteria. Their modifications are given for a number of techniques. Based on the results of the analysis of the methods, their main advantages and disadvantages were established. As a proposal to improve the existing approaches, a methodology is proposed in which the interval between visual examinations is taken for the remaining period of operation

Improving the Regulatory Framework for the Standardization of Precast Concrete Structures

The article considers the structure of regulatory documents for precast reinforced concrete structures. The directions of development of the regulatory framework by updating and developing standards (GOST and GOST R) for certain types of precast reinforced concrete structures are given. It is noted that the purpose of the development and updating of standards is to establish current technical requirements for precast reinforced concrete structures, due to changes in the regulatory framework for the design of reinforced concrete structures, in particular in SP 63.13330.2018 "SNiP 52-01-2003 Concrete and reinforced concrete structures. The main provisions", and the improvement of technological requirements. In recent years, JSC "Tsniipromzdaniy" has developed and updated more than 20 standards (GOST and GOST R) only by the Department of Structural Systems No. 1, in which a number of new provisions have been adjusted and developed based on the analysis of domestic and foreign regulatory framework, modern manufacturing and installation technologies. It is advisable to develop standards for individual structures taking into account the requirements given in the fundamental GOST 13015-2012 "Concrete and reinforced concrete products for construction. General technical requirements. Rules of acceptance, marking, transportation and storage". The structure of the standard standard for precast reinforced concrete structures is considered

Development of a Stress Sensor for Solids

The paper presents the results of experimental design of a cortex of the embedded stress sensor, which allows to determine stresses in the cross-section of large-scale laboratory monolithic structures made on the basis of mineral and polymer binders (concrete, gypsum, etc.). The objectives of the design were to develop a constructive solution of the stress sensor housing based on strain gauges, which has small dimensions, low manufacturing cost, as well as high resolution and stability of readings over the entire sensitivity area (stress up to 400 kgf/cm2).The stress sensor allows to determine the stress in laboratory structures with high accuracy, without significantly affecting the stress-strain state of the section at different stages of operation of the structural element

Landscape and selection of vaccine epitopes in SARS-CoV-2

Background: Early in the pandemic, we designed a SARS-CoV-2 peptide vaccine containing epitope regions optimized for concurrent B cell, CD4+ T cell, and CD8+ T cell stimulation. The rationale for this design was to drive both humoral and cellular immunity with high specificity while avoiding undesired effects such as antibody-dependent enhancement (ADE). Methods: We explored the set of computationally predicted SARS-CoV-2 HLA-I and HLA-II ligands, examining protein source, concurrent human/murine coverage, and population coverage. Beyond MHC affinity, T cell vaccine candidates were further refined by predicted immunogenicity, sequence conservation, source protein abundance, and coverage of high frequency HLA alleles. B cell epitope regions were chosen from linear epitope mapping studies of convalescent patient serum, followed by filtering for surface accessibility, sequence conservation, spatial localization near functional domains of the spike glycoprotein, and avoidance of glycosylation sites. Results: From 58 initial candidates, three B cell epitope regions were identified. From 3730 (MHC-I) and 5045 (MHC-II) candidate ligands, 292 CD8+ and 284 CD4+ T cell epitopes were identified. By combining these B cell and T cell analyses, as well as a manufacturability heuristic, we proposed a set of 22 SARS-CoV-2 vaccine peptides for use in subsequent murine studies. We curated a dataset of ~ 1000 observed T cell epitopes from convalescent COVID-19 patients across eight studies, showing 8/15 recurrent epitope regions to overlap with at least one of our candidate peptides. Of the 22 candidate vaccine peptides, 16 (n = 10 T cell epitope optimized; n = 6 B cell epitope optimized) were manually selected to decrease their degree of sequence overlap and then synthesized. The immunogenicity of the synthesized vaccine peptides was validated using ELISpot and ELISA following murine vaccination. Strong T cell responses were observed in 7/10 T cell epitope optimized peptides following vaccination. Humoral responses were deficient, likely due to the unrestricted conformational space inhabited by linear vaccine peptides. Conclusions: Overall, we find our selection process and vaccine formulation to be appropriate for identifying T cell epitopes and eliciting T cell responses against those epitopes. Further studies are needed to optimize prediction and induction of B cell responses, as well as study the protective capacity of predicted T and B cell epitopes