Mechanical safety of reinforced concrete structures at all stages of the life cycle

Ensuring the mechanical safety of operated buildings at all stages of the life cycle is an urgent task. This is especially important when planning major repairs and reconstruction in buildings, as well as determining the period of safe operation from the moment of the survey, i.e. clarification of the remaining service life. The total service life at the design stage is set by the customer and the general designer in accordance with the recommendations of GOST 27751-2014 «Reliability for constructions and foundations. General principles». Mechanical safety and durability are ensured when calculating structures using the limit state method, assigning protection measures depending on the operating conditions, as well as complying with the requirements of SP 255.1325800.2016 «Buildings and structures. Operating rules. General Provisions». A method for preliminary assessment of the mechanical safety of buildings and their structures is proposed for consideration, which eliminates some of the shortcomings of existing methods for calculating the residual life by physical wear (damage) of building structures based on the results of a visual inspection, the basis of which is the dependence of the allowable safe operation period on the percentage of reduced bearing capacity. It is proposed to use the results of a visual inspection performed in accordance with GOST 31937-2011 «Buildings and constructions. Rules of inspection and monitoring of the technical condition»

Mechanical safety of reinforced concrete structures at all stages of the life cycle

Ensuring the mechanical safety of operated buildings at all stages of the life cycle is an urgent task. This is especially important when planning major repairs and reconstruction in buildings, as well as determining the period of safe operation from the moment of the survey, i.e. clarification of the remaining service life. The total service life at the design stage is set by the customer and the general designer in accordance with the recommendations of GOST 27751-2014 «Reliability for constructions and foundations. General principles». Mechanical safety and durability are ensured when calculating structures using the limit state method, assigning protection measures depending on the operating conditions, as well as complying with the requirements of SP 255.1325800.2016 «Buildings and structures. Operating rules. General Provisions». A method for preliminary assessment of the mechanical safety of buildings and their structures is proposed for consideration, which eliminates some of the shortcomings of existing methods for calculating the residual life by physical wear (damage) of building structures based on the results of a visual inspection, the basis of which is the dependence of the allowable safe operation period on the percentage of reduced bearing capacity. It is proposed to use the results of a visual inspection performed in accordance with GOST 31937-2011 «Buildings and constructions. Rules of inspection and monitoring of the technical condition»

Selectively Initiated Ship-In-A-Bottle Assembly of Yolk–Shell Nanostructures

Yolk–shell nanostructures, or nanorattles, are created by growing metal nanoparticles exclusively inside hollow porous polymer nanocapsules. Metal ions enter the nanocapsules through size-selective nanopores. Synthesis of metal nanoparticles is initiated by an agent entrapped in nanocapsules. Tannic acid, β-cyclodextrin, and polyether dendrimer were used as sacrificial molecules for initiation and growth of gold nanoparticles. If needed, initiator molecules can be fragmented by acid hydrolysis and removed from nanocapsules. Variations in reaction conditions yield encapsulated nanoparticles with different size and shape. Further functionalization of nanorattles forms encapsulated core–shell nanoparticles

Controlled Permeability in Porous Polymer Nanocapsules Enabling Size- and Charge-Selective SERS Nanoprobes

Nanoprobes for surface-enhanced Raman scattering (SERS) were prepared by creating nanorattles, or yolk−shell structures, containing gold or silver nanoparticles entrapped in porous hollow polymer nanocapsules. Controlled permeability of the shells of nanocapsules, achieved by controlling the pore size and/or shell surface functionalization, resulted in size- and charge-selective SERS analyses. For example, a trace amount of phenanthroline, a model analyte, was detected in human blood plasma without preprocessing of plasma samples. Comparison with commercially available nanoparticles showed superior performance of the newly prepared nanorattle structures

Facile directed assembly of hollow polymer nanocapsules within spontaneously formed catanionic surfactant vesicles

Surfactant vesicles containing monomers in the interior of the bilayer were used to template hollow polymer nanocapsules. This study investigated the formation of surfactant/monomer assemblies by two loading methods, concurrent loading and diffusion loading. The assembly process and the resulting aggregates were investigated with dynamic light scattering, small angle neutron scattering, and small-angle X-ray scattering. Acrylic monomers formed vesicles with a mixture of cationic and anionic surfactants in a broad range of surfactant ratios. Regions with predominant formation of vesicles were broader for compositions containing acrylic monomers compared with blank surfactants. This observation supports the stabilization of the vesicular structure by acrylic monomers. Diffusion loading produced monomer-loaded vesicles unless vesicles were composed from surfactants at the ratios close to the boundary of a vesicular phase region on a phase diagram. Both concurrent-loaded and diffusion-loaded surfactant/monomer vesicles produced hollow polymer nanocapsules upon the polymerization of monomers in the bilayer followed by removal of surfactant scaffolds. © 2013 American Chemical Society