Concrete members at bending strengthened by fibre-reinforced plastics

Рассмотрены конструктивные и технологические решения по усилению изгибаемых железобетонных конструкций композитными материалами на основе углеродного волокна. Выявлены используемые системы для усиления железобетонных конструкций. Проведен сравнительный анализ существующих систем усиления на основе углеродных волокон. Определена экономическая эффективность такого способа усиления для изгибаемых железобетонных элементов. Приведена методика расчета усиления изгибаемых железобетонных элементов композитными материалами. Произведен расчет усиления различными композитными материалами на примере железобетонных элементов: балка, монолитная плита перекрытия. Выполнено сравнение различных вариантов усилений и предложен коэффициент условной полезности, позволяющий экономически обосновать выбор способа усиления и прогнозировать стоимость усиления конструкции.Design and technological solutions for reinforcing of bending concrete structures with composite materials based on carbon fiber are considered. The used systems for strengthening reinforced concrete structures are re-vealed. A comparative analysis of existing reinforcement systems based on carbon fibers is carried out. The economic efficiency of this reinforcement method for bending concrete elements is determined. The calculation technique for bending concrete elements reinforced by composite materi-als is given. The calculation of reinforcement by various composite materials is made on the example of reinforced concrete elements: a beam and a monolithic floor slab. The comparison of various amplification variants is made and the conditional utility coefficient is proposed, which makes it possible to economically justify the choice of the gain method and to predict the cost of strengthening the structure

Observation of local electron states linked to the quasi-Fermi level

We report on the observation of semiconductor local electron states linked to the quasi-Fermi level and, consequently, not characterized by the defined position in the energy spectrum which is familiar for shallow and deep impurities. This type of local electron states have been found in the doped narrow-gap semiconductor Pb1−xSnxTe(In). The binding energy of these states is less than 10 meV providing photoresponse at the wavelengths exceeding 100 μm

Photoconductivity of PbTe:In films with variable microstructure

It is shown that the microstructure and features of formation of surface states in nanocrystalline and polycrystalline PbTe:In films most significantly affect the character of photoconductivity in the spectral range of 1–2.5 THz. We present the results of a study and comparative analysis of the character of conductivity of PbTe:In films in the temperature range from 4.2 to 300 K in a static mode and in variable electric fields with a frequency of up to 1 MHz with illumination with white light and under the effect of high-power terahertz laser pulses with a wavelength of up to 280 μm