scholarly journals Assessment of structural reliability of precast concrete buildings

2018 ◽  
Vol 143 ◽  
pp. 01001
Author(s):  
Alexandr Koyankin ◽  
Valeriy Mitasov
Keyword(s):  
Structural Reliability ◽  
Precast Concrete ◽  
Rapid Development ◽  
Objective Assessment ◽  
Experimental Studies ◽  
Full Scale ◽  
Building Structures ◽  
Numerical Studies ◽  
Floor Slabs ◽  
Precast Buildings

Precast housing construction is currently being under rapid development, however, reliability of building structures made from precast reinforced concrete cannot be assessed rationally due to insufficient research data on that subject. In this regard, experimental and numerical studies were conducted to assess structural reliability of precast buildings as described in the given paper. Experimental studies of full-scale and model samples were conducted; numerical studies were held based on finite element models using “Lira” software. The objects under study included fragment of flooring of a building under construction, full-size fragment of flooring, full-scale models of precast cross-beams-to-columns joints and joints between hollow-core floor slabs and precast and cast-in-place cross-beams. Conducted research enabled to perform an objective assessment of structural reliability of precast buildings.

scholarly journals INFLUENCE OF FIRE PARTITIONS FOR SPEED FIRE DISTRIBUTION IN CLOSED PREMISES OF PRODUCTION AND STORAGE FACILITIES

Fire Safety ◽  
2021 ◽  
Vol 37 ◽  
pp. 44-51
Author(s):  
E. Hulida ◽  
V. Sharуу
Keyword(s):  
Fire Protection ◽  
Rapid Development ◽  
Research Work ◽  
Experimental Studies ◽  
Fire Spread ◽  
Building Structures ◽  
Fire Load ◽  
The Impact ◽  
And Storage ◽  
Storage Facilities

Introduction. Fires in closed premises of production and storage facilities are the most dangerous, because they hold large areas with a significant fire load. The current direction of providing a fire safety system at production and storage facilities in closed premises is to eliminate the conditions of the rapid development of fire and minimizing its effect through the use of fire curtains. This method of fire protection is practically not used in closed premises of production and storage facilities at the present stage. In most cases, fire partitions are used in such situations. Therefore, a topic issue today is the research of limiting the development of fires with the use of fire partitions and minimizing fire effects.Purpose. Investigate the process of spreading the fire in closed premises of production and storage facilities by using fire partitions to limit the speed of fire spread. Problem statement and solution. The following tasks must be solved to provide fire protection of production and storage facilities:1. to investigate the process of fire spread in closed premises of production and storage facilities without the use of fire partitions;2. to investigate the impact of fire partitions use on fire rate.Two possible modes of development fire in the premises are considered to solve the first problem: 1) with the presence of sufficient air (oxygen), with fire occurred in regulated fire load; 2) with insufficient air (oxygen), with fire occurred in regulated ventilation.It is necessary to choose the material and fire partition design accordingly to solve the second problem. The results of experimental studies [11] showed that fire partitions vermiculite-silicate plates can be used for various building structures manufacturing. Closed production and storage facilities structure analysis showed that these premises are constructed in most cases with a grid of columns 9Х12 m.Conclusions and proposals:1) There is only the first mode of fire with sufficient oxygen (air) in closed premises of production and storage facilities with a total area of more than 5000 m2 in the process of fire. The fire that occurred is regulated only by the fire load.2) The use of fire partitions between sections of the premises of production and storage facilities reduces the probability of fire spreading in the premises by about 3 times.3) It is necessary to continue research work in this direction to obtain more significant results of the process of development and spread of fire in the premises of production and storage facilities.

scholarly journals Experimental study of the operation of the bolt joint of a bearerwith a column in precast-monolithic ceiling

Vestnik MGSU ◽  
2015 ◽  
pp. 27-35
Author(s):  
Aleksandr Aleksandrovich Koyankin ◽  
Valeriy Mikhaylovich Mitasov
Keyword(s):  
Experimental Data ◽  
Experimental Study ◽  
Crack Resistance ◽  
Strain State ◽  
Structural Reliability ◽  
Objective Assessment ◽  
Wide Distribution ◽  
Experimental Investigations ◽  
Building Structures ◽  
The Given

Precast-monolithic construction is becoming an increasingly popular form of housing. The wide distribution of this type of construction is explained by the possibility to successfully combine the advantages of precast and monolithic construction, at the same time reducing their disadvantages. Though there is a significant lack of data, including experimental data, for objective assessment of the stress-strain state of precast-monolithic floor structures. In order to investigate the structural reliability of the bolt joint of a bearer with a column in a precast-monolithic building a series of experimental investigations were carried out in the laboratory of testing the building structures of the Siberian Federal University.One of the main conclusions is that the bolt joint of a bearer with a column is characterized by sufficient rigidity, crack resistance and bearing capacity. The results of the given work have proved the data obtained in previously conducted investigations on a fragment of a precast-monolithic ceiling.

Bearing Capacity of Restored and Strengthened Reinforced Concrete Floor Slabs

2020 ◽  
pp. 21-27
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
High Efficiency ◽  
Raw Materials ◽  
Experimental Studies ◽  
Building Structures ◽  
Concrete Floor ◽  
Reinforced Concrete Slabs ◽  
Floor Slabs ◽  
External Reinforcement

The influence of various repair compositions on the bearing capacity of restored and strengthened floor slabs modeling flat reinforced concrete floor slabs of communication collectors is considered. Industrial brands of repair compositions based on cement binder, repair compositions containing quartz sand and mixing water after treatment with low-temperature non-equilibrium plasma, and materials for external reinforcement of building structures were used. It is shown that industrial repair compositions based on cement and repair compositions based on modified raw materials restore the bearing capacity of model floor slabs in almost the same way. In this case, the destruction of floor slabs occurs on the repair composition. It was established that the external reinforcement of reinforced concrete slabs restored with repair compositions using carbon mesh or tape significantly increases their bearing capacity. The high efficiency of the use of epoxy polymer composite materials for the repair and strengthening of reinforced concrete structures of various functional purposes is confirmed by the results of verification calculations of the initial and model floor slabs, as well as conducted experimental studies.

Innovative Construction Technology with High Factory Readiness from the Chuvash Republic

2020 ◽  
pp. 29-35
Author(s):  
V.A. SHEMBAKOV ◽  
Keyword(s):  
High Speed ◽  
Load Capacity ◽  
Precast Concrete ◽  
Construction Materials ◽  
Engineering Industry ◽  
Housing Construction ◽  
Building Structures ◽  
Construction Technology ◽  
Floor Slabs ◽  
Large Panel

The technology that fully meets the modern requirements of the market in the Russian Federation is presented – stand technology of precast-monolithic frame and large-panel housing construction with the use of floor slabs with pre-stressing up to 8 m, both solid and caisson versions on universal stands. This technology, which combines the best solutions of prefabricated, monolithic, panel, brick and other construction technologies, competes with the latest Western developments. The advantages of the proposed technology are as follows: high factory readiness and quality, versatility and architectural expressiveness of building structures (97% of the frame), precast building; energy savings – consumption is three times less compared to existing technologies for the production of reinforced concrete products; material savings (1.5 times less than for monolithic and panel housing construction); high speed of construction (up to 5 ths. m2 of prefabricated monolithic frame per month for one tower crane; lower weight of bearing structures compared to other structures (0.146 m3 of precast concrete per 1 m2 of the total area of the building) and, as a result, lower costs for foundations and the use of mechanisms with a lower load capacity on construction sites; reliable erection without welding; usable area – more than 80% of the total area; free planning solutions; quick adjustment of equipment for the production of products necessary for the market at a given time. The bench technology of precast-monolithic frame and large-panel housing construction with the use of floor slabs with pre-stressing up to 8 m is an example of the implementation of inter-industry cooperation in the construction materials and mechanical engineering industry based on Russian scientific developments and adapted modern foreign technologies. Keywords: innovations, construction technology with high factory readiness, modernization of large-panel housing construction and construction industry plants, industrial housing construction, prefabricated monolithic frame, energy efficiency, construction speed.

scholarly journals Modeling damaged precast structural system when its robustness check

2021 ◽  
pp. 63-81
Author(s):  
Viktar TUR ◽  
Andrei TUR ◽  
Aliaksandr LIZAHUB
Keyword(s):  
Progressive Collapse ◽  
Precast Concrete ◽  
Experimental Studies ◽  
Resistance Mechanisms ◽  
Calculation Model ◽  
Dynamic Resistance ◽  
Building Structures ◽  
Structural System ◽  
Non Linear ◽  
Central Column

Within the framework of traditional approaches to checking for resistance of reinforced concrete buildings and structures to the progressive collapse development, membrane (chain) forces in a damaged structural system are calculated separately, without considering its non-linear bending behavior during the formation of the plastic hinges and without checking the possibility of achieving large deflections.The authors propose an approach to modelling a nonlinear quasi-static reaction of a damaged structural system in an accidental design situation. This approach considers non-linear bending and the resistance of reserved horizontal ties, considering their ultimate ductility. The authors verified the proposed approach based on the results of experimental studies by others researchers.An example of the application of the proposed approach in assessing the robustness of a structural system made of precast concrete with a sudden removal of the central column is considered. In accordance with the provisions of the energy approach, an analysis is made of the contribution of individual resistance mechanisms to the total quasi-static and dynamic resistance of the damaged structural system.We show that the proposed calculation model adequately describes the behavior of a damaged structural system in an accidental design situation, and therefore to carry out parametric studies and check the robustness of building structures.

Computational and experimental studies of the strength of full-scale samples of pipes with defects "metal loss" and "dent with groove"

2020 ◽  
Vol 10 (3) ◽  
pp. 226-233
Author(s):  
Dmitry A. Neganov ◽  
◽  
Victor M. Varshitsky ◽  
Andrey A. Belkin ◽  
◽  
...  
Keyword(s):  
Internal Pressure ◽  
Experimental Studies ◽  
Full Scale ◽  
The Other ◽  
Metal Loss ◽  
Calculation Methods ◽  
Reliable Operation ◽  
Sufficient Stability ◽  
Comparative Results ◽  
The Moment

The article contains the comparative results of the experimental and calculated research of the strength of a pipeline with such defects as “metal loss” and “dent with groove”. Two coils with diameter of 820 mm and the thickness of 9 mm of 19G steel were used for full-scale pipe sample production. One of the coils was intentionally damaged by machining, which resulted in “metal loss” defect, the other one was dented (by press machine) and got groove mark (by chisel). The testing of pipe samples was performed by applying static internal pressure to the moment of collapse. The calculation of deterioration pressure was carried out with the use of national and foreign methodical approaches. The calculated values of collapsing pressure for the pipe with loss of metal mainly coincided with the calculation experiment results based on Russian method and ASME B31G. In case of pipe with dent and groove the calculated value of collapsing pressure demonstrated greater coincidence with Russian method and to a lesser extent with API 579/ASME FFS-1. In whole, all calculation methods demonstrate sufficient stability of results, which provides reliable operation of pipelines with defects.

Assessment of the volume activity of α-radioactive wastes on surface and specific contamination by portable γ-spectrometry method

2020 ◽  
pp. 468-473
Author(s):  
I. P. Korenkov ◽  
A. I. Ermakov ◽  
A. B. Mayzik ◽  
T. N. Laschenova ◽  
V. N. Klochkov ◽  
...  
Keyword(s):  
Specific Activity ◽  
Experimental Studies ◽  
Germanium Detector ◽  
Low Energy ◽  
Gamma Ray Spectrometry ◽  
Building Structures ◽  
Germanium Detectors ◽  
Volume Activity ◽  
Β Decay ◽  
Γ Spectrometry

The aim of the study is to evaluate the volume activity of radioactive waste (RW) by surface and specific alpha contamination using portable gamma-spectrometry.Materials and methods. Methods of rapid assessment of the content of α-emitting radionuclides in solid waste of various morphologies using gamma-spectrometers based on germanium detectors are considered. Computational methods for determining the effectiveness of radionuclide registration are presented.Results. The possibility of using portable gamma-ray spectrometry to assess the surface and specific activity of various materials contaminated with α-emitters (232Th, 235U, 238U, 237Np, 239Pu, 240Pu and 241Am) is shown. The calculated values of the registration efficiency of low-energy gamma-emitters obtained by modeling the spatial-energy parameters of the detector are given.To simplify the solution of this problem, the calculation program used 20 standard templates of various geometries (rectangular, cylindrical, conical, spherical, etc.). The main sources of error in the survey of contaminated surfaces, largesized equipment and building structures were investigated.Conclusions. The possibilities of portable γ-spectrometry for estimating the volume of RW based on the surface density of contamination of materials with radionuclides of uranium and transuranic elements are investigated. When using γ-spectrometer with a high-purity germanium detector with a range of γ-quanta extended in the low-energy region, radionuclides such as 232Th, 235U,238U, 237Np, 241Am were determined by their own radiation or by the radiation of their daughter products.The “problem” element is plutonium, for rapid evaluation of which it is proposed, in accordance with the radionuclide vector methodology, to use 241Am, which accumulates during the β-decay of 241Pu.According to calculations, the most likely value of the activity ratio 239Pu/241Am for the object where the work was performed (scaling factor) varies in the range from 5.0 to 9.0.Based on the results of calculations and experimental studies, the parameters of the efficiency of registration of various α-emitting radionuclides by portable γ-spectrometers. It has been found that for germanium detectors with an absolute efficiency of registering a point source of 7÷15%, it is n×10–5÷n×10–4%.

scholarly journals Evaluation of the impact of compliance of precast discs of overlapping on the work of the frame of a multi-storey building

2019 ◽  
Vol 97 ◽  
pp. 04022
Author(s):  
Nikolay Trekin ◽  
Emil Kodysh ◽  
Alexander Bybka ◽  
Alexander Yamalov ◽  
Nikita Konkov
Keyword(s):  
Economic Performance ◽  
Computational Models ◽  
Precast Concrete ◽  
Building Frames ◽  
Frame Building ◽  
Numerical Studies ◽  
Frame Buildings ◽  
The Impact ◽  
Structural Solutions ◽  
Storey Building

The article provides an analysis and justification of the need to take into account the compliance of discs of overlapping and coatings when calculating frames from precast concrete structures. Previously conducted full-scale experiments showed that the rigidity of the precast overlapping with full filling of the seams, in comparison with the monolithic overlapping, decreases by 3-15 times due to the ductility of the joints. The use of refined computational models of structural solutions for frames, which take into account the compliance of the conjugations of elements, makes it possible to trace possible redistribution of efforts. Such an approach when reconstructing, it is possible to optimally select and calculate the enforcement of structure, and on new designing, to increase reliability and / or improve the economic performance of frame buildings. According to the results of analytical studies, formulas were adopted for the parameters that allow one to take into account the overall compliance of overlapping disks and coatings in computational models of building frames. Numerical studies on the computational model of a frame building made it possible to evaluate the effect of accounting for compliance on the stress-strain state of a multi-storey frame.

scholarly journals Experimental and Numerical Studies on the Structural Performance of a Double Composite Wall

2021 ◽  
Vol 11 (2) ◽  
pp. 506
Author(s):  
Sun-Jin Han ◽  
Inwook Heo ◽  
Jae-Hyun Kim ◽  
Kang Su Kim ◽  
Young-Hun Oh
Keyword(s):  
Shear Strength ◽  
Precast Concrete ◽  
Structural Performance ◽  
Behavioral Characteristics ◽  
Element Analysis ◽  
Numerical Studies ◽  
Shear Performance ◽  
Flexural Analysis ◽  
Composite Wall ◽  
Current Code

In this study, experiments and numerical analyses were carried out to examine the flexural and shear performance of a double composite wall (DCW) manufactured using a precast concrete (PC) method. One flexural specimen and three shear specimens were fabricated, and the effect of the bolts used for the assembly of the PC panels on the shear strength of the DCW was investigated. The failure mode, flexural and shear behavior, and composite behavior of the PC panel and cast-in-place (CIP) concrete were analyzed in detail, and the behavioral characteristics of the DCW were clearly identified by comparing the results of tests with those obtained from a non-linear flexural analysis and finite element analysis. Based on the test and analysis results, this study proposed a practical equation for reasonably estimating the shear strength of a DCW section composed of PC, CIP concrete, and bolts utilizing the current code equations.

scholarly journals The Cartis Form for the Seismic Vulnerability Assessment of Timber Large-Span Structures

Buildings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 45
Author(s):  
Beatrice Faggiano ◽  
Giacomo Iovane ◽  
Andrea Gaspari ◽  
Eric Fournely ◽  
AbdelHamid Bouchair ◽  
...  
Keyword(s):  
Seismic Vulnerability ◽  
Precast Concrete ◽  
Structural Type ◽  
General Description ◽  
Seismic Zone ◽  
Building Structures ◽  
Timber Structures ◽  
Recent Past ◽  
Seismic Vulnerability Assessment ◽  
Large Span

Italy is located in a very active seismic zone, and many earthquakes have marked the country, some of them in the recent past. In order to take adequate measures of seismic prevention and protection, in the last decades, the Italian Civil Protection Department (DPC) initiated a survey and introduced a specific form for the quick and/or post-seismic assessment of buildings. This is useful to obtain statistics on the types of structures and their vulnerability and a judgement on the damage, leading to a decision about the possibility of reuse and/or the level of retrofitting to be applied. Those activities have been developed since the beginning of 2000. This task is currently carried out by the Italian DPC-ReLUIS project research, line WP2 on the inventory of building structures, setting up the CARTIS form for any structural type, like masonry, reinforced concrete, precast concrete, steel, and timber structures, the latter being mainly related to large span buildings, extensively used in Italy. In this context, the paper presents the first draft of the CARTIS form for large span timber structures that provides a general description for typical structural schemes, through the singular points commonly considered as seismic structural vulnerabilities. Moreover, the statistics on timber large span structures based on a sample of 10 buildings is presented.

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