Tracking modal parameters of building structures from experimental studies and earthquake response measurements

2017 ◽  
Vol 16 (5) ◽  
pp. 551-567 ◽  
Author(s):  
Jun-Da Chen ◽  
Chin-Hsiung Loh
Keyword(s):  
Experimental Studies ◽  
Modal Parameters ◽  
Earthquake Response ◽  
Building Structures

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%.

Adaptive multiple tuned mass dampers based on modal parameters for earthquake response reduction in multi-story buildings

2016 ◽  
Vol 20 (9) ◽  
pp. 1375-1389 ◽  
Author(s):  
Mohammad Sabbir Rahman ◽  
Md Kamrul Hassan ◽  
Seongkyu Chang ◽  
Dookie Kim
Keyword(s):  
Tuned Mass Damper ◽  
Primary Objective ◽  
Modal Parameters ◽  
Earthquake Response ◽  
Tuned Mass Dampers ◽  
Mass Damper ◽  
Modal Mass ◽  
Story Building ◽  
Selection Of ◽  
Multiple Tuned Mass Dampers

The primary objective of this research is to find the effectiveness of an adaptive multiple tuned mass damper distributed along with the story height to control the seismic response of the structure. The seismic performance of a 10-story building was investigated, which proved the efficiency of the adaptive multiple tuned mass damper. Structures with single tuned mass damper and multiple tuned mass dampers were also modeled considering the location of the dampers at the top of the structure, whereas adaptive multiple tuned mass damper of the structure was modeled based on the story height. Selection of the location of the adaptive multiple tuned mass damper along with the story height was dominated by the modal parameters. Participation of modal mass directly controlled the number of the modes to be considered. To set the stage, a comparative study on the displacements and modal energies of the structures under the El-Centro, California, and North-Ridge earthquakes was conducted with and without various types of tuned mass dampers. The result shows a significant capability of the proposed adaptive multiple tuned mass damper as an alternative tool to reduce the earthquake responses of multi-story buildings.

scholarly journals Optimization of plastic foam composition for insulation systems

2019 ◽  
Vol 91 ◽  
pp. 02017 ◽  
Author(s):  
Anton Pilipenko ◽  
Ekaterina Bobrova ◽  
Alexey Zhukov
Keyword(s):  
Heat Loss ◽  
Experimental Studies ◽  
Point Of View ◽  
Structural Safety ◽  
Vapor Permeability ◽  
Building Structures ◽  
Polystyrene Foam ◽  
Building Systems ◽  
Insulation Systems ◽  
Extruded Polystyrene Foam

Construction insulation systems should provide solutions to the problems of creation of suitable conditions of load-bearing construction elements and whole construction, reduction of heat loss through thermal insulation layer, and creation of living comfort in buildings. The article presents the results of experimental studies, the purpose of which is to optimize the composition of extruded polystyrene foam, the formation of methods for selecting its composition and the development of systems for the use of products based on extruded polystyrene foam. Main provisions of the method of analytical optimization, which allows significantly reducing the material and time costs for processing the experimental results, are also provided. Aspects of the implementation of building systems using extruded polystyrene foam both from the point of view of minimizing heat loss through contact areas and the degree of influence of vapor permeability of building structures on the temperature and humidity conditions of premises are studied. Mandatory criteria for construction with the use of building systems are safety conditions, including both structural safety (including maintenance-free cycle) and fire safety.

Theoretical and Experimental Study of Viscoelastic Damper Based on Fractional Derivative Approach and Micromolecular Structures

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Yeshou Xu ◽  
Zhao-Dong Xu ◽  
Ying-Qing Guo ◽  
Teng Ge ◽  
Chao Xu ◽  
...  
Keyword(s):  
Experimental Studies ◽  
Network Models ◽  
Regular Polyhedron ◽  
Building Structures ◽  
Viscoelastic Materials ◽  
Viscoelastic Damper ◽  
Viscoelastic Dampers ◽  
Different Temperatures ◽  
Energy Dissipation Capacity ◽  
Environmental Temperatures

Viscoelastic dampers are one of the most popular earthquake mitigation devices for building structures with a large number of applications in civil engineering. The seismic performance of viscoelastic dampers is greatly affected by viscoelastic materials. The present paper addresses the theoretical and experimental studies of the viscoelastic damper. The regular polyhedron chain network models for viscoelastic materials are proposed based on the molecular chain network microstructures and the temperature–frequency equivalent principle. Several dynamic property tests for the viscoelastic damper at different temperatures, frequencies, and displacements are carried out, and the proposed models are verified by comparing the numerical and experimental results. The comparisons show that the viscoelastic damper has perfect energy dissipation capacity, and the regular polyhedron chain network models can well describe the mechanical properties of the viscoelastic damper at different environmental temperatures and excitation frequencies.

Material Properties of Fibre-Cement and Fibre-Concrete Composites Used for Plated Components of Building Structures

2013 ◽  
Vol 1612 ◽  
Author(s):  
Marcela Karmazínová
Keyword(s):  
Building Materials ◽  
Bending Strength ◽  
Experimental Studies ◽  
Cement Composite ◽  
Building Structures ◽  
The Czech Republic ◽  
Manufacturing Plants ◽  
Fibre Concrete ◽  
Load Carrying ◽  
Fibre Cement

ABSTRACTThe paper presents the brief information on particular results of experimental studies dealing with the problems of properties of materials based on fibre-cement and fibre-concrete composites, which are being recently developed, tested and verified, to use them in the plated components of load-carrying structures of building constructions. The problems mentioned are solved in the co-operation with the company of the Research Institute of Building Materials Inc. (“VUSTAH a.s.”) at Brno city in the Czech Republic. The attention is paid to two basic types of material: (i) fibre-cement composite used for the slab components intended for vertical or horizontal building or technology structures, such as permanent shuttering of bridges, timber floor structures and slab flooring, the wall cladding of buildings and formwork of components in manufacturing plants of the concrete units; (ii) glass-fibre-concrete composite mainly intended for the building façade claddings, but also for the objects of daily use. The experimental verification has been mainly oriented to the investigation of physical-mechanical properties, like as the tensile-bending strength, as well as the corresponding modulus of elasticity.

Recorded Responses of Building Structures during the 2011 Tohoku-Oki Earthquake with Some Implications for Design Practice

2013 ◽  
Vol 29 (1_suppl) ◽  
pp. 245-264 ◽  
Author(s):  
Izuru Okawa ◽  
Toshihide Kashima ◽  
Shin Koyama ◽  
Masanori Iiba
Keyword(s):  
Structural Design ◽  
Earthquake Response ◽  
Building Structures ◽  
Design Practice ◽  
Large Earthquakes

During the 2011 Tohoku-oki earthquake, a large number of response records from various types of buildings were obtained. The records give us the actual motions of buildings during the exceptionally large earthquakes that are considered comparable with design earthquakes. Various types of earthquake response records have been collected, and their properties with several buildings that will exhibit implications for structural design are discussed.

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 The current state and tendencies of using rheological models for self-forming wooden structures

2020 ◽  
pp. 112-122
Author(s):  
V. S Ponomarev ◽  
G. G Kashevarova
Keyword(s):  
Rheological Model ◽  
Experimental Studies ◽  
The Self ◽  
Building Structures ◽  
Forming Process ◽  
Rheological Models ◽  
Factors Affecting ◽  
Wooden Structure ◽  
Shrinkage And Swelling ◽  
Wooden Structures

Wood is a natural and ecological material. Exceptional mechanical properties of wood allow it to be used in building structures subject to chemically active substances. However some changes in mechanical characteristics of wood under the influence of water and temperature, as well as its anisotropy, limit the application areas of this material. Based on the results of the research by S.P. Timoshenko, foreign scientists proposed a method that makes it possible to use these shortcomings of wood to create wooden structures of unique shapes. This article considers the self-forming process of glued layered wooden structures, which is based on various rheological processes taking place in wood. In order to predict the shape of a glued layered wooden structure obtained with the self-forming method, an accurate rheological model is required, which takes into account all wood deformation mechanisms. We analyzed the available rheological models of wood proposed or described both by Russian and foreign scientists, as well as the international experimental studies and numerical modeling results of the self-formed glued layered wooden structures. Based on the analysis results, it was found that the present rheological models do not take into account a number of factors that influence the process of self-forming of glued layered wooden structures. The rheological model, which includes a complete list of factors affecting wood deformation (elastic and plastic deformation, wood shrinkage or swelling, viscous-elastic creep deformation and mechanical and sorption deformation), is the most promising for creating unique architectural objects from glued wood. But it also has a number of shortcomings, mainly due to inconsideration of some factors and few experimental studies. Such factors include the geometric parameters of layers of the glued wooden structures, the surface treatment of layers, temperature, as well as wood species. These factors influence the process of wood shrinkage and swelling, thus the final shape of a wooden structure. It is necessary to have additional experimental and theoretical studies of the mechanical behavior of glued wooden structures which will take into account these factors, as well as to study other species of wood including their combinations.

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