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.

scholarly journals Assessment of Progressive Collapse Resistance of Steel Structures with Moment Resisting Frames

Buildings ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 19 ◽  
Author(s):  
Osama Mohamed ◽  
Rania Khattab
Keyword(s):  
Progressive Collapse ◽  
Three Dimensional ◽  
The United States ◽  
Dimensional System ◽  
Structural System ◽  
Linear Elastic ◽  
Load Carrying ◽  
Non Linear ◽  
Moment Resisting ◽  
Primary Load

This paper evaluates the practice of using moment connections in the perimeter of the structural system and shear connections within the interior connections of the three-dimensional structural system from the perspective of resistance to progressive collapse. The enhanced resistance to progressive collapse associated with using moment resisting connections at the perimeter as well as internal to the three-dimensional system is assessed. Progressive collapse occurrence and system resistance are determined using the alternate path method which presumes a primary load carrying-member is notionally removed. The paper compares the structural response determined using linear elastic, non-linear elastic and non-linear dynamic analyses. Linear and non-linear static analyses are found to be incapable of capturing the response pursuant to the loss of the primary load carrying member. The analysis procedures used in this study followed (for the most part) the United States Department of Defense Guide for Progressive Collapse Resistant Design of Structures.

scholarly journals A Review on Progressive Collapse of Building Structures

2014 ◽  
Vol 8 (1) ◽  
pp. 183-192 ◽  
Author(s):  
Hao Wang ◽  
Anqi Zhang ◽  
Yi Li ◽  
Weiming Yan
Keyword(s):  
Design Method ◽  
Progressive Collapse ◽  
Experimental Studies ◽  
Experimental Tests ◽  
Theoretical Models ◽  
Collapse Mechanism ◽  
Building Structures ◽  
Wide Range ◽  
Collapse Behavior ◽  
Element Method

Progressive collapse of building structures is generally triggered by a local failure due to accidental actions, followed by subsequent chain effect of the structures which may result in wide range failure or even collapse of the entire buildings. Since the “911” event, progressive collapse of building structures has been widely concerned by engineers and researchers. This paper assesses the current researches on this issue from experimental study, numerical simulation and theoretical analysis. Given the limitation of costs and difficulties of experimental tests, the experimental studies investigate the collapse mechanism, such as development of stress/strain and damage/failure of materials, mainly via the scaled down specimens of structural components and substructures. On the other hand, the collapse behavior of entire building structures is analyzed via the numerical methods, such as the finite element method and the discrete element method. Further, the collapse resistance demand and the robustness assessment for building structures are theoretically studied in depth in which the simplified theoretical models of the collapse-resisting demand and the collapse risk assessment are proposed respectively. At last, the design method to prevent progressive collapse for building structures is also discussed.

scholarly journals Checking of the robustness of precast structural systems based on the energy balance method

Vestnik MGSU ◽  
2021 ◽  
pp. 1015-1033
Author(s):  
Viktor V. Tur ◽  
Andrei V. Tur ◽  
Aliaksandr A. Lizahub
Keyword(s):  
Energy Balance ◽  
Progressive Collapse ◽  
Precast Concrete ◽  
Analytical Models ◽  
Structural Systems ◽  
Structural System ◽  
Cross Sectional ◽  
Basic Parameters ◽  
Comparison Of The Results ◽  
Methods Analytical

Introduction. The robustness requirements should be fulfilled already at the stage of conceptual design of the structural system, taking into account the use of various strategies for its protection from progressive collapse. Compared to monolithic reinforced concrete structural systems, precast concrete systems are more susceptible to the effects of accidental actions. To ensure the integrity of the damaged system in the original prefabricated structural system, it is necessary to provide (reserve) a sufficient number of horizontal (internal and perimetric) and vertical ties with the required degree of continuity and plastic deformability. Materials and methods. Analytical models of the resistance of horizontal ties based on the equations of the energy balance of the system. Results. On a real example of a prefabricated floor, calculations of the required parameters of horizontal ties were performed according to the proposed dependencies, based on the model of the energy balance of the system and the design models included in the standards of various countries. Comparison of the results obtained showed that the calculation models of the norms in a number of cases can give an unsafe result, underestimating the required cross-sectional area of horizontal ties. This is due to the fact that all dependencies for calculating the tie forces are based on constant values of the ultimate deflection (usually from 1/6 to 1/10 of the span) without checking the limiting deformability of horizontal ties. Conclusions. Deformability of ties is one of the basic parameters that should be monitored when checking the robustness of structural systems made of precast concrete. The proposed method, based on the provisions of the energy balance, makes it possible to take into account the limiting deformability of horizontal ties when determining the membrane (chain) forces and calculate the maximum dynamic response of the damaged structural system.

scholarly journals Simplified analytical method for the robustness assessment of precast reinforced concrete structural systems

2022 ◽  
Vol 20 (4) ◽  
pp. 093-114
Author(s):  
Viktar Tur ◽  
Andrei Tur ◽  
Aliaksandr Lizahub
Keyword(s):  
Energy Balance ◽  
Balance Method ◽  
Analytical Models ◽  
Dynamic Resistance ◽  
Structural System ◽  
Load Path ◽  
Energy Balance Method ◽  
Central Column ◽  
Simplified Calculation ◽  
Energy Balance Approach

The article presents the simplified implementation of alternative load path method based on the energy balance approach. This method should be used to check the global resistance of a damaged structural system after the occurrence of an accidental event. Basic assumptions of simplified analytical models for modelling resistance of horizontal ties in a damaged structural system, taking into account the membrane (chain) effects, were presented. An approach to modelling the dynamic resistance of a damaged structural system based on the energy balance method is described. Calculated dependencies for checking the robustness of a prefabricated multi-storey building with hollow-core slabs after the loss of the central column are proposed and considered using an example. On the considered example, a comparison of the required tie sections area with the dynamic resistance designed using the energy balance method (EBM) and according to the current standards, and a statistical assessment of the reliability of the load-bearing capacity models are carried out. In the end, a brief algorithm for the simplified calculation of the dynamic resistance of a damaged structural system is proposed.

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.

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 Effect of blast loading and resulting progressive failure of a cable-stayed bridge

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
Ravi Mudragada ◽  
S. S. Mishra
Keyword(s):  
Progressive Failure ◽  
Blast Resistance ◽  
Progressive Collapse ◽  
Building Structures ◽  
Structural Elements ◽  
Blast Loads ◽  
Cable Stayed Bridge ◽  
Bridge Performance ◽  
Cable Stayed Bridges

AbstractMany researchers have carried out experimental and numerical investigations to examine building structures’ response to explosive loads. Studies of bridges subjected to blast loads are limited. Hence, in this study, we present a case study on a cable-stayed bridge, namely, Charles River Cable-Stayed Bridge-Boston, to assess its robustness and resistance against the progressive collapse resulting from localized failure due to blast loads. Three different blast scenarios are considered to interpret the bridge performance to blast loads. To monitor the progressive failure mechanisms of the structural elements due to blast, pre-defined plastic hinges are assigned to the bridge deck. The results conclude that the bridge is too weak to sustain the blast loads near the tower location, and the progressive collapse is inevitable. Hence, to preserve this cable-stayed bridge from local and global failure, structural components should be more reinforced near the tower location. This case study helps the designer better understand the need for blast resistance design of cable-stayed bridges.

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