Prediction of average debris launch velocity from a reinforced concrete structure based on SDOF system

2020 ◽  
pp. 136943322096027
Author(s):  
Seung-Hun Sung ◽  
Hun Ji ◽  
Surin Kim ◽  
Jinwung Chong
Keyword(s):  
Reinforced Concrete ◽  
Comparative Study ◽  
Conservation Equation ◽  
Reinforced Concrete Structure ◽  
Reinforcing Bars ◽  
Sdof System ◽  
Energy Conservation Equation ◽  
Rc Structure ◽  
Proposed Model ◽  
Velocity Prediction

This study presents a physics-based model for debris launch velocity prediction of a reinforced concrete (RC) structure subjected to a blast load. The model is basically derived from energy conservation equation. Especially, a resistance-deflection relationship for the structural single degree of freedom (SDOF) system is newly considered to evaluate the energy consumed by the damage and fragmentation of the RC structure. By applying the resistance-deflection relationship, the proposed model can consider the interactions between reinforcing bars and concrete. Moreover, since the resistance-deflection curve is evaluated considering various structural properties as well as boundary conditions, the proposed model can be flexibly utilized compared to conventional approaches. In order to confirm the performance of the proposed model, a comparative study was carried out against benchmark experiments on closed concrete box structures under an internal blast. From the comparative study, it was shown that the debris launch velocities estimated from the proposed model had a good agreement with the test results compared with the other models.

Investigation of the Influence of Cracks on Vibration Processes in a Reinforced Concrete Structure

2018 ◽  
Vol 938 ◽  
pp. 132-138
Author(s):  
Igor N. Shardakov ◽  
A. Shestakov ◽  
R.V. Tsvetkov ◽  
V. Yepin ◽  
I. Glot
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structure ◽  
Numerical Experiments ◽  
Crack Nucleation ◽  
Numerical Data ◽  
Diagnostic Parameter ◽  
Reinforced Concrete Structure ◽  
Rc Structure ◽  
Proposed Model ◽  
The Mathematical Model

The validity of the mathematical model describing the propagation of vibrations in a reinforced concrete (RC) structure was verified by comparing the experimental and numerical data. The proposed model allowed one to perform numerical experiments aimed at comparing vibrorecords obtained from the structure without defects and the structure with cracks. A numerical experiment was performed aimed to explore the changes in vibrorecords when cracks appear in the structure. Based on the results these experiments, an informative diagnostic parameter controlling crack nucleation and propagation in the reinforced concrete structure was derived.

scholarly journals Comparison of the stress-strain state of the reinforced concrete structure under various mathematical models of concrete

2018 ◽  
Vol 251 ◽  
pp. 04032
Author(s):  
Dmitriy Sidorov ◽  
Vladimir Dorozhinskiy
Keyword(s):  
Reinforced Concrete ◽  
Mathematical Models ◽  
Strain State ◽  
Concrete Structures ◽  
Seismic Action ◽  
Reinforced Concrete Structure ◽  
Reinforcing Bars ◽  
Plastic Deformations ◽  
Regulatory Documents ◽  
Structural Engineer

Nowadays, reinforced concrete structures are most often used as load-bearing elements of buildings and structures. In the case of alternating loads such as seismic action, there is accumulation of residual plastic deformations in the concrete structures, which leads to a significant complication in the calculation of structures by “standard” methods. For such problems, it is advisable to use computational complexes in which mathematical models of structural materials are implemented, which allow to describe the work of concrete and reinforcing bars for various types of impacts more properly. However, when applying such methods, the results obtained should not contradict the requirements of the existing regulatory documents, which, in the first place, the structural engineer should be guided by. Before solving more complex problems, the applied methods should be verified and analyzed for fairly simple structures and types of loads.

Comparison between Experiments and FEM Simulations of the Reinforced Concrete Structure under Shake Table Test

2013 ◽  
Vol 842 ◽  
pp. 477-481
Author(s):  
Ren Zuo Wang ◽  
Wen Yu Chang ◽  
Bing Chang Lin ◽  
Chao Hsun Huang
Keyword(s):  
Reinforced Concrete ◽  
Structural Model ◽  
Plastic Hinge ◽  
Structural Models ◽  
Shake Table ◽  
Reinforced Concrete Structure ◽  
Simulation Procedure ◽  
Nonlinear Responses ◽  
Rc Structure ◽  
Hinge Model

In this paper, the numerical simulation procedure of the reinforced concrete (RC) structure is purposed using SAP2000 software. The plastic hinge model (PHM) is using SWPH code. This PHM is to simulate the nonlinear responses of the RC structure under seismic. The numerical structural models are established using FEM models. The test specimen under shake table is two-span RC structure. In order to demonstrate the accuracy of RC structural model, comparisons between the experimental and numerical results are close. The proposed procedure can be used to simulate the nonlinear responses of RC structure under seismic.

scholarly journals Capacity Assessment of Existing RC Columns

Buildings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 161
Author(s):  
Francesca Vecchi ◽  
Beatrice Belletti
Keyword(s):  
Experimental Data ◽  
Reinforced Concrete ◽  
Capacity Assessment ◽  
Crack Model ◽  
Longitudinal Reinforcement ◽  
Reinforcing Bars ◽  
Inelastic Buckling ◽  
Collapse Mechanisms ◽  
Proposed Model ◽  
Capacity Prediction

Existing reinforced concrete (RC) members, designed in accordance with obsolete codes, are often characterized by high stirrup spacing. The collapse mechanisms generated by high stirrup spacing are typically related to the buckling of longitudinal reinforcement and can be accentuated when corrosion takes place. In this paper, new refined material constitutive laws for steel, including inelastic buckling and corrosion of reinforcement, are implemented in a fixed crack model suitable for RC elements subjected to cyclic loadings called the PARC_CL 2.1 crack model. The effectiveness of the proposed model is validated through comparison with available experimental data and analytical predictions. Finally, the proposed model is used to calibrate correction coefficients to be applied to current codes formulation for the ultimate rotational capacity prediction of non-conforming elements subjected to buckling phenomena and characterized by corrosion of reinforcing bars.

scholarly journals Dynamic Disintegration of Explosively-Driven Metal Cylinder with Internal V-Grooves

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 584
Author(s):  
Mingxue Zhou ◽  
Cheng Wu ◽  
Fengjiang An ◽  
Shasha Liao ◽  
Dongyu Xue ◽  
...  
Keyword(s):  
Fracture Strain ◽  
Cylindrical Shells ◽  
Internal Surface ◽  
Deformation Energy ◽  
Conservation Equation ◽  
Energy Conservation Equation ◽  
Crack Penetration ◽  
Proposed Model ◽  
Theoretical Predictions ◽  
Good Agreement

Machining V-shaped grooves to the internal surface of cylindrical shells is one of the most common technologies of controlled fragmentation for improving warhead lethality against targets. The fracture strain of grooved shells is a significant concern in warhead design. However, there is as yet no reasonable theory for predicting the fracture strain of a specific grooved shell; existing approaches are only able to predict this physical regularity of non-grooved shells. In this paper, through theoretical analysis and numerical simulations, a new model was established to study the fracture strain of explosively driven cylindrical shells with internal longitudinal V-grooves. The model was built based on an energy conservation equation in which the energy consumed to create a new fracture surface in non-grooved shells was provided by the elastic deformation energy stored in shells. We modified the energy approach so that it can be applicable to grooved shells by adding the elastic energy liberated for crack penetration and reducing the required fracture energy. Cylinders with different groove geometric parameters were explosively expanded to the point of disintegration to verify the proposed model. Theoretical predictions of fracture strain showed good agreement with experimental results, indicating that the model is suitable for predicting the fracture strain of explosively driven metal cylinders with internal V-grooves. In addition, this study provides an insight into the mechanism whereby geometric defects promote fracturing.

Analytical modeling of combustion of a single iron particle burning in the gaseous oxidizing medium

2012 ◽  
Vol 227 (5) ◽  
pp. 1006-1021 ◽  
Author(s):  
Mehdi Bidabadi ◽  
Majid Mafi
Keyword(s):  
Thermal Radiation ◽  
Separation Of Variables ◽  
Mass Conservation ◽  
Iron Particle ◽  
Conservation Equation ◽  
Particle Combustion ◽  
Energy Conservation Equation ◽  
Proposed Model ◽  
Combustion Processes ◽  
Mass Conservation Equation

In the present study, a theoretical investigation is accomplished to model the combustion of a single iron particle by virtue of a novel thermophysical approach. It is assumed that a spherical iron particle falls freely in the gaseous medium and preheats and then burns heterogeneously on its external surface in this hot oxidizing environment and oxygen diffuses inward to the particle. A new physical parameter for thermal radiation is introduced. By solving the energy conservation equation for the iron particle, the temperature distribution of the iron particle during the preheating and combustion processes is calculated analytically. Also, by solving the oxygen mass conservation equation, the variation of oxygen concentration within the iron particle during the combustion stage is estimated. In the proposed model, the effect of thermal radiation and dynamic behavior of burning iron particle are considered. Because of high thermal conductivity and micro size of iron particle, the Biot number is negligibly small. The non-homogeneous partial differential equations of energy and mass species resulted from the modeling of combustion are solved by utilizing the method of separation of variables. The assumptions applied in the modeling are such that do not violate the actual combustion phenomenon. Also, the numerical solution of energy equation in the combustion stage is presented and compared with the obtained analytical solution. Also, the burnout time of iron particle is evaluated in this article. This investigation is one of the first performed efforts for analyzing and modeling of single iron particle combustion.

The Effect of the Realkalisation on the Corroded Reinforcing Bar

2010 ◽  
Vol 133-134 ◽  
pp. 1201-1206
Author(s):  
Wen Jun Qu ◽  
Kun Wang ◽  
Yan Xiong
Keyword(s):  
Reinforced Concrete ◽  
Service Life ◽  
Surface State ◽  
Ferric Oxide ◽  
Concrete Structure ◽  
Electrochemical Reaction ◽  
Reinforced Concrete Structure ◽  
Reinforcing Bars ◽  
Reinforcing Bar ◽  
Repairing Effect

This work is aimed at answering the question that whether the realkalisation as a rehabilitation method is effective on the corroded reinforced concrete structure or not. To this aim, the behaviour in a sodium carbonated solution whose concentration is 0.5 mol/L of reinforcing bars from an reinforced concrete structure that failed through carbonation after 70 years of service life is examined. The results show the electrochemical reaction on the rebar is closely related with the surface state of reinforcing bar electrode. During the electrochemical realkalisation treatment, the reduction of ferric oxide or ferrous oxide formed on the surface of reinforcing bar will occur in company with the producing of H2; The realkalisation treatment not only resumes the alkalescence of the carbonated concrete , but also rehabilitates the corroded reinforcing bar by reducing the rust to iron. The electrochemical realkalisation treatment is a rehabilitation method and has a repairing effect on some extent of corroded reinforcing bar.

Analyses of High Grade Strength Steel Bars in the Design of a Five-Storey Reinforced Concrete Structure with Comparison of Energy Consumption and CO2 Emission

2012 ◽  
Vol 511 ◽  
pp. 64-69
Author(s):  
Pei Zhang ◽  
Han Zhu ◽  
Apostolos Fafitis
Keyword(s):  
Energy Consumption ◽  
Reinforced Concrete ◽  
Structural Design ◽  
Energy Cost ◽  
High Energy ◽  
Maximum Energy ◽  
Reinforced Concrete Structure ◽  
Design Code ◽  
Rc Structure ◽  
Steel Bars

Energy consumption and CO2 emissions in buildings is becoming an increasingly important issue. Steel is a major building material with high energy cost. In a reinforced concrete (RC) structure, it accounts for the maximum energy consumption. There is a need to quantify the steel amount in RC for various situations so that reduction or optimization in steel usage can be analyzed. In this paper two different calculations (Calculation-I and Calculation-II) are conducted by using two groups of steel in designing beams, columns and plates for a 20000 m2 five-storeyed frame RC structure. In Calculation-I, or Cal-I in abbreviation, the steel used for beams, columns and plates is HRB335, HRB400 and HPB235 respectively. In Calculation-II, or Cal-II in abbreviation, the steel used for beams, columns and plates is HRB400, HRB500 and CRB550 respectively. The strength of steel used in Cal-II is higher than that in Cal-I. The calculation is carried out by following the standardized concrete structural design code, and the steps involved in calculation are given in certain details as seen necessary. The corresponding energy for producing the steel used in beams, columns and plates is also computed and normalized on per square meter basis. The results show that Cal-II saves 101.76 tons of steel than Cal-I, or 5.09kg/m2, which means a saving of about 64.11 t of standard coal or 1.6×102 t CO2 for the whole structure, or 3.2 kg of standard coal or 7.98kg CO2 for per square meter.

scholarly journals Braking Indices of Pulsars Obtained in the Presence of an Effective Force

2017 ◽  
Vol 45 ◽  
pp. 1760037
Author(s):  
Nadja S. Magalhães ◽  
André S. Okada ◽  
Carlos Frajuca
Keyword(s):  
Energy Conservation ◽  
Theoretical Calculation ◽  
Open Problem ◽  
Tangential Velocity ◽  
Conservation Equation ◽  
Magnetic Dipoles ◽  
Effective Force ◽  
Energy Conservation Equation ◽  
Proposed Model ◽  
Using Data

The theoretical calculation of braking indices of pulsars is still an open problem. In this work we present a study on this issue which adapts the model that assumes that pulsars are rotating magnetic dipoles by introducing a compensating component in the energy conservation equation of the system. Such component relates to an effective force that varies with the first power of the tangential velocity of the pulsar’s crust. We tested the proposed model using data available.

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