Influence Imperfections on the Difference between the Numerical and Experimental Investigations of a Punching in the Central Slab-Column Connections of RC Structures

2015 ◽  
Vol 769 ◽  
pp. 264-269
Author(s):  
Barbara Wieczorek
Keyword(s):  
Numerical Model ◽  
Laboratory Tests ◽  
Progressive Collapse ◽  
Numerical Calculations ◽  
Experimental Investigations ◽  
Material Models ◽  
Rc Structures ◽  
Non Linear ◽  
Australian Standard ◽  
The Difference

This paper presents the results of laboratory tests concerning the central connection of the slab with the column, in which an additional reinforcement ensuring the structure against a progressive collapse was applied as to recommended in the standard PN-EN 1991-1-7:2008 as well as in PN-EN 1992-1-1:2008. Regulations concerning the necessity of such a reinforcement are also contained in the American and Australian standard as well as in the Bulletin FIB. The obtained results of investigations have been compared with calculations based on a spatial numerical model representing the analyzed phenomenon. The numerical model bases on predefined material models of steel and concrete, taking into account non-linear dependences of the strength of these materials. The values of displacements of the upper surface of the slab depending on the exerted load were compared with the values of numerical calculations.

scholarly journals Experimental and Numerical Evaluation of Progressive Collapse Behavior in Scaled RC Beam-Column Subassemblage

2016 ◽  
Vol 2016 ◽  
pp. 1-17 ◽  
Author(s):  
Rasool Ahmadi ◽  
Omid Rashidian ◽  
Reza Abbasnia ◽  
Foad Mohajeri Nav ◽  
Nima Usefi
Keyword(s):  
Numerical Model ◽  
Progressive Collapse ◽  
Experimental Tests ◽  
Resistance Mechanisms ◽  
Full Scale ◽  
Displacement Curve ◽  
Rc Beam ◽  
Rc Structures ◽  
Collapse Behavior ◽  
Column Removal Scenario

An experimental test was carried out on a 3/10 scale subassemblage in order to investigate the progressive collapse behavior of reinforced concrete (RC) structures. Investigation of alternative load paths and resistance mechanisms in scaled subassemblage and differences between the results of full-scale and scaled specimens are the main goals of this research. Main characteristics of specimen response including load-displacement curve, mechanism of formation and development of cracks, and failure mode of the scaled specimen had good agreement with the full-scale specimen. In order to provide a reliable numerical model for progressive collapse analysis of RC beam-column subassemblages, a macromodel was also developed. First, numerical model was validated with experimental tests in the literature. Then, experimental results in this study were compared with validated numerical results. It is shown that the proposed macromodel can provide a precise estimation of collapse behavior of RC subassemblages under the middle column removal scenario. In addition, for further evaluation, using the validated numerical model, parametric study of new subassemblages with different details, geometric and boundary conditions, was also done.

Onset of Scour Below Pipeline Under Combined Waves and Current

2010 ◽  
Author(s):  
Zhipeng Zang ◽  
Liang Cheng ◽  
Ming Zhao
Keyword(s):  
Numerical Model ◽  
Pressure Drop ◽  
Empirical Model ◽  
Empirical Formula ◽  
Laboratory Tests ◽  
Numerical Results ◽  
Numerical Calculations ◽  
Submarine Pipeline ◽  
Oscillatory Flows ◽  
Steady Current

Onset of scour below a submarine pipeline under waves and current is studied experimentally and numerically in this paper. A series of laboratory tests were conduced in a mini O-tube (MOT) facility to investigate the onset conditions of scour below a pipeline subject to oscillatory flows superimposed on a steady current. The effect of parameter α, which is defined as α = Uc/(Uc+Uw), on the onset of scour under combined waves and current was investigated and a simple empirical formula for evaluating the criterion for onset of scour is presented. The numerical calculations were carried out to simulate the onset of scour using a calibrated numerical model. The pressure drop coefficient over a pipe under combined waves and current was studied. The effectiveness and accuracy of the empirical model was calibrated by the numerical results.

Distribution of Forces in Reinforcing Bars in Slab-Column Connections of RC Structures

2016 ◽  
Vol 837 ◽  
pp. 79-84 ◽  
Author(s):  
Barbara Wieczorek
Keyword(s):  
Structural Integrity ◽  
Progressive Collapse ◽  
Tensile Force ◽  
Calculation Model ◽  
Experimental Investigations ◽  
Reinforcing Bars ◽  
Linear Change ◽  
Rc Structures ◽  
Support Zone ◽  
Internal Forces

The article deals with the analysis of the problem of the load-bearing capacity of reinforcing bars placed above the columns in slab-column connections of reinforced concrete structures. Failure of the support zone by punching and lack of proper structural integrity reinforcement can lead to a progressive collapse. The EC2 standard guidelines recommend the use of integrity reinforcement, however, they lack any instructions concerning the amount of necessary reinforcement. The article presents a theoretical calculation model that permits a more detailed analysis of internal forces in reinforcing bars located directly above the column. Adopting a solution in the form of exact equations makes it possible to take into account the influence of a non-linear change of the bar stiffness and considerable deflections. The calculation model is based on the results of experimental investigations. On the basis of a theoretical model it is possible to estimate the tensile force of the bar at which the bars located directly in the support zone are ruptured.

scholarly journals Effect of load sequence interaction on bond-wire lifetime due to power cycling

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zoubir Khatir ◽  
Son-Ha Tran ◽  
Ali Ibrahim ◽  
Richard Lallemand ◽  
Nicolas Degrenne
Keyword(s):  
High Stress ◽  
Bipolar Transistors ◽  
Junction Temperature ◽  
Experimental Investigations ◽  
Power Cycling ◽  
Power Modules ◽  
Bond Wire ◽  
Load Sequence ◽  
The Difference ◽  
Heating Duration

AbstractExperimental investigations on the effects of load sequence on degradations of bond-wire contacts of Insulated Gate Bipolar Transistors power modules are reported in this paper. Both the junction temperature swing ($$\Delta T_{j}$$ Δ T j ) and the heating duration ($$t_{ON}$$ t ON ) are investigated. First, power cycling tests with single conditions (in $$\Delta T_{j}$$ Δ T j and $$t_{ON}$$ t ON ), are performed in order to serve as test references. Then, combined power cycling tests with two-level stress conditions have been done sequentially. These tests are carried-out in the two sequences: low stress/high stress (LH) and high stress/low stress (HL) for both $$\Delta T_{j}$$ Δ T j and $$t_{ON}$$ t ON . The tests conducted show that a sequencing in $$\Delta T_{j}$$ Δ T j regardless of the direction “high-low” or “low–high” leads to an acceleration of degradations and so, to shorter lifetimes. This is more pronounced when the difference between the stress levels is large. With regard to the heating duration ($$t_{ON}$$ t ON ), the effect seems insignificant. However, it is necessary to confirm the effect of this last parameter by additional tests.

scholarly journals Seismic Strengthening Effects of Full-Size Reinforced Concrete Frame Retrofitted with Novel Concrete-Filled Tube Modular Frame by Pseudo-Dynamic Testing

2021 ◽  
Vol 11 (11) ◽  
pp. 4898
Author(s):  
Jin-Seon Kim ◽  
Ju-Seong Jung ◽  
Dong-Keun Jung ◽  
Eui-Yong Kim ◽  
Kang-Seok Lee
Keyword(s):  
Dynamic Analysis ◽  
Shear Failure ◽  
Dynamic Testing ◽  
Seismic Intensity ◽  
Seismic Retrofitting ◽  
Restoring Force ◽  
Rc Structures ◽  
Linear Dynamic ◽  
Non Linear ◽  
Force Characteristics

The present study proposes a new seismic retrofitting method using a concrete-filled tube modular frame (CFT-MF) system, a novel technique to overcome and improve the limitations of existing seismic strengthening methods. This CFT-MF seismic retrofitting method makes the most of the advantages of both concrete and steel pipes, thereby significantly improving constructability and increasing integration between the existing structure and the reinforcement joints. This method falls into the category of typical seismic retrofitting methods that focus on increasing strength, in which the required amount of seismic reinforcement can be easily estimated. Therefore, the method provides an easy solution to improving the strength of existing reinforced concrete (RC) structures with non-seismic details that are prone to shear failure. In the present study, a full-size two-story test frame modeled from existing domestic RC structures with non-seismic details was subjected to pseudo-dynamic testing. As a result, the effect of the CFT-MF system, when applied to existing RC structures, was examined and verified, especially as to its seismic retrofitting performance, i.e., restoring force characteristics, stiffness reinforcement, and seismic response control. In addition, based on the pseudo-dynamic testing results, a restoring force characteristics model was proposed to implement non-linear dynamic analysis of a structure retrofitted with the CFT-MF system (i.e., the test frame). Finally, based on the proposed restoring force characteristics, non-linear dynamic analysis was conducted, and the results were compared with those obtained by the pseudo-dynamic tests. The results showed that the RC frame (building) with no retrofitting measures applied underwent shear failure at a seismic intensity of 200 cm/s2, the threshold applied in seismic design in Korea. In contrast, in the frame (building) retrofitted with the CFT-MF system, only minor earthquake damage was observed, and even when the maximum seismic intensity (300 cm/s2) that may occur in Korean was applied, small-scale damage was observed. These results confirmed the validity of the seismic retrofitting method based on the CFT-MF system developed in the present study. The non-linear dynamic analysis and the pseudo-dynamic test showed similar results, with an average deviation of 10% or less in seismic response load and displacement.

Non-linear dynamics, chaos, complexity and enclaves in granitoid magmas

1996 ◽  
Vol 87 (1-2) ◽  
pp. 217-223 ◽  
Author(s):  
James Flinders ◽  
John D. Clemens
Keyword(s):  
Deterministic Chaos ◽  
Interfacial Area ◽  
Two Dimensions ◽  
Mixing Processes ◽  
Nd Isotope ◽  
Natural Systems ◽  
Non Linear ◽  
The Difference ◽  
Magma System ◽  
Isotope Systematics

ABSTRACT:Most natural systems display non-linear dynamic behaviour. This should be true for magma mingling and mixing processes, which may be chaotic. The equations that most nearly represent how a chaotic natural system behaves are insoluble, so modelling involves linearisation. The difference between the solution of the linearised and ‘true’ equation is assumed to be small because the discarded terms are assumed to be unimportant. This may be very misleading because the importance of such terms is both unknown and unknowable. Linearised equations are generally poor descriptors of nature and are incapable of either predicting or retrodicting the evolution of most natural systems. Viewed in two dimensions, the mixing of two or more visually contrasting fluids produces patterns by folding and stretching. This increases the interfacial area and reduces striation thickness. This provides visual analogues of the deterministic chaos within a dynamic magma system, in which an enclave magma is mingling and mixing with a host magma. Here, two initially adjacent enclave blobs may be driven arbitrarily and exponentially far apart, while undergoing independent (and possibly dissimilar) changes in their composition. Examples are given of the wildly different morphologies, chemical characteristics and Nd isotope systematics of microgranitoid enclaves within individual felsic magmas, and it is concluded that these contrasts represent different stages in the temporal evolution of a complex magma system driven by nonlinear dynamics. If this is true, there are major implications for the interpretation of the parts played by enclaves in the genesis and evolution of granitoid magmas.

DENSITY DISCONTINUITIES AT THE CRITICAL TEMPERATURE

1933 ◽  
Vol 9 (6) ◽  
pp. 613-629 ◽  
Author(s):  
C. A. Winkler ◽  
O. Maass
Keyword(s):  
Critical Temperature ◽  
Small Region ◽  
Density Difference ◽  
Experimental Investigations ◽  
Sharp Change ◽  
Two Component System ◽  
Medium Increase ◽  
The Difference ◽  
Temperature Equilibrium ◽  
Continuous Relation

A technique for measuring densities in various parts of a one- or two-component system, raised above its critical temperature, is described. Considerable improvements over a method for this purpose recently described by one of the writers consist in greater flexibility of manipulation and in making possible a variation in the volume of space confining the medium during the experiment. Propylene and methyl-ether were the two media examined. From the results the following generalizations regarding aberrations from the continuity of state were found to hold for both.When either liquid was heated above the temperature at which the visible meniscus disappeared, the density below this point of disappearance was found to be greater than that above. The density was uniform throughout each portion, undergoing a relatively sharp change in the small region where the meniscus was last seen. After one hour of temperature equilibrium, the difference in density between top and bottom became constant and remained unaltered for six hours. Constant stirring or temperature fluctuations of the order of 0.02 °C. do not alter this density difference. A decrease in the volume available for the medium increases the density difference between the top and bottom, a continuous relation existing between available space and density difference. With decrease in available space, the densities of both upper and lower portions of the medium increase, the density of the lower more rapidly than that of the upper. These results were reproducible quantitatively in the experiments carried out to date. The density difference for a fixed available space decreases with rise in temperature and is measurable up to at least 10 °C. above the critical temperature. A number of miscellaneous experiments are described which form the basis of work now being carried out. The theoretical significance of aberrations from the continuity of state is discussed to the extent warranted by the present stage of the experimental investigations, and tentative conclusions are drawn.

Torsional oscillation of a homogeneous elastic spheroid

1962 ◽  
Vol 52 (3) ◽  
pp. 469-484 ◽  
Author(s):  
Tatsuo Usami ◽  
Yasuo Satô
Keyword(s):  
Fundamental Mode ◽  
Free Oscillation ◽  
Torsional Oscillation ◽  
Numerical Calculations ◽  
Higher Harmonics ◽  
Oblate Spheroidal ◽  
The Earth ◽  
Spectral Peaks ◽  
The Difference ◽  
Spheroidal Coordinates

abstract There are several causes for the observations of splitting of the spectral peaks determined from the free oscillation of the earth. In this paper, the splitting due to the ellipticity is studied assuming a homogeneous earth described by oblate spheroidal coordinates. Ellipticity causes the iTn mode to split into (n + 1) modes, while the earth's rotation causes it to split into (2n + 1) modes. 1/297.0 is adopted as the ellipticity of the earth. Numerical calculations are carried out for the fundamental mode (n = 2, 3, 4) and for the first higher harmonics (n = 1). The difference between the extreme frequencies for each value of n is 0.7% (n = 2), 0.5% (n = 3), and 0.4% (n = 4).

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