Evaluation of a Gravity Load Designed Reinforced Concrete Structure Failed under its Own Weight due to Creep in Concrete

2013 ◽  
Vol 747 ◽  
pp. 441-444
Author(s):  
Mevlut Yasar Kaltakci ◽  
Hasan Husnu Korkmaz ◽  
Mehmet Kamanli ◽  
Murat Ozturk ◽  
Musa Hakan Arslan
Keyword(s):  
Reinforced Concrete ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Central Anatolia ◽  
Reinforced Concrete Structure ◽  
Building Stock ◽  
Gravity Load ◽  
Moment Resisting ◽  
The One ◽  
Recent Earthquakes

Turkish building stock is commonly composed of reinforced concrete moment resisting frames. Recent earthquakes in Turkey resulted thousands of failed or heavily damaged residential houses and office buildings. In addition of the earthquake failures, reinforced concrete structures may also failed only under their own weight. There are several examples such as Hicret Apartment in Diyarbakir (1983), Zumrut Apartment in Konya, in central Anatolia, Huzur Apartment in Istanbul (2007). On February 2nd, 2004 a 9-story reinforced concrete building in Konya (Zumrut Apartment) collapsed leaving 92 people dead. The first author of the paper was governmentally charged about the investigation of the failure causes. Carrot samples were taken from the concrete columns and steel samples were obtained from the disaster area. The dimensions of the structural members were determined. The structure was modeled in three dimensional space and vertical collapse analyses were conducted. The one of the main cause of failure was determined as the creep of the concrete occurred in excessively loaded columns. The main reasons of the damages and failures were determined to be the insufficiency in material quality, mistakes made in load selection and the inappropriate load-carrying dimensions. The construction mistakes and not obeying the design drawings are the other flaws. In this paper detailed information about the structure, creep analyses and vertical collapse analyze results were depicted in understandable format.

Diffraction contrast of dislocations in icosahedral quasicrystals

1990 ◽  
Vol 48 (4) ◽  
pp. 454-455
Author(s):  
K. Urban ◽  
Z. Zhang ◽  
M. Wollgarten ◽  
D. Gratias
Keyword(s):  
Dimensional Space ◽  
Three Dimensional ◽  
Complete Characterization ◽  
Extinction Condition ◽  
Burgers Vector ◽  
Diffraction Contrast ◽  
Lattice Geometry ◽  
Reference Space ◽  
Icosahedral Quasicrystals ◽  
The One

Recently dislocations have been observed by electron microscopy in the icosahedral quasicrystalline (IQ) phase of Al65Cu20Fe15. These dislocations exhibit diffraction contrast similar to that known for dislocations in conventional crystals. The contrast becomes extinct for certain diffraction vectors g. In the following the basis of electron diffraction contrast of dislocations in the IQ phase is described. Taking account of the six-dimensional nature of the Burgers vector a “strong” and a “weak” extinction condition are found.Dislocations in quasicrystals canot be described on the basis of simple shear or insertion of a lattice plane only. In order to achieve a complete characterization of these dislocations it is advantageous to make use of the one to one correspondence of the lattice geometry in our three-dimensional space (R3) and that in the six-dimensional reference space (R6) where full periodicity is recovered . Therefore the contrast extinction condition has to be written as gpbp + gobo = 0 (1). The diffraction vector g and the Burgers vector b decompose into two vectors gp, bp and go, bo in, respectively, the physical and the orthogonal three-dimensional sub-spaces of R6.

Periodic distributions of dislocations

1964 ◽  
Vol 280 (1383) ◽  
pp. 528-544 ◽  
Keyword(s):  
Dimensional Space ◽  
Three Dimensional ◽  
Edge Length ◽  
Internal Stresses ◽  
Periodic Distribution ◽  
Stress And Deformation ◽  
The One ◽  
Distribution Of Dislocations ◽  
Distributed Dislocations ◽  
Three Dimensional Space

First, explicit expressions are obtained for the state of stress and deformation due to a periodic distribution of dislocations with respect to three-dimensional space and time. Further, equilibrium conditions for continuously distributed dislocations are derived from the law of energy conservation. The conditions are applied to determine several equilibrium states of periodic distributions. It was found that the distributions of edge and screw dislocations must have a phase difference of ½π when all the Burgers vectors are limited to the one direction. A sudden application of constant stress will cause the dislocations to move spontaneously to their new equilibrium positions. Also, an expression for dislocation velocity is established. In addition, expressions for internal stresses due to the periodic distribution of dislocations are used to find the stress field induced by a Frank network of dislocations. It was found that the normal stress acting on planes parallel to the network has a maximum value at a distance equal to one-half of the edge length of the hexagon of the net. The stress is propor­tional to the sum of the edge components of the three Burgers vectors at a node of the net­work, and decreases exponentially with distance from the network plane.

Strengthening of Gravity Load Designed Reinforced Concrete Frames with the External RC Shear Walls

2013 ◽  
Vol 747 ◽  
pp. 265-268 ◽  
Author(s):  
Fatih Bahadir ◽  
Mehmet Kamanli ◽  
Hasan Husnu Korkmaz ◽  
Fatih Suleyman Balik ◽  
Alptug Unal ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Shear Walls ◽  
Seismic Action ◽  
Concrete Frames ◽  
Building Stock ◽  
Existing Structures ◽  
Lateral Resistance ◽  
Gravity Load ◽  
Earthquake Zone ◽  
Rc Framed Structures

Turkey is situated on a very earthquake zone of the world namely Alp-Himalayan Earthquake Zone. Several destructive earthquakes resulted in high dead losses in the last century. Turkish building stock consisted of nonductile RC framed structures commonly 3 to 7 stories. The common properties of the existing structures is the poor lateral resistance. The residental buildings with poor earthquake resistance must be rehabilitated with a rapid, economical, feasible and effective strengthening methods. The external shear wall addition to the existing poor frame is studied experimentally in this study. 6 specimens were tested under reversed cyclic lateral loading simulating the seismic action. The first specimen was the reference specimen and didn't contain any strengthening and tested to see reference behaviour. The other specimens were strengthened with external shear walls with or without openings. The size of the openings is a parameter in the study. Secons specimen didn't contain any opening. Columns of the frames also jacketed with reinforced concrete. The maximum lateral load carrying capacity, ductility capacities, energy consuption capacities, improvement in the lateral rigidities were investigated.

Parametric Study on the Influence of Bays Number and Frame-Span Length on the Redundancy Indices of Reinforced Concrete Structures

2016 ◽  
Vol 845 ◽  
pp. 259-264
Author(s):  
Mutiara Puspahati Cripstyani ◽  
Stefanus Adi Kristiawan ◽  
Edy Purwanto
Keyword(s):  
Reinforced Concrete ◽  
Parametric Study ◽  
Load Distribution ◽  
Three Dimensional ◽  
Alternative Possibilities ◽  
Span Length ◽  
Reinforced Concrete Structure ◽  
Strength Index ◽  
Capacity Curves ◽  
Variation Index

The role of redundancy in a structure that receives earthquake load is very important. It provides alternative possibilities of load distribution in the event of a local collapse of the system before it reaches the total collapse of the structure. This mechanism of load distribution provides time for the users of the building to escape. A parametric study is carried out to investigate the effect of bays number and frame-span length in order to identify factors affecting the redundancy of the reinforced concrete structural system. Non-linear analysis (pushover) using SAP2000 on three-dimensional structural frames system are performed to obtain the capacity curves of the structures from which redundancies are calculated. Redundancy on the system is determined into two redundancy indices i.e. redundancy strength index (rs) and redundancy variation index (rv) which are, respectively, deterministic and probabilistic measure of the stuctural redundancy. This study points out that frame-span length has more significant effect on redundancy indices compared to the bays number. It is also shown that a reinforced concrete structure with a higher redundancy strength index tends to have a lower redundancy variation index.

GEOMETRIC REGULARIZATION AND GAUGE INVARIANCE IN CHERN–SIMONS THEORIES

1992 ◽  
Vol 07 (02) ◽  
pp. 235-256 ◽  
Author(s):  
MANUEL ASOREY ◽  
FERNANDO FALCETO
Keyword(s):  
Dimensional Space ◽  
Three Dimensional ◽  
Gauge Condition ◽  
Simons Theory ◽  
Coupling Constant ◽  
Gauge Transformations ◽  
Yang Mills ◽  
The One ◽  
Chern Simons ◽  
Three Dimensional Space

Some perturbative aspects of Chern–Simons theories are analyzed in a geometric-regularization framework. In particular, we show that the independence from the gauge condition of the regularized theory, which insures its global meaning, does impose a new constraint on the parameters of the regularization. The condition turns out to be the one that arises in pure or topologically massive Yang–Mills theories in three-dimensional space–times. One-loop calculations show the existence of nonvanishing finite renormalizations of gauge fields and coupling constant which preserve the topological meaning of Chern–Simons theory. The existence of a (finite) gauge-field renormalization at one-loop level is compensated by the renormalization of gauge transformations in such a way that the one-loop effective action remains gauge-invariant with respect to renormalized gauge transformations. The independence of both renormalizations from the space–time volume indicates the topological nature of the theory.

On the Interpretation of Vowel “Quality”: The Dimension of Rounding

1989 ◽  
Vol 19 (1) ◽  
pp. 24-30 ◽  
Author(s):  
Leigh Lisker
Keyword(s):  
Vocal Tract ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Vowel Space ◽  
Tongue Position ◽  
Two Measures ◽  
The One ◽  
Jaw Position ◽  
Three Dimensional Space

The usual description of vowels in respect to their “phonetic quality” requires the linguist to locate them within a so-called “vowel space,” apparently articulatory in nature, and having three dimensions labeled high-low (or close-open), front-back, and unrounded-rounded. The first two are coordinates of tongue with associated jaw position, while the third specifies the posture of the lips. It is recognized that vowels can vary qualitatively in ways that this three-dimensional space does not account for. So, for example, vowels may differ in degree of nasalization, and they may be rhotacized or r-colored. Moreover, it is recognized that while this vowel space serves important functions within the community of linguists, both the two measures of tongue position and the one for the lips inadequately identify those aspects of vocal tract shapes that are primarily responsible for the distinctive phonetic qualities of vowels (Ladefoged 1971). With all this said, it remains true enough that almost any vowel pair of different qualities can be described as occupying different positions with the space. Someone hearing two vowels in sequence and detecting a quality difference will presumably also be able to diagnose the nature of the articulatory shift executed in going from one vowel to the other.

scholarly journals Development of Seismic Fragility Functions for a Moment Resisting Reinforced Concrete Framed Structure

2016 ◽  
Vol 10 (1) ◽  
pp. 42-51 ◽  
Author(s):  
D. P. McCrum ◽  
G. Amato ◽  
R. Suhail
Keyword(s):  
Reinforced Concrete ◽  
Mechanical Model ◽  
Seismic Vulnerability ◽  
Fragility Curves ◽  
Pushover Analysis ◽  
Frame Structure ◽  
Building Structures ◽  
Reinforced Concrete Structure ◽  
Moment Resisting ◽  
Damage States

Understanding the seismic vulnerability of building structures is important for seismic engineers, building owners, risk insurers and governments. Seismic vulnerability defines a buildings predisposition to be damaged as a result of an earthquake of a given severity. There are two components to seismic risk; the seismic hazard and the exposure of the structural inventory to any given earthquake event. This paper demonstrates the development of fragility curves at different damage states using a detailed mechanical model of a moment resisting reinforced concrete structure typical of Southern Europe. The mechanical model consists of a complex three-dimensional finite element model of the reinforced concrete moment resisting frame structure and is used to define the damage states through pushover analysis. Fragility curves are also defined using the HAZUS macro-seismic methodology and the Risk-UE macro-seismic methodology. Comparison of the mechanically modelled and HAZUS fragility curve shows good agreement while the Risk-UE methodology shows reasonably poor agreement.

scholarly journals Building and design defects observed in the residential sector and the types of damage observed in recent earthquakes in Turkey

2015 ◽  
Vol 3 (1) ◽  
pp. 697-760
Author(s):  
M. Tolga Çöğürcü
Keyword(s):  
Reinforced Concrete ◽  
Residential Buildings ◽  
Economic Losses ◽  
Structural Systems ◽  
Building Stock ◽  
Van Earthquake ◽  
Soft Story ◽  
Short Columns ◽  
Concrete Quality ◽  
Recent Earthquakes

Abstract. Turkey is situated in a very active earthquake region. In the last century, several earthquakes resulted in thousands of deaths and enormous economic losses. In 1999, the Marmara earthquake had an approximate death toll of more than 20 000, and in 2011, the Van earthquake killed 604 people. In general, Turkish residential buildings have reinforced concrete structural systems. These reinforced concrete structures have several deficiencies, such as low concrete quality, non-seismic steel detailing, and inappropriate structural systems including several architectural irregularities. In this study, the general characteristics of Turkish building stock and the deficiencies observed in structural systems are explained, and illustrative figures are given with reference to Turkish Earthquake Code 2007 (TEC, 2007). The poor concrete quality, lack of lateral or transverse reinforcement in beam-column joints and column confinement zones, high stirrup spacings, under-reinforced columns and over-reinforced beams are the primary causes of failures. Other deficiencies include weak column-stronger beam formations, insufficient seismic joint separations, soft story or weak story irregularities and short columns. Similar construction and design mistakes are also observed in other countries situated on active earthquake belts. Existing buildings still have these undesirable characteristics, so to prepare for future earthquakes, they must be rehabilitated.

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