Papers by THEODOROS CHRYSANIDIS
8th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering Methods in Structural Dynamics and Earthquake Engineering, 2021
Many times, either the research engineer or the design engineer needs to model reinforced concret... more Many times, either the research engineer or the design engineer needs to model reinforced concrete (R/C) structural elements in order to study their behavior. In the present research work, an attempt is made to study the correct way of modeling a reinforced concrete column using the finite element ANSYS software. Three-dimensional finite elements are used to model the column. The results of the column modeling and analysis using ANSYS software are compared with the corresponding experimental results of a column with the same geometric characteristics and the same material and load properties as those of the analytical modeling. The only difference between the analytical column modeling and the experimental specimen is the difference in the loading rate. The analytical and experimental results are compared with each other. The influence of the loading rate as well as the mesh method is examined. Useful conclusions are drawn regarding the influence of the loading rate and the mesh method on the behavior and results of reinforced concrete components.
Proceedings of the 6th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COMPDYN 2015), 2017
Several researchers propose placing diagonal reinforcing bars at the base of the wall to treat th... more Several researchers propose placing diagonal reinforcing bars at the base of the wall to treat the shear slip, while others have suggested various ways to address this problem associated with the halting of the effects incurred by the through-crack in the base of the wall during recycling of loading. An indicative proposal of the bibliography is using large diameter reinforcement bars in the web of the wall as vertical reinforcements, so that through the dowel action of these bars to be able to better control the shear action. The two aforementioned proposals, while adequately address the phenomenon of shear slip, present significant disadvantages: The use of diagonal reinforcement is very difficult to be constructed, because of the density of existing reinforcement in the base of the walls, which involves compromising good concrete condensation. Also, the use of large diameter vertical reinforcement along the length of the whole wall section, including its web, leads to a strongly uneconomical solution. This works examines a solution without the aforementioned side effects. Innovation of the present work is the fact that it positions stoppers in combination with the use of conventional reinforcing bars at positions of the critical zones of the walls, in order to further prevent the expected slip along the through-crack in the base of the rigidly supported wall. The work is mainly experimental and includes investigation of the seismic mechanical properties of a wall specimen with conventional reinforcement according to EC8. This study presents the investigation on the effect of the shear span as resistance parameter, on the design of concrete interfaces. In the first part of the study the shear transfer between concrete interfaces, in which the value of the shear span is equal to zero, is investigated. The experimental investigation is extended to include values of the shear span greater than zero. These values are usually observed at bridge seismic stoppers. The experimental results presented in this study are used to derive an analytical expression of the resistance of bridge seismic stoppers.
Sustainability, 2022
Greece is divided into three earthquake hazard zones: Zone I, Zone II and Zone III. In the presen... more Greece is divided into three earthquake hazard zones: Zone I, Zone II and Zone III. In the present research work, the same building in the three seismic zones in Greece was modeled, analyzed and dimensioned. Then, the construction cost of its structural body was estimated. The building modeling was performed in SAP2000 using frame elements. The analysis of the building was performed by dynamic spectral analysis methods using the design spectrum EC8. A five-story building with a standard rectangular floor plan per floor was used. The purpose of this research
paper is to demonstrate whether the cost of construction of a load-bearing body of a reinforced concrete (R/C) building is influenced by the area of an earthquake hazard through a comparative analytical estimation of construction costs. It was determined if this impact is important and to what extent. Helpful conclusions were drawn in relation to the influence of seismicity on the construction cost of the load-bearing structure of R/C buildings. Furthermore, the probable environmental impact was examined.
Case Studies in Construction Materials, 2022
The safe design of modern structures against earthquake excitation is a matter that troubles cons... more The safe design of modern structures against earthquake excitation is a matter that troubles consultant engineers worldwide. Given the random nature of crack formation, research into reinforced concrete members, in the context of cracking behavior, has proved difficult. Sometimes, depending on the crack width and spacing, cracking can affect general behavior and, specifically, the seismic behavior of reinforced concrete in multi-story buildings. Widely accepted methodologies for predicting crack characteristics, e.g. crack width and spacing and number of cracks, have not been developed yet. Furthermore, the phenomenon of cracking in highly-strained members, which takes place during earthquakes, needs to be investigated more. The characteristics of cracks affect the appearance of catastrophic phenomena, e.g. transverse buckling of reinforced concrete structural walls. In the context of the present work, the impact of the mechanical factors of tensile deformation is investigated, in terms of cracking behavior. Eight test specimens were divided into two groups according to their longitudinal reinforcement ratio (1.79% and 3.19%) and strained under uniaxial tensile loading. The degrees of elongation used were equal to 10‰, 20‰, 30‰ and 50‰. Extreme tensile strains were also used, e.g. 30‰ and 50‰, in order to take into account the cases of extreme seismic excitations. Apart from the investigation of the tensile strain factor, this work also examines the influence of the rebar content. The test results can be used to establish an experimental database, in order to develop an empirical equation that can forecast the quantity of cracks, their width and spacing. The experimental study is followed by an analytical investigation that aims to develop an empirical equation, predicting the average width of cracks. The results are basically given in terms of diagrams showing the development of cracking characteristics in relation to the tensile strain applied. Useful conclusions concerning cracking behavior are derived.
WSEAS Transactions on Applied and Theoretical Mechanics, 2021
The factors that determine the geotechnical behavior of soils are mainly their composition, the s... more The factors that determine the geotechnical behavior of soils are mainly their composition, the size of their grains and their moisture content. The design of a soil structure or foundation project must ensure the shear adequacy of the soil in all phases of construction and throughout the life of the project. However, the shear strength, in general, of the soil is not "constant" but depends on key external factors such as the prehistory of loads, the time and succession of load states, the overpressure of the pore water as well as other factors such as relative density, or any preload, the pressure field, the rate of change of the intensive state, etc. The influence of the deformations as well as the change of the intensive state during the sampling should not be ignored. Unlike other materials, in clay materials the determination of shear strength and its interpretation is a very complex problem. The aim of this article is to search for the mechanical behavior of clay soils (lignite, kaolinite, marl) as shown by the laboratory illustration related with the problems on shear strength of materials, based on the results of experimental research.
WSEAS Transactions on Advances in Engineering Education, 2021
The behavior of soil either as a building material or as a load receiver is particularly importan... more The behavior of soil either as a building material or as a load receiver is particularly important and presents a paramount significance in both infrastructure and building construction. Geotechnical engineering has shown a rapid development over the last fifty years and holds a prominent position in all scientific fields of engineers. This paper mainly aims at the historical background along with the progress made on Soil Engineering as an important branch of Surveyors, Civil and Mining Engineers, where, through an important citation of technical works and constructions over time, may be considered as a significant tool for teaching and education of students.
WSEAS Transactions on Advances in Engineering Education, 2021
In engineering, the foundation is a special element of a building. It is the connecting part with... more In engineering, the foundation is a special element of a building. It is the connecting part with the soil, which transfers loads from the structure to the ground, so that they are distributed on a wider area, thus avoiding high levels of soil stresses. Furthermore, they help the structure to withstand various natural forces like earthquakes, floods, tornadoes, and also to anchor the structure into the ground, thus increasing its stability. Over time, people aim to build elaborate structures, first to facilitate the standard living and then, utilizing this primary purpose, to make a substantial contribution to the progress and development of science, through the discovery of new methods. This work aims to briefly record, analyze, and comment on special cases of building foundations and infrastructure projects that are in line with modern requirements of research and technology. The work furthermore presents the advantages of static and seismic behavior of the foundations which may present significant structures over similar ones of the same or smaller scale. There was an effort to develop and comment on the information which explains the general nature of the foundations with their evolutionary activity. These concepts, combined with a description of the typical building or infrastructure project, with their characteristics may be a powerful tool not only for future constructions and research but mainly for education. The work also emphasizes the connection between theory and practice.
IOSR Journal of Mechanical and Civil Engineering, 2014
The current work investigates one of the most basic parameters affecting the stability of structu... more The current work investigates one of the most basic parameters affecting the stability of structural walls, which is (apart from the wall thickness) the degree of tensile strain of the longitudinal reinforcement of the boundary edges of load-bearing walls. The present work is experimental and in its framework, 5 test specimens of scale 1:3 simulating the boundary edges of structural walls were used. These specimens were reinforced with the same amount of reinforcement equal to a high longitudinal reinforcement ratio (3.68%). The degree of tensile strain applied was different for each specimen and it took values equal to 0‰, 10‰, 20‰, 30‰ and 50‰. The present research work tries to investigate the influence of the degree of tensile strain to the ultimate bearing capacity of walls using test specimens detailed with a high longitudinal reinforcement ratio.
European Academic Research, 2014
Framing walls within the framework of the structure of a building aims at: (a) the receipt by the... more Framing walls within the framework of the structure of a building aims at: (a) the receipt by them of a large part of the seismic loads and (b) a drastic reduction of seismic displacements of the 3D frame system. Both indirectly contribute to the effective protection of the existing supporting structure with the most economical way. In pursuit of a pre-estimation of the walls' cross-sections, a strengthening methodology is proposed based on the displacements of existing spatial system. According to this methodology, using linear analysis and the spectral response method, seismic stresses (corresponding to the admissible performance) of the vertical components of the existing supporting structure are determined. Then based on these stresses and their corresponding strength using a certain procedure, loads and safety displacements of the supporting structure are determined. If the displacements of the existing supporting structure for the aforementioned loads, as typically happens, are larger than the safety displacements of the structure, then the reduction of the displacements of the existing supporting structure is aimed through the construction of walls inside existing frames at locations specified according to technical and economic criteria. The amount of the walls to be constructed is proportional to the gap between safety displacements and design displacements. The methodology is applied in the case of a building designed according to the Greek Seismic Code of 1959 and for two expected performance levels according to ΚΑΝΕΠΕ (Greek Retrofitting Code).
International Journal of Civil Engineering and Technology (IJCIET), 2014
In the past few years, a concern is observed internationally regarding the seismic mechanical beh... more In the past few years, a concern is observed internationally regarding the seismic mechanical behavior of reinforced concrete walls, especially against their transverse instability under extreme seismic loads. The present work is experimental and examines the influence of tensile strain on out-of-plane buckling of reinforced concrete seismic walls. The experimental work herein consists of 5 scaled test specimens simulating the end regions of structural walls. These specimens were reinforced with the same high longitudinal reinforcement ratio (3.68%). The degree of tensile strain applied was different for each specimen and it took values equal to 0‰, 10‰, 20‰, 30‰ and 50‰. The present work tries to investigate the influence of the degree of tensile strain to the displacements (horizontal and vertical) and the modes of failure of test specimens.
Journal of Civil Engineering and Architecture, 2014
It is known that the slabs on soil constitute one of the most difficult types of structures despi... more It is known that the slabs on soil constitute one of the most difficult types of structures despite their apparent simplicity. The objective of this paper is to give a general survey of the design of ground supported slabs with the interposition of a suitable subbase. A solution is proposed with the following characteristics: (1) complete suppression of joints; (2) conventional reinforcement with meshes in the upper and lower fiber of the slab in order to confront and distribute cracking that is caused by hindrance of free contractions and expansions; (3) effective confrontation of problems of bulging. The proposal is in effect on one hand for industrial floorings and on the other hand for concrete pavings with large durability requirement.
International Journal of Scientific and Engineering Research, 2014
Columns of a rectangular cross-section with interlocking spirals are the latest development in br... more Columns of a rectangular cross-section with interlocking spirals are the latest development in bridge-building, where they are applied on piers of high earthquake-resistance requirements. This method can be applied also on soft stories of buildings, like pilotis. Flexural behavior of structural elements with interlocking spirals, but mainly their behavior due to shear, must be further investigated, both analytically and experimentally. This study refers to these problems, comprising an experimental and an analytical part. More precisely in the experimental part, the response of columns and beams with interlocking spirals is compared to the response of conventionally reinforced ones. Useful conclusions are drawn on the performance of these structural elements with the proposed reinforcement arrangement.
International Journal of Civil Engineering and Technology (IJCIET), 2016
Large tensile deformations are expected in the walls' plastic hinge region of their base, dependi... more Large tensile deformations are expected in the walls' plastic hinge region of their base, depending on their geometric characteristics and their level of ductility design. Due to the cycling nature of loading, these tensile deformations, depending on their size, can cause lateral instability of seismic walls. The present work investigates experimentally one of the most crucial parameters affecting the stability of structural walls, which is the degree of tensile strain of the longitudinal reinforcement of the extreme edges of RC shear walls. Its influence to strength and failure is investigated using 5 test specimens reinforced with the same longitudinal reinforcement ratio (3.19%) but strained to different degrees of elongation.
International Journal of Trend in Research and Development (IJTRD), 2016
Depending on the geometric characteristics and the level of ductility design of walls, large tens... more Depending on the geometric characteristics and the level of ductility design of walls, large tensile deformations are expected to the R/C structural walls designed and detailed according to modern international seismic codes. These tensile deformations can cause their lateral instability depending on their size. The current work investigates one of the most basic parameters affecting the stability of structural walls, which is (apart from the wall thickness) the degree of tensile strain of the longitudinal reinforcement of the boundary edges of load-bearing walls. The present work is experimental and tries to investigate the influence of the degree of tensile strain to the displacements and the modes of failure of test specimens. 5 test specimens of scale 1:3 simulating the boundary edges of structural walls were used. These specimens were reinforced with the maximum code-prescribed longitudinal reinforcement ratio (4.02%) and they all had the same reinforcement ratio. The degree of elongation which was applied was different for each specimen and it took values equal to 0‰, 10‰, 20‰, 30‰ and 50‰.
International Journal of Science and Engineering Investigations (IJSEI), 2016
The past few years, it has become explicit that failure due to transverse instability is difficul... more The past few years, it has become explicit that failure due to transverse instability is difficult to be observed in actual structures after the event of seismic excitation, even if it is certain that it exists as phenomenon and can even lead to general collapse of structures. Consequently, because of the big importance of transverse instability and the role that plays in the seismic behavior and safety of constructions, a sedulous study is required about the mechanism of occurrence of this phenomenon and the factors that lead to its growth. The present work is experimental and consists of 5 test specimens of scale 1:3 simulating the boundary edges of structural walls. These specimens were reinforced with the same low longitudinal reinforcement ratio (1.79%). The degree of elongation applied was different for each specimen. The present paper tries to investigate the influence of the degree of elongation to the displacements and the modes of failure of test specimens.
International Journal of Engineering Development and Research (IJEDR), 2016
The past few years, it has become explicit that failure due to transverse instability is difficul... more The past few years, it has become explicit that failure due to transverse instability is difficult to be observed in actual structures after the event of seismic excitation, even if it is certain that it exists as phenomenon and can even lead to general collapse of structures. Consequently, because of the big importance of transverse instability and the role that plays in the seismic behavior and safety of constructions, a sedulous study is required about the mechanism of occurrence of this phenomenon and the factors that lead to its growth. The present work is experimental and consists of 5 test specimens of scale 1:3 simulating the boundary edges of structural walls. These specimens were reinforced with the same medium high longitudinal reinforcement ratio (3.19%). The degree of elongation applied was different for each specimen. The present paper tries to investigate the influence of the degree of elongation to the displacements and the modes of failure of test specimens.
International Journal of Civil Engineering and Technology (IJCIET), 2016
In the framework of the current work, a design proposal for a high-rise building is investigated.... more In the framework of the current work, a design proposal for a high-rise building is investigated. This design proposal for the structural system of the high-rise building is the type of a braced shear wall core system. First, a preliminary design for the design proposal in question takes place. Afterwards, a parametrical cost analysis of the building's structural system takes place based on the member sections derived from the final detailed design of the building. Finally, based on the aforementioned preliminary design and the parametrical cost analysis, several conclusions are stated concerning the usefulness of the preliminary design and the huge number of parameters affecting the cost estimation of a building.
International Journal of Engineering Research & Technology (IJERT), 2016
This work analyzes a tall building using two different design methods. One is the preliminary des... more This work analyzes a tall building using two different design methods. One is the preliminary design and the other is the final design. The structural system used for supporting the building is a widely used worldwide system of the type of a brace shear wall core system. The preliminary analysis takes place using hand calculations while the final analysis takes place using computer software suitable for static and dynamic analysis and design. After analysis and design have taken place for both methods (preliminary and detailed method), the calculation of the cost for the reinforced concrete part of the structural system takes place. The reinforced concrete part has to do basically with the shear wall core placed at the center of the tall building in question. A parametrical comparison of the cost of the reinforced concrete part of the structural system leads to useful conclusions.
International Journal of Applied Engineering Research (IJAER), 2016
The present work analyzes parametrically the cost of an ultra high-rise building after the final ... more The present work analyzes parametrically the cost of an ultra high-rise building after the final and detailed design has taken place. Also, although this is not the major reason of the present research, it proposes a structural system for this kind of buildings, meaning the ultra high-rise ones. A braced shear wall core system is proposed as the structural system that supports the building in question. At the beginning of this work, a detailed design of the proposed structural system takes place. Having calculated the required sections of the building's frame members, a parametrical cost analysis of the building's structural system takes place based on the member sections derived from the final design of the building. Conclusions, at the final part of this paper, have to do with: (a) The usefulness of the braced shear wall core system as main system for this kind of buildings, (b) The parameters which affect the cost of such buildings and how they interrelate between each other.
ARPN Journal of Engineering and Applied Sciences (ARPN JEAS), 2016
In the past few years, a concern is observed internationally regarding the seismic mechanical beh... more In the past few years, a concern is observed internationally regarding the seismic mechanical behavior of reinforced concrete walls, especially against their transverse instability under extreme seismic loads. This is one of the reasons that relevant code provisions for minimum wall thickness exist in several modern international codes, as is e.g. EC8: 2004, NZS 3101: 2006. Consequently, because of the big importance of transverse instability and the role that plays in the seismic behavior and safety of constructions, a sedulous study is required about the mechanism of occurrence of this phenomenon and the factors that lead to its growth. The present work is experimental and tries to investigate the influence of the degree of elongation to the displacements (horizontal and vertical) and the modes of failure of test specimens using 5 test specimens with the same longitudinal reinforcement ratio (6.03%) but strained to different degrees of elongation.
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Papers by THEODOROS CHRYSANIDIS
paper is to demonstrate whether the cost of construction of a load-bearing body of a reinforced concrete (R/C) building is influenced by the area of an earthquake hazard through a comparative analytical estimation of construction costs. It was determined if this impact is important and to what extent. Helpful conclusions were drawn in relation to the influence of seismicity on the construction cost of the load-bearing structure of R/C buildings. Furthermore, the probable environmental impact was examined.