Recent researches have shown that under cyclic loading an early crack initia- tion and subsequent... more Recent researches have shown that under cyclic loading an early crack initia- tion and subsequent crack propagation occurs at the weld collar of headed shear studs trans- ferring the longitudinal shear forces between steel and concrete. This results in a decrease of the static resistance of the studs and the structure and clearly indicates that the static and fati- gue resistance of composite steel-concrete structures should not be considered as separate lim- it states which is the case in most design codes. This paper deals with the results of a series of experimental work with more than 90 standard EC4-push-out test specimens and two full scale-beam tests which considers the crack propagation through the stud foot and the local damage of concrete surrounding the studs as relevant consequences of high cycle loading. Based on the test results new design method to predict the residual strength of headed shear studs after high cycle loading were developed. Additionally an improved dam...
La resistance statique et a la fatigue des structures mixtes acier-beton est prise en compte dans... more La resistance statique et a la fatigue des structures mixtes acier-beton est prise en compte dans la plupart des codes de dimensionnement au moyen de deux verifications separees pour l'etat limite ultime et l'etat limite de fatigue. La transmission du cisaillement longitudinal au niveau de l'interface acier-beton est le plus souvent assuree par des goujons connecteurs qui - particulierement dans les ponts - sont soumis a des charges cycliques elevees provoquees par les charges de trafic. Cet article concerne les resultats d'une serie de travaux experimentaux effectues sur des echantillons au moyen d'essais de type push-out conformes a l'EC4 afin de determiner la duree de vie a la fatigue et l'eventuelle reduction de la resistance statique des goujons soumis a un chargement cyclique unidirectionnel. Sur la base des resultats obtenus lors de ces essais, les essais push-out realises a l'echelle internationale pour determiner la duree de vie a la fatigue ...
Haydarpasa Railway Station, a well-known symbolic gateway to the metropolitan city Istanbul, was ... more Haydarpasa Railway Station, a well-known symbolic gateway to the metropolitan city Istanbul, was built at the beginning of the 20th century. It was designed by the architects Otto Ritter and Helmuth Conu and built by the German construction company Philipp Holzmann. The neo-classical structure is the first station of the Anatolian Railroad and an important piece of Turkish cultural heritage. Following the fire in 2010 that caused serious damages on the central and northern parts of the roof, restoration of the building was initiated. Detailed structural and architectural site investigations were performed in order to identify structural weaknesses such as material flaws, cracking, and inappropriate interventions. This study deals generally with the structural analysis and evaluation of the station based on numerical analyses. In order to examine the seismic performance of the structure, a finite element model of the existing structural system was created and analyzed using a finite ...
In current national and international standards of composite structures of steel and concrete the... more In current national and international standards of composite structures of steel and concrete the determination of the ultimate load capacity and the fatigue life of headed shear studs takes place with separate and independent verifications at the ultimate limit state, serviceability limit state and fatigue limit state. The effect of pre-damage due to fatigue loading is not considered. This paper deals with the results of a comprehensive program of experimental work with more than 90 standard EC4-push-out test specimens and two full scale-beam tests which consider the crack propagation through the stud foot and the local damage of concrete surrounding the studs as relevant consequences of high cycle loading. Based on the results of the push-out tests, new design methods were developed to predict the fatigue life and the residual strength of headed shear studs after high cycle loading. Considering the interaction between the local damage and the behaviour of the global structure, the...
In recent years, FRCM systems have become a preferred strengthening system in reinforced concrete... more In recent years, FRCM systems have become a preferred strengthening system in reinforced concrete structures together with masonry structures. The most important factor in the choice of FRCM as a strengthening system is its compatibility with concrete or masonry substrates. In addition, high fire resistance is an important factor in their preference. The components of FRCM composites are known to have high durability separately. However, the durability of composites, composed of a combination of fabric and matrices is still a matter of no detailed reported knowledge. In this experimental study, the durability properties of FRCM composites with lime matrix reinforced with glass and glass-polypropylene hybrid fabrics were investigated. Composite samples were subjected to tensile and bending tests before and after freeze thaw cycles. Load-deformation relations were obtained. As a result of the experimental study, the following results can be drawn: Following freeze thaw cycles, reducti...
In current German and international standards for composite structures of steel and concrete, the... more In current German and international standards for composite structures of steel and concrete, the determination of the ultimate load capacity and the fatigue life of headed shear studs is carried out with separate and independent verifications at the ultimate, serviceability and fatigue limit states. The fatigue resistance is verified in a similar way to steel structures, based on a nominal stresses concept and linear damage accumulation according to Palmgren-Miner. The effect of pre-damage due to fatigue loading at both the ultimate and serviceability limit states is not considered. Because cyclic loading of headed shear studs leads to a decrease in the static strength of stud connectors, the assumptions for independent limit states are not given and the reliability index of steel-concrete composite structures subjected to fatigue loading may fall below the target values in codes. This paper deals with the results of a comprehensive programme of experimental work with more than 90 standard EC4 push-out test specimens and two full-scale beam tests which consider the crack propagation through the stud foot and the local damage to the concrete surrounding the studs as relevant consequences of highcycle loading. Based on the results of the push-out tests, new design methods were developed to predict the fatigue life and the residual strength of headed shear studs after high-cycle loading. Considering the interaction between the local damage and the behaviour of the global structure, these research results were taken as the basis for simulating the cyclic behaviour of composite beams by means of a damage accumulation method.
Periodical monitoring and maintenance is a necessity for timber buildings to prevent severe damag... more Periodical monitoring and maintenance is a necessity for timber buildings to prevent severe damage and problems. Unfortunately, there is a lack of maintenance of timber buildings and this would become to a critical point if the building stays vacant or neglected for a period of time. Even the situation of the structure is not severe, during the preparation of conservation projects assessment of the timber structure becomes a necessity for accurate interventions. This paper would try to present the main problems of the timber buildings that have been investigated in the Bosporus area in the previous years in these terms. In the context, architectural loss, material loss and structural deformations of the investigated buildings would be described in detail. The paper also aims to display the difficulties that has to be braced during the assessment and the results of the mechanical tests including flexural and compressive strength carried out on the timber samples taken from different buildings with various health conditions in order to make a conclusion for an assessment method.
Recent researches have shown that under cyclic loading an early crack initia- tion and subsequent... more Recent researches have shown that under cyclic loading an early crack initia- tion and subsequent crack propagation occurs at the weld collar of headed shear studs trans- ferring the longitudinal shear forces between steel and concrete. This results in a decrease of the static resistance of the studs and the structure and clearly indicates that the static and fati- gue resistance of composite steel-concrete structures should not be considered as separate lim- it states which is the case in most design codes. This paper deals with the results of a series of experimental work with more than 90 standard EC4-push-out test specimens and two full scale-beam tests which considers the crack propagation through the stud foot and the local damage of concrete surrounding the studs as relevant consequences of high cycle loading. Based on the test results new design method to predict the residual strength of headed shear studs after high cycle loading were developed. Additionally an improved dam...
La resistance statique et a la fatigue des structures mixtes acier-beton est prise en compte dans... more La resistance statique et a la fatigue des structures mixtes acier-beton est prise en compte dans la plupart des codes de dimensionnement au moyen de deux verifications separees pour l'etat limite ultime et l'etat limite de fatigue. La transmission du cisaillement longitudinal au niveau de l'interface acier-beton est le plus souvent assuree par des goujons connecteurs qui - particulierement dans les ponts - sont soumis a des charges cycliques elevees provoquees par les charges de trafic. Cet article concerne les resultats d'une serie de travaux experimentaux effectues sur des echantillons au moyen d'essais de type push-out conformes a l'EC4 afin de determiner la duree de vie a la fatigue et l'eventuelle reduction de la resistance statique des goujons soumis a un chargement cyclique unidirectionnel. Sur la base des resultats obtenus lors de ces essais, les essais push-out realises a l'echelle internationale pour determiner la duree de vie a la fatigue ...
Haydarpasa Railway Station, a well-known symbolic gateway to the metropolitan city Istanbul, was ... more Haydarpasa Railway Station, a well-known symbolic gateway to the metropolitan city Istanbul, was built at the beginning of the 20th century. It was designed by the architects Otto Ritter and Helmuth Conu and built by the German construction company Philipp Holzmann. The neo-classical structure is the first station of the Anatolian Railroad and an important piece of Turkish cultural heritage. Following the fire in 2010 that caused serious damages on the central and northern parts of the roof, restoration of the building was initiated. Detailed structural and architectural site investigations were performed in order to identify structural weaknesses such as material flaws, cracking, and inappropriate interventions. This study deals generally with the structural analysis and evaluation of the station based on numerical analyses. In order to examine the seismic performance of the structure, a finite element model of the existing structural system was created and analyzed using a finite ...
In current national and international standards of composite structures of steel and concrete the... more In current national and international standards of composite structures of steel and concrete the determination of the ultimate load capacity and the fatigue life of headed shear studs takes place with separate and independent verifications at the ultimate limit state, serviceability limit state and fatigue limit state. The effect of pre-damage due to fatigue loading is not considered. This paper deals with the results of a comprehensive program of experimental work with more than 90 standard EC4-push-out test specimens and two full scale-beam tests which consider the crack propagation through the stud foot and the local damage of concrete surrounding the studs as relevant consequences of high cycle loading. Based on the results of the push-out tests, new design methods were developed to predict the fatigue life and the residual strength of headed shear studs after high cycle loading. Considering the interaction between the local damage and the behaviour of the global structure, the...
In recent years, FRCM systems have become a preferred strengthening system in reinforced concrete... more In recent years, FRCM systems have become a preferred strengthening system in reinforced concrete structures together with masonry structures. The most important factor in the choice of FRCM as a strengthening system is its compatibility with concrete or masonry substrates. In addition, high fire resistance is an important factor in their preference. The components of FRCM composites are known to have high durability separately. However, the durability of composites, composed of a combination of fabric and matrices is still a matter of no detailed reported knowledge. In this experimental study, the durability properties of FRCM composites with lime matrix reinforced with glass and glass-polypropylene hybrid fabrics were investigated. Composite samples were subjected to tensile and bending tests before and after freeze thaw cycles. Load-deformation relations were obtained. As a result of the experimental study, the following results can be drawn: Following freeze thaw cycles, reducti...
In current German and international standards for composite structures of steel and concrete, the... more In current German and international standards for composite structures of steel and concrete, the determination of the ultimate load capacity and the fatigue life of headed shear studs is carried out with separate and independent verifications at the ultimate, serviceability and fatigue limit states. The fatigue resistance is verified in a similar way to steel structures, based on a nominal stresses concept and linear damage accumulation according to Palmgren-Miner. The effect of pre-damage due to fatigue loading at both the ultimate and serviceability limit states is not considered. Because cyclic loading of headed shear studs leads to a decrease in the static strength of stud connectors, the assumptions for independent limit states are not given and the reliability index of steel-concrete composite structures subjected to fatigue loading may fall below the target values in codes. This paper deals with the results of a comprehensive programme of experimental work with more than 90 standard EC4 push-out test specimens and two full-scale beam tests which consider the crack propagation through the stud foot and the local damage to the concrete surrounding the studs as relevant consequences of highcycle loading. Based on the results of the push-out tests, new design methods were developed to predict the fatigue life and the residual strength of headed shear studs after high-cycle loading. Considering the interaction between the local damage and the behaviour of the global structure, these research results were taken as the basis for simulating the cyclic behaviour of composite beams by means of a damage accumulation method.
Periodical monitoring and maintenance is a necessity for timber buildings to prevent severe damag... more Periodical monitoring and maintenance is a necessity for timber buildings to prevent severe damage and problems. Unfortunately, there is a lack of maintenance of timber buildings and this would become to a critical point if the building stays vacant or neglected for a period of time. Even the situation of the structure is not severe, during the preparation of conservation projects assessment of the timber structure becomes a necessity for accurate interventions. This paper would try to present the main problems of the timber buildings that have been investigated in the Bosporus area in the previous years in these terms. In the context, architectural loss, material loss and structural deformations of the investigated buildings would be described in detail. The paper also aims to display the difficulties that has to be braced during the assessment and the results of the mechanical tests including flexural and compressive strength carried out on the timber samples taken from different buildings with various health conditions in order to make a conclusion for an assessment method.
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