As a general trend, in order to reduce material consumption or to reduce the mass of the structur... more As a general trend, in order to reduce material consumption or to reduce the mass of the structures, composite floor slabs solutions are used to achieve large spans floor slabs. This solutions led to floors sensitive to vibrations induced generally by human activities. As a verification of the design concepts of the composite floors, usually, it is recommended a further examination of the floor after completion by experimental tests. Although the experimental values of the dynamic response of the floor are uniquely determined, the processing can take two directions of evaluation. The first direction consist in determining the dynamic characteristics of the floor and their comparison with the design values. Another way that can be followed in the processing of the experimental results is to consider the human perception and comfort to the vibration on floors. The paper aims to present a case study on a composite floor, with steel beams and concrete slab, tested on-site. Both aspects ...
In case of laminated glass strips, the mechanical characteristics of the composite element are di... more In case of laminated glass strips, the mechanical characteristics of the composite element are different from the values that are obtained for the same element from a homogeneous and isotropic material. The experimental tests presented in the paper aims to determine the mechanical characteristics of laminated glass strips used to make a staircase. For the experiment, quasi-static and dynamic tests were conducted on different glass stair steps, made from normal and tempered glass, with different number and thicknesses glass sheets. The paper presents the carrying out conditions for the experiments, the synthesis of data processing and comments on the experimental results. Experimental test results led to the constructive solution of the glass staircase steps. For staircase building up, tempered glass was chosen and the values obtained for the mechanical properties, strength and deformation capacity of the system were used in its design. Whole set of experimental tests led to a succes...
Dynamic testing of road bridges is vaguely national regulated. As result, the importance and the ... more Dynamic testing of road bridges is vaguely national regulated. As result, the importance and the necessity of static and dynamic tests is diminished by various factors, human, technic or economic ones. The standard which regulates the experimental testing of rail and road bridges in Romania is STAS 12504-86. For the dynamic testing case, the Romanian standard provides some information on how to ensure the dynamic loading of bridges, it enumerates some of the characteristics that can be pursued through testing, but without giving information on how to process experimental data. The present paper illustrates a dynamic test of a road bridge, located on the A2 highway crossing the Danube-Black Sea Channel. There are presented bearings about the testing conditions, the experimental test results and a comparison with the bridge design values. The experimental results are proximate to the dynamic characteristics established in the bridge design, test algorithm and experimental data process...
In this paper, a rail joint model consisting of three Euler-Bernoulli beams connected via a Winkl... more In this paper, a rail joint model consisting of three Euler-Bernoulli beams connected via a Winkler foundation is proposed in order to point out the influence of the joint gap length upon the stiffness of the rail joint. Starting from the experimental results aiming the stiffness of the rail joint, the Winkler foundation stiffness of the model has been calculated. Using the proposed model, it is shown that the stiffness of the rail joint of the 49 rail can decreases up to 10 % when the joint gap length increases from 0 to 20 mm.
The testing program of the bridges before commissioning is mandatory for almost all the bridges. ... more The testing program of the bridges before commissioning is mandatory for almost all the bridges. Usually, for bridges with small spans and a simple structural type, the testing program consists only from static loading tests. When special building technologies, materials or structural models are involved in the bridge building, the dynamic testing of the bridge is required, also. The overpass from the Câmpina city entrance consists of a main passage with two lanes and, at the ends, four access roads with one lane each. The overpass is divided in five sections, acting as independent structures. These are composed from steel piers with composite decks. Each composite deck is made from a main steel girder with cross steel girders and reinforced concrete slab. Taking into account the curved shape of the bridge and the special structural type of the bridge, it was required an extended dynamic testing program, for every section of the bridge. This paper presents the dynamic test condition...
As result of the efficiency of seismic isolation to seismic actions highlighted during seismic ev... more As result of the efficiency of seismic isolation to seismic actions highlighted during seismic events, over the last 20 years the base isolation method has experienced a huge applicability. However, in Romania this method has not grown very much due the special characteristics of Vrancea earthquakes. Seismic isolation system is composed of isolator bearings, with large horizontal deformation capacity and high vertical load capacity, and damping devices. Thus isolators can take earthquake-induced displacements. This paper aims to highlight the effectiveness of base isolation systems by modeling the three structures, which has different fundamental periods of vibration, applied to a recorded seismic action (INCERC March 1977). Three target periods of isolation system were chosen and there were calculated the characteristics of the isolators. For each structure, and isolation system were compared displacements at the top and the base shear, showing the effectiveness of the isolation sy...
The paper studies the influence of an optimal inter-storey isolation system on seismic behaviour ... more The paper studies the influence of an optimal inter-storey isolation system on seismic behaviour of a concrete structure. The inter-storey isolation system uses lead rubber bearings at a certain level of the structure. The structure will be subjected to a series of pulse like earthquakes in order to account for the variability of the hazard of the Vrancea source. The article will study a concrete structure which will be modelled using finite element software. The parameters and location of the story isolation system will be studied and optimized using genetic algorithms. The optimization will be applied in order to minimise displacements. The parameters which will be optimized will be the story where isolation system is equipped and its dimensions.
The testing program of the bridges before commissioning is mandatory for almost all the bridges. ... more The testing program of the bridges before commissioning is mandatory for almost all the bridges. Usually, for bridges with small spans and a simple structural type, the testing program consists only from static loading tests. When special building technologies, materials or structural models are involved in the bridge building, the dynamic testing of the bridge is required, also. The overpass from the Câmpina city entrance consists of a main passage with two lanes and, at the ends, four access roads with one lane each. The overpass is divided in five sections, acting as independent structures. These are composed from steel piers with composite decks. Each composite deck is made from a main steel girder with cross steel girders and reinforced concrete slab. Taking into account the curved shape of the bridge and the special structural type of the bridge, it was required an extended dynamic testing program, for every section of the bridge. This paper presents the dynamic test condition...
The testing program of the bridges before commissioning is mandatory for almost all the bridges. ... more The testing program of the bridges before commissioning is mandatory for almost all the bridges. Usually, for bridges with small spans and a simple structural type, the testing program consists only from static loading tests. When special building technologies, materials or structural models are involved in the bridge building, the dynamic testing of the bridge is required, also. The overpass from the Câmpina city entrance consists of a main passage with two lanes and, at the ends, four access roads with one lane each. The overpass is divided in five sections, acting as independent structures. These are composed from steel piers with composite decks. Each composite deck is made from a main steel girder with cross steel girders and reinforced concrete slab. Taking into account the curved shape of the bridge and the special structural type of the bridge, it was required an extended dynamic testing program, for every section of the bridge. This paper presents the dynamic test condition...
In this paper, the dynamic response of an isolated structure supported by lead rubber bearings is... more In this paper, the dynamic response of an isolated structure supported by lead rubber bearings is studied. The isolated building is modeled using finite element software. Each bearing is modeled using its yield force, elastic stiffness and plastic stiffness. The main objective of the paper is to find the optimal parameters of the base isolation system using genetic algorithms in order to minimize the displacement of the building. In order to minimize the objective function an elitist non-dominated sorting genetic algorithm is employed. The study focuses on a 10 story concrete structure rehabilitated according to new design prescriptions. The optimal distribution is determined using nonlinear time history analysis and three earthquakes pertinent to the Vrancea source.
ABSTRACT A method used world-wide to reduce the effects of seismic motion it is represented by th... more ABSTRACT A method used world-wide to reduce the effects of seismic motion it is represented by the base isolation of the structure. The application of this method aims to an increase of the base flexibility in the horizontal plane. In order to illustrate the advantages of the base isolation system an experimental analysis in frequency domain was achieved. The test specimen was represented by a small scale model of a simple structure. Frequency domain analysis has allowed a comparison between the response of the structure with and without base isolation. The comparison pointed the positive effect of base isolation in order to reduce the resonant response of the fixed base structure. In order to validate the experimental results and to extrapolate response to cases closer to real isolation systems, finite element models of the structure with and without isolated base were made. The numerical models were calibrated with experimental models in terms of natural vibration period and damping ratio and they were designed to describe the real experiments, as far as possible. Comparative response analysis of the two models has allowed experimental data validation and the numerical model acceptance. The average error between the two response curves in the frequency domain was considered acceptable, taking into account the general precision of an experimental test. In order to fill some gaps due to boundary conditions of the experiment a finite elements analysis was performed to extrapolate the response of the isolated structure for higher values of the damping ratio at the base isolation system level and for random seismic motion.
ABSTRACT Modern age manufacture technology requires controlled conditions for the burning and pre... more ABSTRACT Modern age manufacture technology requires controlled conditions for the burning and pressing of the clay bricks, while in the past these aspects weren't strictly controlled. It is expected to have different behaviours of the brick units for existing masonry buildings, as a result of the diverse fabrication technologies at different moments in time. The present paper presents a case study about the experimental testing on two batches of clay fired bricks. First batch is obtained from an existing structures and the second batch is represented by new bricks. Compression tests were conducted on specimens extracted from every batch of bricks. The experimental tests were carried out according to the current national standard for masonry units. For every tested batch of bricks, the standardized compression strength was computed as an arithmetic mean of the corrected ultimate stress. Following the large dispersion of the results for the specimens obtained from old bricks, the authors consider the standard method to determine the compressive strength of the bricks isn’t suitable for the determination of the brick batch class. Therefore, a series of probabilistic calculation were conducted by the assimilation of the experimental tests results to the processing methods characteristic for masonry. Using these procedures, the characteristic and the 5% fractile value of the compressive strength were determined for every batch of masonry units.
ABSTRACT Considering on one hand the calculation model of the bridge, simplifying assumptions and... more ABSTRACT Considering on one hand the calculation model of the bridge, simplifying assumptions and design criteria and on the other hand the inherent differences between the project and final structure, the real structure behaviour under traffic loads can be different from that one considered in the design stage. Therefore the need of experimental tests before commissioning of bridges arises and this task is generally conditioned by complexity of the structure, the technologies used in construction and the requirements of the relevant stakeholders. The paper presents the test conditions for a reinforced concrete road bridge in Romania and the results obtained following the experimental tests. The experimentally determined dynamic characteristics of the bridge and the peek vertical accelerations are compared with those obtained by performing numerical analyses of the bridge. Due to the fact that the bridge is provided with walkways, it is appropriate to presume that the vibrations induced by road traffic will affect the pedestrians walking on the bridge. Same experimental data presented above can provide a view into how traffic induced vibrations can affect pedestrians on the bridge. For this reason, in the paper are presented the results in terms of human perception and the comparison between the resulting values and some generally accepted values.
ABSTRACT In case of laminated glass strips, the mechanical characteristics of the composite eleme... more ABSTRACT In case of laminated glass strips, the mechanical characteristics of the composite element are different from the values that are obtained for the same element from a homogeneous and isotropic material. The experimental tests presented in the paper aims to determine the mechanical characteristics of laminated glass strips used to make a staircase. For the experiment, quasi-static and dynamic tests were conducted on different glass stair steps, made from normal and tempered glass, with different number and thicknesses glass sheets. The paper presents the carrying out conditions for the experiments, the synthesis of data processing and comments on the experimental results. Experimental test results have led to the constructive solution for the glass staircase steps. For staircase building up, tempered glass was chosen and the values obtained for the mechanical properties, strength and deformation capacity of the system were used in its design. Whole set of experimental tests have led to a successful design and build-up of the glass staircase.
As a general trend, in order to reduce material consumption or to reduce the mass of the structur... more As a general trend, in order to reduce material consumption or to reduce the mass of the structures, composite floor slabs solutions are used to achieve large spans floor slabs. This solutions led to floors sensitive to vibrations induced generally by human activities. As a verification of the design concepts of the composite floors, usually, it is recommended a further examination of the floor after completion by experimental tests. Although the experimental values of the dynamic response of the floor are uniquely determined, the processing can take two directions of evaluation. The first direction consist in determining the dynamic characteristics of the floor and their comparison with the design values. Another way that can be followed in the processing of the experimental results is to consider the human perception and comfort to the vibration on floors. The paper aims to present a case study on a composite floor, with steel beams and concrete slab, tested on-site. Both aspects ...
In case of laminated glass strips, the mechanical characteristics of the composite element are di... more In case of laminated glass strips, the mechanical characteristics of the composite element are different from the values that are obtained for the same element from a homogeneous and isotropic material. The experimental tests presented in the paper aims to determine the mechanical characteristics of laminated glass strips used to make a staircase. For the experiment, quasi-static and dynamic tests were conducted on different glass stair steps, made from normal and tempered glass, with different number and thicknesses glass sheets. The paper presents the carrying out conditions for the experiments, the synthesis of data processing and comments on the experimental results. Experimental test results led to the constructive solution of the glass staircase steps. For staircase building up, tempered glass was chosen and the values obtained for the mechanical properties, strength and deformation capacity of the system were used in its design. Whole set of experimental tests led to a succes...
Dynamic testing of road bridges is vaguely national regulated. As result, the importance and the ... more Dynamic testing of road bridges is vaguely national regulated. As result, the importance and the necessity of static and dynamic tests is diminished by various factors, human, technic or economic ones. The standard which regulates the experimental testing of rail and road bridges in Romania is STAS 12504-86. For the dynamic testing case, the Romanian standard provides some information on how to ensure the dynamic loading of bridges, it enumerates some of the characteristics that can be pursued through testing, but without giving information on how to process experimental data. The present paper illustrates a dynamic test of a road bridge, located on the A2 highway crossing the Danube-Black Sea Channel. There are presented bearings about the testing conditions, the experimental test results and a comparison with the bridge design values. The experimental results are proximate to the dynamic characteristics established in the bridge design, test algorithm and experimental data process...
In this paper, a rail joint model consisting of three Euler-Bernoulli beams connected via a Winkl... more In this paper, a rail joint model consisting of three Euler-Bernoulli beams connected via a Winkler foundation is proposed in order to point out the influence of the joint gap length upon the stiffness of the rail joint. Starting from the experimental results aiming the stiffness of the rail joint, the Winkler foundation stiffness of the model has been calculated. Using the proposed model, it is shown that the stiffness of the rail joint of the 49 rail can decreases up to 10 % when the joint gap length increases from 0 to 20 mm.
The testing program of the bridges before commissioning is mandatory for almost all the bridges. ... more The testing program of the bridges before commissioning is mandatory for almost all the bridges. Usually, for bridges with small spans and a simple structural type, the testing program consists only from static loading tests. When special building technologies, materials or structural models are involved in the bridge building, the dynamic testing of the bridge is required, also. The overpass from the Câmpina city entrance consists of a main passage with two lanes and, at the ends, four access roads with one lane each. The overpass is divided in five sections, acting as independent structures. These are composed from steel piers with composite decks. Each composite deck is made from a main steel girder with cross steel girders and reinforced concrete slab. Taking into account the curved shape of the bridge and the special structural type of the bridge, it was required an extended dynamic testing program, for every section of the bridge. This paper presents the dynamic test condition...
As result of the efficiency of seismic isolation to seismic actions highlighted during seismic ev... more As result of the efficiency of seismic isolation to seismic actions highlighted during seismic events, over the last 20 years the base isolation method has experienced a huge applicability. However, in Romania this method has not grown very much due the special characteristics of Vrancea earthquakes. Seismic isolation system is composed of isolator bearings, with large horizontal deformation capacity and high vertical load capacity, and damping devices. Thus isolators can take earthquake-induced displacements. This paper aims to highlight the effectiveness of base isolation systems by modeling the three structures, which has different fundamental periods of vibration, applied to a recorded seismic action (INCERC March 1977). Three target periods of isolation system were chosen and there were calculated the characteristics of the isolators. For each structure, and isolation system were compared displacements at the top and the base shear, showing the effectiveness of the isolation sy...
The paper studies the influence of an optimal inter-storey isolation system on seismic behaviour ... more The paper studies the influence of an optimal inter-storey isolation system on seismic behaviour of a concrete structure. The inter-storey isolation system uses lead rubber bearings at a certain level of the structure. The structure will be subjected to a series of pulse like earthquakes in order to account for the variability of the hazard of the Vrancea source. The article will study a concrete structure which will be modelled using finite element software. The parameters and location of the story isolation system will be studied and optimized using genetic algorithms. The optimization will be applied in order to minimise displacements. The parameters which will be optimized will be the story where isolation system is equipped and its dimensions.
The testing program of the bridges before commissioning is mandatory for almost all the bridges. ... more The testing program of the bridges before commissioning is mandatory for almost all the bridges. Usually, for bridges with small spans and a simple structural type, the testing program consists only from static loading tests. When special building technologies, materials or structural models are involved in the bridge building, the dynamic testing of the bridge is required, also. The overpass from the Câmpina city entrance consists of a main passage with two lanes and, at the ends, four access roads with one lane each. The overpass is divided in five sections, acting as independent structures. These are composed from steel piers with composite decks. Each composite deck is made from a main steel girder with cross steel girders and reinforced concrete slab. Taking into account the curved shape of the bridge and the special structural type of the bridge, it was required an extended dynamic testing program, for every section of the bridge. This paper presents the dynamic test condition...
The testing program of the bridges before commissioning is mandatory for almost all the bridges. ... more The testing program of the bridges before commissioning is mandatory for almost all the bridges. Usually, for bridges with small spans and a simple structural type, the testing program consists only from static loading tests. When special building technologies, materials or structural models are involved in the bridge building, the dynamic testing of the bridge is required, also. The overpass from the Câmpina city entrance consists of a main passage with two lanes and, at the ends, four access roads with one lane each. The overpass is divided in five sections, acting as independent structures. These are composed from steel piers with composite decks. Each composite deck is made from a main steel girder with cross steel girders and reinforced concrete slab. Taking into account the curved shape of the bridge and the special structural type of the bridge, it was required an extended dynamic testing program, for every section of the bridge. This paper presents the dynamic test condition...
In this paper, the dynamic response of an isolated structure supported by lead rubber bearings is... more In this paper, the dynamic response of an isolated structure supported by lead rubber bearings is studied. The isolated building is modeled using finite element software. Each bearing is modeled using its yield force, elastic stiffness and plastic stiffness. The main objective of the paper is to find the optimal parameters of the base isolation system using genetic algorithms in order to minimize the displacement of the building. In order to minimize the objective function an elitist non-dominated sorting genetic algorithm is employed. The study focuses on a 10 story concrete structure rehabilitated according to new design prescriptions. The optimal distribution is determined using nonlinear time history analysis and three earthquakes pertinent to the Vrancea source.
ABSTRACT A method used world-wide to reduce the effects of seismic motion it is represented by th... more ABSTRACT A method used world-wide to reduce the effects of seismic motion it is represented by the base isolation of the structure. The application of this method aims to an increase of the base flexibility in the horizontal plane. In order to illustrate the advantages of the base isolation system an experimental analysis in frequency domain was achieved. The test specimen was represented by a small scale model of a simple structure. Frequency domain analysis has allowed a comparison between the response of the structure with and without base isolation. The comparison pointed the positive effect of base isolation in order to reduce the resonant response of the fixed base structure. In order to validate the experimental results and to extrapolate response to cases closer to real isolation systems, finite element models of the structure with and without isolated base were made. The numerical models were calibrated with experimental models in terms of natural vibration period and damping ratio and they were designed to describe the real experiments, as far as possible. Comparative response analysis of the two models has allowed experimental data validation and the numerical model acceptance. The average error between the two response curves in the frequency domain was considered acceptable, taking into account the general precision of an experimental test. In order to fill some gaps due to boundary conditions of the experiment a finite elements analysis was performed to extrapolate the response of the isolated structure for higher values of the damping ratio at the base isolation system level and for random seismic motion.
ABSTRACT Modern age manufacture technology requires controlled conditions for the burning and pre... more ABSTRACT Modern age manufacture technology requires controlled conditions for the burning and pressing of the clay bricks, while in the past these aspects weren't strictly controlled. It is expected to have different behaviours of the brick units for existing masonry buildings, as a result of the diverse fabrication technologies at different moments in time. The present paper presents a case study about the experimental testing on two batches of clay fired bricks. First batch is obtained from an existing structures and the second batch is represented by new bricks. Compression tests were conducted on specimens extracted from every batch of bricks. The experimental tests were carried out according to the current national standard for masonry units. For every tested batch of bricks, the standardized compression strength was computed as an arithmetic mean of the corrected ultimate stress. Following the large dispersion of the results for the specimens obtained from old bricks, the authors consider the standard method to determine the compressive strength of the bricks isn’t suitable for the determination of the brick batch class. Therefore, a series of probabilistic calculation were conducted by the assimilation of the experimental tests results to the processing methods characteristic for masonry. Using these procedures, the characteristic and the 5% fractile value of the compressive strength were determined for every batch of masonry units.
ABSTRACT Considering on one hand the calculation model of the bridge, simplifying assumptions and... more ABSTRACT Considering on one hand the calculation model of the bridge, simplifying assumptions and design criteria and on the other hand the inherent differences between the project and final structure, the real structure behaviour under traffic loads can be different from that one considered in the design stage. Therefore the need of experimental tests before commissioning of bridges arises and this task is generally conditioned by complexity of the structure, the technologies used in construction and the requirements of the relevant stakeholders. The paper presents the test conditions for a reinforced concrete road bridge in Romania and the results obtained following the experimental tests. The experimentally determined dynamic characteristics of the bridge and the peek vertical accelerations are compared with those obtained by performing numerical analyses of the bridge. Due to the fact that the bridge is provided with walkways, it is appropriate to presume that the vibrations induced by road traffic will affect the pedestrians walking on the bridge. Same experimental data presented above can provide a view into how traffic induced vibrations can affect pedestrians on the bridge. For this reason, in the paper are presented the results in terms of human perception and the comparison between the resulting values and some generally accepted values.
ABSTRACT In case of laminated glass strips, the mechanical characteristics of the composite eleme... more ABSTRACT In case of laminated glass strips, the mechanical characteristics of the composite element are different from the values that are obtained for the same element from a homogeneous and isotropic material. The experimental tests presented in the paper aims to determine the mechanical characteristics of laminated glass strips used to make a staircase. For the experiment, quasi-static and dynamic tests were conducted on different glass stair steps, made from normal and tempered glass, with different number and thicknesses glass sheets. The paper presents the carrying out conditions for the experiments, the synthesis of data processing and comments on the experimental results. Experimental test results have led to the constructive solution for the glass staircase steps. For staircase building up, tempered glass was chosen and the values obtained for the mechanical properties, strength and deformation capacity of the system were used in its design. Whole set of experimental tests have led to a successful design and build-up of the glass staircase.
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Papers by Radu Cruciat