ABSTRACT The mechanical behaviour of the rounded dovetail connection subjected to shear load is a... more ABSTRACT The mechanical behaviour of the rounded dovetail connection subjected to shear load is analysed experimentally and numerically. The brittle failure of the joist member is observed in the experimental investigation. The experimental results are used to validate a three-dimensional (3D) non-linear finite element model. The non-linear models use the Hill criterion to manage the plastic yielding of the wood material. The modified Hill failure criteria, managing the damage evolution in wood, are used to take into account the brittle failure in shear and tension. Besides, the models also incorporate the contact and the geometric non-linearity. The comparison with experimental results shows that the numerical models are in good agreement with real behaviour. The validated models can be used to predict the strength and failure position of the rounded dovetail connection for parametric studies.
Abstract. This paper deals with the prediction of the response of strutures with gaps excited by ... more Abstract. This paper deals with the prediction of the response of strutures with gaps excited by a white noise. This model is frequently introduced for practical analysis of dynamic systems such as pipings having a clearance into the supporting device, mechanical equipments ...
ABSTRACT Steel-to-timber connections, loaded in tension perpendicular to grain, are tested in col... more ABSTRACT Steel-to-timber connections, loaded in tension perpendicular to grain, are tested in cold and ISO-fire conditions. The experimental results are used to validate a 3D finite element model. This model is based on two different meshes for thermal and thermo-mechanical calculations. To manage the plastic yielding of materials, the mechanical model is based on von Mises criterion for steel and Hill criterion for timber. To take into account the brittle character of wood in transversal directions, Hill criterion is combined with Tsaï–Wu failure criterion. The thermal model, based on a continuous mesh, simulates the evolution of the temperature field inside the connections. The thermal and mechanical models are validated by comparison of their results with those from tests (temperatures, load–displacement curves). The developed thermo-mechanical model considers the mechanical properties evolution as a function of the temperature. The comparisons of calculated and experimental fire resistances show that the model predicts accurately the thermo-mechanical behavior of the connections. The validated model is used to observe mechanical parameters which are difficult to obtain experimentally, such as the load distribution among fasteners in fire conditions.
ABSTRACT The steady-state response of a free and infinite Timoshenko beam is specified analytical... more ABSTRACT The steady-state response of a free and infinite Timoshenko beam is specified analytically in terms of non-dimensional displacements and stresses. The beam is supposed loaded by a travelling concentrated force or a moving step load. By a validated explicit numerical calculation, it is shown how a load travelling on a beam at constant velocity, from defined time and abscissa, generates a response which evolves towards the steady-state solution for a part, and towards a quantified transient solution for another part. Asymptotic values are given for the transient displacements and stresses according to the time and the speed of the loading. The solution is also found for a plate subject to a pressure, which spreads respecting the cylindrical symmetry. It is possible to identify in the response a part which follows the pressure front, and which is comparable with the steady-state response of a beam, and another transient part, which generates displacements and stresses with a much less oscillating character. An asymptotic solution is also presented for the plate.The whole series of the results makes it possible to better understand qualitatively the beginning of the transient response of a beam or of a plate to a moving load, and also makes it possible to estimate the stresses and displacements without needing specialised numerical codes.
European Journal of Environmental and Civil engineering, 2011
Experimentations on composite slabs have been carried out during 1 250 days in order to exhibit t... more Experimentations on composite slabs have been carried out during 1 250 days in order to exhibit the behavior of timber-concrete structures in outdoor climatic conditions leading to high moisture content. Successive bending loadings are applied during this test; deflection and slip modulus of joints are studied. Real climatic conditions and moisture contents are recorded. Numerical modeling using FEM (Cast3m) is
ABSTRACT This study focuses on the load distributions among fasteners in steel-to-timber connecti... more ABSTRACT This study focuses on the load distributions among fasteners in steel-to-timber connections loaded in tension parallel-to-grain under fire exposure. The experimental results of some types of connections with various geometrical configurations are available. The influence of the type of fasteners (bolt, dowel) on the thermo-mechanical behavior of the connections is studied. A three-dimensional finite element model validated on the basis of experimental results is used. Good agreements were observed between the simulated and the experimental values of temperatures and failure times. The type of metal fasteners is crucial to the thermo-mechanical behavior of connections. In the studied connections, one bolt is used in each row of fasteners to prevent the separation between the assembled members. The presence of the bolts greatly influences the behavior of the connections mainly under fire. Various geometrical configurations of connections with only dowels or changing the positions of the bolts are studied. An analytical approach is proposed, from a specific type of connections, by varying some influent geometrical characteristics. A numerical experimental design is realized from the calculated time to failure of the connections.
ABSTRACT The mechanical behaviour of the rounded dovetail connection subjected to shear load is a... more ABSTRACT The mechanical behaviour of the rounded dovetail connection subjected to shear load is analysed experimentally and numerically. The brittle failure of the joist member is observed in the experimental investigation. The experimental results are used to validate a three-dimensional (3D) non-linear finite element model. The non-linear models use the Hill criterion to manage the plastic yielding of the wood material. The modified Hill failure criteria, managing the damage evolution in wood, are used to take into account the brittle failure in shear and tension. Besides, the models also incorporate the contact and the geometric non-linearity. The comparison with experimental results shows that the numerical models are in good agreement with real behaviour. The validated models can be used to predict the strength and failure position of the rounded dovetail connection for parametric studies.
Abstract. This paper deals with the prediction of the response of strutures with gaps excited by ... more Abstract. This paper deals with the prediction of the response of strutures with gaps excited by a white noise. This model is frequently introduced for practical analysis of dynamic systems such as pipings having a clearance into the supporting device, mechanical equipments ...
ABSTRACT Steel-to-timber connections, loaded in tension perpendicular to grain, are tested in col... more ABSTRACT Steel-to-timber connections, loaded in tension perpendicular to grain, are tested in cold and ISO-fire conditions. The experimental results are used to validate a 3D finite element model. This model is based on two different meshes for thermal and thermo-mechanical calculations. To manage the plastic yielding of materials, the mechanical model is based on von Mises criterion for steel and Hill criterion for timber. To take into account the brittle character of wood in transversal directions, Hill criterion is combined with Tsaï–Wu failure criterion. The thermal model, based on a continuous mesh, simulates the evolution of the temperature field inside the connections. The thermal and mechanical models are validated by comparison of their results with those from tests (temperatures, load–displacement curves). The developed thermo-mechanical model considers the mechanical properties evolution as a function of the temperature. The comparisons of calculated and experimental fire resistances show that the model predicts accurately the thermo-mechanical behavior of the connections. The validated model is used to observe mechanical parameters which are difficult to obtain experimentally, such as the load distribution among fasteners in fire conditions.
ABSTRACT The steady-state response of a free and infinite Timoshenko beam is specified analytical... more ABSTRACT The steady-state response of a free and infinite Timoshenko beam is specified analytically in terms of non-dimensional displacements and stresses. The beam is supposed loaded by a travelling concentrated force or a moving step load. By a validated explicit numerical calculation, it is shown how a load travelling on a beam at constant velocity, from defined time and abscissa, generates a response which evolves towards the steady-state solution for a part, and towards a quantified transient solution for another part. Asymptotic values are given for the transient displacements and stresses according to the time and the speed of the loading. The solution is also found for a plate subject to a pressure, which spreads respecting the cylindrical symmetry. It is possible to identify in the response a part which follows the pressure front, and which is comparable with the steady-state response of a beam, and another transient part, which generates displacements and stresses with a much less oscillating character. An asymptotic solution is also presented for the plate.The whole series of the results makes it possible to better understand qualitatively the beginning of the transient response of a beam or of a plate to a moving load, and also makes it possible to estimate the stresses and displacements without needing specialised numerical codes.
European Journal of Environmental and Civil engineering, 2011
Experimentations on composite slabs have been carried out during 1 250 days in order to exhibit t... more Experimentations on composite slabs have been carried out during 1 250 days in order to exhibit the behavior of timber-concrete structures in outdoor climatic conditions leading to high moisture content. Successive bending loadings are applied during this test; deflection and slip modulus of joints are studied. Real climatic conditions and moisture contents are recorded. Numerical modeling using FEM (Cast3m) is
ABSTRACT This study focuses on the load distributions among fasteners in steel-to-timber connecti... more ABSTRACT This study focuses on the load distributions among fasteners in steel-to-timber connections loaded in tension parallel-to-grain under fire exposure. The experimental results of some types of connections with various geometrical configurations are available. The influence of the type of fasteners (bolt, dowel) on the thermo-mechanical behavior of the connections is studied. A three-dimensional finite element model validated on the basis of experimental results is used. Good agreements were observed between the simulated and the experimental values of temperatures and failure times. The type of metal fasteners is crucial to the thermo-mechanical behavior of connections. In the studied connections, one bolt is used in each row of fasteners to prevent the separation between the assembled members. The presence of the bolts greatly influences the behavior of the connections mainly under fire. Various geometrical configurations of connections with only dowels or changing the positions of the bolts are studied. An analytical approach is proposed, from a specific type of connections, by varying some influent geometrical characteristics. A numerical experimental design is realized from the calculated time to failure of the connections.
Uploads
Papers by Mustapha Taazount