Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Shrinkage Influence on Tension-Stiffening of Concrete Structures ; Susitraukimo įtaka gelžbetoninių elementų tempiamosios zonos elgsenai
Due to the use of refined ultimate state theories as well as high strength concrete and reinforcement, resulting in longer spans and smaller depths, the serviceability criteria often limits application of modern reinforced concrete (RC) superstructures. In structural analysis, civil engineers can choose between traditional design code methods and numerical techniques. In order to choose a particular calculation method, engineers should be aware of accuracy of differ-ent techniques. Adequate modelling of RC cracking and, particularly, post-cracking behaviour, as one of the major sources of nonlinearity, is the most im-portant and difficult task of deformational analysis. In smeared crack approach dealing with average cracking and strains, post-cracking effects can be modelled by a stress-strain tension-stiffening relationship. Most known tension-stiffening relationships have been derived from test data of shrunk tension or shear mem-bers. Subsequently, these constitutive laws were applied for modelling of bend-ing elements which behaviour differs from test members. Furthermore, such re-lationships were coupled with shrinkage effect. Therefore, present research aims at developing a technique for deriving a free-of-shrinkage tension-stiffening re-lationship using test data of shrunk bending RC members. The main objective of this PhD dissertation is to investigate shrinkage influence on deformations and tension-stiffening of RC members subjected to short-term loading. Present study reviews empirical and numerical techniques of deformation analysis of RC members as well as material models with the emphasis on shrin-kage and tension-stiffening effects. Experimental investigation results on con-crete shrinkage effect on cracking resistance, tension-stiffening and short-term deformations of lightly reinforced beams have been reported. An innovative numerical procedure has been proposed for deriving free-of-shrinkage tension-stiffening relationships using moment-curvature relationships of RC flexural members. The proposed procedure has been applied to the test data reported by the author. For beams of same reinforcement ratio, it was shown that tension-stiffening was more pronounced in those with a larger num-ber of tensile reinforcing bars. A statistical procedure for checking adequacy of theoretical predictions to the test data taking into account inconsistency of the data has been developed. Using this procedure, comparative statistical analyses of various free shrinkage and deflection/curvature prediction models have been performed. It was concluded that accuracy of deflection/curvature predictions by design codes and numerical techniques varied for different ranges of reinforcement ra-tio and load intensity. Numerical techniques gave more accurate predictions of short-term deflections when shrinkage effect was taken into account.
Shrinkage Influence on Tension-Stiffening of Concrete Structures ; Susitraukimo įtaka gelžbetoninių elementų tempiamosios zonos elgsenai
Due to the use of refined ultimate state theories as well as high strength concrete and reinforcement, resulting in longer spans and smaller depths, the serviceability criteria often limits application of modern reinforced concrete (RC) superstructures. In structural analysis, civil engineers can choose between traditional design code methods and numerical techniques. In order to choose a particular calculation method, engineers should be aware of accuracy of differ-ent techniques. Adequate modelling of RC cracking and, particularly, post-cracking behaviour, as one of the major sources of nonlinearity, is the most im-portant and difficult task of deformational analysis. In smeared crack approach dealing with average cracking and strains, post-cracking effects can be modelled by a stress-strain tension-stiffening relationship. Most known tension-stiffening relationships have been derived from test data of shrunk tension or shear mem-bers. Subsequently, these constitutive laws were applied for modelling of bend-ing elements which behaviour differs from test members. Furthermore, such re-lationships were coupled with shrinkage effect. Therefore, present research aims at developing a technique for deriving a free-of-shrinkage tension-stiffening re-lationship using test data of shrunk bending RC members. The main objective of this PhD dissertation is to investigate shrinkage influence on deformations and tension-stiffening of RC members subjected to short-term loading. Present study reviews empirical and numerical techniques of deformation analysis of RC members as well as material models with the emphasis on shrin-kage and tension-stiffening effects. Experimental investigation results on con-crete shrinkage effect on cracking resistance, tension-stiffening and short-term deformations of lightly reinforced beams have been reported. An innovative numerical procedure has been proposed for deriving free-of-shrinkage tension-stiffening relationships using moment-curvature relationships of RC flexural members. The proposed procedure has been applied to the test data reported by the author. For beams of same reinforcement ratio, it was shown that tension-stiffening was more pronounced in those with a larger num-ber of tensile reinforcing bars. A statistical procedure for checking adequacy of theoretical predictions to the test data taking into account inconsistency of the data has been developed. Using this procedure, comparative statistical analyses of various free shrinkage and deflection/curvature prediction models have been performed. It was concluded that accuracy of deflection/curvature predictions by design codes and numerical techniques varied for different ranges of reinforcement ra-tio and load intensity. Numerical techniques gave more accurate predictions of short-term deflections when shrinkage effect was taken into account.
Shrinkage Influence on Tension-Stiffening of Concrete Structures ; Susitraukimo įtaka gelžbetoninių elementų tempiamosios zonos elgsenai
Gribniak, Viktor (Autor:in) / Kaklauskas, Gintaris
06.10.2009
Hochschulschrift
Elektronische Ressource
Lithuanian , Englisch
DDC:
690