Flexural rigidity

About: Flexural rigidity is a research topic. Over the lifetime, 3829 publications have been published within this topic receiving 56780 citations.

Mechanics of Distension of Dog Veins and Other Very Thin-Walled Tubular Structures

Abstract: We present first phenomenological characterizations of the pressure-volume relationships (a) in veins excised from dogs under anesthesia and (b) in thinwalled latex tubes. We measured their cross-sectional areas and perimeters from cinefluorographic enlargements during distension. From flattened to circular cross sections, the perimeter of latex tubes remained constant while the area increased exclusively by bending of the walls. Compliance was large in this regime. After circular cross sections were reached, further increases in area were associated with increments in perimeter and there was stretching of the wall. Compliance declined sharply. Veins did not show a distinct two-regime behavior but a combination of bending and stretching which extended the region of large compliance to values of transmural pressure of physiological interest. Using classical theory of elasticity, we propose mathematical relationships describing the proportionality between the pressure and the curvature of the wall during the regime where bending is the primary controlling mechanism. We mechanized these relationships on an analog computer and correlated the solutions with the physical experiments. We conclude that no modulus of elasticity, alone, can relate the pressure and the volume when bending is predominant. In this regime the significant quantity is the modulus of flexural rigidity.

Strength and Stiffness of Circular Concrete-Filled Tubes

Abstract: Concrete-filled tubes (CFTs) are composite structural members that consist of a steel tube and concrete infill. CFTs optimize the contributions of both components by improving their geometric efficiency and fully using their inherent strengths. The concrete infill is confined by the steel tube, resulting in a triaxial state of compression that increases the strength and strain capacity of the concrete. The perimeter steel is at its optimal location, and the concrete infill delays local and global buckling of the tube. CFTs are easily and rapidly constructed and provide significant compression, bending, and shear resistance. They may be used for bridge piers and building columns. However, current design specifications for CFTs vary significantly, thereby limiting the current understanding and use of these components. This study addresses combined axial and flexural loading and determines the best models for predicting the stiffness and resistance of circular CFT. A database of 122 test specimens was compiled and evaluated. The results indicate that the plastic stress method is a simple yet effective method to predict the resistance of circular CFT components under combined loading. These data show that current specifications provide inaccurate predictions of the flexural stiffness, and a new stiffness expression is proposed. The proposed models permit simple yet accurate predictions of stiffness and resistance and allow engineers to use CFT components routinely in structural design.

The size-dependent bending elastic properties of nanobeams with surface effects

Abstract: A theoretical model is presented to investigate the size-dependent bending elastic properties of a nanobeam with the influence of the surface relaxation and the surface tension taken into consideration. The surface layer and its thickness of a nanostructure are defined unambiguously. A three-dimensional (3D) crystal model for a nanofilm with n layers of relaxed atoms is investigated. The four nonzero elastic constants of the nanofilm are derived, and then the Young's modulus for simple tension is obtained. Using the relation of energy equilibrium, the size-dependent effective elastic modulus and effective flexural rigidity of a nanobeam with two kinds of cross sections are derived, and their dependence on the surface relaxation and the surface tension is analysed.

Flexural Behavior of Hybrid FRP-Concrete-Steel Double-Skin Tubular Members

Abstract: This paper presents the results of an experimental study on the flexural behavior of a new type of hybrid FRP-concrete-steel member as well as results from a corresponding theoretical model based on the plane section assumption and the fiber element approach. This new type of hybrid member is in the form of a double-skin tube, composed of a steel inner tube and an FRP outer tube with a concrete infill between the two tubes, and may be employed as columns or beams. The parameters examined in this study include the section configuration, the concrete strength, and the thicknesses of the steel tube and the FRP tube, respectively. The results presented in this paper show that these hybrid beams have a very ductile response because the compressive concrete is confined by the FRP tube and the steel tube provides ductile longitudinal reinforcement. The beams' flexural response, including the flexural stiffness, ultimate load, and cracking, can be substantially improved by shifting the inner steel tube toward the...