The Experts below are selected from a list of 153 Experts worldwide ranked by ideXlab platform
Zhongdao Ren - One of the best experts on this subject based on the ideXlab platform.
-
dynamic method of neutral axis position determination and damage identification with distributed long gauge fbg sensors
Sensors, 2017Co-Authors: Yongsheng Tang, Zhongdao RenAbstract:The neutral axis position (NAP) is a key parameter of a Flexural Member for structure design and safety evaluation. The accuracy of NAP measurement based on traditional methods does not satisfy the demands of structural performance assessment especially under live traffic loads. In this paper, a new method to determine NAP is developed by using modal macro-strain (MMS). In the proposed method, macro-strain is first measured with long-gauge Fiber Bragg Grating (FBG) sensors; then the MMS is generated from the measured macro-strain with Fourier transform; and finally the neutral axis position coefficient (NAPC) is determined from the MMS and the neutral axis depth is calculated with NAPC. To verify the effectiveness of the proposed method, some experiments on FE models, steel beam and reinforced concrete (RC) beam were conducted. From the results, the plane section was first verified with MMS of the first bending mode. Then the results confirmed the high accuracy and stability for assessing NAP. The results also proved that the NAPC was a good indicator of local damage. In summary, with the proposed method, accurate assessment of Flexural structures can be facilitated.
I. Židonis - One of the best experts on this subject based on the ideXlab platform.
-
The third equilibrium equation for forces of Flexural Member cross-section
Mechanics, 2014Co-Authors: I. ŽidonisAbstract:In earlier articles of the author two equilibrium equations of fairly general ZI method for calculation of real parameter values of stress-strain states for normal to longitudinal axes sections of Flexural Members at any loading stage are presented. It required in advance to have or to calculate by the method of successive approximation strain value of any one layer. The third equation for force static is presented in this article. The main purpose of the equation is calculation of neutral axes location in cases when external actions are given but strain value of any layer is not given in advance. Strain is calculated from other equations and then it enables calculation of values for all other parameters. Such calculation is especially relevant for reinforced concrete Members with cracks in tension zone because at present calculation of neutral axes location is carried out either by empirical formula or in very approximate way. It can be considered that creation of ZI method is finished by the third force equilibrium equation. Applica-tion of ZI method three equation system enables solution of many theoretical and practical problems. Application for particular practical problems examples of ZI method three equations in general case are presented in this article as well. DOI: http://dx.doi.org/10.5755/j01.mech.20.2.6942
Yongsheng Tang - One of the best experts on this subject based on the ideXlab platform.
-
dynamic method of neutral axis position determination and damage identification with distributed long gauge fbg sensors
Sensors, 2017Co-Authors: Yongsheng Tang, Zhongdao RenAbstract:The neutral axis position (NAP) is a key parameter of a Flexural Member for structure design and safety evaluation. The accuracy of NAP measurement based on traditional methods does not satisfy the demands of structural performance assessment especially under live traffic loads. In this paper, a new method to determine NAP is developed by using modal macro-strain (MMS). In the proposed method, macro-strain is first measured with long-gauge Fiber Bragg Grating (FBG) sensors; then the MMS is generated from the measured macro-strain with Fourier transform; and finally the neutral axis position coefficient (NAPC) is determined from the MMS and the neutral axis depth is calculated with NAPC. To verify the effectiveness of the proposed method, some experiments on FE models, steel beam and reinforced concrete (RC) beam were conducted. From the results, the plane section was first verified with MMS of the first bending mode. Then the results confirmed the high accuracy and stability for assessing NAP. The results also proved that the NAPC was a good indicator of local damage. In summary, with the proposed method, accurate assessment of Flexural structures can be facilitated.
Jang Jay Ho Kim - One of the best experts on this subject based on the ideXlab platform.
-
effect of specimen size on Flexural compressive strength of reinforced concrete Members
Cement & Concrete Composites, 2007Co-Authors: Minsu Kim, Jin Keun Kim, Jang Jay Ho KimAbstract:Abstract It is important to consider the effect of Member size when estimating the ultimate strength of a concrete Flexural Member, because the strength always decreases with an increase of Member size except for well-reinforced Members. Research conducted previously in this area include axial compressive strength size effect on cylindrical specimens and Flexural compressive strength size effect on C-shaped specimens, notched cylindrical specimens, and axially loaded double cantilever beam (DCB) specimens. Since the most widely used Flexural Member type is reinforced concrete (RC) beams, it is logical to extend the study of Flexural compressive strength size effect to Flexural loaded RC beam Members. Previously, several researchers have reported from their studies that Flexural compressive strength size effect does not exist. However, the analyses show that the specimens used for the study had limited size variation and the neutral axis depth variations were too similar to show distinct size effect. Therefore, this study enforced distinct neutral axis depth variations for all of the tested specimens. In this study, the size effect of a RC beam was experimentally investigated. For this purpose, a series of beam specimens subjected to four-point loading was tested. RC beams with three different effective depths were tested to investigate the size effect. The shear-span to depth ratio and the thickness of the specimens were kept constant to eliminate the out-of-plane size effect. The test results are curve fitted using Levenberg–Marquardt’s Least Square Method (LSM) to obtain parameters for Modified Size Effect Law (MSEL) by Kim et al. The analysis results show that the Flexural compression strength and ultimate strain decrease as the specimen size increases. Comparisons with existing research results considering the depth of neutral axis were also performed. They also show that the current strength criteria-based design practice should be reviewed to include Member size effect.
M A Bradford - One of the best experts on this subject based on the ideXlab platform.
-
a direct stiffness analysis of a composite beam with partial interaction
International Journal for Numerical Methods in Engineering, 2004Co-Authors: Gianluca Ranzi, M A BradfordAbstract:The use of the conventional semi-analytical stiffness method in finite element analysis, in which interpolation polynomials are used to develop the stiffness relationships, leads to problems of curvature locking when beam-type elements are developed for composite Members with partial interaction between the materials of which it is comprised. The curvature locking phenomenon that occurs for composite steel–concrete Members is quite well reported, and the general approach to minimizing the undesirable ramifications of curvature locking has been to use higher-order polynomials with increasing numbers of internal nodes. This paper presents an alternate formulation based on a direct stiffness approach rather than starting from pre-defined interpolation polynomials, and which does not possess the undesirable locking characteristics. The formulation is based on a more general approach for a bi-material composite Flexural Member, whose constituent materials are joined by elastic shear connection so as to provide partial interaction. The stiffness relationships are derived, and these are applied to a simply supported and a continuous steel–concrete composite beam to demonstrate the efficacy of the method, and in particular its ability to model accurately both very flexible and very stiff shear connection that causes difficulties when implemented in competitive semi-analytical algorithms. Copyright © 2004 John Wiley & Sons, Ltd.
