纖維混凝土結構數值模型之建立與應用

• Main Authors: Chin Hua-Sheng, 金驊生
• Other Authors: Chang Fwu-An
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/88833524465434357862

博士 === 國防大學中正理工學院 === 國防科學研究所 === 91 === The equivalent inclusion method (EIM) is applied to treat the steel-fiber reinforced concrete as an equivalent homogeneous material, in order to simplify the finite element modeling for associated structural analyses. Using the Mori-Tanaka’s averaged strain theory, the equivalent material moduli (e.g., the equivalent elastic moduli, shear moduli and the Poisson’s ratios) of the homogenized steel-fiber reinforced concrete can be derived. The strain fields within the equivalent inclusions (i.e., the reinforcing steel fibers) are evaluated by the Eshelby’s solutions, which ensures the strain compatibility between the equivalent inclusions (fibers) and the matrix (concrete) to be satisfied. Two sets of examples are present to demonstrate the proposed methodology. One is the load-deflection of a simply supported steel-fiber reinforced concrete beam under static concentration loading. Another is the simulation of an ogive-nosed steel projectile impacting into a steel-fiber reinforced concrete slab. Both of the finite element computational results based on the proposed method agree well with the test data respectively, indicating that the proposed method is promising and viable for future studies on finite element analyses of fiber reinforced concrete structures. The EIM model can also be adopted to study the influence characteristics of the equivalent material properties of the steel-fiber reinforced concrete as a function of the volume fraction and the length to diameter ratio of the reinforcing steel-fibers. It is discovered that the equivalent material moduli of the randomly orientated and distributed steel-fiber reinforced concrete are insensitive to the length to diameter ratio of the common used steel-fibers. However, the equivalent material strength will be increasing gradually due to the volume fraction of the steel-fibers increase. Based on the parametric studies, a set of empirical formulae to estimate the equivalent material moduli is proposed for the purposes of simplify the associated applications for engineering design and analysis. Verifications of the proposed empirical formula with the EIM model and the experimental data are performed with two examples. The first is a compression test and the second is the load-deflection test of a four point loading simply supported beam. The computational results based on the proposed empirical model agree with the EIM method and the test data. The empirical formulae, based on the equivalent inclusion method proposed in this study, represent an alternative means of quickly calculating the effective elastic modulus of steel-fiber reinforced concrete materials. The finite element model based on the EIM model and the proposed empirical formulae are applicable for future studies on engineering designs of steel-fiber reinforced concrete structures like military defense shelters and nuclear power plants. Keywords：equivalent inclusion method, fiber reinforced concrete, finite element model