|主題||Effects of the Position of Inflexure Points on the Ultimate Shear Capacity of Reinforced Concrete Beams|
|筆頭著者||Yukio Aoyagi（Asian Institute of Technology）|
|連名者1||Taweep Chaisomphob（Thammasat University）|
|連名者2||Shahidul Islam（Asian Institute of Technology）|
|要旨||1. BACKGROUND OF STUDY
In most of the design codes, shear capacity of reinforced concrete linear members without web reinforcements is calculated by an empirical formula which is principally based on the experimental results of simply supported beams. However, in such structures as frames or continuous beams, inflexure points located within shear span influence the shear capacity. Y. Aoyagi and T. Endo conducted an experimental research, in which they simulated the structural conditions prevalent in statically indeterminate reinforced concrete structures. Referring their experimental data, they proposed a method to estimate shear capacity of the specific members based on the provisions specified in JSCE Code. However, in the JSCE code no clear descriptions are made regarding the definition of shear span "a" for the cases of statically indeterminate linear members with an inflexure point in the shear span. The authors assumed a fictitious support at the inflexure point and divided the shear span "a" into two portions, i.e. the equivalent shear spans "a1" an "a2" as shown in Fig.1. Except for the definition of the shear span, the JSCB formula for ultimate shear capacities of a simple beams were applied.
1)The positions of inflexure points have greater effects on the ultimate shear capacity of reinforced concrete beams. It can be assumed that at the position of inflexure point in the span an imaginary hinge is generated and divide the shear span into two equivalent ones. Hence, the section can take more shear capacity as much as 70% for the case of concentrated load obtained in the present study and 25% for that of distributed load. Therefore, it is very important to consider this effect in practical design.
2)By using the equation proposed by Y. AoyaBi et.al. considering the effects of inflexure points, the experimental results, for an cases of the ratio of distance of inflexure point from the nearest support and effective depth of beam = 0.5~4, are most closer to the calculated ones compared with other proposed equations.