• Advances in Computational Design
• /
• v.8 no.2
• /
• pp.147-177
• /
• 2023

Elliptical concrete-filled steel tubular (CFST) column is widely used in modern structures for both aesthetical appeal and structural performance benefits. The ultimate axial load is a critical factor for designing the elliptical CFST short columns. However, there are complications of geometric and material interactions, which make a difficulty in determining a simple model for predicting the ultimate axial load of elliptical CFST short columns. This study aims to propose an efficient adaptive neuro-fuzzy inference system (ANFIS) model for predicting the ultimate axial load of elliptical CFST short columns. In the proposed method, the ANFIS model is used to establish a relationship between the ultimate axial load and geometric and material properties of elliptical CFST short columns. Accordingly, a total of 188 experimental and simulation datasets of elliptical CFST short columns are used to develop the ANFIS models. The performance of the proposed ANFIS model is compared with that of existing design formulas. The results show that the proposed ANFIS model is more accurate than existing empirical and theoretical formulas. Finally, an explicit formula and a Graphical User Interface (GUI) tool are developed to apply the proposed ANFIS model for practical use.

• Structural Engineering and Mechanics
• /
• v.88 no.1
• /
• pp.95-107
• /
• 2023

In this study, circular thin-walled reinforced high strength concrete-filled steel tube (RHSCFST) stub columns with various tube thicknesses (i.e., 1.8, 2.5 and 3.0mm) and reinforcement ratios (i.e., 0, 1.6%, 2.4% and 3.2%) were fabricated to explore the influence of these factors on the axial compressive behavior of RHSCFST. The obtained test results show that the failure mode of RHSCFST transforms from outward buckling and tearing failure to drum failure with the increasing tube thickness. With the tube thickness and reinforcement ratio increased, the ultimate load-carrying capacity, compressive stiffness and ductility of columns increased, while the lateral strain in the stirrup decreased. Comparisons were also made between test results and the existing codes such as AIJ (2008), BS5400 (2005), ACI (2019) and EC4 (2010). It has been found that the existing codes provide conservative predictions for the ultimate load-carrying capacity of RHSCFST. Therefore, an accurate model for the prediction of the ultimate load-carrying capacity of circular thin-walled RHSCFST considering the steel reinforcement is developed, based on the obtained experimental results. It has been found that the model proposed in this study provides more accurate predictions of the ultimate load-carrying capacity than that from existing design codes.

• Journal of the Daesoon Academy of Sciences
• /
• v.32
• /
• pp.137-173
• /
• 2019

Modern scientists are trying to find the basic unit of order, fractal geometry, in the complex systems of the universe. Fractal is a term often used in mathematics or physics, it is appropriate as a principle to explain why some models of ultimate reality are represented as multifaceted. Fractals are already widely used in the field of computer graphics and as a commercial principle in the world of science. In this paper, using observations from fractal geometry, I present the embodiment of ultimate reality as understood in Daesoon Thought. There are various models of ultimate reality such as Dao (道, the way), Sangje (上帝, supreme god), Sinmyeong (神明, Gods), Mugeuk (無極, limitlessness), Taegeuk (太極, the Great Ultimate), and Cheonji (天地, heaven and earth) all of which exist in Daesoon Thought, and these concepts are mutually interrelated. In other words, by revealing the fact that ultimate reality is embodied within fractal geometry, it can be shown that concordance and transformation of various models of ultimate reality are supported by modern science. But when the major religions of the world were divided along lines of personality (personal gods) and non-personality (impersonal deities), most religions came to assume that ultimate reality was either transcendental or personal, and they could not postulate a relationship between God and humanity as Yin Yang (陰陽) fractals (Holon). In addition, religions, which assume ultimate reality as an intrinsic and impersonal being, are somewhat different in terms of their degree of Holon realization - all parts and whole restitution. Daesoon Thought most directly states that gods (deities) and human beings are in a relationship of Yin Yang fractals. In essence, "deities are Yin, and humanity is Yang" and furthermore, "human beings are divine beings." Additionally, in the Daesoon Thought, these models of ultimate reality are presented through various concepts from various viewpoints, and they are revealed as mutually interrelated concepts. As such, point of view regarding the universe wherein Holarchy becomes a models in a key idea within perennial philosophy. According to a universalized view of religious phenomena, perennial philosophy was adopted by the world's great spiritual teachers, thinkers, philosophers, and scientists. From this viewpoint, when ultimate reality coincides, human beings and God are no longer different. In other words, the veracity of the theory of ultimate reality that has appeared in Daesoon Thought can find support in both modern science and perennial philosophy.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1994.04a
• /
• pp.7-12
• /
• 1994

In structural analysis of prestressed concrete continuous flexural mambers, secondary effects produced by tendon forces should be reasonably estimated. The secondary moment at service load stags is normally used for ultimate required moment caculation in strength design. This concept has to be reviewed when precise analysis is performed considering construction step, time dependent properties of concrete and tendon. An ultimate moment computation proposed, concept and structural behavior. The previously proposed procedure by other researcher and the proposed procedure are compared and reviewed for the currently constructed precast prestressed concrete bridge.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1990.04a
• /
• pp.51-56
• /
• 1990

Investigations on the behavior of steel fiber reinforced high strength concrete beams subjected to predominant shear are accomplished to determine their diagonal shear strength including ultimate shear strength. The parameters varied were the volume fraction(Vf) of the fibers, shear span depth ratio(a/d). The test result show that diagonal shear strength and ultimate shear strength are increased siginificantly due to crack arrest mechanism. Predictive equations are suggested for evaluating the diagonal cracking strength and ultimate shear strength of the fiber reinforced high strength concrete beams.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2005.11a
• /
• pp.209-212
• /
• 2005

This paper presents, basic concepts on deformation models for D-regions critical to shear. Strut-and-tie models are used to construct for deformation estimation at yielding and ultimate deformation. A generic: strut-and-tie model is proposed to investigate deformation patterns and failure mode identification. Superposition of the basic models enables us to explain deformation limits of arch action and truss action. Displacement at yielding is assessed by consideration of deformation of reinforcing steel only while the ultimate displacement is calculated by limits of ultimate strain of concrete in compression and failure mechanisms.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2005.11a
• /
• pp.331-334
• /
• 2005

Three RC beams are fabricated and tested to assess the ultimate load-carrying capacity. Depending on the crackings, the flexural stiffness of the RC beams are changed. However, these variations of the flexural stiffness do not influenced on the ultimate load-carrying capacity of the tested beams. Based on the behaviors of RC beams, the validation of the current assessment codes to discussed.

• Journal of applied mathematics & informatics
• /
• v.22 no.1_2
• /
• pp.149-158
• /
• 2006

In this paper, we consider the Lotka- Volterra predator-prey system, in which constant quantity of the prey is harvested in regular pulses. The ultimate behavior of the solutions starting from different regions is mainly studied. Further, some examples are given to illustrate our results.

• Proceeding of KASS Symposium
• /
• 2006.05a
• /
• pp.81-87
• /
• 2006

This study has been conducted to predict the ultimate moment capacities of double angle connections with various angle thicknesses and bolt gage distances. Considering the results of experimental tests conducted previously, a simplified analytical model is suggested in this research. In addition, some basic data are also provided for structural engineers to design a double angle connection preliminary.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.11a
• /
• pp.357-360
• /
• 2004

Estimation of deformation capacity of non-flexural reinforced concrete members is proposed using basic concepts of limit analysis and the virtual work method. This new approach starts with construction of admissible stress field as for an equilibrium set. Failure mechanisms compatible with admissible stress fields are postulated as for displacement set. It is assumed that the ultimate deformations as result of failure mechanisms are controlled by ultimate strain of concrete in compression. The derived formula for deformability of deep beams in shear shows reasonable range of ultimate displacement.