• Steel and Composite Structures
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• 제44권5호
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• pp.691-705
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• 2022

Shear failure in reinforced concrete (RC) structures is very hazardous. This failure is rarely predicted and may occur without any prior signs. Accurate shear strength prediction of the RC members is challenging, and traditional methods have difficulty solving it. This study develops a JAYA-GBRT model based on the JAYA algorithm and the gradient boosting regression tree (GBRT) to predict the shear strength of RC slender beams without stirrups. Firstly, 484 tests are carefully collected and divided into training and test sets. Then, the hyperparameters of the GBRT model are determined using the JAYA algorithm and 10-fold cross-validation. The performance of the JAYA-GBRT model is compared with five well-known empirical models. The comparative results show that the JAYA-GBRT model (R² = 0.982, RMSE = 9.466 kN, MAE = 6.299 kN, µ = 1.018, and Cov = 0.116) outperforms the other models. Moreover, the predictions of the JAYA-GBRT model are globally and locally explained using the Shapley Additive exPlanation (SHAP) method. The effective depth is determined as the most crucial parameter influencing the shear strength through the SHAP method. Finally, a Graphic User Interface (GUI) tool and a web application (WA) are developed to apply the JAYA-GBRT model for rapidly predicting the shear strength of RC slender beams without stirrups.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2000년도 봄 학술발표회논문집
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• pp.51-58
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• 2000

Lateral buckling behavior of laminated composite thin-walled I-section beams subjected to bending moment is investigated by applying the nonlinear anisotropic thin-walled beam theory. The constituent laminated thin-walled elements of I-section are assumed to be symmetrically laminated. The bending, twisting, and warping stiffnesses of the cross section are obtained based on the definitions of these stiffnesses In the thin-walled anisotropic beam theory In numerical examples, singly-symmetric I-beams with specially orthotropic, quasi-isotropic, angle-plys and various boundary conditions are considered. To validate the proposed theoretical approach, present analytical solutions are compared with three dimensional finite element solutions.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표논문집(II)
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• pp.399-404
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• 1998

Analysis of partially prestressed beams in which cracking under service loads is allowed requires a knowledge of geometric cross section properties such as neutral axis, centroid, area and moment of initia of this cracked transformed section. Especially an exact calculation for the stresses of steel and concrete and the width of crack and the amount of deflection can be obtained with accrurate prediction of neutral of centroidal axis location. In this paper, the procedures for predicting the centroidal axis location of partially cracked prestressed concrete members, using the compatibility of deformation of concrete and steel are formulated and compared with Dilger`s computed results. And also the computed results according to this paper are compared with Branson`s experimental results.

• 대한기계학회논문집A
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• 제20권7호
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• pp.2174-2181
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• 1996

Equations of chordwise and flapwise bending motions of pretwisted rotatin cantilever beams are derived. The two motions are coupled to each other due to the pretwist angle of the beam cross section. As the angular speed, hub radius ratio, and pretwist angle vary, the vibration characteristics of the beam change. It is found that engenvalue loci veering phenomena and associated mode shape variations occur between two vibration modes due to the pretwist angle. The effect of the pretwist angle on the critical angular speed is also investigated.

• Advances in aircraft and spacecraft science
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• 제1권1호
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• pp.93-123
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• 2014

A variational asymptotic composite beam model has been developed for thermoelastic analysis. Composite beams, including sandwich structure and laminates, under different boundary conditions are examined. Previously developed beam model, which is based on variational-asymptotic method, is extended to incorporate temperature-dependent materials experiencing large temperature changes. The recovery relations have been derived so that the temperatures, heat fluxes, stresses, and strains can be recovered over the cross-section. The present theory is implemented into the computer program VABS (Variational Asymptotic Beam Sectional analysis). Numerical results are compared with the 3D analysis for the purpose of demonstrating advantages of the present theory and use of VABS.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 하계종합학술대회 논문집
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• pp.629-632
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• 1989

The scattered light intensity from a spherical particle passing through the cross-over region of two coherent laser beams, varies periodically. Photodetection of this light beams produces a periodic signal of varying amplitude. The phase of the signal varies with the particle size and refractive index, the beam crossing angle and wavelength, and the position and size of the scattered ligth collecting aperture. In this paper the phase variation with respect to the particle absorptive index of retraction, collecting lens size and beam crossing angle is calculated using both Mie scattering theory and reflection theory. The two theories show good agreement in phase predictions, especially for large absorptive indices and for small collection lenses. Both theories predict phase to be inversely proportional to the beam crossing angle.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 1999년도 추계학술발표대회 논문집
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• pp.215-218
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• 1999

A general structural model, which is an extension of the Vlassov theory, is developed for the analysis of composite rotor blades with elastic couplings. A comprehensive analysis applicable to both thick-and thin-walled composite beams, which can have either open- or closed profile is formulated. The theory accounts for the effects of elastic couplings, shell wall thickness, and transverse shear deformations. A semi-complementary energy functional is used to account for the shear stress distribution in the shell wall. The bending and torsion related warpings and the shear correction factors are obtained in closed form as part of the analysis. The resulting first order shear deformation theory describes the beam kinematics in terms of the axial, flap and lag bending, flap and lag shear, torsion and torsion-warping deformations. The theory is validated against experimental results for various cross-section beams with elastic couplings.

• 대한기계학회논문집A
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• 제24권10호
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• pp.2637-2645
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• 2000

We propose a new one-dimensional theory for thin-walled curved box beams having rectangular cross sections, in which torsional, out-of-plane bending, warping and distortional deformations are coupled. The major difference between the present theory and existing theories lies in that the present theory takes into account additional distortion as well as warping. To verify the present theory, a standard finite element based on the present theory is developed and used for numerical analysis. A couple of numerical examples indeed confirm that the consideration of warping and distortional deformations is very important.

• 한국화재소방학회논문지
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• 제22권2호
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• pp.84-90
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• 2008

본 연구는 H형강과 콘크리트 슬래브가 전단연결재로 일체화된 합성보의 화재 시 거동에 관한 실험적 연구로, 합성율과 재하율의 영향을 내화실험을 통해 평가하였다. 실험체는 H형강에 스터드 커넥터를 전단연결재로 사용하여 제작한 6개로 구성되며, 화재거동에 대한 전열특성을 열전대를 통해 확인하였다. 실험은 표준화재곡선에 의해 진행하였으며, 건설기술연구원 화재시험실에서 수행하였다. 실험결과 합성율과 재하율에 따른 합성보의 내화 특성을 확인하였으며, 화재에 의한 보형강과 콘크리트, 전단연결재의 열 특성을 확인할 수 있는 기초자료를 확보하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2000년도 추계학술대회 논문집
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• pp.358-365
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• 2000

For the general case of loading conditions and boundary conditions, it is very difficult to obtain closed form solutions for buckling loads and natural frequencies of thin-walled structures because its behaviour is very complex due to the coupling effect of bending and torsional behaviour. In consequence, most of previous finite element formulations are introduce approximate displacement fields to use shape functions as Hermitian polynomials, and so on. The Purpose of this study is to presents a consistent derivation of exact dynamic stiffness matrices of thin-walled straight beams, to be used ill tile free vibration analysis, in which almost types of boundary conditions are exist An exact dynamic element stiffness matrix is established from governing equations for a uniform beam element of nonsymmetric thin-walled cross section. This numerical technique is accomplished via a generalized linear eigenvalue problem by introducing 14 displacement parameters and a system of linear algebraic equations with complex matrices. The natural frequency is evaluated for the thin-walled straight beam structure, and the results are compared with analytic solutions in order to verify the accuracy of this study.