http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Use of artificial damping factors to enhance numerical stability for irregular joints
Nzabonimpa, J.D.,Hong, Won-Kee Elsevier 2018 Journal of constructional steel research Vol.148 No.-
<P><B>Abstract</B></P> <P>The authors previously proposed a fast and easy assembly method for wide flange steel column-beam frames in which the column and beam steel web had skew cuts and the lower flange of the steel beam was partially removed to prevent the bottom flange of the steel beam from running into the flanges of the L-shaped guide angles (which were pre-installed on the column bracket) when they were erected. However, the joint experienced convergence difficulties at the irregular structural configuration of the skewed web connections when cyclic finite element analysis was performed. This study introduced artificial damping factors, implemented during nonlinear numerical computation, to balance the internal and external forces. The influence of the damping factors was explored to ameliorate the numerical instabilities by removing the aforementioned convergence difficulties. It was shown that a solution converged while the dissipated stabilization energy was sufficiently small, ensuring that the analysis results were not distorted by the use of damping factors in the range of 1.0 × 10<SUP>−5</SUP> to 5.0 × 10<SUP>−5</SUP>. The best matches with monotonic runs and the convergence for steels with yield strength of 325 MPa were obtained by applying damping factors of 0.0002 and 0.0005.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Easy and fast installation method for wide flange steel beam sections is proposed. </LI> <LI> Erection test was performed to verify the applicability of the proposed joint. </LI> <LI> Artificial damping factors were introduced to overcome numerical instabilities. </LI> <LI> The influence of damping factor on solution accuracy was discussed in this study. </LI> </UL> </P>
Structural performance of detachable precast composite column joints with mechanical metal plates
Nzabonimpa, J.D.,Hong, Won-Kee Elsevier 2018 ENGINEERING STRUCTURES Vol.160 No.-
<P><B>Abstract</B></P> <P>The seismic performance of the novel precast concrete frame with mechanical joints using metal plates proposed to provide moment connections was estimated by the numerical analysis verified by experimental investigations. Nonlinear finite element analyses of mechanical column-to-column joints with metal filler plates under static loadings were performed to determine their failure modes and deformations in the column plates. Damages to the proposed novel mechanical connections for composite precast columns using metal plates that create a rigid joint were also elicited. This study also identified the material parameters of the damaged concrete using a plasticity model that were suitable for the prediction of the proposed precast columns. The calibrated dilation angle and concrete damage factor were validated by experimental investigations of the specimens subjected to cyclic loadings; the required stiffness of the column metal plates for rigid joints was identified. A comparison between numerical and experimental results showed that the calibrated FE models accurately predicted the joint behavior of the mechanical column-column joint. Recommendations were made for the practical and optimal design of the mechanical column connections based on the nonlinear behavior of the joints.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Numerical model was developed to predict mechanical joint behavior for precast column. </LI> <LI> Test failure modes were accurately predicted by the calibrated FE models. </LI> <LI> Numerical parameters for contact surface were identified for the joint analysis. </LI> </UL> </P>