Buckling Research Papers - Academia.edu (original) (raw)

In this study, buckling restrained braces (BRBs) are implemented as a potential retrofit strategy to mitigate damage in skewed bridges. For this purpose, a three-span reinforced concrete (RC) box girder skewed bridge was used as a case... more

In this study, buckling restrained braces (BRBs) are implemented as a potential retrofit strategy to mitigate damage in skewed bridges. For this purpose, a three-span reinforced concrete (RC) box girder skewed bridge was used as a case study. A three-dimensional (3-D) model was developed in OpenSees to incorporate BRBs between bent columns. The model includes soil-structure interaction effects adjusted by recent results from skewed backfill-abutment interaction experiments. This paper assesses the impacts of five different BRB designs on the performance of skewed concrete box girder bridges with different skewed angles. Nonlinear time history analyses (THAs) were performed to assess effect of BRBs on the seismic performance of skewed bridges. The seismic behavior of skewed bridges can be significantly different from that of straight bridges due to potential torsional effects caused by the combination of longitudinal and transverse seismic responses. Therefore, optimized BRB designs ...

One of the seismic load resistant systems is the slit steel shear wall system. Using inclined slits in the plate, the performance of the strips is flexural-axial and they act as a passive damper by forming plastic deformations. In this... more

One of the seismic load resistant systems is the slit steel shear wall system. Using inclined slits in the plate, the performance of the strips is flexural-axial and they act as a passive damper by forming plastic deformations. In this model, by changing the length of these axial members, the yield displacement and other seismic parameters of the shear wall can be changed. The purpose of this study is to numerically evaluate the slit steel shear wall with oblique slots and with different slit composition and end stiffener. For this purpose, after modeling validation, a parametric study was performed on the steel wall with different placement of different slits and end stiffeners. The reversed cyclic behavior was compared with a non-slot sample. Comparison of the results shows that despite the reduction of initial strength and stiffness in the slit model, this wall has a better cyclic behavior and dissipated energy. The results show less resistance drop and better performance in drifts above 2%. The results also show that only by changing the location of the slots, the final strength and initial stiffness will be changed up to 19 and 25%, respectively. Using end stiffeners with higher inertia moment is one of the most effective methods to increase energy dissipation; The use of Box100 cross section as a stiffener, increases the energy dissipation up to 2 times compared to the normal sample. Overall, the performance of the steel shear wall with the proposed groove shape is excellent.

A solid shell element model is proposed for the elastic bifurcation buckling analysis of double-walled carbon nanotubes (DWCNTs) under axial compression. The solid shell element allows for the effect of transverse shear deformation which... more

A solid shell element model is proposed for the elastic bifurcation buckling analysis of double-walled carbon nanotubes (DWCNTs) under axial compression. The solid shell element allows for the effect of transverse shear deformation which becomes significant in a stocky DWCNT with relatively small radius-to-thickness ratio. The van der Waals (vdW) interaction between the adjacent walls is simulated by linear springs. Using this solid shell element model, the critical buckling strains of DWCNTs with various boundary conditions are obtained and compared with molecular dynamics results and those obtained by other existing shell and beam models. The results obtained show that the solid shell element is able to model DWCNTs rather well, with the appropriate choice of Young’s modulus, tube thickness, and spring constant for modeling the vdW forces.

In the present paper, based on the classical plate theory, buckling analysis of piezoelectric coupled FGM rectangular plates is investigated. By assuming the transverse distribution of electric potential to be a combination of a parabolic... more

In the present paper, based on the classical plate theory, buckling analysis of piezoelectric coupled FGM rectangular plates is investigated. By assuming the transverse distribution of electric potential to be a combination of a parabolic and a linear function of thickness, the equiblirium equations for buckling analysis of plate with surface bonded piezoelectric layers are established. The Maxwell's equation and all boundary conditions including the conditions on the top and bottom surfaces of the plate for closed and open circuited and Levy type of boundary conditions are satisfied. Numerical results show that, the critical buckling load for open circuit is more than that of closed circuit. Furthermore, the critical buckling loads increase by increasing the thickness of piezoelectric layers.

The use of back-to-back built-up C-section beams is becoming increasingly common in CFS construction due to their cost-effectiveness and enhanced load-carrying capacity, making them suitable for longer beam spans and convenient for... more

The use of back-to-back built-up C-section beams is becoming increasingly common in CFS construction due to their cost-effectiveness and enhanced load-carrying capacity, making them suitable for longer beam spans and convenient for transportation. These built-up sections are utilized in wall studs, truss components, and floor joists, with intermediate screw fasteners placed at specific intervals to prevent the separate bowing of channels. This study reveals a ratio of 1.003 between experimental findings and finite element analysis results, and 1.002 between experimental findings and direct strength method results, indicating a strong correlation between experimental data from nonlinear finite element analysis and predictions based on the American Iron and Steel Institute and Australian and New Zealand Standards, particularly in predicting the flexural buckling strength of beam specimens. Furthermore, ongoing research is investigating the impact of screw spacing on flexural strength. This study presents results from 175 finite element tests, evaluating seven distinct cross-sections with twelve unique screw spacings. These spacings correspond to the half wavelength of local, distortional, and global buckling, divided by values from one to four. It was found that screw spacing based on half the local buckling half-wavelength along the centerline of the webs increased the critical global buckling moment capacity and the nominal flexural strength by 56 % and 27 %, respectively. For double-lane screws with the same spacing, these increases were even more substantial, reaching 65 % and 31 %, respectively. Economically, the recommended spacing for single-lane screws is half the local buckling half-wavelength.

Loss of cross section due to corrosion is a main factor in deterioration of steel bridges. Therefore, carbon fiber reinforced plastic (CFRP) is paid to attentions for repairing and reinforcing the steel bridges since CFRP is light weight,... more

Loss of cross section due to corrosion is a main factor in deterioration of steel bridges. Therefore, carbon fiber reinforced plastic (CFRP) is paid to attentions for repairing and reinforcing the steel bridges since CFRP is light weight, high strength and high durability. Although many researches relating to this topic have been reported so far, previous researches mainly focused on the application of CFRP to axial or bending members. On the other hand, most of the corrosion is found on web at the end of main girders. Investigations on repairing and reinforcing corroded web using CFRP have been reported few. In this research, shear buckling test for steel girder bonded by CFRP sheets on web is carried out. Low elastic putty layers are inserted between steel and CFRP sheets in order to improve the performance of out-of-plane deformation. An evaluation method of shear strength of the girder is also proposed.

This study aims to investigate the influence of the plate uncertainty elastic modulus on free vibration response and buckling behavior. To this purpose, elastic modulus of plate is modeled as a random variable with a normal distribution.... more

This study aims to investigate the influence of the plate uncertainty elastic modulus on free vibration response and buckling behavior. To this purpose, elastic modulus of plate is modeled as a random variable with a normal distribution. Spatial autocorrelation function is used for random fields. In this method, the correlation is dependent on the distance, as the points be far away from each other, the correlation is also reduced. Then, applying the powerful finite element method stochastic finite element relations were calculated using Monte Carlo simulation. To this purpose, a four-node Kirchhoff’s element was used with twelve degrees of freedom. For the analysis, random variable is simulated 5,000 times. At last, by numerical tests, the effects of uncertainty on elastic modulus are investigated on the natural frequencies and buckling loads of plate. The results of these tests show that the effect of uncertainty in elastic modulus of the plate has a different effect on the response of vibration and buckling of plate. So that these changes have low effect on free vibration responses of plate. But buckling loads are highly dependent on the elasticity coefficient.

An approach is presented for the estimation of the parameters required to simulate the nonlinear monotonic (i.e., backbone) rotational response of Exposed-Column-Base-Plate (ECBP) connections subjected to moment and axial compression. A... more

An approach is presented for the estimation of the parameters required to simulate the nonlinear monotonic (i.e., backbone) rotational response of Exposed-Column-Base-Plate (ECBP) connections subjected to moment and axial compression. A trilinear backbone curve is selected to represent the rotational response, defined by three deformation and two strength parameters; these properly represent the stiffness, strength, and ductility of the connections. This approach is accompanied by a tool to facilitate convenient estimation of the parameters. The approach is based on a combination of behavioral insights and physics-based models (for some parameters) as well as regression for other parameters, which are estimated from a dataset of eighty-four experiments on ECBP connections conducted over the last forty years in the United States, Europe, and Asia. Predictive equations are provided to estimate the various parameters defining the nonlinear response, and their efficacy is examined by comparing them with the test data; in addition, well-established techniques are implemented to avoid collinearity and the overfitting of regression models. The results show that the models presented in this work provide robust and accurate predictions for in-sample and out-of-sample data. Limitations are outlined.

Multiphysics or multiscale problems naturally involve coupling at interfaces which are manifolds of lower dimensions. The block-diagonal preconditioning of the related saddle-point systems is among the most efficient approaches for... more

Multiphysics or multiscale problems naturally involve coupling at interfaces which are manifolds of lower dimensions. The block-diagonal preconditioning of the related saddle-point systems is among the most efficient approaches for numerically solving large-scale problems in this class. At the operator level, the interface blocks of the preconditioners are fractional Laplacians. At the discrete level, we propose to replace the inverse of the fractional Laplacian with its best uniform rational approximation (BURA). The goal of the paper is to develop a unified framework for analysis of the new class of preconditioned iterative methods. As a final result, we prove that the proposed preconditioners have optimal computational complexity O(N), where N is the number of unknowns (degrees of freedom) of the coupled discrete problem. The main theoretical contribution is the condition number estimates of the BURA-based preconditioners. It is important to note that the obtained estimates are c...

In this article, a new three-dimensional finite element modeling approach with less computing time and space is introduced to study the buckling behavior of sandwich panels, containing a face–core debond. The finite element model... more

In this article, a new three-dimensional finite element modeling approach with less computing time and space is introduced to study the buckling behavior of sandwich panels, containing a face–core debond. The finite element model presented in this study relates the motion of the face sheets to the core through constraint equations utilizing the concept of slave and master nodes, thus representing a more realistic model of the sandwich panel. The composite face sheets are modeled with shell elements, and the core is modeled using the 3D structural solid elements capable of taking transverse flexibility into consideration. In order to model the debond, the constraints between the nodes of the face sheet and the core are removed and replaced with contact elements in the debonded region to avoid interpenetration. The model is validated through comparison with experimental results reported in the literature. The validated model is then used to study the effects of the size, shape, aspect...