scholarly journals Cyclic Experiments and Global Buckling Design of Steel-Angles-Assembled Buckling-Restrained Braces

2021 ◽  
Author(s):  
Jing-Zhong Tong ◽  
En-Yuan Zhang ◽  
Yan-Lin Guo ◽  
Chao-Qun Yu
Keyword(s):  
Inner Core ◽  
Hysteretic Behavior ◽  
Engineering Practice ◽  
Fe Model ◽  
Ratio Requirement ◽  
Design Formula ◽  
Hysteretic Performance ◽  
Global Buckling ◽  
Steel Angles ◽  
Restraining Ratio

Abstract Compared with traditional BRB, the steel-angles-assembled buckling-restrained brace (SAA-BRB) is an innovative BRB with light-weight, accurate control of the geometrical dimensions, easy installation and convenient disassembly. The SAA-BRB is composed of an external restraining system and a cruciform-sectional inner core. The external restraining system is assembled by four steel angles with the connection of high-strength bolts, and the spacers are installed between the inner core and the restraining system. In this study, the hysteretic behavior of SAA-BRB was investigated by experiments and finite element (FE) simulations. Firstly, three SAA-BRB specimens with different restraining ratios were tested under cyclic loads to investigate the hysteretic performance. It was found that all specimens exhibited stable responses and satisfactory energy-dissipating capabilities during the whole loading process. Then, a refined FE model was established, and its validity in predicting the hysteretic responses of SAA-BRB was verified by the experiments. Moreover, based on the yielding criteria of the outmost fiber for the restraining member section, a design formula for the restraining ratio requirements to avoid global buckling of the SAA-BRB was deduced. Finally, extensive parametric analysis was conducted to verify the accuracy of the design formula by changing the geometric dimensions (the restraining ratio) of models. It was found that the proposed formula for the restraining ratio requirement could lead to a conservative prediction with reasonable accuracy, thus providing valuable references for global buckling design of SAA-BRBs in engineering practice.

Global Buckling Behavior of CFST Columns with Assembling Errors

2022 ◽  
Author(s):  
Si-Ming Zhou ◽  
Jing-Zhong Tong ◽  
Gen-Shu Tong ◽  
Zhang Lei ◽  
Xiang Jiang ◽  
...  
Keyword(s):  
Theoretical Formula ◽  
Engineering Practice ◽  
Fe Model ◽  
Stability Performance ◽  
Buckling Behavior ◽  
Buckling Resistance ◽  
Global Buckling ◽  
Cfst Columns ◽  
The Stability ◽  
Slender Column

Concrete-filled steel tubular (CFST) column has been widely used in engineering practice. In the process of assembling two columns to form a slender member, assembling errors (AE) are inevitably produced at the section of connection. When the AE are too large, the global buckling resistance of slender column would be significantly affected. Therefore, it is necessary to investigate the influence of AE on the stability performance of slender CFST columns. In this study, an axial compressive test involving three CFST columns with AE (AE-CFST columns) was conducted. A refined finite element (FE) model is established for further parametric analysis. Based on a simplified analytical model by analyzing the isolated steel connecting plate, a theoretical formula is proposed for predicting the critical thickness [Formula: see text] of the connecting plate. When the thickness [Formula: see text] of the connecting plate meets its requirement, the failure at the section of connection caused by AE could be effectively prevented. Stability design curves considering the influence of AE ratio (the ratio between assembling error and sectional depth of column) are proposed based on numerous FE examples. It is found that the proposed design curves are reliable for the design of AE-CFST columns with different AE ratios.

scholarly journals A Finite Element Study on Compressive Resistance Degradation of Square and Circular Steel Braces under Axial Cyclic Loading

2021 ◽  
Vol 11 (13) ◽  
pp. 6094
Author(s):  
Hubdar Hussain ◽  
Xiangyu Gao ◽  
Anqi Shi
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Cyclic Loading ◽  
Slenderness Ratio ◽  
Hysteretic Behavior ◽  
Element Analysis ◽  
Section Shape ◽  
Axial Cyclic Loading ◽  
Global Buckling ◽  
Parametric Studies

In this study, detailed finite element analysis was conducted to examine the seismic performance of square and circular hollow steel braces under axial cyclic loading. Finite element models of braces were constructed using ABAQUS finite element analysis (FEA) software and validated with experimental results from previous papers to expand the specimen’s matrix. The influences of cross-section shape, slenderness ratio, and width/diameter-to-thickness ratio on hysteretic behavior and compressive-tensile strength degradation were studied. Simulation results of parametric studies show that both square and circular hollow braces have a better cyclic performance with smaller slenderness and width/diameter-to-thickness ratios, and their compressive-tensile resistances ratio significantly decreases from cycle to cycle after the occurrence of the global buckling of braces.

INHOMOGENEOUS LARGE DEFORMATION KINETICS OF POLYMERIC GELS

2013 ◽  
Vol 05 (01) ◽  
pp. 1350001 ◽  
Author(s):  
WILLIAM TOH ◽  
ZISHUN LIU ◽  
TENG YONG NG ◽  
WEI HONG
Keyword(s):  
Large Deformation ◽  
Soft Matter ◽  
Inner Core ◽  
Kinetic Studies ◽  
Fe Model ◽  
One Dimensional ◽  
Simplified Approach ◽  
Deformation Kinetics ◽  
Polymeric Gels ◽  
Kinetics Of

This work examines the dynamics of nonlinear large deformation of polymeric gels, and the kinetics of gel deformation is carried out through the coupling of existing hyperelastic theory for gels with kinetic laws for diffusion of small molecules. As finite element (FE) models for the transient swelling process is not available in commercial FE software, we develop a customized FE model/methodology which can be used to simulate the transient swelling process of hydrogels. The method is based on the similarity between diffusion and heat transfer laws by determining the equivalent thermal properties for gel kinetics. Several numerical examples are investigated to explore the capabilities of the present FE model, namely: a cube to study free swelling; one-dimensional constrained swelling; a rectangular block fixed to a rigid substrate to study swelling under external constraints; and a thin annulus fixed at the inner core to study buckling phenomena. The simulation results for the constrained block and one-dimensional constrained swelling are compared with available experimental data, and these comparisons show a good degree of similarity. In addition to this work providing a valuable tool to researchers for the study of gel kinetic deformation in the various applications of soft matter, we also hope to inspire works to adopt this simplified approach, in particular to kinetic studies of diffusion-driven mechanisms.

Finite Element Simulation and Experimental Study on Blow Forming of Plastic Cups

2011 ◽  
Vol 148-149 ◽  
pp. 1319-1322
Author(s):  
Xiao Hu ◽  
Yi Sheng Zhang ◽  
Hong Qing Li ◽  
De Qun Li
Keyword(s):  
Finite Element ◽  
Thickness Distribution ◽  
Viscoelastic Model ◽  
Engineering Practice ◽  
Fe Model ◽  
Thin Wall ◽  
Forming Process ◽  
Element Simulation ◽  
Physically Based ◽  
Set Up

Blow forming process of plastic sheets is simple and easy to realize, thus, it is widely used for plastic thin-wall parts. In the practical production, an effective method is needed for the preliminary set-up of process parameters in order to achieve accurate control of thickness distribution. Thus, a finite element method (FEM) code is used to simulate blow forming process. For better description of complex material theological characteristics, a physically based viscoelastic model (VUMAT forms Buckley model) to model the complex constitutive behavior is used. Nonlinear FE analyses using ABAQUS were carried out to simulate the blow forming process of plastic cups. The actual values at different locations show a satisfactory agreement with the simulation results: as a matter of fact the error along the cell mid-section did not exceed 0.02 mm on average, corresponding to 5% of the initial thickness, thus the FE model this paper can meet the requirements of the engineering practice.

scholarly journals Effect of Steel Fibers on the Hysteretic Performance of Concrete Beams with Steel Reinforcement—Tests and Analysis

Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 2923 ◽  
Author(s):  
Violetta K. Kytinou ◽  
Constantin E. Chalioris ◽  
Chris G. Karayannis ◽  
Anaxagoras Elenas
Keyword(s):  
Reinforced Concrete ◽  
Steel Reinforcement ◽  
Steel Fibers ◽  
Experimental Program ◽  
Engineering Practice ◽  
Cracking Behavior ◽  
Tension Softening ◽  
Proposed Model ◽  
Hysteretic Performance ◽  
Cracking Performance

The use of fibers as mass reinforcement to delay cracking and to improve the strength and the post-cracking performance of reinforced concrete (RC) beams has been well documented. However, issues of common engineering practice about the beneficial effect of steel fibers to the seismic resistance of RC structural members in active earthquake zones have not yet been fully clarified. This study presents an experimental and a numerical approach to the aforementioned question. The hysteretic response of slender and deep steel fiber-reinforced concrete (SFRC) beams reinforced with steel reinforcement is investigated through tests of eleven beams subjected to reversal cyclic loading and numerical analysis using 3D finite element (FE) modeling. The experimental program includes flexural and shear-critical SFRC beams with different ratios of steel reinforcing bars (0.55% and 1.0%), closed stirrups (from 0 to 0.5%), and fibers with content from 0.5 to 3% per volume. The developed nonlinear FE numerical simulation considers well-established relationships for the compression and tensional behavior of SFRC that are based on test results. Specifically, a smeared crack model is proposed for the post-cracking behavior of SFRC under tension, which employs the fracture characteristics of the composite material using stress versus crack width curves with tension softening. Axial tension tests of prismatic SFRC specimens are also included in this study to support the experimental project and to verify the proposed model. Comparing the numerical results with the experimental ones it is revealed that the proposed model is efficient and accurately captures the crucial aspects of the response, such as the SFRC tension softening effect, the load versus deformation cyclic envelope and the influence of the fibers on the overall hysteretic performance. The findings of this study also reveal that SFRC beams showed enhanced cyclic behavior in terms of residual stiffness, load-bearing capacity, deformation, energy dissipation ability and cracking performance, maintaining their integrity through the imposed reversal cyclic tests.

scholarly journals A robust 3D finite element model for concrete columns confined by FRCM system

2019 ◽  
Vol 281 ◽  
pp. 01006 ◽  
Author(s):  
Majid M.A. Kadhim ◽  
Mohammed J Altaee ◽  
Ali Hadi Adheem ◽  
Akram R. Jawdhari
Keyword(s):  
Finite Element ◽  
Cement Mortar ◽  
Three Dimensional ◽  
Concrete Columns ◽  
Element Model ◽  
Fe Model ◽  
3D Finite Element ◽  
Composite Failure ◽  
Global Buckling ◽  
Fibre Reinforced Polymer

Fibre reinforced cementitious matric (FRCM) is a recent application of fibre reinforced polymer (FRP) reinforcement, developed to overcome several limitations associated with the use of organic adhesive [e.g. epoxies] in FRPs. It consists of two dimensional FRP mesh saturated with a cement mortar, which is inorganic in nature and compatible with concrete and masonry substrates. In this study, a robust three-dimensional (3D) finite element (FE) model has been developed to study the behaviour of slender reinforced concrete columns confined by FRCM jackets, and loaded concentrically and eccentrically. The model accounts for material nonlinearities in column core and cement mortar, composite failure of FRP mesh, and global buckling. The model response was validated against several laboratory tests from literature, comparing the ultimate load, load-lateral deflection and failure mode. Maximum divergence between numerical and experimental results was 12%. Following the validation, the model will be used later in a comprehensive parametric analysis to gain a profound knowledge of the strengthening system, and examine the effects of several factors expected to influence the behaviour of confined member.

Global Buckling of Frames with Laced Compression Members

2016 ◽  
Vol 837 ◽  
pp. 103-108 ◽  
Author(s):  
Michal Kovac ◽  
Zsuzsanna Vanik
Keyword(s):  
Order Theory ◽  
Second Order ◽  
Order Effects ◽  
Engineering Practice ◽  
Buckling Mode ◽  
Column Method ◽  
Global Buckling ◽  
Second Order Effects ◽  
Buckling Length ◽  
Simplified Procedure

The planar frames whose members consist of a laced built-up members are often used in civil engineering practice. For chords of these structures the 1st order theory internal forces and the assessment by equivalent column method are mostly used. In the equivalent column method the buckling length according to the global buckling mode of the structures should be used. If the distance between neighboring nodes is used as the buckling length of the chord, which is the common case, the second order effects with only the bow imperfections between nodes are taken into account in the equivalent column method. For frames sensitive to buckling in a sway mode the second order effects on structures with initial sway imperfection should be taken into account. Therefore, also in frames with the laced compression columns, where the effects of additional sway deformation cause additional normal forces in the chords, the sway imperfection should be applied and the second order in frame analysis should be performed to check these additive forces. This paper deals with the simplified procedure how to evaluate additive forces due to second order effects on the structure with the global sway imperfection.

Fatigue Analysis of a Jacket Structure to Linear and Weakly Nonlinear Random Waves

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Naser Shabakhty ◽  
Arash Khansari
Keyword(s):  
Dynamic Response ◽  
Engineering Practice ◽  
Linear Wave ◽  
Fe Model ◽  
Random Waves ◽  
Weakly Nonlinear ◽  
Analysis And Design ◽  
Jacket Structures ◽  
Wave Models ◽  
Nonlinear Random Waves

Jacket structures have been widely used in oil and gas industry and are increasingly becoming competitive as a support structure of wind turbines at different water depths. These types of structures usually fix in transition or shallow waters where numerous field observations and experiments have shown that water particles tend to exhibit non-Gaussian characteristics. However, current engineering practice ignores the wave nonlinearity for the analysis and design of these structures. The application of linear irregular models might result in considerable uncertainties in the obtained wave loads and consequently the dynamic response and thus it is highly questionable. Therefore, it is crucial to calculate the dynamic response of jacket structures under both linear and nonlinear wave models to investigate the validity of linear wave models in different sea states. In this paper, the finite element (FE) model of a jacket structure located in Persian Gulf (SP17 jacket) is setup and applied to perform a comparative study of the dynamic response to both linear and weakly nonlinear random waves. The fatigue life of the jacket structure is then calculated under both wave models. This paper will substantially improve the understanding of the dynamic response of jacket structures under fatigue damage.

Framework for virtual hybrid simulation of TADAS frames using opensees and abaqus

2016 ◽  
Vol 24 (11) ◽  
pp. 2165-2179 ◽  
Author(s):  
Azin Ghaffary ◽  
Reza Karami Mohammadi
Keyword(s):  
Hybrid Simulation ◽  
Sufficient Accuracy ◽  
Hysteretic Behavior ◽  
Software Framework ◽  
Fe Model ◽  
Computationally Efficient ◽  
Element Analysis ◽  
Efficient Manner ◽  
Coupled Codes ◽  
Comparison Of The Results

Virtual hybrid simulation is a computationally-efficient method that enables coupling of two or more finite element analysis programs. In this study, benefits of this technique in predicting both cyclic and seismic response of a one-story one-bay frame equipped with a Triangular-plate Added Damping and Stiffness (TADAS) damper are evaluated. For this purpose, a detailed FE model of the damper is built in Abaqus to take into account precise modelling of its hysteretic behavior as well as a number of important features related to the geometric characteristics of the including parts of the device, while the remainder of the structure is modelled in OpenSees. Continuous exchange of the data between the coupled codes is conducted through the software framework, OpenFresco. Comparison of the results with experimental outcomes is presented, which proves the ability of the introduced technique in modelling the behavior of such structures in an efficient manner while preserving sufficient accuracy. At the end, a series of dynamic virtual hybrid simulations of the frame are performed which provide useful insights into design of TADAS frames.

scholarly journals Investigating the Hysteretic Behavior of Concrete-Filled Steel Tube Arch by Using a Fiber Beam Element

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Jun Ma ◽  
Yang Liu ◽  
Qingfei Gao ◽  
Kang Hou
Keyword(s):  
Experimental Data ◽  
Transverse Direction ◽  
Vertical Direction ◽  
Beam Element ◽  
Steel Tube ◽  
Hysteretic Behavior ◽  
Constitutive Relationship ◽  
Concrete Filled Steel Tube ◽  
Hysteretic Performance ◽  
Fiber Beam Element

A fiber beam finite element that could account for the nonlinear constitutive relationship between steel and concrete was applied to investigate the hysteretic behavior of concrete filled steel tube (CFT) arch ribs of bridges. At first, the effectiveness of this fiber beam element using for nonlinear analysis was verified by comparing the analytical results with the experimental data, and then this composite element was applied to analyze the hysteretic performance of CFT arch ribs. The following hysteretic behavior of CFT arch ribs of bridges was investigated such as the hysteretic behaviors of moment-curvature of arch ribs in vertical direction of bridge and the hysteretic relationship between load and displacement of arch ribs in longitudinal and transverse direction of bridge. Finally, some parameters affecting the hysteretic behaviors of CFT arch ribs were presented by evaluating the capacity of ductility of CFT arch ribs.

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