scholarly journals Explicit Simulation of Circular CFST Stub Columns with External Steel Confinement under Axial Compression

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 23 ◽  
Author(s):  
Faesal Alatshan ◽  
Siti Aminah Osman ◽  
Fidelis Mashiri ◽  
Roszilah Hamid
Keyword(s):  
Failure Modes ◽  
Axial Loading ◽  
Steel Tube ◽  
Fe Model ◽  
Explicit Finite Element ◽  
Steel Ratio ◽  
Short Columns ◽  
Early Loading ◽  
Experimental Findings ◽  
The Impact

Concrete-filled steel tube (CFST) structural members have been widely used in engineering projects for their superior strength and ductility. However, the different lateral dilation characteristics between concrete infill and steel tube have caused imperfect composite interaction during the early loading stage. To overcome this issue, external steel confinements in the form of rings and spiral were previously suggested to minimise the lateral expansion of the steel tube and enhance the concrete confinement effects. This study presented the analytical behaviour of circular CFST short columns with an external ring or spiral confinements which are subjected to axial loading. An explicit finite element (FE) model was developed and verified based on previous experimental findings. Besides that, this study analysed the failure modes, axial load–strain relationship, stress distributions, and bond strength of the composite column components. Parametric analysis was also undertaken to evaluate the impact of material strengths, total steel ratio, and diameter-to-thickness ratio. The results suggest that the use of external steel confinement can enhance the compressive behaviour of CFSTs better than increasing the thickness of the steel tube when using the same steel ratio. Finally, simplified design formulations were developed to accurately calculate the ultimate capacity of CFST columns with and without external steel confinement.

scholarly journals Falling weight impact test of a new-type flexible rock-shed

2018 ◽  
Vol 38 (2) ◽  
pp. 242-252
Author(s):  
Jianrong Yang ◽  
Zhiyu Zhang
Keyword(s):  
Experimental Studies ◽  
Steel Tube ◽  
Time Interval ◽  
Explicit Finite Element ◽  
Numerical Studies ◽  
Structural Details ◽  
Tensile Forces ◽  
New Type ◽  
Falling Weight ◽  
The Impact

A new concept of a flexible rock-shed is presented for protection of the railway from falling rocks. The flexible rock-shed is made of flexible nets connected by specific spring spacer bars to an array of reinforced concrete portable frames which are linked by a longitudinal steel tube truss. To evaluate the performance of the flexible rock-shed, experimental and numerical studies are carried out in the present study. Impact tests are conducted on a full-scale partial model of the prototype structure when it is subjected to a falling block of 340 kg. The impact time interval, maximum deflection of the flexible net, tensile forces in the supporting ropes, and axial strains of spring spacer bars are recorded. To further examine the dynamic behavior of the flexible rock-shed, numerical simulations are also carried out by using the explicit finite element code ANSYS/LS-DYNA. It is found that the numerical results coincide well with the experimental data and both the numerical and experimental studies reveal that the structure can withstand impact energy of 50 kJ with all the materials working in the elastic range. The structural details are improved and the basis for the design and construction of similar structures in the future is provided.<br>

Axial impact behaviors of stub concrete-filled square steel tubes

2019 ◽  
Vol 22 (11) ◽  
pp. 2490-2503 ◽  
Author(s):  
YT Zhang ◽  
B Shan ◽  
Y Xiao
Keyword(s):  
Finite Element ◽  
Failure Modes ◽  
Steel Tube ◽  
Experimental Results ◽  
Parameter Analysis ◽  
Steel Tubes ◽  
Simple Method ◽  
Concrete Filled Steel Tube ◽  
Drop Weight ◽  
The Impact

Existing research on the widely used concrete-filled steel tubes is mainly focused on static or cyclic loading, and the studies on effects of high strain rate are relatively rare. In this article, seven stub concrete-filled steel tubular columns with square section were tested under both static and impact loads, using a large-capacity drop-weight testing machine. The research parameters were variable height of the drop-weight and different load types. The experimental results show that the failure modes of the concrete-filled steel tube columns from the impact tests are similar with those under static load, characterized by the local buckling of the steel tube. The time history curves of impact force and steel strain were investigated. The results indicate that with increasing impact energy, the concrete-filled steel tube stub columns had a stronger impact-resistant behavior. The dynamic analysis software LS-DYNA was employed to simulate the impact behaviors of the concrete-filled steel tube specimens, and the finite element results were reasonable compared with the test results. The parameter analysis on the impact behavior of concrete-filled steel tube columns was performed using the finite element model as well. A simple method was proposed to calculate the impact strength of square concrete-filled steel tube columns and compared favorably with experimental results.

scholarly journals Test and Numerical Study on Monotonic Behavior of Complex CFT Column Joints

2019 ◽  
Vol 2019 ◽  
pp. 1-20
Author(s):  
Zeliang Yu ◽  
Bin Yang ◽  
Bin Jia ◽  
Yuhong Yan ◽  
Shaowen Xiao ◽  
...  
Keyword(s):  
Failure Modes ◽  
Numerical Study ◽  
Local Buckling ◽  
Steel Tube ◽  
Load Test ◽  
Fe Model ◽  
Beam Design ◽  
Overlap Joint ◽  
Cft Column ◽  
Steel Trusses

This paper presents a test and numerical investigation into the monotonic behavior of three different complex steel trusses to concrete-filled tubular (CFT) column joints. Based on an engineering structure, 1 : 4 reduced-scale specimens are manufactured and the three-dimensional subassembly testing system is designed to apply the monotonic load. Test phenomena and load-stress curves show that all three types of joints have a considerable load-carrying capacity and joint rigidity. Finite element (FE) analysis is adopted, and the stress distribution shows good agreement with test data. Both test and FE results show that local buckling and yielding in the root region of steel truss are the main failure modes of test joints and the core area of the CFT column remains intact which are in accordance with the design conception of “strong column and weak beam.” Design conception of proposed overlap joint form is then investigated based on the FE model, and results show that the optimized overlap joint can effectively reduce the stress concentration in the adjacent steel tube and beam member when compared to the traditional N-type overlap joint. Finally, the influence of the outer diaphragm on the stiffness of joint is analyzed. By comparing the end-displacement of the beam member, conclusion can be obtained that the beam flange thickness is suggested to be chosen as the outer diaphragm thickness. The forms of three different proposed joints and their design conceptions can provide good guidance for designers and engineers.

Experimental Study on the Axial Loading Tests of RC Columns Strengthened with Steel Tube

2012 ◽  
Vol 204-208 ◽  
pp. 2878-2882 ◽  
Author(s):  
Miao Zhou ◽  
Jian Wei Li ◽  
Jing Min Duan
Keyword(s):  
Experimental Study ◽  
Bearing Capacity ◽  
Axial Loading ◽  
Steel Tube ◽  
Experimental Results ◽  
Engineering Practice ◽  
Rc Columns ◽  
Short Columns ◽  
Loading Tests ◽  
Engineering Staff

This paper carries out a series of experimental study on 6 column specimens, analyses and compares with the different parameters on the axial loading tests of RC columns and RC columns strengthened with steel tube. The experimental results show that the RC columns strengthened with steel tube take full advantage of loading properties of both materials, thus greatly improve the bearing capacity of specimens. With the same wall thickness steel tube, the improving degree of bearing capacity of long columns is bigger than the short columns, and the reinforcement effect is more obvious. The experimental results can offer reference for scientific research and engineering staff, and promote this reinforcement method to be widely used in engineering practice.

FE Modeling of Elliptical Concrete-Filled Steel Tubular Members Subjected to Pure Bending

2013 ◽  
Vol 859 ◽  
pp. 105-108
Author(s):  
Xiong Zhao ◽  
Xu Kuan Li ◽  
Qing Xin Ren ◽  
Tai Cheng ◽  
Xiao Lian Long
Keyword(s):  
Failure Modes ◽  
Steel Tube ◽  
Fe Model ◽  
Stress Distributions ◽  
Fe Modeling ◽  
Pure Bending ◽  
Element Analysis ◽  
Elliptical Section ◽  
As Stress ◽  
Good Agreement

This paper reports a finite element analysis of the flexural behaviour of concrete-filled steel tubular members with elliptical section. A set of test data were used to verify the FE modeling. generally, good agreement was achieved. Typical curves of moment (M) versus deflection at mid-span (um), as well as stress distributions of steel tube and concrete of the composite members were compared and discussed. The results clearly show that the FE model is available for predicting the load-bearing capacities and the failure modes of the specimens.

scholarly journals Study on the Mechanical Properties of BFRP Tube Confined Concrete Short Columns under Axial Compression

2020 ◽  
Author(s):  
Xindong Ding ◽  
Shuqing Wang ◽  
Yu Liu ◽  
Zepeng Zheng
Keyword(s):  
Axial Compression ◽  
Brittle Failure ◽  
Failure Modes ◽  
Concrete Strength ◽  
Steel Tube ◽  
Confined Concrete ◽  
Test Results ◽  
Compression Tests ◽  
Short Columns ◽  
Square Steel Tube

Axial compression tests were carried out on 6 square steel tube confined concrete short columns and 6 BFRP square pipe confined concrete axial compression tests. The concrete strength grades were C30, C40, and C50. The test results show that the failure modes of steel pipe and BFRP pipe are obviously different, and the BFRP pipe undergoes brittle failure. Compared with the short columns of concrete confined by BFRP pipes, the ultimate bearing capacity of axial compression is increased by -76.46%, -76.01%, and -73.06%, and the ultimate displacements are -79.20%, -80.78%, -71.71%.

scholarly journals Axial Loading Behaviour of Self-Compacting Concrete-Filled Thin-Walled Steel Tubular Stub Columns

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Yunyang Wang ◽  
Lei Xiao ◽  
Chu Jiang ◽  
Yandong Jia ◽  
Guang Yang ◽  
...  
Keyword(s):  
Failure Modes ◽  
Ultimate Load ◽  
Local Buckling ◽  
Axial Loading ◽  
Steel Tube ◽  
Self Compacting Concrete ◽  
Steel Tubes ◽  
Thin Walled ◽  
Stub Columns ◽  
Versus Strain

This paper presents an experimental investigation on the mechanical behaviour of self-compacting concrete-filled thin-walled steel tubular (SCCFTST) stub columns loaded in axial compression to failure. Four specimens were tested to study the effect of diameter to wall thickness (D/t) ratios on the ultimate load, failure modes, and ductility of the columns. Confinement of the steel tube to concrete was also addressed. The failure modes, load versus displacement curves, and load versus strain curves were examined in detail. The experimental results showed that the ultimate state is reached when severe local buckling and rupture occurred on the steel tubes, and the concrete near the rupture has been crushed. The columns with larger D/t ratios appeared more local buckling, and its location is more close to the end of the columns. The SCCFTST stub columns with smaller D/t ratios show higher ultimate load and better ductility, and the steel tubes can exert higher confinement to the concrete.

scholarly journals A Study of Multi-Objective Crashworthiness Optimization of the Thin-Walled Composite Tube under Axial Load

Vehicles ◽  
2020 ◽  
Vol 2 (3) ◽  
pp. 438-452
Author(s):  
Mohammad Reza Seyedi ◽  
Abolfazl Khalkhali
Keyword(s):  
Failure Mechanism ◽  
Energy Absorption ◽  
Failure Modes ◽  
Matrix Material ◽  
Load Condition ◽  
Fe Model ◽  
Absorption Mechanism ◽  
Multi Objective ◽  
Thin Walled ◽  
The Impact

In recent decades, thin-walled composite components have been widely used in the automotive industry due to their high specific energy absorption. A large number of experimental and numerical studies have been conducted to characterize the energy absorption mechanism and failure criteria for different composite tubes. Their results indicate that the energy absorption characteristics depend highly on the failure modes that occur during the impact. And failure mechanism is dependent on fiber material, matrix material, fiber angle, the layout of the fibers, as well as the geometry of structure and load condition. In this paper, first, the finite element (FE) model of the CFRP tube was developed using the Tsai-Wu failure criterion to model the crush characteristics. The FE results were validated using the published experimental. Then, a series of FE simulations were conducted considering different fiber directions and the number of layers to generate enough data for constructing the GMDH-type neural network. The polynomial expression of the three outputs (energy absorption, maximum force, and critical buckling force) was extracted using the GMDH algorithm and was used to perform the Pareto-based multi-objective optimizations. Finally, the failure mechanism of the optimum design point was simulated in LS-DYNA. The main contribution of this study was to successfully model the CFRP tube and damage mechanism using appropriate material constitutive model’s parameters and present the multi-objective method to find the optimum crashworthy design of the CFRP tube.

Cold-formed elliptical concrete-filled steel tubular columns subjected to monotonic and cyclic axial compression

2019 ◽  
Vol 23 (7) ◽  
pp. 1383-1396 ◽  
Author(s):  
Youwu Xu ◽  
Jian Yao ◽  
Xin Sun
Keyword(s):  
Axial Compression ◽  
Failure Modes ◽  
Axial Strain ◽  
Residual Deformation ◽  
Steel Tube ◽  
Superposition Method ◽  
Fe Model ◽  
Hoop Strain ◽  
Tubular Columns ◽  
Stub Columns

Concrete-filled steel tubular columns are widely used in structural systems, and elliptical concrete-filled steel tubular columns are receiving more and more attention. An experimental study on cold-formed elliptical concrete-filled steel tubular stub columns was carried out under monotonic and cyclic axial compression. The failure modes, axial load–displacement curves, ultimate loads, hoop strain–axial strain behavior, strength deterioration, and residual deformation were obtained and discussed. Complementary finite element models considering the complex non-uniform confinement between steel tube and concrete were developed and validated by experimental results. Then, the validated FE model was used to study the influence of aspect ratio, yield strength of steel, and compressive strength of concrete on the axial capacity of elliptical concrete-filled steel tubular stub columns. Finally, a relatively simple superposition method was put forward to predict the axial bearing capacity of elliptical concrete-filled steel tubular stub columns. Compared with the test data, both the numerical method and superposition method can generate accurate predictions.

Study of Dynamic Impact Behaviors and Ballistic Properties of Ceramic/UHMWPE Composite Armor

2011 ◽  
Vol 121-126 ◽  
pp. 397-400 ◽  
Author(s):  
Ying Nan Guo ◽  
Qin Sun ◽  
Ling Wu
Keyword(s):  
Impact Behavior ◽  
Testing System ◽  
Fe Model ◽  
Explicit Finite Element ◽  
Ballistic Properties ◽  
Composite Armor ◽  
The Impact ◽  
Different Thickness ◽  
Good Agreement ◽  
Uhmwpe Composite

The ballistic properties of different thickness combinations of ceramic/UHMWPE composite armors were studied in this paper, in order to find a better ballistic property structure subject to 12.7mm bullet. Powder-gun ballistic testing system was used to carry out the normal impact tests to determine the response and the ballistic limit of these combinations of ceramic/UHMWPE composite armors subject to impact loading. Compared with the test, an explicit finite element (FE) model was built with LS-DYNA Code to simulate the impact process. The influence of different parameters on the impact behavior was considered analytically. Results show very good agreement with the experimental data.

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