scholarly journals EXPERIMENTAL BEHAVIOR AND DESIGN OF RECTANGULAR CONCRETE-FILLED TUBULAR BUCKLING-RESTRAINED BRACES

2021 ◽  
Keyword(s):  
Failure Modes ◽  
Design Method ◽  
Concrete Strength ◽  
Steel Tube ◽  
Influential Factors ◽  
Steel Buildings ◽  
Initial Stiffness ◽  
Buckling Restrained Braces ◽  
Ultimate Failure ◽  
Series Of Experiments

This paper proposes a new design method for concrete-filled tubular buckling-restrained braces (CFT-BRBs) by incorporating the confinement effect on pre-buckling rigidity. A series of experiments are performed to investigate the effects of concrete strength and sectional dimension on the initial stiffness, ultimate strength, and energy dissipation behaviors. Experimental results indicate that the confined concrete plays an important role in the energy dissipating capacity of CFT-BRBs. On the other hand, the sectional dimensions of the steel tube and core are influential factors governing the ultimate failure modes of CFT-BRBs. The findings in study provide technical supports to optimize the design methods for ductile seismic performance of CFT-BRBs in low-rise and high-rise steel buildings.

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 A Design Method to Induce Ductile Failure of Flexural Strengthened One-Way Reinforced Concrete Slabs

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7647
Author(s):  
Huy Q. Nguyen ◽  
Tri N. M. Nguyen ◽  
Do Hyung Lee ◽  
Jung J. Kim
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Shear Failure ◽  
Design Method ◽  
Concrete Slab ◽  
Ductile Failure ◽  
Reinforced Concrete Slabs ◽  
Failure Loads ◽  
Ultimate Failure ◽  
Rc Slabs

Strengthening existing reinforced concrete (RC) slabs using externally bonded materials is increasingly popular due to its adaptability and versatility. Nevertheless, ductility reduction of the rehabilitated flexural members with these materials can lead to brittle shear failure. Therefore, a new approach for strengthening is necessary. This paper presents a methodology to induce ductile failure of flexural strengthened one-way RC slabs. Ultimate failure loads can be considered to develop the proposed design methodology. Different failure modes corresponding to ultimate failure loads for RC slabs are addressed. Flexural and shear failure regions of RC slabs can be established by considering the failure modes. The end span of the concrete slab is shown for a case study, and numerical examples are solved to prove the essentiality of this methodology.

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 Cyclic Testing of Concrete-Filled Steel Tube Columns in Diagrid Structures

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Qingxuan Shi ◽  
Wenzhe Cai ◽  
Bin Wang
Keyword(s):  
Energy Dissipation ◽  
Failure Modes ◽  
Concrete Strength ◽  
Steel Tube ◽  
Concrete Filled Steel Tube ◽  
Compression Direction ◽  
Axial Cyclic Loading ◽  
Energy Dissipation Capacity ◽  
Cfst Columns ◽  
Diagrid Structure

Inclined concrete-filled steel tube (CFST) columns in a diagrid structure system can efficiently carry large vertical loads and horizontal forces. This paper presents an experimental study of the stress characteristics of engineered inclined CFST columns under axial cyclic loading. Ten specimens were tested, including two hollow steel tube (HST) columns and eight CFST columns, and the influences of loading scheme, aspect ratio, concrete strength, and steel ratio were examined. The seismic behaviours were investigated, including mechanical behaviour, failure modes and hysteretic curves, and ductility, and the interaction between the steel tube and concrete was examined as well. Better ductility and energy dissipation capacity are achieved in the tension direction, whereas higher bearing capacity and stiffness are achieved in the compression direction. Compared with hollow steel tube columns, the supporting effect of concrete on the steel tube for CFST columns in tension and the restraining effect of the steel tube on concrete for CFST columns in compression ensure higher capacity, deformability, and energy dissipation capacity.

scholarly journals Performance of Special-Shaped Concrete-Filled Square Steel Tube Column under Axial Compression

2020 ◽  
Vol 2020 ◽  
pp. 1-16 ◽  
Author(s):  
Zhen Wang ◽  
Xuejun Zhou ◽  
Fangshuai Wei ◽  
Mingyang Li
Keyword(s):  
Yield Strength ◽  
Failure Modes ◽  
Slenderness Ratio ◽  
Concrete Strength ◽  
Local Buckling ◽  
Steel Tube ◽  
Element Analysis ◽  
Fea Model ◽  
Compressive Performance ◽  
Square Steel Tube

The axial compressive performance of novel L-shaped and T-shaped concrete-filled square steel tube (L/T-CFSST) column was assessed in this study. Ten L/T-CFSST columns were tested to failure under axial load. The experimental data were used to determine various failure modes, bearing capacities, and load-displacement curves. The test parameters included the section form, steel tube thickness, steel yield strength, and slenderness ratio. The axial compressive performance of the L/T-CFSST column proved favorable, and each square steel tube showed strong cooperative performance. The failure mode of the stub column specimen (H/D ≤ 3) was strength failure caused by local buckling of the steel tube and that of the medium-long column member (H/D > 3) was instability failure caused by overall bending of the specimen. A finite element analysis (FEA) model was established and successfully validated by comparison against the test results. Based on the FEA model, parametric analyses were conducted to investigate the effects of steel tube thickness, concrete strength, steel yield strength, and slenderness ratio. The ultimate loads obtained from the experiments and FEA were compared to the results calculated by the available design codes. A formula was established to calculate the axial compressive strength and stability bearing capacity of the L/T-CFSST column accordingly. The calculation results are in close agreement with the FEA and experimental results, and the proposed formula may provide a workable reference for practicing engineers.

scholarly journals Axial Compression Behaviors of the Steel Tube Confined Reinforced Concrete Columns with Binding Bars

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Hao Hu ◽  
Zhengliang Li ◽  
Xi Tu ◽  
Junfeng Tang
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Axial Compression ◽  
Failure Modes ◽  
Tube Wall ◽  
Concrete Strength ◽  
Steel Tube ◽  
Ultimate Bearing Capacity ◽  
Axial Deformation ◽  
Section Dimension

An experimental study on the steel tube confined reinforced concrete (STCRC) column with binding bars under axial compression is conducted. The bearing capacity and failure modes are obtained. It can be known that the axial deformation of concrete occurred under compression. The core concrete is wrapped and constrained by the steel tube wall, and the steel tube wall is constrained by binding bars locally, so the local buckling shape of the wall between the binding bars is like wave shape. The 3D finite element model is also developed to analyze the behavior of this type of column under axial compression. Good agreement is shown between the test and predicted results in terms of the load-deformation curves and ultimate strength. The parametric studies indicate that the spacing of binding bars, diameter of longitudinal bars, concrete strength, thickness of the steel tube wall, and section dimension of the column generate different influence on the mechanical properties and bearing capacity. The diameter of longitudinal bars, concrete strength, and section dimension of the column have a great effect on the ultimate bearing capacity. The numerical results also show that the spacing of binding bars has little effect on the ultimate bearing capacity. The larger thickness of the steel tube wall leads to adverse effect on the specimen performance. Finally, the theoretical calculation is carried out, and the result is good.

scholarly journals Flexural behavior of steel-concrete composite beams with U-shaped steel girders

2018 ◽  
Author(s):  
Yong Liu ◽  
Lanhui Guo ◽  
Zhiguo Li
Keyword(s):  
Failure Modes ◽  
Concrete Strength ◽  
Composite Beams ◽  
Flexural Behavior ◽  
Bottom Flange ◽  
Steel Girders ◽  
Initial Stiffness ◽  
Short Channel ◽  
Element Analysis ◽  
Steel Girder

This paper focuses on a new type of steel-concrete composite beams consisting of U-shaped steel girders and angle connectors. Compared with conventional composite beams consisting of wide flange girders and headed stud connectors (or short channel connectors), the composite beams considered in this study have favorable flexural performance while reducing the excessive costs and potential construction challenges due to installation of the stud and/or channel shear connectors. Through four-point bending tests on five specimens, this research team experimentally investigated flexural behavior of such new composite beams. The five specimens were varied to have different angle connector intervals and installation locations. Test results showed that composite beams with angle connectors welded to the webs of U-shaped steel girder failed in brittle failure modes while composite beams with angle connectors welded on the top flange of U-shaped steel girder failed in ductile failure mode. Moreover, finite element analysis were performed and the results were verified by the experimental results. According to the parametric analysis results, concrete strength has little effect on flexural behavior of composite beams while increasing yield stress of steel girder could significantly increase the flexural resistance but could not change the initial stiffness. Increasing the height of steel girder, the thickness and width of bottom flange are recommended to improve the flexural behavior of composite beams. 

scholarly journals Experimental Research on Reinforced Concrete Columns Strengthened with Steel Jacket and Concrete Infill

2021 ◽  
Vol 11 (9) ◽  
pp. 4043
Author(s):  
Aleksandar Landović ◽  
Miroslav Bešević
Keyword(s):  
Compressive Strength ◽  
Reinforced Concrete ◽  
Cross Section ◽  
Experimental Research ◽  
Failure Modes ◽  
Steel Tube ◽  
Rc Columns ◽  
Rc Column ◽  
Steel Jacket ◽  
Ductile Behavior

Experimental research on axially compressed columns made from reinforced concrete (RC) and RC columns strengthened with a steel jacket and additional fill concrete is presented in this paper. A premade squared cross-section RC column was placed inside a steel tube, and then the space between the column and the tube was filled with additional concrete. A total of fourteen stub axially compressed columns, including nine strengthened specimens and five plain reinforced concrete specimens, were experimentally tested. The main parameter that was varied in the experiment was the compressive strength of the filler concrete. Three different concrete compression strength classes were used. Test results showed that all three cross-section parts (the core column, the fill, and the steel jacket) worked together in the force-carrying process through all load levels, even if only the basic RC column was loaded. The strengthened columns exhibited pronounced ductile behavior compared to the plain RC columns. The influence of the test parameters on the axial compressive strength was investigated. In addition, the specimen failure modes, strain development, and load vs. deformation relations were registered. The applicability of three different design codes to predict the axial bearing capacity of the strengthened columns was also investigated.

Study on shear performance of the connection with external stiffening ring between square steel tubular column and unequal-depth steel beams

2020 ◽  
pp. 136943322098166
Author(s):  
Shuhao Yin ◽  
Bin Rong ◽  
Lei Wang ◽  
Yiliang Sun ◽  
Wuchen Zhang ◽  
...  
Keyword(s):  
Failure Modes ◽  
Plastic Hinge ◽  
Steel Tube ◽  
Nonlinear Finite Element ◽  
Steel Beams ◽  
Finite Element Models ◽  
Test Results ◽  
Panel Zone ◽  
Load Paths ◽  
Shear Performance

This paper studies the shear performance of the connection with the external stiffening ring between the square steel tubular column and unequal-depth steel beams. Two specimens of interior column connections were tested under low cyclic loading. The deformation characteristics and failure modes exhibited by the test phenomena can be summarized as: (1) two specimens all exhibited shear deformation in steel tube web of the panel zone and (2) weld fracture in the panel zone and plastic hinge failure at beam end were observed. Besides, load-displacement behaviors and strain distributions have been also discussed. The nonlinear finite element models were developed to verify the test results. Comparative analyses of the bearing capacity, failure mode, and load-paths between the equal-depth and unequal-depth beam models have been carried out.

Concrete Strength and Deformation Property under Sea Water Erosion Environment

2012 ◽  
Vol 446-449 ◽  
pp. 2554-2559 ◽  
Author(s):  
Jian Jun Cai ◽  
Feng Zhang ◽  
Wei Cui ◽  
Shou Shan Chen ◽  
Pu Lun Liu
Keyword(s):  
Large Scale ◽  
Failure Modes ◽  
Deformation Property ◽  
Sea Water ◽  
Dynamic Stiffness ◽  
Concrete Strength ◽  
Strain Curve ◽  
Water Erosion ◽  
Strength And Deformation ◽  
Erosion Environment

In order to effectively assess the concrete strength and deformation property under sea water erosion environment, concrete stress and strain curve was researched with the number of wet and dry cycle of 0 times, 10 times , 20 times, 30 times, 40 times, 50 times and 60 times based on the large-scale static and dynamic stiffness servo test set. The stress - strain curves of concrete was tested for the lateral pressure 10.8MPa, 14.4MPa, and 18.8MPa at different dry-wet cycles, The failure modes and superficial cracking characteristics of specimens are reported at different dry-wet cycles. Concrete elastic modulus and compressive strength were researched. Based on concrete mechanical theory , the classic Kufer-Gerstle strength criteria of concrete was used, a large number of test samples of multivariate data were nonlinear regressed, a biaxial concrete strength criterion was established taking into account the stress ratio and the number of dry-wet cycles.

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