scholarly journals Strength enhancement of cold-formed steel tubular column using GFRP strip subjected to axial compression

2021 ◽  
Vol 64 (4) ◽  
pp. 251-260
Author(s):  
Sangeetha Palanivelu ◽  
Dhinagaran Moorthy ◽  
Gobinaath Subramani ◽  
Jeevan Dhayanithi
Keyword(s):  
Axial Compression ◽  
Failure Modes ◽  
Axial Deformation ◽  
Hollow Section ◽  
Tubular Columns ◽  
Load Carrying ◽  
Externally Bonded ◽  
Cold Formed Steel ◽  
Tubular Sections ◽  
Circular Hollow Section

The experimental and analytical evaluation of externally reinforced square and circular cold-formed steel tubular columns with GFRP strips is presented in this study. Under axial compression, fourteen tubular columns with pinned support, seven square tubular sections, and seven circular hollow section columns with externally bonded GFRP strips at various points were tested to failure. The GFRP strips improved the load-carrying capacity of the columns according to the trial results. The GFRP strip at the ends and intermediate regions, with a clear spacing of 100 to 150 mm between the strips, has been proven to be the most effective in achieving ultimate strength, especially for column specimens with full wrapping. Wrapping the GFRP strips increases the strength of square and circular columns by 24 % and 5%, respectively, when compared to unwrapped specimens. The percentage gain in strength is 16% when the cross-section is changed from circular to square. Local and overall flexural buckling, respectively, are the failure modes seen in the square and circular sections. The experimental strength and axial deformation were compared to the analytical results, which showed a satisfactory correlation.

IMPROVED END BEARING CAPACITIES OF SHARP-CORNER ALUMINUM TUBULAR SECTIONS WITH CFRP STRENGTHENING

2012 ◽  
Vol 12 (01) ◽  
pp. 109-130 ◽  
Author(s):  
C. WU ◽  
X. L. ZHAO ◽  
W. H. DUAN ◽  
P. PHIPAT
Keyword(s):  
Failure Modes ◽  
Fem Simulation ◽  
Underlying Mechanism ◽  
Sharp Corner ◽  
Web Crippling ◽  
Hollow Section ◽  
Load Carrying ◽  
Concentrated Loading ◽  
Cold Formed Steel ◽  
Tubular Sections

Web crippling is the major failure mode of thin-walled members when they are subjected to concentrated loading. Carbon fiber-reinforced polymer (CFRP) is found to be promising for strengthening metallic structural members. This paper reports improved web-crippling capacity of sharp-corner aluminum tubular sections: rectangular hollow section (RHS) and square hollow section (SHS), by attaching CFRP to their webs. Twenty four specimens were tested with four CFRP strengthening configurations applied on each of six different aluminum RHS and SHS sections. Significant increase in load-carrying capacity was obtained. Further comparison is made between CFRP strengthened aluminum tubular sections and cold-formed steel counterparts in respect of strengthening efficiency. Underlying mechanism of different failure modes and strengthening efficiencies of various strengthening configurations are discussed with the assistance of FEM simulation.

scholarly journals Seismic Behavior of Elliptical Concrete-Filled Steel Tubular Columns under Combined Axial Compression and Cyclic Lateral Loading

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
YouWu Xu ◽  
Jian Yao ◽  
Feng Hu ◽  
Ying Zhou ◽  
Shuai Jiang
Keyword(s):  
Axial Compression ◽  
Failure Modes ◽  
Mechanical Performance ◽  
Lateral Loading ◽  
Load Carrying Capacity ◽  
Test Results ◽  
Static Behavior ◽  
Tubular Columns ◽  
Load Carrying ◽  
Cfst Columns

Elliptical concrete-filled steel tubular (CFST) column is a new form of CFST columns, consisting of an outer elliptical tube filled with concrete. Although the study on mechanical performance of the elliptical CFST members is receiving more and more attention, they have been limited to static behavior. Against this background, an experimental study on elliptical CFST columns was carried out under combined axial compression and cyclic lateral loading. The failure modes, hysteretic curves, skeleton curves, load carrying capacity, deformability, stiffness degradation, and energy dissipation ability was obtained and discussed. The test results indicated that the elliptical CFST columns possess excellent seismic performance and ductility. Valuable experimental data were provided for the formulation of the theoretical hysteresis model of the elliptical CFST columns.

Axial behaviour of HSS tubular sections strengthened by CFRP strips: an experimental investigation

2012 ◽  
Vol 19 (2) ◽  
pp. 159-168 ◽  
Author(s):  
Muthukamatchi Chelliah Sundarraja ◽  
Sandrasekaran Sivasankar
Keyword(s):  
Carrying Capacity ◽  
Failure Modes ◽  
Load Carrying Capacity ◽  
Structural Behaviour ◽  
Steel Tubes ◽  
Strain Behaviour ◽  
Load Carrying ◽  
Externally Bonded ◽  
Fibre Reinforced Polymer ◽  
Tubular Sections

AbstractThe main objective of this investigation is to assess the feasibility of strengthening square hollow steel tubular sections subjected to compression and to develop or predict the suitable wrapping scheme of fibre reinforced polymer (FRP) to enhance the structural behaviour of it. For this study, compact mild steel tubes were used with the main variable being FRP characteristics. Carbon fibre has been considered and used as strips with several other parameters such as the number of layers, width and spacing of strips, the sectional area of strips, and wrapping scheme. Experiments were undertaken until column failure to fully understand the influence of FRP characteristics on the compressive behaviour of square hollow steel tubes including their failure modes, stress-strain behaviour, enhancement in load carrying capacity and effect of distribution of CFRP layers. The behaviour of externally bonded hollow steel tubular sections was compared with one another and also with the control specimen. From the test results, it was found that CFRP strengthening significantly increases the load carrying capacity and ductility of the hollow steel tubular members further.

C-section Cold-Formed Steel as Structural Members in Housing Construction in the Philippines

2019 ◽  
Author(s):  
Bernardo A. Lejano
Keyword(s):  
Axial Compression ◽  
High Speed ◽  
Failure Modes ◽  
Weight Ratio ◽  
High Strength ◽  
The Philippines ◽  
Bending Test ◽  
Housing Construction ◽  
Distortional Buckling ◽  
Cold Formed Steel

<p>Getting good lumber for housing construction is becoming difficult in the Philippines due to existing partial log ban. Although, the use of reinforced concrete is still the most popular in construction, an emerging alternative is the use of cold-formed steel (CFS). It is gaining popularity because of its high strength-to- weight ratio. However, information about the structural performance of locally-produced cold-formed steel is almost nonexistent. Although, design provisions are stipulated in the local Code, these are based on formulas developed abroad, hence the need to investigate these cold-formed steel. This study focuses on the C-section cold-formed steel, which is the most popularly used. The objective is to verify its performance when subjected to axial compression and flexure, both experimentally and computationally. For the computational part, the formulas stipulated in the National Structural Code of the Philippines were followed. For the experimental part, the cold-formed steel members were subjected to compression loads and flexural loads. Aside from usual sensors, high-speed cameras were used to capture the failure modes. For axial compression test, 80 specimens with different lengths and thicknesses were tested. For flexure, 24 specimens of back-to-back C-sections were subjected to 4-point bending test. Results showed the predicted strengths were well below the experimental values. In design, this means the use of Code-based formulas is conservative. Failure modes observed were torsional buckling and distortional buckling. Comparison of failure modes between experiment and computation shows 70% agreement for compression and 75% for flexure. Finite element method calculations were also done and were compared with experimental results.</p>

An Investigation of the Debonding Mechanism between FRCM Composites and a Masonry Substrate

2017 ◽  
Vol 747 ◽  
pp. 382-389 ◽  
Author(s):  
Mattia Santandrea ◽  
Gilda Daissè ◽  
Claudio Mazzotti ◽  
Christian Carloni
Keyword(s):  
Failure Modes ◽  
Stress Transfer ◽  
High Strength ◽  
Steel Fibers ◽  
Vapor Permeability ◽  
Fiber Reinforced ◽  
Direct Shear Tests ◽  
Frp Composites ◽  
Load Carrying ◽  
Externally Bonded

Fiber reinforced cementitious matrix (FRCM) composites have recently become a hot topic in Europe as an alternative to traditional fiber reinforced polymer (FRP) composites for several strengthening applications of existing masonry buildings. The terrific success of this new retrofitting system is mainly due to some advantages that it offers when compared to FRP, such as the possibility of application of the composite to wet surfaces and the vapor permeability featured by the inorganic matrix. In this work, the stress transfer between FRCM composites and a masonry substrate is investigated. FRCM strips comprised of ultra-high-strength steel fibers embedded in a cementitious grout are externally bonded to masonry blocks. Single-lap direct shear tests are performed. Parameters studied are bonded length and density of the steel fibers. Load responses are presented and failure modes are discussed. Change in the bond behavior and load carrying capacity with increasing bonded length is analyzed to determine the effective bond length.

scholarly journals Analysis of concrete-filled stainless steel tubular columns under combined fire and loading

2018 ◽  
Author(s):  
Qinghua Tan ◽  
Leroy Gardner ◽  
Linhai Han ◽  
Dianyi Song
Keyword(s):  
Stainless Steel ◽  
Fire History ◽  
Failure Modes ◽  
Structural Response ◽  
Fe Model ◽  
Axial Deformation ◽  
Tubular Columns ◽  
Deformation Curves ◽  
Heating And Cooling ◽  
Fire Scenarios

In fire scenarios, concrete-filled stainless steel tubular (CFSST) columns undergo initial loading at ambient temperature, loading during the heating phase as the fire develops, loading during the cooling phase as the fire dies out and continual loading after the fire. CFSST columns may fail some points during this process under combined fire and loading. In this paper, the failure modes and corresponding working mechanism of CFSST columns subjected to an entire loading and fire history are investigated. Sequentially coupled thermal-stress analyses in ABAQUS are employed to establish the temperature field and structural response of the CFSST column. To improve the precision of the finite element (FE) model, the influence of moisture on the thermal conductivity and specific heat of concrete during both the heating and cooling phases is considered using subroutines. Existing fire and post-fire test data of CFSST columns are used to validate the FE models. Comparisons between predicted and test results confirm that the accuracy of the FE models is acceptable; the FE models are then extended to simulate a typical CFSST column subjected to the entire loading and fire history. The behaviour of the CFSST column is explained by analysis of the temperature distribution, load versus axial deformation curves and failure response.

scholarly journals EXPERIMENTAL COMPRESSION TESTS OF COLD-FORMED STEEL (CFS) TO VERIFY ITS CODE-BASED STRENGTH

2021 ◽  
Vol 10 (2) ◽  
Author(s):  
Bernardo Lejano ◽  
James Matthew De Jesus ◽  
Arvin Patrick Yu
Keyword(s):  
Axial Compression ◽  
High Speed ◽  
Failure Modes ◽  
Weight Ratio ◽  
The Philippines ◽  
Structural Performance ◽  
Computational Aspect ◽  
Compression Tests ◽  
Flexural Buckling ◽  
Cold Formed Steel

Cold-Formed Steel (CFS) is a good construction material because of its high strength-to-weight ratio, that is, it exhibits efficient load carrying capabilities in combination with its lightweight characteristics. Although CFS is already being used in construction, information on structural performance of locally-produced CFS in the Philippines is scarce. To date, the authors have not found any experimental study done in the Philippines regarding the structural performance of locally-produced CFS. In this study, C-section and Z-section are being studied since these members exhibit buckling failures that may be difficult to predict due to complexity of their section geometry. The objective of this paper is to present the performance of these CFS sections when subjected to concentric axial compression both experimentally and computationally. For the experimental part, the CFS members were subjected to axial compression using a hydraulic jack. High-speed video cameras were used to capture the different failure modes. For the computational aspect, provisions found in the National Structural Code of the Philippines (NSCP) were used to calculate the compression strength of the members. A total of 80 C-section specimens with 5 different lengths and 5 different thicknesses were tested. It was found that the strength calculations using the NSCP provisions were not consistent with the results of the compression tests. For shorter lengths, distortional buckling prevailed as the main failure, while for longer lengths, torsional-flexural buckling occurred. All of the predicted strengths were highly conservative. For the Z-section, a total of 180 specimens with 6 different lengths and 6 different thicknesses were tested. Torsional-flexural buckling was observed in majority of the specimens. Although most of the failure modes were predicted correctly, it was found that the predicted strengths using the NSCP were relatively high compared to the experimental results, thus non-conservative. Finite Element Method (FEM) analyses using ANSYS were conducted. Findings indicate that the experiment results agreed well with the FEM results.

Capacity Difference of Circular Hollow Section X-joints Under Brace Axial Compression and Tension

2020 ◽  
Vol 20 (5) ◽  
pp. 1443-1453
Author(s):  
Bida Zhao ◽  
Chengqing Liu ◽  
Zeyang Yao ◽  
Yangzheng Cai
Keyword(s):  
Axial Compression ◽  
Hollow Section ◽  
Circular Hollow Section

scholarly journals Experimental Study on the Static Behavior of Reinforced Warren Circular Hollow Section (CHS) Tubular Trusses

2018 ◽  
Vol 8 (11) ◽  
pp. 2237 ◽  
Author(s):  
Wenwei Yang ◽  
Jiankang Lin ◽  
Ni-na Gao ◽  
Ruhao Yan
Keyword(s):  
Experimental Study ◽  
Carrying Capacity ◽  
Truss Structures ◽  
Load Carrying Capacity ◽  
Static Behavior ◽  
Hollow Section ◽  
Surface Plasticity ◽  
Load Carrying ◽  
Circular Hollow Section ◽  
Chord Member

For truss structures, the question of whether to weld hidden welds or not has been controversial. In the actual construction process of truss structures, the members are usually spot welded in place on the assembly platform, and then welded as a whole, while the hidden welds of the truss are not welded, especially for small pipe diameter trusses. Furthermore, in this study, under hidden weld unwelded conditions, two kinds of reinforcing method (adding a half outer sleeve on each joint and filling concrete into the chord members) are adopted to achieve the purpose of strengthening the truss. Therefore, this paper presents an experimental study on the static behavior of four types of Warren tubular trusses made of CHS members. These four types are (1) T-HW: The truss with hidden welds welded; (2) T-HN: The truss with hidden welds unwelded; (3) TS-AS: The truss strengthened on the basis of T-HN by adding a half outer sleeve on each joint; (4) TS-FC: The truss strengthened on the basis of T-HN by filling concrete into the top and bottom chord members. The mechanical behavior, failure mode, bearing capacity, and load-displacement of all specimens were investigated. The surface plasticity of the bottom chord member, the weld fracture around tubular joints at the bottom chord member, and the bending deformation of the bottom chord member were observed in the tests. Compared with the T-HW specimen, the load carrying capacity of the T-HN specimen decreased by 18%. On the other hand, the T-HN specimen has better deformability than the T-HW specimen. The reinforcing method of adding a half outer sleeve on each joint and filling concrete into the chord members can effectively improve the load carrying capacity and stiffness of the truss, thus reducing the overall deformation of the truss, but the reinforcing method of filling concrete into the chord members is more efficient.

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