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 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.

Strength of wind load bearing wall stud-to-track connections

2002 ◽  
Vol 29 (5) ◽  
pp. 777-786
Author(s):  
Steven R Fox ◽  
Reinhold M Schuster
Keyword(s):  
Failure Modes ◽  
Wind Load ◽  
Bearing Steel ◽  
Load Bearing ◽  
Web Crippling ◽  
Modes Of Failure ◽  
Cold Formed Steel ◽  
Design Documents ◽  
Wall Assembly ◽  
Common Application

Cold-formed steel structural members are often used in building construction, with a common application being wind load bearing steel studs. The studs frame into horizontal steel track members at the top and bottom of the wall assembly, with the stud-to-track connection typically being made with self-drilling screws or welds. The design of the wall stud must include a check of the web crippling capacity at the end reactions. The type of end bearing that exists in these stud-to-track connections is not explicitly addressed by the current North American cold-formed steel design documents. Reported in this paper are the results and analysis of a collection of end-one-flange web crippling tests of common stud-to-track connections. The tests show that there are two failure modes: web crippling of the stud, and punch-through of the track flange. Design expressions are proposed to predict the capacity of the connection based on these two modes of failure. The effects of increasing the gap between the stud and the track and the effects of missing screws in the stud-to-track connection are also discussed.Key words: cold-formed steel, steel studs, structural design, connections, web crippling.

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.

scholarly journals Strength of Reinforced Reactive Powder Concrete Hollow Beams

2019 ◽  
Vol 26 (2) ◽  
pp. 15-22
Author(s):  
Mazin Abdulrahman ◽  
Saba Mahmood
Keyword(s):  
Concrete Strength ◽  
Reactive Powder Concrete ◽  
Load Carrying Capacity ◽  
Hollow Section ◽  
Hollow Beam ◽  
Strength Capacity ◽  
Load Carrying ◽  
Concentrated Loading ◽  
Reactive Powder ◽  
Hollow Beams

The main objective of this research is to investigate the structural behavior and strength of reinforced reactive powder concrete beams with a hollow section subjected under two point concentrated loading. The experimental work consist of ten beams with dimensions (150mm width×200mm height×1000 mm length), eight of them are hollow beams and two solid beams were cast and tested up to failure. The major parameters adopted in the current research includes the hollowness ratio (10% and15%), hollow location (at top or at bottom), and hollow shape (circle or square). The amount of longitudinal and transverse reinforcement, concrete strength and the other parameters were kept constant for all the specimens. The comparisons between all specimens (hollow and solid) are based on the load carrying capacity, deflection, crack pattern and mode of failures. Results showed that the strength capacity of hollow beam when the hollow lies in the bottom is much higher than for top hollow, and the square hollow will lead to more decrease in the beam strength compared with the circular hollow and this is more evident when the hollowness ratio increases from (10% to 15%).

scholarly journals Design and analysis of concrete-filled tubular flange girders under combined loading

2021 ◽  
pp. 136943322110015
Author(s):  
Rana Al-Dujele ◽  
Katherine Ann Cashell
Keyword(s):  
Finite Element ◽  
Axial Force ◽  
Failure Modes ◽  
Numerical Study ◽  
Combined Loading ◽  
Torsional Stiffness ◽  
Fe Model ◽  
Combined Effects ◽  
Element Analysis ◽  
Hollow Section

This paper is concerned with the behaviour of concrete-filled tubular flange girders (CFTFGs) under the combination of bending and tensile axial force. CFTFG is a relatively new structural solution comprising a steel beam in which the compression flange plate is replaced with a concrete-filled hollow section to create an efficient and effective load-carrying solution. These members have very high torsional stiffness and lateral torsional buckling strength in comparison with conventional steel I-girders of similar depth, width and steel weight and are there-fore capable of carrying very heavy loads over long spans. Current design codes do not explicitly include guidance for the design of these members, which are asymmetric in nature under the combined effects of tension and bending. The current paper presents a numerical study into the behaviour of CFTFGs under the combined effects of positive bending and axial tension. The study includes different loading combinations and the associated failure modes are identified and discussed. To facilitate this study, a finite element (FE) model is developed using the ABAQUS software which is capable of capturing both the geometric and material nonlinearities of the behaviour. Based on the results of finite element analysis, the moment–axial force interaction relationship is presented and a simplified equation is proposed for the design of CFTFGs under combined bending and tensile axial force.

scholarly journals Compression Test on Cold-Formed Steel Built-Up Back-to-Back Channels Stub Columns

2011 ◽  
Vol 201-203 ◽  
pp. 2900-2903 ◽  
Author(s):  
Chui Huon Tina Ting ◽  
Hieng Ho Lau
Keyword(s):  
Compression Test ◽  
Failure Modes ◽  
Local Buckling ◽  
Effective Width ◽  
Test Results ◽  
Direct Strength Method ◽  
Cold Formed Steel ◽  
Stub Column ◽  
Hot Rolled ◽  
Stub Columns

Built-up sections are used to resist load induced in a structure when a single section is not sufficient to carry the design load for example roof trusses. In current North American Specification, the provision has been substantially taken from research in hot-rolled built-up members connected with bolts or welds [1]. The aim of this paper is to investigate on built-up back-to-back channels stub columns experimentally and theoretically using Effective Width Method and Direct Strength Method. Compression test was performed on 5 lipped channel and 5 back-to-back channels stub columns fabricated from cold-formed steel sheets of 1.2mm thicknesses. The test results indicated that local buckling is the dominant failure modes of stub columns. Therefore, Effective Width Method predicts the capacity of stub columns compared to Direct Strength Method. When compared to the average test results, results based on EWM are 5% higher while results based on DSM are 12% higher for stub column.

EXPERIMENTAL INVESTIGATION OF CFRP STRENGTHENED I-SHAPED COLD FORMED STEEL BEAMS

2017 ◽  
Vol 79 (5) ◽  
Author(s):  
Nahushananda Chakravarthy ◽  
Sivakumar Naganathan ◽  
Jonathan Tan Hsien Aun ◽  
Sreedhar Kalavagunta ◽  
Kamal Nasharuddin Mustapha ◽  
...  
Keyword(s):  
Carrying Capacity ◽  
Experimental Results ◽  
Steel Beams ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Length Width ◽  
Cold Formed Steel ◽  
Formed Channel ◽  
Hot Rolled ◽  
Hot Rolled Steel

Cold formed steel differ from hot rolled steel by its lesser thickness and weight. The cold formed steel applicable in roof purlin, pipe racks and wall panels etc. Due its lesser wall thickness the cold formed steel member subjected to buckling. The enhancement of load carrying capacity of the cold formed steel member can be achieved by external strengthening of CFRP. In this study cold formed channel members connected back to back to form I shaped cross section using screws. These built up beam members were 300mm, 400mm and 500mm in length with 100mm screw spacing and edge distance of 50mm were chosen for testing. CFRP fabric cut according to length, width of built up beams and wrapped outer surface of beam using epoxy resin. Experiments were carried out in two sets firstly plain built up beams and secondly CFRP wrapped beams. The test results shows that increased load carrying capacity and reduction in deflection due to CFRP strengthening. Experimental results were compared with AISI standards which are in good agreement. Experimental results shows that CFRP strengthening is economic and reliable.

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