No

Elliptical hollow sections (EHS) are the newest steel shape to emerge in the industry, but appropriate design guidance is lacking, being completely absent from Canadian codes and guidelines. Geometric property and compressive resistance tables were established to be potentially added to the Canadian guides. The equivalent RHS method, originally proposed by Zhao and Packer in 2009, was simplified and modified to validate its use for the design of EHS columns and beams. An experimental programme was developed to investigate the behaviour of EHS-to-EHS welded connections. Twelve T and X connection tests were performed to study the effect of connection angle, orientation type and loading. Two methods were developed to predict connection capacities and failure modes: the equivalent CHS and the equivalent RHS approaches. Both methods proved to be conservative on average, but the equivalent RHS approach proved to be more successful at capturing the actual failure mode of EHS-to-EHS connections.

Elliptical hollow sections (EHS) are the newest steel shape to emerge in the industry, but appropriate design guidance is lacking, being completely absent from Canadian codes and guidelines. Geometric property and compressive resistance tables were established to be potentially added to the Canadian guides. The equivalent RHS method, originally proposed by Zhao and Packer in 2009, was simplified and modified to validate its use for the design of EHS columns and beams. An experimental programme was developed to investigate the behaviour of EHS-to-EHS welded connections. Twelve T and X connection tests were performed to study the effect of connection angle, orientation type and loading. Two methods were developed to predict connection capacities and failure modes: the equivalent CHS and the equivalent RHS approaches. Both methods proved to be conservative on average, but the equivalent RHS approach proved to be more successful at capturing the actual failure mode of EHS-to-EHS connections.

Hot-dip galvanizing is widely used for corrosion protection of steel structures. However, there has been a plethora of recent reports on premature cracking in galvanized steel structures, which have resulted in some early decommissions or even hazardous collapses. This research focuses on cold-formed Rectangular Hollow Sections (RHS). A total of 108 tensile coupons were tested to investigate the effects of galvanizing as well as different pre-galvanizing treatments on the material properties around the cross sections of the specimens. For the first time, this thesis reports a comprehensive measurement of residual stresses in different directions at the member ends which are directly relevant to the cracking issue. The results were also compared to the residual stresses far away from the member ends, which are relevant to structural stability research. In all, the research provides a better understanding of the characteristics and structural performance of galvanized RHS to facilitate its application. The recommendations can help engineers, fabricators, and galvanizers mitigate the risk of cracking in RHS during galvanizing. / Graduate

This thesis presents the results of a research project to develop methods to carry out fire safety design of welded steel tubular trusses at elevated temperatures due to fire exposure. It deals with three subjects: resistance of welded tubular joints at elevated temperatures, effects of large truss deflection in fire on member design and effects of localised heating. The objectives of the project are achieved through numerical finite element modelling at elevated temperatures using the commercial Finite Element software ABAQUS v6.10-1 (2011). Validation of the simulation model for joints is based on comparison against the test results of Nguyen et al. (2010) and Kurobane et al. (1986). Validation of the simulation model for trusses is through checking against the test results of Edwards (2004) and Liu et al. (2010).For welded tubular joints, extensive numerical simulations have been conducted on T-, Y-, X-, N- and non-overlapped K-joints subjected to brace axial compression or tension, considering a wide range of geometrical parameters. Uniform temperature distribution was assumed for both the chord and brace members. Results of the numerical simulations indicate for gap K- and N-joints (two brace members, one in tension and the other in compression) and for T-, Y- and X-joints with the brace member under axial tensile load (one brace member only, in tension), it is suitable to use the same ambient temperature calculation equation as in the CIDECT (2010) or EN 1993-1-8 (CEN, 2005a) design guides and simply replace the ambient temperature strength of steel with the elevated temperature value. However, for T-, Y- and X-joints under brace compression load (one brace member only, in compression), the effect of large chord deformation should be considered. Large chord deformation changes the chord geometry and invalidates the assumed yield line mechanism at ambient temperature. For approximation, the results of this research indicate that it is acceptable to modify the ambient temperature joint strength by a reduction factor for the elastic modulus of steel at elevated temperatures. In the current fire safety design method for steel truss, a member based approach is used. In this approach, the truss member forces are calculated at ambient temperature based on linear elastic analysis. These forces are then used to calculate the truss member limiting temperatures. An extensive parametric study has been carried out to investigate whether this method is appropriate. The parametric study encompasses different design parameters over a wide range of values, including truss type, joint type, truss span-to-depth ratio, critical member slenderness, applied load ratio, number of brace members, initial imperfection and thermal elongation. The results of this research show that due to a truss undergoing large displacements at elevated temperatures, some truss members (compression brace members near the truss centre) experience large increases in member forces. Therefore, using the ambient temperature member force, as in the current truss fire safety design method, may overestimate the truss member critical temperature by 100 °C. A method has been proposed to analytically calculate the increase in brace compressive force due to large truss deformation. In this method, the maximum truss displacement is assumed to be span/30. A comparison of the results calculated using the proposed method against the truss parametric study results has shown good agreement with the two sets of results, with the calculation results generally being slightly on the safe side. When different members of a truss are heated to different temperatures due to localised fire exposure, the brace members in compression experience increased compression due to restrained thermal expansion. To calculate the critical temperature of a brace member in a localised heated truss, it is necessary to consider this effect of restrained thermal expansion. It is also necessary to consider the beneficial effects of the adjacent members being heated, which tends to reduce the increase in compressive force in the critical member under consideration. Again, an extensive set of parametric studies have been conducted, for different load ratio, slenderness and axial restraint ratio. The results of this parametric study suggest that to calculate the critical temperature of a brace member, it is not necessary to consider the effects of the third or further adjacent members being heated. For the remainder of the heated members, this thesis has proposed a linear elastic, static analysis method at ambient temperature to calculate the additional compressive force (some negative, indicating tension) in the critical member caused by the heated members (including the critical member itself and the adjacent members). The additional compressive force is then used to calculate the limiting temperature of the critical member. For this purpose, the approximate analytical equation of Wang et al. (2010) has been demonstrated to be suitable.

Concrete-filled tubular (CFT) columns have been widely adopted in building structures owing to their superior structural performance, such as enhanced load bearing capacity, compared to hollow tubes. Circular, square and rectangular hollow sections are most commonly used in the past few decades. Elliptical hollow section (EHS) available recently is regarded as a new cross-section for the CFT columns due to its attractive appearance, optional orientation either on major axis or minor axis and improved structural efficiency. The state of the research in terms of elliptical columns, tubular joints between EHSs and connections with CFT columns, etc., are reviewed in this thesis, showing a lack of investigations on EHSs, especially on beam to elliptical column connections which are essential in framed structures. The structural behaviour of elliptical column to I-beam connections under bending is studied in this thesis to fill the research gap. Overall ten specimens with various joint assemblies were tested to failure to highlight the benefits of adopting concrete infill and stiffeners in the columns. A three-dimensional finite element model developed by using ABAQUS software is presented and verified against obtained experimental results, which shows acceptable accuracy and reliability in predicting failure modes of the connections and their moment capacities. Parametric studies were performed to access the main parameters that affecting the bending behaviour of the connections. A simple hand calculation method in terms of ultimate moment capacity is proposed according to experiments conducted for connections with concrete-filled columns.

This Master´s thesis describes the design and assessment of steel structure of a hangar located in Znojmo. The supporting structure of a hangar is 37,475 m span, 48 m lenght, clear hight at the highest point is 15,5 m. Main construction material is steel, grade S355J2. The supporting structure consist of a truss girders. The distance of each cross link sis 4 m. There is prepared statics calculation of the main load-bearing parts of the structure, including joints and details. The valid standards CSN EN were used in processing of this dissertation.

Yes / Elliptical Hollow Sections (EHSs) have been utilized in construction recently because of their visual appearance as well as the potential structural efficiency owing to the presence of the two principle axes. However, little information currently exists for the design of beam to elliptical column connections, which is an essential part of a building structure. Thus, to ensure the safe and economic application of EHSs, a new research project has been initiated. Rotation behaviour of simply bolted beam to concrete-filled elliptical steel column connections was investigated experimentally. Various joint types were considered and the benefits of adopting core concrete and stiffeners were highlighted. This paper covers the experimental studies and simulation of the connections using the ABAQUS standard solver. Comparisons of failure modes and moment vs. rotation relationships of the connections between numerical and experimental results were given. Good agreement has been obtained and the developed finite element model was therefore adopted to conduct a preliminary parametric study to explore the effect of critical parameters on the structural behaviour of beam to concrete-filled elliptical column connections.

Yes / This paper investigated the rotation behaviour of simply bolted I-beam to concrete-filled elliptical steel tubular (CFEST) column connections experimentally. Ten different joint assemblies were tested to failure, with a constant axial compressive load applied to the column and upwards concentrated loads at the beam ends. All of the steel tubes were hot-finished and had a cross-sectional aspect ratio of 2. The orientation of the column and the arrangement of the stiffening plates were taken into consideration. Moment versus rotation relationships and failure modes were compared for each joint, highlighting the benefits of using core concrete and stiffeners in these connections.

Concrete-filled tubular (CFT) columns have been widely adopted in building structures owing to their superior structural performance, such as enhanced load bearing capacity, compared to hollow tubes. Circular, square and rectangular hollow sections are most commonly used in the past few decades. Elliptical hollow section (EHS) available recently is regarded as a new cross-section for the CFT columns due to its attractive appearance, optional orientation either on major axis or minor axis and improved structural efficiency. The state of the research in terms of elliptical columns, tubular joints between EHSs and connections with CFT columns, etc., are reviewed in this thesis, showing a lack of investigations on EHSs, especially on beam to elliptical column connections which are essential in framed structures. The structural behaviour of elliptical column to I-beam connections under bending is studied in this thesis to fill the research gap. Overall ten specimens with various joint assemblies were tested to failure to highlight the benefits of adopting concrete infill and stiffeners in the columns. A three-dimensional finite element model developed by using ABAQUS software is presented and verified against obtained experimental results, which shows acceptable accuracy and reliability in predicting failure modes of the connections and their moment capacities. Parametric studies were performed to access the main parameters that affecting the bending behaviour of the connections. A simple hand calculation method in terms of ultimate moment capacity is proposed according to experiments conducted for connections with concrete-filled columns.