Analysis of the Interchurch World Movement Report on the steel strike /

Pt. 1. Analysis of the Interchurch World Movement Report on the steel strike -- pt. 2. History of the Interchurch Report on the steel strike.

Strength analysis of steel-concrete composite beams in combined bending and shear

Despite experimental evidences, the contributions of the concrete slab and composite action to the vertical shear strength of simply supported steel-concrete composite beams are not considered in current design codes, which lead to conservative designs. In this paper, the finite element method is used to investigate the flexural and shear strengths of simply supported composite beams under combined bending and shear. A three-dimensional finite element model has been developed to account for geometric and material nonlinear behavior of composite beams, and verified by experimental results. The verified finite element model is than employed to quantify the contributions of the concrete slab and composite action to the moment and shear capacities of composite beams. The effect of the degree of shear connection on the vertical shear strength of deep composite beams loaded in shear is studied. Design models for vertical shear strength including contributions from the concrete slab and composite action and for the ultimate moment-shear interaction ate proposed for the design of simply supported composite beams in combined bending and shear. The proposed design models provide a consistent and economical design procedure for simply supported composite beams.

Failure analysis of cold-formed steel sections

The purlin-sheeting system has been the subject of numerous theoretical and experimental investigations over the past 30 years, but the complexity of the problem has led to great difficulty in developing a sound and general model. The primary aim of the thesis is to investigate the failure behaviours of cold-formed zed and channel sections for use in purlin-sheeting systems. Both the energy method and finite strip method are used to develop an approach to investigate cold-formed zed and channel section beams with partial-lateral restraint from the metal sheeting when subjected to a uniformly distributed transverse load. The stress analysis of cold-formed zed and channel section beams with partially-lateral restraint from the metal sheeting when subjected to a uniformly distributed transverse load is investigated firstly by using the analytical model based on the energy method in which the restraint actions of the sheeting are modelled by using two springs representing the translational and rotational restraints. The numerical results have showed that the two springs have significantly different influences on the stresses of the beams. The influence of the two springs has also been found to depend on the anti-sag bar and the position of the loading line. A novel method is presented for analysing the elastic local buckling behaviour of cold-formed zed and channel section beams with partial-lateral restraint from metal sheeting when subjected to a uniformly distributed transverse load, which is carried out by inputting the cross sectional stresses with the largest compressive stress into the finite strip analysis. By using the presented novel method, individual influences of warning stress, partially lateral restraints from the sheeting and the dimensions of the cross section and position of the loading line on the buckling behaviour are investigated.

The analysis of potentiostatic transients applied to the corrosion of steel in concrete

Potentiostatically induced current transients obtained on a range of reinforced concrete specimens were analysed to give estimates of the polarisation resistance and interfacial capacitance. The polarisation resistance was compared with the values obtained using more conventional DC methods of analysis and, while it was consistently lower, it was within the error normally attributed to the polarisation resistance method of corrosion rate determination. The interfacial capacitance values determined increased from 0.44 F m -2 for passive steel (polarisation resistance of 132 Ω m 2) to 26.5 F m -2 for active steel (polarisation resistance of 0.34 Ω m 2). This has a dominant effect on the time required for potentiostatically induced current transients to reach a steady state with a longer time being required by actively corroding steel. By contrast the potential decay time constants describing galvanostatically or coulostatically induced potential transients decrease with an increase in corrosion rate and values less than 25 s for active specimens and greater than 40 s for passive specimens were determined in this work. © 1997 Elsevier Science Ltd.

Effect of web holes on web crippling strength of cold-formed steel channel sections under end-one-flange loading condition – Part I: Tests and finite element analysis

Web openings could be used in cold-formed steel beam members, such as wall studs or floor joints, to facilitate ease of services in buildings. In this paper, a combination of tests and non-linear finite element analyses is used to investigate the effect of such holes on web crippling under end-one-flange (EOF) loading condition; the cases of both flanges fastened and unfastened to the bearing plates are considered. The results of 74 web crippling tests are presented, with 22 tests conducted on channel sections without web openings and 52 tests conducted on channel sections with web openings. In the case of the tests with web openings, the hole was either located centred above the bearing plates or having a horizontal clear distance to the near edge of the bearing plates. A good agreement between the tests and finite element analyses was obtained in term of both strength and failure modes.

Analysis of texture and R value variations in asymmetric rolling of if steel

Asymmetric rolling (ASR) is a potential process to reach better grain refinement than in conventional rolling, thus, can lead to better mechanical properties. It is not known, however, how the introduction of a shear component will change the ideal orientations of the textures, and consequently, the evolution of plastic anisotropy. To understand the effect of the added shear on texture evolution in ASR, a stability analysis is carried out in orientation space and the variations in the position and strength of the ideal orientations are analysed as a function of the shear component. Then, modelling of R values is presented for various cases. On that basis, it is shown that there is an upper limit for the shear component in asymmetric rolling that still retains the 〈1 1 1〉 ND fibre (ND: direction normal to the sheet) which is good for formability. It is also found that better persistence of the ND fibre can be obtained by cyclically alternating the shear component. The theoretical results are well supported by comparison to experimental evidences. © 2011 Elsevier B.V. All rights reserved.

Microstructural and surface texture analysis due to machining in Super Austenitic Stainless Steel

Inferior surface quality is a significant problem faced by machinist. The purpose of this study is to present a surface texture analysis undertaken as part of machinability assessment of Super Austenitic Stainless Steel alloy-AL6XN. The surface texture analysis includes measuring the surface roughness and investigating the microstructural behaviour of the machined surfaces. Eight milling trials were conducted using combination of cutting parameters under wet machining. An optical profilometer (non-contact), was used to evaluate the surface texture at three positions. The surface texture was represented using the parameter, average surface roughness. Scanning Electron Microscope was utilised to inspect the machined surface microstructure and co relate with the surface roughness results. Results showed that maximum roughness values recorded at the three positions in the longitudinal direction (perpendicular to the machining grooves) were 1.21 μm (trial 1), 1.63 μm (trial 6) and 1.68 μm (trial 7) respectively whereas the roughness values were greatly reduced in the lateral direction. Also, results showed that the feed rate parameter significantly influences the roughness values compared to the other cutting parameters. The microstructure of the machined surfaces was distorted by the existence of cracks, deformed edges and bands and wear deposition due to machining process.

Age-Dependent Fragility and Life-Cycle Cost Analysis of Timber and Steel Distribution Poles Subjected to Hurricanes

Power distribution systems are susceptible to extreme damage from natural hazards especially hurricanes. Hurricane winds can knock down distribution poles thereby causing damage to the system and power outages which can result in millions of dollars in lost revenue and restoration costs. Timber has been the dominant material used to support overhead lines in distribution systems. Recently however, utility companies have been searching for a cost-effective alternative to timber poles due to environmental concerns, durability, high cost of maintenance and need for improved aesthetics. Steel has emerged as a viable alternative to timber due to its advantages such as relatively lower maintenance cost, light weight, consistent performance, and invulnerability to wood-pecker attacks. Both timber and steel poles are prone to deterioration over time due to decay in the timber and corrosion of the steel. This research proposes a framework for conducting fragility analysis of timber and steel poles subjected to hurricane winds considering deterioration of the poles over time. Monte Carlo simulation was used to develop the fragility curves considering uncertainties in strength, geometry and wind loads. A framework for life-cycle cost analysis is also proposed to compare the steel and timber poles. The results show that steel poles can have superior reliability and lower life-cycle cost compared to timber poles, which makes them suitable substitutes.

Experimental and finite element analysis of machinability of AL-6XN super austenitic stainless steel

This paper presents a finite element cutting modelbased on physical microstructure to investigate the thermomechanicalbehaviour of AL-6XN Super AusteniticStainless Steel in the primary shear zone. Frozen chip rootsamples were created under dry turning operation to observethe plasticity behaviour occurring in the shear zones to comparewith the model for analysis. Chip samples were generatedunder cutting velocities at 65 and 94 m/min, feed rate at0.2 mm/rev and depth of cut at 1 mm. Temperature on thecutting zone was recorded by infrared thermal camera.Secondary and backscatter electron detectors were used toinvestigate the deformed microstructure and to calculate theplastic strain. Experimental results showed the formation ofmicrocracks (build-up edge triggers) at the chip root stagnationzone of both samples. The austenite phase patterns wereevident against the cutting tool tip in the stagnation zone of thechip root fabricated at 65 m/min. The movement of thesepatterns caused the formation of the slip lines within thegrains. The backscatter diffraction maps showed the formationof special grain boundaries within the slip lines, workhardeninglayer and in the chip region. Strain measurementsin the microstructures of the chip roots fabricated at 94 and65 m/min showed high values of 6.5 and 5.7 (mm/mm) respectively.The finite element model was used to measure thestress, strain, temperature and chip morphology. Numericalresults were compared to the outcomes of the experimentalwork to validate the finite element model. The model validatingprocess showed good agreement between theexperimental and numerical results, and the error values werecalculated. For a 94- and 65-m/min cutting speeds, 7.5 and5.2% were the errors in the strain, 3 and 2.5% were the error inthe temperature and 4.7 and 6.8% were the error in the shearplane angles.