Fatigue of Bolted High Strength Structural Steel

published or submitted for publicatio

Computer program simplifies selection of structural steel columns

Computer program rapidly selects appropriate size steel columns and base plates for construction of multistory structures. The program produces a printed record containing the size of a section required at a particular elevation, the stress produced by the loads, and the allowable stresses for that section

Increasing information feed in the process of structural steel design

Research initiatives throughout history have shown how a designer typically makes associations and references to a vast amount of knowledge based on experiences to make decisions. With the increasing usage of information systems in our everyday lives, one might imagine an information system that provides designers access to the ‘architectural memories’ of other architectural designers during the design process, in addition to their own physical architectural memory. In this paper, we discuss how the increased adoption of semantic web technologies might advance this idea. We investigate to what extent information can be described with these technologies in the context of structural steel design. This investigation indicates significant possibilities regarding information reuse in the process of structural steel design and, by extent, in other design contexts as well. However, important obstacles and question remarks can still be outlined as well

Resolving retention polarity: the perceptions of structural steel fabricators

This study aims to understand the perceived polarity between main contractors and subcontractors with a view to resolving problems connected with retentions in an environment where a sliding-retention regime is utilised with a retention rate of 10% for work below NZ $ 200,000. Eight structural steel subcontractors operating in Auckland were interviewed. Contrary to popular belief, subcontractors are not averse to retentions with most taking a middle ground. Nevertheless, the apparently fair practice of using back-to-back contract terms is not seen as fair and reasonable. Most solutions acceptable to subcontractors impact negatively on contractors’ cash flow highlighting the need for some form of reciprocity from subcontractors (price discounts, improved performance, etc.) to induce contractors to offer favourable retention regimes. This highlights the need for a theory on ‘retention reciprocity’ to supplement the five theories on retentions. However, given that not all contractors can be expected to display reciprocity fairness, an interventionist approach may be necessary in order to neutralise any imbalances in power between the contracting parties possibly through amendments to the Construction Contracts Act, and when doing so, there is a need to exercise much caution as the outcome of chaotic systems could be quite unpredictable

Coupled thermo-mechanical damage modelling for structural steel in fire conditions

This paper aims at developing a coupled thermo-mechanical damage model for structural 6 steel at elevated temperatures. The need for adequate modelling of steel deterioration behaviour 7 remains a challenging task in structural fire engineering because of the complexity inherent in 8 the damage states of steel under combined actions of mechanical and fire loading. A fully three9 dimensional damage-coupled constitutive model is developed in this work based on the hypothesis 10 of effective stress space and isotropic damage theory. The new coupling model, adapted from 11 an enhanced Lemaitre’s ductile damage equation and taking into account temperature-dependent 12 thermal degradation, is a phenomenological approach where the underlying mechanisms that govern 13 the damage processes have been retained. The proposed damage model comprises a limited number 14 of parameters that could be identified using unloading slopes of stress-strain relationships through 15 tensile coupon tests. The proposed damage model is successfully implemented in the finite element 16 software ABAQUS and validated against a comprehensive range of experimental results. The 17 damage-affected structural response is accurately reproduced under various loading conditions and 18 a wide temperature range, demonstrating that the proposed damage model is a useful tool in giving a 19 realistic representation of steel deterioration behaviour for structural fire engineering applications

Experimental Investigation on Residual Stresses in Welded Medium-Walled I-shaped Sections Fabricated from Q460GJ Structural Steel Plates

GJ steel is a new type of high-performance structural steel which has been increasingly adopted in practical engineering. Q460GJ structural steel has a nominal yield strength of 460 MPa, which does not decrease significantly with the increase of steel plate thickness like normal structural steel. Thus, Q460GJ structural steel is normally used in medium-walled welded sections. However, research works on the residual stress in GJ steel members are few though it is one of the vital factors that can affect the member and structural behavior. This article aims to investigate the residual stresses in welded I-shaped sections fabricated from Q460GJ structural steel plates by experimental tests. A total of four full scale welded medium-walled I-shaped sections were tested by sectioning method. Both circular curve correction method and straightening measurement method were adopted in this study to obtain the final magnitude and distribution of the longitudinal residual stresses. In addition, this paper also explores the interaction between flanges and webs. And based on the statistical evaluation of the experimental data, a multilayer residual stress model is proposed

The Molybdenum-Boron Structural Steel

THE production, properties and applications of alloy and special steels form a very wide subject. The decision to select the comparatively small area of this vast field, covered by the patented' lowcarbon 2 per cent molybdenum-boron steel first described by Bardgett and Reeve2, was made in the expectation that, during the early stages of improving the status of alloy steels in your country, you would Wish to employ, as far as possible, existing facil-ities for steel production. It, therefore, seemed reason-able that this low-alloy structural steel which can be manufactured in the form of flat products or sections in the same plant which is used for the familiar plain carbon product and yet possesses a very much higher tensile strength without any sacrifice in other properties should have wide appeal

Finite Element Modelling of Concrete-Encased Steel Columns Subjected to Eccentric Loadings

This paper presents the 3D finite element (FE) analysis of the concrete-encased steel (CES) columns subjected to concentric or eccentric loadings. A new simplified technique of FE modelling that incorporates the concrete confinement behavior of the composite columns is proposed. This technique eliminates the need of predefining zones and constitutive properties of the confined concrete. After validated with past experimental data, the FE analysis is conducted to construct the strength interaction diagrams of the short CES columns. The effects of material properties including the compressive strength of concrete and yield strength of structural steel on the strength interaction diagrams of CES columns are numerically investigated. The FE results show that the concrete strength only has a significant effect on the column strength under combined compression and bending (compression phase) of the interaction diagram, while the yield strength of structural steel has a significant effect on both compression and tension phases. A comparison between the strength interaction diagrams predicted by FE analysis and the plastic stress distribution method specified in AISC360-16 “Specification for Structural Steel Buildings” shows that the design provision underestimates the strength of the short CES columns subjected to concentric or eccentric loadings. Such underestimation reduces as the compressive strength of concrete decreases or yield strength of structural steel increases