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All articles published in the September 2012 issue.
(NB Technical Guidance Note Level 1, No. 15 contained within this issue was updated in October 2016. For the updated article, see the individual article entry for this issue.)
Publish Date ‐ 31 August 2012
This paper discusses the relevance of physical models in the contemporary design of building structures. It starts with a brief overview of the use of physical models in the last 100 years, followed by a description of some recent projects where physical scale modelling played an active role in the design development. The examples are used to illustrate various categories of physical models: namely conceptual models; form-fi nding models and experimental scale models, and to analyse the limitations of physical models in contrast to digital tools. Ultimately, physical models are presented as a tool to be used in conjunction with and alongside the computer.
Common construction hazards
This article considers safety hazards in construction (as opposed to health hazards, e.g. noise, vibration etc). Hazards are ‘something with the potential to cause harm’ and the corresponding risk incorporates ‘the likelihood of occurrence and the severity of the consequences’.
Tension cable and rod connectors
When analysing structures it is important to adopt a methodical approach wherever possible. By breaking down the structure into manageable portions, the complexity of the analysis is reduced and thus becomes easier to control and review. By adopting such an approach, a seemingly insurmountable task becomes a much more approachable one. This Technical Guidance Note is a good practice guide for analysing and designing structures. It explains how structures are given form, modelled, analysed and designed. Mention is made of the need to rationalise the analysis process, but not at the expense of an economic design.
While the advancement of computer based analysis continues to grow exponentially within the field of structural engineering, the tools that are used to analyse structures by hand are no less relevant. Many would argue that such tools are even more vital today than they have ever been if we are to fully understand the output of analysis applications. With this in mind, this Technical Guidance Note describes one of the most powerful analysis tools available: moment distribution.
Moment distribution is a method by which statically indeterminate structures are analysed elastically. It’s based on the relative stiffness of elements that make up a structure and shifts bending moments from one section of the structure to another until they become balanced. Once this balance has been achieved, the forces and bending moments within the structure are modelled.
(This article was updated in October 2016 to reflect errata issued since its original publication.)
In this paper a procedure for the comparison of steel column design by load and resistance factor design (LRFD) method, between the Egyptian code and other codes of practice, is set out. A column design curve for slender sections was established by applying a reduction factor, Q, to the LRFD column design curve. A stability analysis was conducted to study the effect of plate local buckling on flexural column buckling. A finite element model of an axially loaded I-column was developed using shell elements. Material and geometric nonlinearities were incorporated.
Geometric imperfections similar to the first buckling mode with amplitude of 1/750 of column length, L, were applied. The analysis was carried out using a general purpose finite element program ANSYS. A wide range of plate width-to-thickness ratios and column
slenderness ratios was studied.
Column sections were grouped into three: Group 1; sections with slender unstiffened plate elements, Group 2; sections with slender stiffened plate elements, and Group 3; sections composed of slender stiffened and unstiff ened elements. The buckling loads for 144 I-column configurations made of steel St.37, St.44 and St.52 were compared to respective values adopted by the AISC-LRFD and Eurocode 3 specifications.
This paper presents the results of an experimental study on the shear behaviour of reinforced concrete beams with circular pre-cast web openings. 11 simply supported reinforced concrete beams, with and without web openings located in the shear zone of the beams, were tested using a fourpoint loading procedure. Test variables included size of the web openings, horizontal location of the web openings and shear span to effective depth ratio. The test results showed an almost linear reduction of the ultimate strength of the beams with increasing size of the web openings. The most critical location for the web openings was found to be in the centre of the shear zones where the critical load path directly crosses the web openings. The shear span to effective depth ratio was also found to influence the structural performance and strength of the beams. The results of the experiments are compared with ACI code based predictions.
Topics of importance openly discussed...
Arup’s Naeem Hussain comments on a recently published book
from one of the industry’s most eminent bridge designers: Professor Holger Svensson