Ali Bahadori-Jahromi

A parametric evaluation of multi-webbed composite joists based on EC5

Abstract The introduction of engineered beams offers long span, low cost and light weight joists in comparison to traditional solid timber sections. However, the vibration criteria in the design codes may significantly reduce the permissible span of the joists for domestic construction. This paper investigates the influence of geometric and material variability on permissible spans of a series of multi-webbed composite joists, which are designed in accordance with the requirements of Eurocode 5 and its UK National Annex. Geometric variability comprises four different profiles, namely; I-beams, Double I-beams, Box beams and Box I-beams/joists. The variations between the profiles are web-flange connection details and the number of webs, which vary from one to three depending on the profile. Material variability involves two different web materials, OSB and plywood, which are considered together with two different flange materials, C16 and C24. This study shows that serviceability would in general govern design requirements in UK timber flooring systems. Out of four different sub-criteria defined under the serviceability conditions, the deflection under unit point load is the governing condition in most cases. It was found that the correct choice of materials and beam profile can enhance the permissible span by up to 34%. When lateral restraint is not provided, lateral stability becomes the controlling criterion as beam depth increases. An inverse relationship has been found between the permissible span and the beam depth for an I-beam profile, whereas for the Double I-beams a constant permissible span was observed for varied beam depths. For the Box beams and Boxed I-beams, the permissible span will increase in proportion to beam depth. This study also shows that the effect of lateral stability on solid timber joists is less pronounced than for engineered beams.

Effect of class F fly ash on fine sand compaction through soil stabilization

This paper presents the results of an experimental investigation carried out to evaluate the effect of fly ash (FA) on fine sand compaction and its suitability as a material for embankments. The literature review demonstrates the lack of research on stabilization of sandy material using FA. The study is concerned with the role of FA content in stabilized soil physical characteristics. The main aim of this paper is to determine the optimum quantity of FA content for stabilization of this type of soil. This is achieved through particle size distribution and compaction (standard proctor) tests. The sand was stabilized with three proportions of FA (5%, 10% and 15%) and constant cement content of 3% was used as an activator. For better comparison, the sand was also stabilized by 3% cement only so that the effect of FA could be observed more clearly. The results were in line with the literature for other types of soil, i.e. as the % of FA increases, reduction in maximum dry density and higher optimum moisture content were observed.

Government's influence on the implementation of BIM

The governments construction strategy requires construction projects for central government to implement level 2 building information modelling as a minimum by 2016. Since it was published, a number of specifications, plans and processes have been released. Government has been involved in their production through being part of steering groups and explaining what they, as construction clients and occupiers of a huge number of built assets, need from the industry. Department projects have also been used to trial new methods and provide feedback from both the clients and the project teams point of view. The governments involvement has resulted in a coordinated response from an industry that is traditionally very fragmented and introduced a real impetus for changing the way the construction industry works and embracing digital technology.

An evaluation of environmental assessment methods

After successive global environmental conferences in which national governments pledged to reduce carbon emissions, there is ever-increasing scrutiny on the construction industry. This is because the energy used in the production of building materials and subsequently required to power a completed building form a substantial part of the overall carbon emissions generated by society. The response from both public and private sector interests around the world has been to enhance the importance of environmental assessments – both of building methods and the finished product – almost in inverse proportion to the tolerance for energy waste. The standards required by individual states vary considerably: part of this is down to local climate and geographical considerations, but a major consideration is the incentives offered for meeting a given standard. These consist primarily of tax credits and quality certificates, and the right to promote a building as “green”, thus improving the reputation of its designers and sales potential for buyers. Some of the various Assessment organisations around the world have already franchised their standards to other countries (both government-sponsored and private enterprises) and continue to form partnerships with each other, usually in the same continent or hemisphere. The principal aim appears to be expanding the influence of that particular environmental standard. There is the real possibility of environmental assessment methods in certain countries becoming counter-productive: in the rush to standardize, actual improvements made possible by new technologies are rendered useless by political manoeuvring to make a particular standard “the one” to use.

Dynamic Performance of Multi-Webbed Engineered Timber Joists

Abstract The introduction of engineered beams offered longer span, lower cost joists in comparison to traditional solid timber sections; however, vibration criteria in the design codes may significantly reduce the permissible span of joists for domestic construction. This research is concerned with the structural performance of engineered, multi-webbed, composite, timber joists of double I, box and box-I, cross sections in comparison with commonly used I beams and solid timber joists for use as repetitive members of flooring systems. The paper details results and findings of a series of experiments designed to ascertain the dynamic performance of empty and polyurethane-filled, multi-webbed, composite, timber beams.