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All articles published in the August 2012 issue.
Publish Date - 2 August 2012
The Awa Shirasagi Ohashi Bridge, which includes novel structural systems, was recently constructed in Tokushima, Japan (Figure 1). There were a number of severe design constraints for the project.
The bridge is located in a very environmentally sensitive area. The site is also in a seismic region and is frequently struck by typhoons. Furthermore, the bridge was to be founded on soft alluvium, and to be constructed to a tight budget.
These exceptionally challenging constraints led engineers to adopt a novel combination of structural forms, including the ‘cable egret’ cable truss system, an improved form of the permanent tubular steel pile cofferdam foundation and a steel- concrete composite sandwich slab deck.
No. 7: Legionnaires’ disease
The recent outbreak of Legionnaires' disease in Edinburgh (June 2012) resulted in 44 confirmed cases, including the desaths of three people, with a further 18 requiring hospital treatment (7 of these requiring intensive care). This makes it timely to remind engineers of the hazard and associated risks.
"Once is happenstance"
Alastair Soane highlights the importance of identifying failure trends in order to help prevent future disasters.
This Technical Guidance Note explains the way in which reinforced concrete drawings should be read. In many cases reinforced concrete drawings are more diagrammatic than their general arrangement counterparts and carry with them their own unique set of rules and nomenclature. Note that the guidance provided here is based on European codes of practice; for all other regions the reader is directed to local guidelines on reinforced concrete detailing methods. This technical guidance note does not cover the rules governing the detailing reinforced concrete. That is a far more complex subject which is dealt with in The Institution of Structural Engineers’ publication Standard Method of Detailing Structural Concrete (3rd edition).
This Technical Guidance Note describes how drawings for structural steelwork are developed and read. They have their own unique set of rules and nomenclature and it is important for engineers to understand all of these rules in order to communicate and interpret the design of steelwork structures.
This guide is split into two sections; the ﬁrst contains the information a designer of the steel elements provides, whilst the second contains the information a fabricator creates in order to manufacture and construct the steel structure. While one feeds into the other, the level of detail each set of information provides is very different, due primarily to the end result. One is informing the manufacture of the steelwork, while the other focuses on its installation.
This paper looks at the possibility of using cross-laminated timber (CLT) construction to support commercial buildings to 30 levels. A prototype building structure is proposed and analysed using an elastic analysis program.
The main structural elements, including a central tube core, columns and beams, are made of cross-laminated timber. The CLT panels are arranged to ensure structural efficiency with minimal material wastage.
The CLT central core is assisted by steel stays (like those of a yacht), and reiforced concrete beams which act like wine barrel hoops. Consideration is given to the design of simple but stiff joints.
The structural elements are examined for strength and the building deﬂections are noted. The paper concludes that the proposed structural system with CLT elements is likely to be suitable for buildings to 30 levels.
There are still hundreds of high-rise large panel system (LPS) dwelling blocks in the UK. These generally contain ﬂats, but in some cases the accommodation is in the form of maisonettes or another multi-level arrangement. Block owners have a continual responsibility for their safety, which requires periodic inspection and structural assessment.
The UK requirements for this particular class of building stem from the 1968 collapse of the southeast corner of Ronan Point, a 22 storey LPS dwelling block.
LPS dwelling blocks are basically gravity structures, as are traditional masonry constructed buildings. Typically they comprise precast reinforced concrete ﬂoor and roof components spanning onto storey high structural precast (generally plain) concrete wall panels.
Vertical loads are carried to the ground through the structural wall panels, which also provide stability against lateral loads.
Historically the guidance used for the structural assessment of LPS dwelling blocks for accidental loads has been the Ministry of Housing and Local Government (MHLG) Circulars 62/68 and 71/68, which were produced shortly after the Ronan Point incident. MHLG Circulars 62/68 and 71/68 together with various other related guidance from that era, were never withdrawn and notionally remain in force today. However, the guidance has been rendered out-dated by subsequent developments.
This paper provides an overview of updated technical evaluation criteria and the associated guidance for undertaking a structural assessment of an LPS dwelling block for accidental loads.
The oldest of the Institution’s international Regional Groups highlights its involvement with the National Building Regulations amongst its other activities
The South Africa Branch (now Regional Group) of the Institution of Structural Engineers became the ﬁrst to be established outside the UK, in 1937. Subsequently it was merged into a joint initiative between the Institution and the South African Institution of Civil Engineers, becoming the Joint Structural Division (JSD).
This Division currently represents some 1345 members in South Africa and is becoming the natural home to members in the Southern African Region. At present there are members of all Institution grades located within the region and the JSD provides a vital linkage between international and local organisations. Having reinvigorated the committee we are gaining traction in many areas and now looking forward to supporting a signiﬁcant number of candidates seeking to participate in the Institution’s examinations.
The focus with the restructuring of the committees is to increase the beneﬁt that this grouping can deliver to its members and to generally uplift the standard of engineering within the region. This approach is aimed initially at universities and student membership but, via the codes of practice and continuous professional development, also assisting the profession and Chartered members alike.