Design of Awa Shirasagi Ohashi Bridge

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.

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.

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.