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Materials teaching vital to halt 'woeful ignorance' - Burdekin

GREATER EMPHASIS on the teaching of materials science in civil engineering degree courses is needed to eliminate the 'woeful ignorance' shown by many structural designers, a leading academic said last week.

Concluding his first presentation of the Brunel International Lecture 2000 at Great George Street, Professor Mike Burdekin of the University of Manchester Institute of Science & Technology insisted that a minimum of two modules of 36 hours contact time per course was essential.

He acknowledged the immense pressures on time and resources in current courses, but added: 'It is my belief . . . that many problems in construction could be avoided if all qualified civil engineers had this basic understanding.'

Entitled Developments in new materials and methods of construction for the new millennium, Burdekin's presentation opened with a brief history of the Brunels - father Marc who built the first tunnel under the Thames and son Isambard Kingdom Brunel, probably the most famous civil engineer of all time.

Most of the lecture, however, concentrated on construction materials old and new, from wood and stone to structural glass, ceramics and composites.

Concrete specialists in the audience may have been slightly nonplussed to hear their preferred material classed as a porous ceramic. Whatever their preference, those attending found the property charts shown by Burdekin equally fascinating.

These compared all construction materials by such rarely considered factors as the relationship between strength and cost per unit volume, between fracture toughness and strength, and resistance to various types of aggressive environments.

Each group of materials was shown to have specific advantages and disadvantages, underlining Burdekin's call for greater understanding of basic material properties.

After reviewing current material practice, Burdekin went on to consider some of the latest developments. He warned that the high strength steels used on projects like the Akashi Kaikyo Bridge had problems, not least greater deflections and shorter fatigue life. 'Bearing in mind that the material costs of the structure form a relatively low proportion of overall costs for building structures it will usually be more economic to use thicker sections of conventional steels in these applications, ' Burdekin added.

Ultra heavy universal column sections with flanges up to 100mm thick are already available, and some steel manufacturers are able to supply 200mm thick plate for the fabrication of very heavy plate girders. By contrast, Burdekin reported less progress on high strength concretes.

Friction stir welding of heattreated high strength aluminium alloys was also recommended.

This recently developed process involves butting two plates together and inserting a hardened rotating tool between them. As the tool moves along the joint material on each side is heated to melting point by the resultant friction and stirred into a defect-free weld.

Speaking of the increasing use of carbon fibre reinforced polymers to strengthen suspect structures, Burdekin warned against applying the CFRP while the structure was still load bearing. 'If it's close to failure when the reinforcement is applied the additional benefit will be minimal, ' he said.

'To obtain full benefit the load in the structure must be reduced by jacking or propping or other means.'

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