Profile: Marelize Visser

This month's letters detail the use of invisible connections in the Leadenhall Building, offer more thoughts on innovation in engineering, make the case for retaining historical building control records, discuss site investigations for basement projects and the strut-and-tie method for concrete detailing, seek advice on water entrapment in hollowcore concrete floors, and ask whether modern codes are overcomplicating design.

Alastair Hughes calls for the simplification of Eurocode 0's combination rule in the name of a clear, simple, safe design approach.

Developing new tools to help structural engineers make more efficient use of materials – and persuading them why they must do so – are key themes for Cambridge academic Dr John Orr. He talks to Helena Russell about his research and plans for the future.