Structural repair of reinforced concrete portal frame

The Paper describes repairs carried out on a reinforced concrete portal frame that had suffered damage over the previous 25 years as a result of alkali–silica reaction (ASR). This particular structure has been the subject of intense study since 1978 and several previous papers have described its behaviour.^3,5 The repair consisted of partly demolishing and rebuilding the upper beam of the portal, while keeping the motorway it supports open to traffic. Results are given for the shrinkage of the replacement concrete, and for depropping movements and surface strain measurements taken on the structure over the year following the repair.