Assessment of 1960’s Reinforced Concrete Frame Shopping Complex

Type: Commercial Development – Concrete Repair Location: Tiverton, Devon

A problem was discovered in one of the shops at first floor level where serious deflection in the floor slab was evident. We were appointed to undertake an investigation into the problem and to make recommendations for remediation. We initially carried out a visual inspection of the slab and were greatly concerned at the degree of deflection, so instigated further investigation. Concrete cores, testing and a level survey were carried out to establish the extent of the problem and design parameters. A design check was then undertaken which indicated the original structure was unsafe.

We searched the records of the local authority to try and locate the original Architect’s and Engineer’s designs. The original Engineer had gone out of business and all records had been lost so we were faced with determining the type of reinforcement provided in floor slabs and beams, together with effective depths, by investigation.

A scheme was drawn up for remediation comprising a grid of steelwork supported on new columns to reduce spans of affected floor slabs and make them safe.

Complications were encountered where previous underground petrol tanks had been removed and backfilled with stone in locations of our proposed foundations to steel posts. We adopted a method of grout injection to overcome this, which was very successful. Progress was monitored by accurate levelling of ground floor slabs and surrounding walls.