STRENGTHENING OF HIGH RISE BUILDINGS

Following the Ronan Point disaster in 1968, all towers should be designed to cater for explosions. In practice many buildings have yet to be fully assessed, and only the most critical connections have been strengthened. We have gained expertise in assessing the capacity of existing structures and in employing innovative strengthening techniques.

One of four recent major collapses in Russia following explosions.

15km of carbon fibre was bonded to the soffit of three tower blocks to enable the slabs to accommodate accidental loads. Strengthening angles and epoxy grout were used to fill gaps at bearings. On other types of blocks, steel flats have been used to strengthen the walls in the top three floors.

The practice is currently working on the refurbishment of our 10th Large Panel System tower. We have presented papers on the subject to the Institution of Structural Engineers (IStructE) and the Institute of Maintenance and Building Management (IMBM) throughout the North of England.

Ferro scan images of floors reveal missing or misplaced reinforcement in Bison-type precast concrete slabs. Load tests were undertaken to indicate how the slabs behave under normal loading and strengthening was undertaken to allow slabs to cater for abnormal (explosive) loads. Another matter of concern was the bearings around the edge of the slabs. These often required strengthening where the grouting had not been effective.

A Typical Large Panel System (LPS) tower before strengthening, over-cladding and refurbishment.