Pipers Row Multi-Storey Car Park was built in 1965 and a 120 tonne section of the top floor collapsed during the night of 20th March 1997. Initial reports identified some of the factors which contributed to the initial punching shear failure which developed into a progressive collapse.
This report has quantified the wider range of factors which, in combination, led to the collapse. It covers more detailed investigation and testing of the construction, materials, degradation and repairs to the reinforced concrete Lift Slab structure. The sensitivity of the reactions, moments and shear stress distributions to construction tolerances, cracking and the repair procedures have been evaluated, as have the actual vehicle and thermal load effects. Comparisons of simplified design analysis with more rigorous analysis have been carried out, including ANSYS plate analysis of the whole slab and detailed DIANA non linear analysis of the stress concentrations around the Lift Slab shear head. The partial factors on load and strength have been compared to the variability of load effects and punching shear strength determined to BS8110 and on the basis of research studies. The reasons for the initial failure and its structural development into a progressive collapse have been considered.
This report brings together and summarises the findings from a number of research projects and other sources to identify the causes of failure. The following supporting documents are available in hard copy to view at HSE's Bootle Information Centre, Magdalen House, Stanley Precinct, Bootle, Merseyside, L20 3QZ:
