C. MELBOURNE and M. WAGSTAFF Bolton Institute of Higher Education

As part of the nationwide research programme three brickwork multi-span arch bridges were constructed and tested. Each structure consisted of three nominally identical two ring segmental arch barrels of 3m span, supported by an abutment at each end and two intermediate piers. The span to rise ratio for alt of the barrels was 4:1. The main conclusions from the tests were that: (1) the mechanism method offers a legitimate procedure to analyze multi-span masonry arch bridges: (2) the observed failure mechanism for the multi-span bridges were not restricted to the loaded span (in each case a global failure occurred); (3) lower failure loads were observed for the multi-span bridges than for similarly proportioned single span bridges; (4)crown loading, was critical; (5) the spandrel walls had a marked effect on the failure mechanism; (6) the backfill offered considerable restraint but foil passive pressures were not recorded.