C. MELBOURNE* and L. WEEKES** * University of Salford ** NNC Ltd

The paper describes a series of large scale laboratory tests on three span brickwork jack arches. This form of construction was very popular in the 19th Century and in the early part of this century. It was used both in bridges and buildings. The tests confirmed the complex nature of this structural form proving its dependence upon the interaction between The masonry arches and their metal support system. Several modes of behaviour are identified and some guidance is given regarding modelling such structures.