THE TAY BRIDGE DISASTER - A STUDY IN STRUCTURAL PATHOLOGY . DEVELOPMENTS IN STRUCTURAL ENGINEERING. PROCEEDINGS OF THE FORTH RAIL BRIDGE CENTENARY CONFERENCE, HERIOT-WATT UNIVERSITY, ENDINBURGH, SCOTLAND, AUGUST 21-23, 1990. VOLUMES 1 AND 2

This paper presents new information about the 1879 collapse of the Tay Rail Bridge based on modern wind loading and analysis techniques. The bridge consisted of lattice girders supported on slender cast iron columns which were braced together with wrought iron ties and struts. There were 13 navigation spans, eleven of 74.7 metres and 2 of 69.2 metres. There were through girders 8.2 metres high, with 26.8 metres clearance above high water. All the navigation span collapsed in the disaster, killing all 75 people aboard the train. Past evidence suggests that the collapse was caused by inadequate strength of the piers. A space frame model of a single pier structure was created in which the members were treated as beam elements with bending and axial deformation. No second order effects were considered except that the compression diagonals were removed. The columns were treated as being continuous and all other members were pin connected. The finite sizes of the columns were neglected. The column bases were treated as being fixed except that a 5 mm uplift was imposed on the windward column in some cases. The effect gave wind loading from the superstructure above the top of the model was simulated by a shear and movement at the top of the model. The movement was treated using pairs of equal and opposite vertical loads. The loading was increased in steps, noting the conditions of the members. The results show that the structure could have failed due to almost simultaneous toppling and bracing failure caused by the wind. The presence of the train would have exacerbated the situation. (TRRL)