NUMERICAL AND EXPERIMENTAL INVESTIGATION ON REAL TEMPORARY STRUCTURES USEFUL FOR INCREMENTAL LAUNCHING BRIDGE CONSTRUCTION

The study is aimed to evaluate the influence of the construction quality on the buckling load as well as on the bearing capacity of the real sub-structural system provided in order to keep the cantilever moment to a reasonable magnitude, during continuous post-tensioned multi-span bridge casting. The clamping bolt quality as well as the stiffness of the flanged joint of the two steel truss piers, which had collapsed during the “Porcaria bridge” construction, are studied. At first, some laboratory tests were carried out on flanged joint specimens. Later, a numerical investigation was carried out on the real model of the towers by varying the quality of the clamping bolt. The data obtained show how the buckling load is highly influenced by the correct erecting of the tower. In fact, a lower stiffness of the flanged link or an insufficient clamping bolt might produce safety coefficient lower than unity. Besides, the perfect accordance between numerical and experimental investigation gave us the possibility of a more accurate design of the temporary towers.