Progressive Collapse Analysis of Intact and Damaged Ships under Unsymmetrical Bending

This study examined the hull girder strength of intact and damaged ships by adopting the incremental-iterative method for progressive collapse analysis, which was extended to the general case of the unsymmetrical bending of beams with an arbitrary cross-section. The sources of an unsymmetrical loading, including rotation of the loading plane and section asymmetry caused by structural damage, are described. A fast and robust procedure is presented to determine the translation and rotation of the instantaneous neutral axis at each curvature increment when applying Smith’s progressive collapse analysis method. A series of analyses were conducted on a double hull VLCC and a bulk carrier, considering various loading plane angles and damage conditions. The decrease in ultimate strength and the influences of rotation of the instantaneous neutral axis and ship heeling are discussed. The proposed method can be used for a rapid and rational assessment of the hull girder strength under adverse conditions.

Mechanical Behaviour of Steel-Concrete Twin I-Girder Bridges

<p>Steel-concrete composite twin I-girder bridges have been built a lot in both Europe and Japan, but the lack of redundancy has always been a concern in U.S. and many other countries. In addition, few experimental studies have been performed on the mechanical performance of such bridges, particularly for the intact bridges. On this background, a steel-concrete composite twin I-Girder bridge model was designed according to the current highway bridge design specification in Japan and tested in the laboratory. The static loading tests were performed, and two loading conditions including both symmetrical loading and unsymmetrical loading were applied. Load versus deflection relationships were measured in the loading test, and the failure mode of the test specimen was discussed. The flexural strain development on bottom flanges of two main girders was also reported in this paper to confirm the load transfer between two main girders. In addition, the theoretical results on the basis of the classic theory were also provided to compare with the test results. The comparison indicates that the theoretical analyses can predict the behaviour of the twin I-girder bridges very well in the elastic stage by considering the effective width of the slab. The load transfer paths in such bridges were also discussed on the basis of the test results under un-symmetrical loading.</p>

PREDICTION OF BEHAVIOUR OF PRESTRESSED SUSPENSION BRIDGE WITH TIMBER DECK PANELS

Cable truss usage allows developing bridges with reduced requirements for girder stiffness, where overall bridge rigidity is ensured by prestressing of the stabilization cable. The advantages of prestressed suspension trusses to provide required stiffness without massive stiffness girders and the ability of cross-laminated timber to behave in both directions are combined in the analysed structure. Prestressed cable truss with coincident (unclear meaning, difficult to translate) in the centre point of the span main and stabilization cables and vertical suspenders only was considered as the main load carrying system in the considered structure of suspension bridge. Two numerical models evaluated influence of cross-laminated timber deck on the behaviour of prestressed cable truss. Two physical models of the structure with the span equal to 2 m were developed for verification of the numerical models. The first physical model was developed for the case, when panels of the deck are placed without clearances and behaving in the longitudinal direction in compression so as in the transversal direction in bending. The second physical model was developed for the case when panels of the deck are placed with clearances and are behaving in the transverse direction in bending only. The dependences of maximum vertical displacements and horizontal support reaction of the cable truss on the intensity of vertical load in cases of symmetric and unsymmetrical loading were obtained for both physical models. Possibility to decrease the cable truss materials consumption by 17% by taking into accountcombined work of prestressed cable trusses and cross-laminated timber panels was stated.