ABSTRACT
If a plate structure has constant cross-section and its end support condition does not change transversely, the finite strip method has proved to be a very efficient numerical structural analysis method. However, if the structure has irregularities, e.g. a rectangular plate with openings, the finite strip method is no longer applicable on its own and the finite element method or the boundary element method has to be used. In this case, however if these methods can be combined together, with the finite strips being used for the regular part of the plate and the finite elements or boundary elements modelling the irregular part, then the efficiency of the finite strip method and the universality of the latter methods are both utilized to their full advantage. Another case favorable for combined analysis is a slabon-girder bridge or box girder bridge under moving-wheel loading. If the local effect of the load is concerned, the semianalytical finite strip method becomes uneconomical because too many series terms must be used (see Chapter 14). In this situation, the spline finite strip method may give better efficiency. However, in order to obtain accurate results for the maximum bending moments, the load application point must be taken as a node and a dense mesh is required around this point. When the load is moving along the bridge, the mesh must be modified for each new position of the load This problem can be solved by using the boundary element method to analyze the slab, because only the boundary of the slab panel is divided into elements and there is no mesh inside the panel. Consequently, no mesh modification is necessary while the load is moving. In this case, the girders are still analyzed by the finite strip method since only their deformation, not stresses, have significant influence on the local bending moments in the slab.
