Author: Abdulkarim Hassan Ali

Publisher:

Published: 2000

Total Pages: 0

ISBN-13:

The dynamic analysis of highway bridges is very complex because of the interaction between the moving vehicle load and the bridge response. Analytical methods such as beam theory and orthotropic plate theory are applicable only to simple structures and highly simplified moving vehicle load models. The beam theory is applicable only to long and narrow bridges since it neglects the effect of transverse flexibility of the bridge. The orthotropic plate theory is only applicable to slab bridges under simple vehicle load models as complex vehicle models render the differential equation of equilibrium difficult or impossible to solve. The finite element method is a very powerful and versatile technique which can be applied to deal with any specific configuration of bridge structure, supports and vehicle load models. However, the efficiency of the method needs to be improved because the finite element solutions usually require too much computer time, too large core storage and too much data input. In addition to these deficiencies, in order to simulate the local of the moving concentrated wheel loads the finite element mesh should be refined in both directions. The finite strip method has already proven to be the most efficient numerical technique for the static analysis of bridges. In fact the method is even more efficient for dynamic analysis of bridges. The structure can be divided into a number of finite strips. In each strip the displacement components at any point are expressed in terms of the displacement parameters of nodal lines by means of simple polynomials in the transverse direction and a continuously differentiable smooth series in the longitudinal direction. Thus, the number of dimensions of the analysis is reduced by one. The minimum number of degrees of freedom along a nodal line in the finite strip method is equal to twice times the number of terms used in the series and this is normally much less than that for finite element method, which requires a minimum of three times the number of nodes along the same line. Hence the size and the bandwidth of the matrices are greatly reduced, and consequently it can be handled by personal computers and solved in much shorter time. In this study the finite strip method is applied to dynamic analysis of simply supported single span slab bridges, slab-on girder bridges, box girder bridges and multi-span bridges by using various vehicle load models. Harmonic analysis of beams is covered in Chapter Two as an introduction for the finite strip method. A FORTRAN computer program capable of analyzing all the topics covered in this thesis is also developed.