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Failure Analysis of Composite Beams under Moving Loads



With the expanded use of composite materials in civil structures such as bridge decks, a moving-load analysis would simulate a truck moving over a composite bridge. Almost all the available research concerning moving-load analysis concerns with results in the form of deflections and dynamic load factors; very little attention has been paid to the stress analysis and using the stress field to ascertain failure. In this research a finite element method employing h-p version finite elements is made and analyzed to determine the failure of a composite beam under the action of a moving load. A computer code is written in MATLAB to accomplish this. Classical laminate plate theory (CLPT) and first order shear deformation theory (FSDT) are considered for the analysis of composite beams. A consistent formulation is used to reduce the composite plate theory to beams. The governing equations are obtained using Hamilton’s principle. Newmark’s time integration scheme is used to determine the dynamic response in the form of the displacement field of the beam. The strain field is obtained using the kinematic relations and then the stress field using the appropriate constitutive equations. Finally, the maximum stress failure theory is applied to determine the factor of safety. Results are presented for a simply-supported beam subjected to a moving load that traverses the entire span of the composite beam. The stress field and factors of safety based on the CLPT is compared with that of FSDT. A parametric study is conducted by considering different laminates and different fiber volume fractions.

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