Dominate frequency tailing embankment interface to bridge by 3D finite element method

Abstract

Due to bridge design with long valley is so expensive and non economical. One of the main points of view for designer is use of two tailing embankments to shortage distance of bridge. Behavior of embankments and interaction between both of them with abutments and bridge is so important during earthquake. Literature review indicated that critical state during dynamic load is related to resonance phenomena and not only dominate frequency (DF) of bridge and embankments should not be equal but also value of the frequency depended to 3D condition for embankments because lateral strain is not to limit of zero value. This paper tried to evaluate dominate frequency in embankments with rigid foundation by numerical modal analysis of the ANSYS13 software regards to three dimensional conditions of finite elements method. Effects of mass, modulus elasticity and slopes of rigid abutment for three height of the embankment (15-20-25 meter) on value of dominate frequency were performed. Result analysis demonstrated that that value of dominate frequency increased with maximum values of the height stiffness, minimum mass or relative density and increase of angular abutment importance respectively. The first mode shape was minimum and critical for frequency and displacements for both of the vertical and horizontal axes. Effect of flexibility foundations for different ratio of modulus elasticity between embankment and foundation on value of dominate frequency is recommended further.