Numerical Evaluation of Dynamic Response by Using Modified Newmark’s Method

It is well known that the Newmark’s method is considered one of the most popular methods for structural dynamic analysis. In this study, starting from the basic Newmark’s method, a new accurate method is investigated and developed. The basic idea of the proposed method is to use Richardson’s extrapolation to improve the basic Newmark’s method. To observe the accuracy of the proposed method, several numerical tests are performed for a single degree-of-freedom (SDM) dynamic system and the results are compared with results from Newmark’s method and the exact solution. The results show that the proposed method improves the solution accuracy of the structural dynamic problems compared to the Newmark’s method. Moreover, the results of the free oscillating case show that the modified Newmark’s method has more computational efficiency compared to the Newmark’s method.Scopu

Experimental Evaluation of a Hybrid FRP-Concrete Bridge Superstructure System under Negative Moment Flexural Loads

Fiber Reinforced Polymer (FRP) bridge systems are gaining wide acceptance among bridge engineers. At the same time, FRP bridge systems are relatively expensive when compared to traditional reinforced concrete bridge systems. In this study, the concept of the hybrid FRP-concrete structural systems is applied to a bridge superstructure. The hybrid FRP-concrete superstructure system is intended to have durable, structurally sound and cost effective hybrid system that will take full advantage of the inherent properties of both FRP materials and concrete. The primary objective of this study is to examine the structural behavior of an FRP-concrete hybrid bridge superstructure system subjected to negative moment flexural loads through experimental procedures. The experimental results showed that the design of the hybrid FRP-concrete bridge superstructure under a negative flexural moment is found to be stiffness- driven instead of strength-driven

A Novel Fiber-Reinforced Composite Bridge Structural System

184 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1997.An integral fiber reinforced plastic bridge structural system is proposed. The design concept is carefully engineered to incorporate new high performance structural materials. As a result, a number of special features evolved to produce an efficient bridge design. Along with structural system development, a design methodology is presented which consists of two stages. First, an optimal preliminary design based on a simplified model is obtained. The combination of a simplified model based on the Ritz solution of a transformed plate with a formal optimization scheme produced an effective tool for preliminary design. Second, detailed finite element analyses are performed to investigate the strength, stiffness and buckling performance of the structure. Design examples are considered to demonstrate the capabilities of this structural system and to study the important features. The design is compared with other fiber reinforced plastic bridges and with a traditional steel-concrete system. The analysis of several design cases shows that stiffness requirements govern the design and the margins of safety for material and structural failures are high.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Generalized spatial aliasing solution for the dispersion analysis of infinitely periodic multilayered composites using the finite element method

The finite element (FE) method offers an efficient framework to investigate the evolution of phononic crystals which possess materials or geometric nonlinearity subject to external loading. Despite its superior efficiency, the FE method suffers from spectral distortions in the dispersion analysis of waves perpendicular to the layers in infinitely periodic multilayered composites. In this study, the analytical dispersion relation for sagittal elastic waves is reformulated in a substantially concise form, and it is employed to reproduce spatial aliasing-induced spectral distortions in FE dispersion relations. Furthermore, through an anti-aliasing condition and the effective elastic modulus theory, an FE modeling general guideline is provided to overcome the observed spectral distortions in FE dispersion relations of infinitely periodic multilayered composites, and its validity is also demonstrated.Qatar National Research Fund through Grant No. NPRP8-1568-2-666. Shim acknowledges start-up funds from the University at Buffalo (UB), and he is grateful to the support of UB Center for Computational Research