Based on meta-modeling which allocates structural mechanics as mathematical approximation of continuum mechanics, we propose a consistent mass spring model (CMSM) for structural seismic response analysis; the consistency guarantees agreement of dynamic characteristics of CMSM with a solid element model. We develop a method of constructing CMSM and verify the method using a simple example. We apply the method to a part of highway bridge consisting of deck and a few piers. It is shown that the constructed CMSM has identical dynamic characteristics of the original model, and is able to estimate dynamic responses such as displacement and cross-sectional forces.
A numerical method for solving 1-D time-independent Hamilton-Jacobi-Bellman equations, which are referred to as 1-D HJBEs, is presented and applied to test cases for assessing its computational performance. An HJBE in this paper is a nonconservative second-order ordinary differential equation having linear diffusion and nonlinear drift terms. This paper applies a regularization method to the drift coefficient of the HJBEs, which helps well-pose the boundary value problems of the equations in the classical sense. A mathematical analysis on consistency errors between the solutions to the original and regularized HJBEs is performed. The derived results of the analysis show that the regularization method is mathematically consistent. The regularized HJBEs are solved with a Petrov-Galerkin finite element scheme, which is referred to as the PGFE scheme. The scheme is based on the fitting technique and is unconditionally stable for linear problems. Application of the scheme with the regularization method to the HJBEs with bounded drift coefficients demonstrates its satisfactory high computational accuracy. The optimal regularization parameter value as a function of the element size is then numerically identified. The computational results show that the PGFE scheme without the regularization method would fail to accurately capture solution profiles even if thousands of elements are used, which is not the case for the scheme with the regularization method even with hundreds of elements. Impacts of incorporating an adaptive re-meshing method, which is the moving mesh partial differential equation method, into the PGFE scheme are also assessed, demonstrating that it can enhance robustness of the scheme with regularization.
This paper proposes and validates a numerical method based on the unconditionally stable dual-finite volume (DFV) scheme for Kolmogorov's forward equations (KFEs) in 1-D unbounded domains, which can be optionally equipped with a mass-conservative moving mesh partial differential equation (MMPDE) method. A KFE is a conservative and linear parabolic partial differential equation (PDE) governing spatio-temporal evolution of a probability density function (PDF) of a continuous time stochastic process. A variable transformation method is proposed for effectively solving the KFEs in 1-D bounded domains. Application of the DFV scheme to a series of test cases demonstrates its satisfactory computational accuracy, robustness, and versatility for both steady and unsteady problems. Impacts of modulating a parameter in the variable transformation method on computational performance of the DFV scheme are then numerically assessed. Advantages and disadvantages of using the MMPDE method are also investigated.
This paper presents two greedy scheduling algorithms for recovery of damaged lifeline network. Unlike genetic algorithms or simulated annealing, the proposed algorithms do not involve random processes. One of the algorithm is for assigning multiple heterogeneous engineers and prepare schedules for repairing independent damaged components, while the other is for finding repair schedule for a single engineer considering network constraint. Both the algorithms uses rate of benefit gain as an index in deciding which component should be repaired next by whom. The target application of these algorithms is to serve as an initial solution for a multi agent system which includes fine grain details. With numerical experiments, it is demonstrated that the proposed algorithms can find near-optimal repair schedules and solve problems involving large number of variables.
This paper presents experimental results and numerical simulation of direct pull-out tests of basalt fiber reinforced polymer (BFRP) bars embedded in concrete. First, two patches of experimental pull-out tests are briefly descried. In the first experimental patch, the influence of surface texture configuration of BFRP bars on the bonding characteristics between BFRP bars and concrete is investigated through direct pull-out tests carried out on concrete cubes reinforced with BFRP bars. Pull-out test on ribbed steel reinforced concrete cube was also carried out for comparison. In the other experimental patch, pull-out tests were carried out on BFRP bars embedded inside pre-drilled holes into heavy concrete blocks. Through these pull-out tests, the efficiency of two different adhesive materials; namely: epoxy putty and polymer cement, and the effect of cross-section diameter of BFRP bars on the BFRP bar-concrete bond mechanism were investigated. Second, a finite element model (FEM) was employed to analyze the interfacial behavior between BFRP bars and the surrounding materials. Through the FEM, the influence of the tested parameters on the characteristics of local bond-slip models of BFRP bars was assessed by considering different material properties as well as different fracturing bond mechanisms. The experimental and numerical results showed that the bonding behavior of BFRP bars-reinforced concrete structures can be improved by treating the surface texture configurations of BFRP bars. In addition, the properties of the adhesive material between BFRP bars and concrete are key factors controlling the bond mechanism of strengthened concrete structures. Moreover, the proposed FEM was found to be capable of simulating the fracturing bond mechanism of BFRP bars.
This paper presents implementation of higher order PDS (HO-PDS) in FEM framework (HO-PDS-FEM) to solve a boundary value problems involving cracks in linear elastic bodies. Further, an alternative approach based on curl free restriction to extend the current PDS is also presented. This alternative curl-free implementation is scrutinized and compared with a former proposal for HO-PDS whose derivative is not guarantee to satisfy curl free condition. Analysis of traditional plate with a hole problem shows that curl free implementation does not have any specific advantage. Further, techniques for modeling cracks in HO-PDS-FEM are presented. Comparison of two formulations with mode-I crack problem indicates that former proposed HO-PDS-FEM is superior to the proposed curl free formulation, and there is a significant improvement compared to 0th-order PDS-FEM.