Topic
Direct stiffness method
About: Direct stiffness method is a research topic. Over the lifetime, 2584 publications have been published within this topic receiving 53131 citations.
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TL;DR: In modeling the fire response of reinforced concrete frame structures, the heat flow problem was separated from the structural analysis and two computer programs were written for solving the separate problems.
Abstract: In modeling the fire response of reinforced concrete frame structures, the heat flow problem was separated from the structural analysis and two computer programs were written for solving the separate problems. Both programs account for the temperature dependence of the thermal and mechanical properties of materials; the structural analysis accounts for the degradation of concrete and steel through cracking, crushing, spalling, and yielding. FIRES-T (FIre REsponse of Structures — Thermal) evaluates the thermal response of reinforced concrete elements using a nonlinear finite element approach coupled with time step integration. Using the thermal histories predicted by FIRES-T, FIRES-RC (FIre REsponse of Structures — Reinforced Concrete Frames) evaluates the structural response of reinforced concrete frames by a nonlinear, direct stiffness method coupled with time step integration. An iterative approach is used within time steps to find deformed shapes which result in equilibrium between forces associated with external load and internal stresses and degradation.
38 citations
TL;DR: In this paper, a finite element technique (FEM) is proposed for solving the boundary value problem for the wavefield in a layered horizontally homogeneous fluid-solid medium at fixed horizontal wavenumber k.
38 citations
TL;DR: In this paper, the free vibration of a three-layered symmetric sandwich beam is investigated using dynamic stiffness and finite element methods, where the core density has been taken into consideration.
38 citations
TL;DR: In this article, the authors demonstrate how to collect in situ field data and solve for stiffness (scaled shear) and damping values by a method consistent with this constitutive model.
Abstract: Determination of in situ dynamic soil properties is fundamental to the prediction of the seismic behavior of foundations and soil embankment structures. Both elastic (stiffness) and inelastic (damping) values are required for computational analysis. To be of value to engineers, the geophysical inversion should employ the same soil model as used in the dynamic analysis software. Current engineering practice employs a Kelvin-Voigt model (spring in parallel with dashpot). The relevant wave equation is a third-order partial differential equation. This paper demonstrates how to collect in situ field data and solve for stiffness (scaled shear) and damping values by a method consistent with this constitutive model. Measurements of seismic wave amplitude decay and velocity dispersion are simultaneously inverted for the required stiffness and damping values. These in situ stiffness and damping values are directly comparable to those obtained by resonant column measurements in the laboratory. Furthermore, the results may be directly input into currently available engineering software to provide values of stiffness and viscous damping. This paper includes both synthetic (finite difference) and field data examples that illustrate the method.
38 citations
18 Apr 2005
TL;DR: The purpose of this work is to evaluate the H4 stiffness, ie the displacement response of the tool controlled point when it is submitted to a given force using an analytical method.
Abstract: The H4 robot is a four-degree of freedom (dof) parallel machine. The purpose of this work is to evaluate the H4 stiffness, ie the displacement response of the tool controlled point when it is submitted to a given force using an analytical method. A stiffness analysis based on analytical calculations is performed. It has the advantage to be rather fast and easy to integrate into a design optimization. This method allows to compute stiffness matrix of parallel robots and takes into account particularity of parallel robots with articulated traveling plate. Some numerical results are presented at the end of this paper for the H4 first prototype.
38 citations