scholarly journals Design of movable frame structures using modified Cross procedure

2020 ◽  
Vol 72 (08) ◽  
pp. 655-671
Keyword(s):  
Algebraic Equation ◽  
Linear Algebraic Equation ◽  
Design Procedure ◽  
Frame Structures ◽  
Design Algorithm ◽  
Plane Frame ◽  
Original Procedure

An original procedure for static design of movable in-plane frame structures is presented in the paper. The presented design procedure was derived using the modified traditional Cross procedure (TCP). The introduction of the TCP modification has resulted in significant improvement of the design algorithm of movable frame structures as compared to TCP, especially as to elimination of the need to conduct greater number of individual iteration procedures, and to solve linear algebraic equation systems.

scholarly journals Design of Reduced-Order Multiple Observers for Uncertain Systems with Unknown Inputs

Complexity ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Mihai Lungu
Keyword(s):  
Linear Time ◽  
Design Procedure ◽  
Lyapunov Theory ◽  
Design Algorithm ◽  
Reduced Order ◽  
Unknown Inputs ◽  
Linear Time Invariant ◽  
Reduced Order Observer ◽  
Multiple Observer ◽  
Takagi Sugeno

The paper presents the design of a new reduced-order multiple observer for the estimation of the state associated with Takagi-Sugeno systems with unknown inputs, this being only the second reduced-order multiple observer ever designed. The design of reduced-order multiple observers which can achieve the finite-time state reconstruction for nonlinear systems described by multiple models is a niche area problem; the author of this paper continuing his work started with the introduction of the reduced-order multiple observer concept. The new multiple observer is a combination of a typical reduced-order observer for linear-time invariant multivariable systems and a full-order multiple observer for Takagi-Sugeno systems. The sufficient stability conditions of the observer are derived via the Lyapunov theory and its robustness is improved by means of a novel and efficient method which cancels the negative effect of the uncertainties appearing in the system. To validate the suggested design algorithm, the steps of the design procedure have been summarized and software implemented for the concrete case of a light aircraft lateral-directional motion.

SEISMIC DESIGN OF FRAME STRUCTURES EQUIPPED WITH INNOVATIVE HYSTERETIC DISSIPATIVE DEVICES

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Michele Palermo ◽  
Vittoria Laghi ◽  
Stefano Silvestri ◽  
Giada Gasparini ◽  
Tomaso Trombetti
Keyword(s):  
Seismic Design ◽  
Design Procedure ◽  
Structural Instability ◽  
Hysteretic Behavior ◽  
Frame Structure ◽  
Frame Structures ◽  
Order Effects ◽  
Final Design ◽  
Structural Engineer ◽  
Performance Based Seismic Design

In the present work, a Performance-Based Seismic Design procedure applied to multi-storey frame structures with innovative hysteretic diagonal steel devices (called Crescent Shaped Braces or CSB) is introduced. CSBs are steel elements of peculiar geometrical shapes that can be adopted in frame buildings as enhanced hysteretic diagonal braces. Based on their "boomerang" configuration and placement inside the frame structure, they are characterized by a lateral stiffness uncoupled from the yield strength and, if properly inserted, by an overall symmetric hysteretic behavior with hardening response at large drifts, thus preventing from global structural instability due to second-order effects. The procedure here presented is intended to guide the structural engineer through all the steps of the design process, from the selection of the performance objectives to the preliminary sizing of the CSB devices, up to the final design configuration. The steps are described in detail through the development of an applicative example.

Fatigue Under Wide Band Random Stresses Using the Rain-Flow Method

1977 ◽  
Vol 99 (3) ◽  
pp. 205-211 ◽  
Author(s):  
P. H. Wirsching ◽  
A. Mohsen Shehata
Keyword(s):  
Fatigue Behavior ◽  
Design Procedure ◽  
Random Variable ◽  
Wide Band ◽  
Stress Process ◽  
Structural Elements ◽  
Constant Amplitude ◽  
Design Algorithm ◽  
Flow Method ◽  
Fatigue Design

A fatigue design procedure is proposed for the structural elements subjected to a stress process, modeled as stationary wide-band gaussian. This procedure, restricted to high cycle fatigue design, uses available constant amplitude material fatigue data and a modified, probability based, Palmgren-Miner (PM) rule. Statistical uncertainty in fatigue behavior and nonstatistical uncertainty in the PM rule are implicitly accounted for by treating the PM index at failure as a random variable. The rain flow method of counting stress cycles is used. The fatigue design algorithm requires only that the RMS and irregularity factor of the stress process be specified in addition to the constant amplitude S-N curve for the material.

scholarly journals Numerical Solution of Multidimensional Stochastic Itô-Volterra Integral Equation Based on the Least Squares Method and Block Pulse Function

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Ting Ke ◽  
Guo Jiang ◽  
Mengting Deng
Keyword(s):  
Integral Equation ◽  
Error Analysis ◽  
Numerical Solution ◽  
Least Squares ◽  
Algebraic Equation ◽  
Volterra Integral Equation ◽  
Linear Algebraic Equation ◽  
Least Squares Method ◽  
Numerical Examples ◽  
Block Pulse Function

In this paper, a method based on the least squares method and block pulse function is proposed to solve the multidimensional stochastic Itô-Volterra integral equation. The Itô-Volterra integral equation is transformed into a linear algebraic equation. Furthermore, the error analysis is given by the isometry property and Doob’s inequality. Numerical examples verify the effectiveness and precision of this method.

Application of Spectral Element Method for Dynamic Analysis of Plane Frame Structures

2019 ◽  
Vol 35 (3) ◽  
pp. 1213-1233 ◽  
Author(s):  
N. Merve Çağlar ◽  
Erdal Şafak
Keyword(s):  
Dynamic Response ◽  
Spectral Element Method ◽  
Computational Cost ◽  
Spectral Element ◽  
Frame Structure ◽  
Frame Structures ◽  
The Finite Element Method ◽  
Plane Frame ◽  
Impedance Functions ◽  
Element Method

The paper presents a methodology to analyze plane frame structures using the Spectral Element Method (SEM) with and without considering Soil-Structure Interaction (SSI). The formulation of spectral element matrices based on higher-order element theories and the assemblage procedure of arbitrarily oriented members are outlined. It is shown that SEM gives more accurate results with much smaller computational cost, especially at high frequencies. Since the formulation is in the frequency domain, the frequency-dependent foundation impedance functions and SSI effects can easily be incorporated in the analysis. As an example, the dynamic response of a plane frame structure is calculated based on the Finite Element Method (FEM) and SEM. FEM and SEM results are compared at different frequency bands, and the effects of SSI on the dynamic response are discussed.

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