Mass Inertia Effect Based Vibration Control Systems for Civil Engineering Structure and Infrastructure

This chapter introduces some recent research works carried out in the Blast Resistance and Protective Engineering laboratory of Harbin Institute of Technology (HIT-BRPE) during the past few years. The EMD control system is shown to be effective and feasible for vibration control of civil engineering structures subjected to, such as earthquake, excitations. The DDVC based AMD control system is suitable for low frequency vibration and motion control. The innovative passive TRID system is applicable for rotation and swing motion control, whereas linear TMD system is shown to be invalid for structural swinging motion. All of the control systems mentioned in this chapter, whatever active or passive or hybrid, have a common characteristic, which is to utilize the mass inertia effect either to provide counter force support for functioning of actuator, e.g. AMD subsystem, or to provide gyrus or rotary inertia for anti-swinging motion of suspended structure. Traditionally, these systems have been called Active Mass Damper/Driver (AMD) or Tuned Mass Damper (TMD), herein we want to emphasize the mass inertia effect and its functions. The basic is to be a necessary component of a control system, and more important is its way of working in the subsystem

DYNAMIC EFFECTS OF EQUIVALENT TRUNCATED MOORING SYSTEMS FOR A SEMI-SUBMERSIBLE PLATFORM

Physical model tests of floater with full-depth mooring system present obstacles because no tank is sufficiently large to perform model testing in reasonable scale. This paper presents numerical simulation on design method of equivalent truncated mooring systems for model testing of offshore platforms in wave basin. Based on static and dynamic equivalent, two approaches are used to design the truncated mooring systems, respectively. Considering a semi-submersible platform with full-depth and corresponding two equivalent truncated mooring systems, the floater responses and mooring line tensions are compared. The feasibility of model test with equivalent truncated mooring systems is discussed

Response Surface Method based on Radial Basis Functions for Modeling Large-Scale Structures in Model Updating

The Response Surface (RS) Method based on Radial Basis Functions (RBFs) is Proposed to Model the Input-Output System of Large-Scale Structures for Model Updating in This Article. as a Methodology Study, the Complicated Implicit Relationships between the Design Parameters and Response Characteristics of Cable-Stayed Bridges Are Employed in the Construction of an RS. the Key Issues for Application of the Proposed Method Are Discussed, Such as Selecting the Optimal Shape Parameters of RBFs, Generating Samples by using Design of Experiments, and Evaluating the RS Model. the RS Methods based on RBFs of Gaussian, Inverse Quadratic, Multiquadric, and Inverse Multiquadric Are Investigated. Meanwhile, the Commonly Used RS Method based on Polynomial Function is Also Performed for Comparison. the Approximation Accuracy of the RS Methods is Evaluated by Multiple Correlation Coefficients and Root Mean Squared Errors. the Antinoise Ability of the Proposed RS Methods is Also Discussed. Results Demonstrate that RS Methods based on RBFs Have High Approximation Accuracy and Exhibit Better Performance Than the RS Method based on Polynomial Function. the Proposed Method is Illustrated by Model Updating on a Cable-Stayed Bridge Model. Simulation Study Shows that the Updated Results Have High Accuracy, and the Model Updating based on Experimental Data Can Achieve Reasonable Physical Explanations. It is Demonstrated that the Proposed Approach is Valid for Model Updating of Large and Complicated Structures Such as Long-Span Cable-Stayed Bridges. © 2012 Computer-Aided Civil and Infrastructure Engineering

Numerical validation of a damage diagnosis method for arch bridges hangers

This paper proposes a test method for damage diagnosis of arch bridge hangers. The acceleration response of every hanger under pulse excitation before and after damage is collected and used to extract the damage feature in time domain directly. Then the damage feature waveform before and after damage is obtained respectively by connecting these damage feature values of all measured hangers one by one. Finally the mean value of normalized curvature difference of damage feature waveforms before and after damage is considered as the damage index to diagnose the hangers. The proposed method has a high sensitivity to small damage and the damage sensitivity has no obvious change to hangers with different lengths; moreover, the proposed method doesn’t require the finite element model of the arch bridge. All of these lay a good foundation for damage diagnosis of arch bridge hangers

Cloud-structural health monitoring based on smartphone

Smartphone, integrated with CPU, sensors, network, and storage capability, is developed rapidly in recent years. A cloud-structural health monitoring method based on smartphone was proposed, and a structural health monitoring system Orion-CC, which integrates functions of data acquisition, data analysis and data upload, was developed on smartphone to perform structural health monitoring without any other professional devices. And the feasibility of Orion-CC was proved by the cable force test. A cloud-SHM data sharing website was built to make the data synchronization between smartphone and website, and realize data uploading and sharing, which can improve the efficiency of monitoring and big data integration, make the possibility for big data collection and quick structural safety evaluation

Mooring Line Damping Estimation for a Floating Wind Turbine

The dynamic responses of mooring line serve important functions in the station keeping of a floating wind turbine (FWT). Mooring line damping significantly influences the global motions of a FWT. This study investigates the estimation of mooring line damping on the basis of the National Renewable Energy Laboratory 5 MW offshore wind turbine model that is mounted on the ITI Energy barge. A numerical estimation method is derived from the energy absorption of a mooring line resulting from FWT motion. The method is validated by performing a 1/80 scale model test. Different parameter changes are analyzed for mooring line damping induced by horizontal and vertical motions. These parameters include excitation amplitude, excitation period, and drag coefficient. Results suggest that mooring line damping must be carefully considered in the FWT design

Self-repairing performance of concrete beams strengthened using superelastic sma wires in combination with adhesives released from hollow fibers

Abstract By taking advantage of the superelastic effect of shape memory alloy (SMA) and the cohering characteristic of repairing adhesive, a smart self-repairing concrete beam with damage self-repairing performance has been developed. In order to verify the potential self-repairing capacity of smart concrete beams reinforced with SMA wires and brittle fibers containing adhesives, static loading tests were conducted. Experimental results show that the superelastic SMA wires added self-restoration capacity to concrete beams, the deflection of the beams reversed and the crack closed almost completely after unloading. After the release of adhesive from the broken-open fibers into the cracks from the first loading, stress was redistributed to the uncracked section where a new crack was formed, while the sealed crack remained closed during reloading for the smart concrete beams reinforced with SMA wires and brittle fibers containing adhesives. While the original cracks experienced reopening, the load was carried directly by the wires during reloading for concrete beams reinforced with SMA wires

An Improved Optimal Elemental Method for Updating Finite Element Models

The Optimal Matrix Method and Optimal Elemental Method Used to Update Finite Element Models May Not Provide Accurate Results. This Situation Occurs When the Test Modal Model is Incomplete, as is Often the Case in Practice. an Improved Optimal Elemental Method is Presented that Defines a New Objective Function, and as a Byproduct, Circumvents the Need for Mass Normalized Modal Shapes, Which Are Also Not Readily Available in Practice. to Solve the Group of Nonlinear Equations Created by the Improved Optimal Method, the Lagrange Multiplier Method and Matlab Function Fmincon Are Employed. to Deal with Actual Complex Structures, the Float-Encoding Genetic Algorithm (FGA) is Introduced to Enhance the Capability of the Improved Method. Two Examples, a 7-Degree of Freedom (DOF) Mass-Spring System and a 53-DOF Planar Frame, Respectively, Are Updated using the Improved Method. the Example Results Demonstrate the Advantages of the Improved Method over Existing Optimal Methods and Show that the Genetic Algorithm is an Effective Way to Update the Models Used for Actual Complex Structures