Dalian University of Technology

Hongnan Li

Xing Fu

Wenlong Du

Tinghua Yi

Gang Li

Zhiqian Dong

Chunxu Qu

Haibin Huang

Xingheng Zhang

Linsheng Huo

Jing Zhou

Xiaomei Yang

Xiaojun Yao

Xu Xu

Liang Ren

Shuwei Ma

Jia Wang

Shengbin Chen

Yao Jiang

Zhuodong Yang

Qing Zhang

Xifeng Zhong

Zhikai Xu

The present invention belong to the technical field of lattice tower structure monitoring, and discloses a displacement reconstruction method for a lattice tower structure based on improved mode superposition. The method comprises: uniformly arranging D strain sensors on main member of a lattice tower along the height, processing collected strain data {ε}using a stochastic subspace identification (SSI) method to obtain a matrix [Ψ]of first n-order strain modes; calculating a function relation y(x) between a distance from a measuring point to a neutral layer and a height according to a lattice tower design drawing; performing polynomial fitting on the first n-order strain modes with a height coordinate x of the lattice tower respectively to obtain a strain mode function Ψ(x), expanding a function according to a Taylor formula, performing double integration on the expansion result and substituting same into a boundary condition, to obtain a displacement mode function Φ(x); evaluating a modal coordinate {q}by means of the least square method, substituting the height coordinate x of a displacement object point to be reconstructed, and multiplying the displacement mode function value Φ(x) by the modal coordinate {q}. The improved mode superposition method of the present invention has the advantages of a small number of sensors required, simple calculation process, accurate calculation result, and strong operability and practicality.

Displacement reconstruction method for lattice tower structure based on improved mode superposition

The present invention belongs to the technical field of disaster prevention and reduction of transmission lines, and provides a quasi-static calculation method for lateral unbalanced force of transmission lines. The present invention can quantify significant unbalanced force caused by a failed tower to an adjacent tower, thus to quantitatively evaluate cascading failure risk of transmission lines. The present invention does not need a lot of iteration, and can parametrically reveal influence of various factors on unbalanced force. The present invention quantifies influence of large deformation effect of a conducting wire on wind load, and at the same time, wind load of the conducting wire is corrected by the trapezoidal equivalent wind pressure proposed, which avoids wind load calculation error of the conducting wire caused by a relatively large vertical height difference, better reflects actual mechanical state of the lines, and optimizes existing wind load calculation method of transmission lines.

Quasi-static calculation method for lateral unbalanced force of transmission lines

A structure multi-dimensional loading test system considering real complex boundary conditions considering real complex boundary conditions comprises a main part of machine, a base part, a hydraulic power supply and a control system. The system can simulate the load borne by a structure in a real working environment better and more accurately, realize multi-dimensional loading of the structure with six degrees of freedom in space and provide more real and valuable experimental data for the research on damage of reinforced concrete materials, components and structures under the action of an earthquake, and the research results will help researchers further reveal the damage mechanism of reinforced concrete structures, put forward the corresponding damage criteria and develop the corresponding seismic design methods.

Structure multi-dimensional loading test system considering real complex boundary conditions

An axial displacement amplified eddy current damper is disclosed. The axial movement of a slide bar is converted into the rotation of copper sheets and generates eddy current for energy consumption. The copper sheets are rotated and amplified by adjusting the sizes of gears. The short displacement of the slide bar can cause a large angle rotation of the copper sheets, so that energy consumption efficiency is high. The damping parameter can be adjusted by adjusting the magnetic field strength of permanent magnets, the thickness of the copper sheets and the distance from the copper sheets to the permanent magnets. The permanent magnets are adopted to provide continuous magnetic field sources, without external energy, thereby generating long-term and stable vibration reduction effect.

Axial displacement amplified eddy current damper

The present invention discloses a coupling beam eddy current damper with shear displacement amplification. The coupling beam eddy current damper with shear displacement amplification comprises a rigid rod, rotating shafts, a pin column, pins, levers, screws, thread sleeves, copper sheets, permanent magnet components, a steel structural component, balls, ball supports and an outer shell. When vibration occurs, coupling beams on both sides of the damper are relatively vertically displaced; at this moment, two levers move up and down relative to the rigid rod; the movement causes the screws and the copper sheets to rotate; the copper sheets rotate in a magnetic field, then induced electromotive force will generates inside the magnetic field, thereby generating eddy current in the copper sheets. The eddy current effect will produce a damping force that impedes the rotation of the copper sheets.

Coupling beam eddy current damper with shear displacement amplification

The present invention belongs to the technical fields of civil engineering, smart material and health monitoring, and provides a viscous damper fluid viscosity monitoring device and method based on piezoceramic transducers, comprising piezoceramic transducers, wires, corks, a baffle and a viscous damper. When the fluid viscosity of the viscous damper changes, the energy dissipation of pressure waves during propagation in a fluid will change, and signals received by the piezoceramic transducers will change, so that the viscosity of the fluid in the viscous damper can be calculated by the amplitude change of the signals received. The device of the present invention has a simple structure and accurate monitoring results, and provides a simple and feasible method for real-time monitoring of fluid viscosity of viscous dampers in engineering.

Viscous damper fluid viscosity monitoring device and method based on piezoceramic transducers

The present invention belongs to the technical field of energy consumption and vibration reduction of assembled building structures, and provides an energy-consuming connecting device for a prefabricated assembled wall. The present invention provides a normal connection function between walls, and also has the functions of energy consumption and vibration reduction. A used viscoelastic material can provide energy consumption and weaken the cold and hot bridge effect, which is beneficial to building thermal insulation. Meanwhile, the energy-consuming connecting device for the prefabricated assembled wall can be connected with a prefabricated wall in advance, which can be carried out at the same time as the wall is inserted during construction, thereby effectively increasing the construction efficiency. Through the design of clamping groove devices, the wall can be connected firmly and reliably while generating displacement and consuming energy. A multi-segment fixing plate is used to replace full-length arrangement to save the steel.

Energy-consuming connecting device for prefabricated assembled wall

The present invention belongs to the technical field of structural vibration control, and provides a composite axial energy consumption device based on piezoelectricity and shape memory alloy, comprising a screw, steel pipes, stiffening ribs, steel sheets, bolt-nuts, piezoceramics, screw caps and SMA wire bundles. The mechanical energy of the structure under pressure is converted into the electric energy of the piezoceramics and then the electric energy is converted into heat energy, so that energy consumption efficiency is high and mechanical performance is good. The SMA wire bundles have large tensile bearing capacity, shape memory effect and good corrosion resistance and fatigue resistance. The number of the segments and the specifications of the piezoceramics and the SMA wire bundles can be adjusted according to the actual needs, so that the structure can be adjusted according to the size of an axial force and specific stress conditions.

Composite axial energy consumption device based on piezoelectricity and shape memory alloy

The present invention discloses a multi-dimensional eddy current tuned mass damper, which belongs to the technical field of structural vibration control. A main body of the multi-dimensional eddy current tuned mass damper is composed of two hollow cylinders, wherein an inner hollow cylinder is located in an outer hollow cylinder, ball grooves are formed in the opposite upper and lower walls of the inner and outer hollow cylinders, rolling balls are installed in the ball grooves, and the inner hollow cylinder is rotated in the outer hollow cylinder through the rolling balls; the inner hollow cylinder is provided with an inner cover plate, and the outer hollow cylinder is provided with an outer cover plate, forming a relatively closed box body structure; an orthogonal bidirectional mass element, a stiffness element and an eddy current damping element are arranged in the inner hollow cylinder, and a torsional stiffness element and an eddy current damping element are arranged between the inner hollow cylinder and the outer hollow cylinder. The multi-dimensional eddy current tuned mass damper of the present invention is not only convenient to adjust in terms of mass, stiffness and damping parameters, but also has regular and beautiful appearance, simple structure, and very simple connection with a main structure.

Multi-dimensional eddy current tuned mass damper

A self-resetting tuned mass damper is based on eddy current and shape memory alloy technology. The self-resetting tuned mass damper comprises a hollow box, a cover plate, a bolt, a mass block, gears a, gears b, gears c, copper sheets, permanent magnet groups, partition boards, balls, pins, levers, shape memory alloys, rotating shafts a, rotating shafts b, a supporting plate and rotating shafts c. The movement of the mass block causes the copper sheets to rotate and generate eddy current for energy consumption. The copper sheets are rotated and amplified by adjusting the sizes of the gears. The displacement of a small mass block can cause rotation of the copper sheets by a large angle, which greatly increases energy consumption efficiency. The elongation of the shape memory alloys is amplified by adjusting the ratio of long and short force arms of the levers.

Self-resetting tuned mass damper based on eddy current and shape memory alloy technology

An inertial mass amplification type tuned mass damper is disclosed. The inertial mass amplification type tuned mass damper comprises a hollow box, an H-shaped mass block, gears a, gears b, a rectangular frame, a steel ring, viscous dampers, a steel sheet, springs, rotating shafts and balls. In the present invention, an inertial damping force is amplified by adjusting the radius ratio of the gears a and the gears b; and damping parameters can be conveniently changed by adjusting the mass of the mass block, the spring stiffness and the like. The present invention has the advantages that the design mass is small, which can avoid the adverse effects of excessive additional gravity on the structure and improve the performance of the structure. The present invention has reasonable design and small occupied space, can save more use area for buildings and can greatly improve the utilization efficiency of the buildings.

Inertial mass amplification type tuned mass damper

An eddy current energy-dissipating spacer is mainly composed of a spacer frame, a conductor clamp and energy-dissipating elements. The eddy current energy-dissipating spacer not only provides the function of an ordinary spacer, but also reduces the vibration of the transmission lines; and at the same time, can effectively reduce the vibration of the transmission lines, especially the torsional vibration by adopting the eddy current and viscoelastic material for energy dissipation; improves the eddy current strength by adjusting the gear radius ratio, thus increasing the damping force; can adjust the damping parameters by adjusting the magnetic field strength of the permanent magnet; can produce long-term stable vibration reduction effect by adopting the permanent magnet to provide continuous magnetic field without additional external energy input; can effectively avoid the magnetic flux leakage of magnetic circuits by adopting the magnetic material.

Eddy current energy-dissipating spacer

A method for automatically detecting the free vibration response segment of the high-speed railway bridges after trains passing. First, pre-select the test response sequence to be decomposed based on the maximum of the time instants corresponding to the absolute maximums of the response vectors at various measuring point. Then, Extract the single-frequency modal response from the test response by the iterative variational mode decomposition and fit the envelope amplitude of the modal response by Hilbert transform. Finally, the vibration features at each time instants are marked as decay vibration or non-decay vibration. The longest structural response segment that meets the decay vibration features is determined as the detected free vibration response segment for modal identification. This invention can effectively detect the free vibration data segment without human participation, which is of great significance for the real-time accurate modal analysis of high-speed railway bridges.

Method for automatically detecting free vibration response of high-speed railway bridge for modal identification

Structural health monitoring providing sparse component analysis method for structural modal identification with incomplete number of sensors. Transforming structural acceleration response data into time frequency domain by short time Fourier transform, detecting time frequency points contributed by only one-order mode where real and imaginary parts have the same direction, and taking the detection result as the initial result of single-source-points; refining the initial result of detection of single-source-point located near the peak of power spectral density, and clustering single-source-points to obtain a mode shape matrix; constructing generalized spectral matrixes using short time Fourier transform coefficients, conducting singular value decomposition on generalized spectral matrix at a single-source-point, taking the first singular value as an auto-spectrum of single-order mode, obtaining the frequency of each order by picking the peak of auto-spectrum, and extracting damping ratio of each order by transforming the auto-spectrum into a time domain through inverse Fourier transform. By means of this method, structural modal parameters are obtained when the number of sensors is incomplete, thereby increasing the identification accuracy of the sparse component analysis method.

Sparse component analysis method for structural modal identification when the number of sensors is incomplete

Structural health monitoring relating to an automatic method for tracking structural modal parameters. First, Natural Excitation Technique is used to transform the random responses into correlation functions and Eigensystem Realization Algorithm combined with the stabilization diagram is used to estimate modal parameters from various response segments. Then, modes from the latter response segment are classified as traceable modes or untraceable modes according to correlations between their observability vectors and subspaces of the existing reference modes. Final, traceable modes will be grouped into specified clusters with the same structural characteristics on the basis of maximum modal observability vector correlation and minimum frequency difference. Meanwhile, union of the untraceable modes and existing reference modes are updated as the new reference modes which can be applied into the next tracking process. This can track the modal parameters automatically without artificial thresholds and the specified reference modes.

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Liaoning, China

Hongnan Li