Dalian University of Technology

Fuyou Xu

Jing Yang

Wenjie Li

Donglei Zeng

Gao Liu

Bo Wang

Taotao Mao

Mingjie Zhang

Weizhi Zhu

Zhaoyu Ma

Minshan Pei

The present invention provides a semi-active vibration absorption and energy dissipation control system for restraining vortex-induced vibration of bridges. It has the advantages and characteristics that: (1) springs are horizontally placed at the bottom of a beam, and lengths are not limited, so that the frequency requirement of a low-frequency target can be satisfied; (2) different target frequencies can be realized through different combinations of a plurality of springs connected in series and in parallel, so that multi-order vortex-induced vibration control needs are satisfied; (3) the springs made of fiber reinforced nylon materials are adopted, and are notched, so that a frequency implementation range can be greatly widened; (4) the material and the form of a mass body are not limited, and a water bag can be used, which has low cost and is convenient for disassembly, assembly and mass adjustment.

Semi-active vibration absorption and energy dissipation control system for restraining vortex-induced vibration of bridges

The present invention belongs to the technical field of wind-induced vibration control study of bridges, and provides a dangling net cloth device for suppressing flutter of a sea-crossing bridge, i.e., a large-area dangling net cloth equipped with multiple balance weights, which is suspended below a girder by ropes and is immersed in water. When wind-induced vibration occurs on a bridge, the device is driven to move in the water, and gravity of the device as well as a huge additional mass force and an additional damping force produced by the water on the net cloth will do negative work on the girder to consume vibration energy of the bridge and effectively suppress large vibration of the bridge. The device adopts lightweight standardized components which are convenient to install, detach, transport, and store, and has the advantages of safety, reliability, economy, and practicality.

Dangling net cloth device for suppressing flutter of sea-crossing bridge

The invention discloses a coupled free vibration wind tunnel testing device with adjustable frequency ratio of torsional-vertical vibration, belonging to the technical field of bridge wind tunnel testing device. The device includes rigid testing model, lightweight rigid rods, lightweight rigid circular hubs, thin strings, linear tensile springs, carbon fiber ropes, and lightweight small hubs. The invention adjusts the torsional stiffness of the system by conveniently changing the diameter of the small hub, the diameter and length of the carbon fiber rope, etc. The device has the advantages of simple structure, convenient installation and avoiding the previous tedious work. It can achieve a variety of torsional-vertical vibration frequency ratio testing conditions by using only one diameter large hub. It can not only greatly save the time of replacing the large hub, but also facilitate the realization of higher torsional-vertical vibration frequency ratio testing conditions which are difficult to achieve by the previous methods.

Wind tunnel testing device for torsional-vertical coupled free vibration with adjustable frequency ratio

The present invention provides large-amplitude vertical-torsional coupled free vibration testing device for bridges in natural winds, which comprises a rigid model, light-weight high-strength thin strings, linear extension springs, a rigid framework, spring protection tubes, a turntable, a rigid column, a motor, heavy blocks, and rigid thin circular rods. Based on the device, free vibration tests of a bridge deck rigid model can be carried out in natural wind with good conditions, and hence the large-scale wind tunnel device is no longer required. The scaling ratio of the rigid model is no longer limited by the wind tunnel size as in a traditional test, and the scaling ratio can be much larger. Compared with traditional wind tunnel test, the device is more suitable for large-amplitude vibration tests since it can reduce the geometrical nonlinearities of the extension springs and the blocking ratio.

Large-amplitude vertical-torsional coupled free vibration testing device for bridges in natural winds

An experimental setup for three-degree-of-freedom large-amplitude free vibration in a wind tunnel test. The setup includes a rigid test model, rigid circular rods, rigid lifting arms, arc blocks with grooves, lightweight high-strength thin strings, linear tensile springs, fixed pulleys, and bearings. Large-amplitude three-degree-of-freedom free vibrations of test models can be adapted by the vertical deformation of the springs without any tilt. The possible nonlinear mechanical stiffness due to vertical spring tilt and lateral spring deflection are excluded. It is convenient to install the test model and adjust the initial angle of attack in the new experimental setup. The linear stiffness property and hence constant vibration frequency can be ensured for very large-amplitude vibrations due to the eliminations of spring deflection and tilt.

Experimental setup for three-degree-of-freedom large-amplitude free vibration in wind tunnel test

The invention provides a large-amplitude vertical-torsional coupled free vibration device, which belongs to the technical field of vertical-torsional coupled free vibration device for wind tunnel test. The gear blocks are consolidated at both ends of the beam. The screws, beam, and the gear blocks are fixed on the model, and they can fulfil the vertical-torsional coupled free vibration. The toothed plate is attached to the sliding block that iteratively moving along the vertical guide rail which is fixed to the ground. The vertical springs attached to the sliding blocks provide both vertical and torsional linear stiffness for the suspension vibration system. The springs only have vertical linear tensile deformations without any lateral tilt, which ensures the linear vertical and torsional stiffness of the model, and the lateral freedom is effectively restrained. This device can achieve the large-amplitude vertical-torsional coupled free vibration of the model, and the deficiency of the traditional device where springs are apparently tilted and the inefficacy of linear stiffness can be avoided. The lateral vibration is restrained, and it is applicable to large-amplitude vertical-torsional coupled free vibrations.

Large-amplitude vertival-torsional coupled free vibration device for wind tunnel test

A large-amplitude vertical-torsional coupled free vibration testing device for wind tunnel test. The large-amplitude vertical-torsional coupled free vibration device for wind tunnel test includes rigid deck model, lightweight rigid rods, lightweight rigid circular aluminium hubs, the first thin strings, linear tensile vertical springs, and the second lightweight strings. Large-amplitude vertical-torsional coupled free vibrations of rigid deck models can be realized by using this device, in which the springs vertically deform without any tilt. In the traditional free vibration device, the spring may obviously tilt, and the linear torsional stiffness cannot be ensured. The device can be conveniently installed and the initial angle of attack can be easily adjusted. The extreme low and stable mechanical damping ratio required for large-amplitude vibrations can be readily guaranteed, owing to the invocation of the negligible rolling friction between the thin strings and the hub.

Large-amplitude vertical-torsional coupled free vibration device for wind tunnel test

An experimental setup for bridge deck large-amplitude vertical-torsional coupled free vibration in wind tunnel test, which belongs to the technical field of wind tunnel test apparatus. The experimental setup includes the rigid model, the rigid circular rods, the lightweight rigid circular sprockets, the chains, the linear tensile vertical springs, the bearings, the sliders, and the guides. For the new setup, large-amplitude vertical-torsional coupled free vibration of a rigid deck model that failed in conventional testing device can be adapted by the vertical deformation of the springs without any lateral tilt. As a result, the possible nonlinear mechanical stiffness due to the springs tilt in conventional testing device is excluded. In addition, owing to the low rolling friction and damping between the sprockets and the chains, the mechanical damping ratio of the system are quite low and stable for very large-amplitude vibrations.

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Dalian, China

Fuyou Xu