浔江大跨越输电线微风振动消振设计试验研究及现场测量

从理论上初步探讨了阻尼线(或防振锤)与输电线振动的耦合特性。结果证明：在阻尼线与输电线固有频率相同，且阻尼线与输电线参振质量比值大的条件下，输电线、阻尼线、防振锤均处于最小和最稳定的振动状态，使输电线得到了保护。如果阻尼线与防振锤联合使用，对输电线的消振，理论和实践证明是令人满意的。     

影响核岛新浇混凝土强度的爆破振动速度阈值研究

针对短龄期混凝土强度容易受到附近爆破振动的影响，进行了一系列有针对性的模型实验，以确定在建核岛新浇灌混凝土强度所能承受的最高爆破振动速度值。实测结果表明C25、C40混凝土在浇筑12h、3d、7d凝期时受到1cm/s、5cm/s振幅的爆破振动后，与未受振动的混凝土相比、其强度、钢筋握裹力都不会受到明显影响。由于核电建设安全性的特殊性要求，本文提出对于核岛新浇筑的混凝土，其爆破振动阈值控制在1cm/s以内时，其强度不会受到影响。     

大跨度结构TMD减震系统多点激励的地震随机响应分析

众多研究表明，对大跨度结构进行抗震分析时，必须采用非一致地震激励模型。本文对带TMD系统的大跨度结构考虑地震行波效应后的随机地震响应问题进行了研究。文中建立了结构的动力方程，并利用虚拟激励法求解。研究结果表明，对于大跨度结构装设TMD子结构以后可显著地降低结构的位移、速度和加速度响应，但在设计TMD减震系统时，必须考虑到地震激励的非一致性，否则可能会使预期的减震效果失效。     

Multiple active–passive tuned mass dampers for structures under the ground acceleration

An Erratum has been published for this article in Earthquake Engineering and Structural Dynamics 2003; 32(15):2451. Multiple active–passive tuned mass dampers (MAPTMD) consisting of many active–passive tuned mass dampers (APTMDs) with a uniform distribution of natural frequencies have been, for the first time here, proposed for attenuating undesirable oscillations of structures under the ground acceleration. The MAPTMD is manufactured by keeping the stiffness and damping coefficient constant and varying the mass. The control forces in the MAPTMD are generated through keeping the identical displacement and velocity feedback gain and varying the acceleration feedback gain. The structure is represented by the mode‐generalized system corresponding to the specific vibration mode that needs to be controlled. Through minimization of the minimum values of the maximum dynamic magnification factors (DMF) of the structure with the MAPTMD (i.e. through implementation of Min.Min.Max.DMF), the optimum parameters of the MAPTMD are investigated to delineate the influence of the important parameters such as mass ratio, total number, normalized acceleration feedback gain coefficient and system parameter ratio on the effectiveness (i.e. Min.Min.Max.DMF) and robustness of the MAPTMD. The optimum parameters of the MAPTMD include the optimum frequency spacing, average damping ratio and tuning frequency ratio. Additionally, for the sake of comparison, the results for a single APTMD are also taken into account in the present paper. It is demonstrated that the proposed MAPTMD can be employed to significantly reduce the oscillations of structures under the ground acceleration. Also, it is shown that the MAPTMD can render high robustness and has better effectiveness than a single APTMD. In particularly, if and when requiring a large active control force, MAPTMD is more promising for practical implementations on seismically excited structures with respect to a single APTMD. Copyright © 2003 John Wiley & Sons, Ltd.     

Application of non‐linear multiple tuned mass dampers to suppress man‐induced vibrations of a pedestrian bridge

This paper presents an application of multiple tuned mass dampers (MTMDs) with non‐linear damping devices to suppress man‐induced vibrations of a 34m long pedestrian bridge. The damping force generated by each of these damping devices is simply a drag force from liquid acting on an immersed section. The quadratic non‐linear property of these devices was directly determined from free vibration tests of a simple laboratory set‐up. Dynamic models of the bridge and pedestrian loads were constructed for numerical investigation based on field measurement data. The control effectiveness of non‐linear MTMDs was examined along with its sensitivity against estimation errors in the bridge's natural frequency and magnitude of pedestrian load. The numerical results indicated that the optimum non‐linear MTMD system was as effective and robust as its linear counterpart. Then, a six‐unit non‐linear MTMD system was designed, constructed, and installed on the bridge. Field measurements after the installation confirmed the effectiveness of non‐linear MTMDs, and the measurement results were in good agreement with numerical predictions. After the installation, the average damping ratio of the bridge was raised from 0.005 to 0.036 and the maximum bridge accelerations measured during walking tests were reduced from about 0.80–1.30 ms^?2 to 0.27–0.40 ms^?2, which were within an acceptable range. Copyright © 2003 John Wiley & Sons, Ltd.     

溢洪道高边坡控制爆破施工

本文分析了单响药量和起爆网络对爆破振动的影响,结合控制爆破技术进行了振速监测,通过爆破监测估算出该地区爆破振动衰减规律,用以指导溢洪道开挖施工,保证了泄洪洞的安全。     

Active multiple tuned mass dampers for structures under the ground acceleration

Active multiple tuned mass dampers (AMTMD) consisting of many active tuned mass dampers (ATMDs) with a uniform distribution of natural frequencies have been, for the first time, proposed for attenuating undesirable vibrations of a structure under the ground acceleration.The multiple tuned mass dampers (MTMD) in the AMTMD is manufactured by keeping the stiffness and damping constant and varying the mass. The control forces in the AMTMD are generated through keeping the identical displacement and velocity feedback gain and varying the acceleration feedback gain. The structure is represented by its mode‐generalized system in the specific vibration mode being controlled using the mode reduced‐order method. The optimum parameters of the AMTMD are investigated to delineate the influence of the important parameters on the effectiveness and robustness of the AMTMD by conducting a numerical searching technique. The parameters include the frequency spacing, average damping ratio, tuning frequency ratio, total number and normalized acceleration feedback gain coefficient. The criterion, which can be stated as the minimization of the minimum values of the maximum dynamic magnification factors (i.e. Min.Min.Max.DMF), is chosen for the optimum searching. Additionally, for the sake of comparison, the results of the optimum MTMD (the passive counterpart of AMTMD) and ATMD are also taken into account in the present paper. It is demonstrated that the proposed AMTMD can be expected to significantly reduce the oscillations of structures under the ground acceleration. It is also shown that the AMTMD can remarkably improve the performance of the MTMD and has higher effectiveness than ATMD. Copyright © 2002 John Wiley & Sons, Ltd.     

Damage identification of structures with uncertain frequency and mode shape data

A statistical method with combined uncertain frequency and mode shape data for structural damage identification is proposed. By comparing the measured vibration data before damage or analytical finite element model of the intact structure with those measured after damage, the finite element model is updated so that its vibration characteristic changes are equal to the changes in the measured data as closely as possible. The effects of uncertainties in both the measured vibration data and finite element model are considered as random variables in model updating. The statistical variations of the updated finite element model are derived with perturbation method and Monte Carlo technique. The probabilities of damage existence in the structural members are then defined. The proposed method is applied to a laboratory tested steel cantilever beam and frame structure. The results show that all the damages are identified correctly with high probabilities of damage existence. Discussions are also made on the applicability of the method when no measurement data of intact structure are available. Copyright © 2002 John Wiley & Sons, Ltd.     

Wind-induced vibration control of bridges using liquid column damper

The potential application of tuned liquid column damper (TLCD) for suppressing wind-induced vibration of long span bridges is explored in this paper. By installing the TLCD in the bridge deck, a mathematical model for the bridge-TLCD system is established. The governing equations of the system are developed by considering all three displacement components of the deck in vertical, lateral, and torsional vibrations, in which the interactions between the bridge deck, the TLCD, the aeroelastic forces, and the aerodynamic forces are fully reflected. Both buffeting and flutter analyses are carried out. The buffeting analysis is performed through random vibration approach, and a critical flutter condition is identified from flutter analysis. A numerical example is presented to demonstrate the control effectiveness of the damper and it is shown that the TLCD can be an effective device for suppressing wind-induced vibration of long span bridges, either for reducing the buffeting response or increasing the critical flutter wind velocity of the bridge.     

鄂东南大沙坪下奥陶统碳酸盐重力流及自发振动成因机理

位于中扬子地台东南缘的大沙坪剖面下奥陶统留咀桥组下段重力流沉积非常发育，重力流沉积类型以富基质的Ａ型碎屑流沉积为主。经区域资料横向对比，这种发育是局部性的。对这种局部性的重力流沉积，本文应用自发振动原理进行了阐述，分析了沉积迁移常数Ｋ、沉积物滑移的最大坡度角αｍａｘ、最小坡度角αｍｉｎ、沉积物输入速率η等参数。αｍａｘ、αｍｉｎ控制了一个自发振动系统，△α（αｍａｘ－αｍｉｎ）、Ｋ、η一起控制了重力流形成的振动周期