两种PTMD对剪切型结构地震反应控制效果比较

研究平动PTMD(translation passive tuned mass dampers)和转动PTMD(rotational passive tunedmass dampers)的参数变化对剪切型结构地震反应的影响.并采用MATLAB中的SIMULINK工具箱进行动态仿真,得出受控结构的动态反应,将两种控制方法应用到某十层建筑上,计算分析的数值结果表明两者用于控制顶层相对位移和绝对加速度都是比较有效的.     

时滞对桥梁主动控制的影响与时滞补偿

桥梁减震主动控制系统中会存在一系列时滞因素,为了探讨时滞对桥梁主动控制效果的影响规律和时滞补偿方法,建立桥梁的有限元模型和减震控制方程,并考虑控制系统不同的滞后时间,对一座大跨连续梁桥进行了主动控制地震反应数值计算分析。结果表明,时间滞后会使桥梁主动控制系统的减震效果随着滞后时间的增大而越来越差,甚至会使地震反应发散;采用移相法对桥梁主动控制时间滞后进行补偿可以取得很好的控制效果,桥梁绝大部分地震反应在时滞补偿后的减震效果能够接近无时间滞后的理想情况的减震效果,有的甚至超过理想情况的减震效果。     

时滞对桥梁半主动控制和主动控制的影响

桥梁减震半主动控制和主动控制系统中会存在一系列时滞因素,为了探讨时滞对桥梁控制效果的影响规律,建立桥梁的有限元模型和减震控制方程,并考虑控制系统不同的滞后时间,采用粘滞阻尼器对一座大跨连续梁桥进行了减震控制地震反应数值计算。结果表明,时间滞后对半主动控制和主动控制的影响趋势基本相同,均会使控制系统的减震效果随着滞后时间的增大而越来越差,甚至会增大桥梁地震反应和使地震反应发散,但是半主动控制出现减震效果为零的滞后时间和地震反应发散的滞后时间均比主动控制更加长一点,这显示了半主动控制的优越性。     

磁流变阻尼器的新型控制方法

应用磁流变阻尼器对结构振动进行了控制,对磁流变阻尼器的力学模型进行了介绍,并提出了混合的控制方法,数值计算表明,通过分别对三层、六层、十二层结构的仿真计算,混合控制方法可有效地减小结构的地震反应。     

模糊逻辑下的MR阻尼器减振控制研究

利用MATLAB Simulink模块对一MR阻尼模糊控制器下的三层钢结构建筑对地震荷载的响应进行了数值仿真。仿真结果表明,钢结构建筑物中采用MR阻尼模糊控制器能对结构的地震响应进行即时、有效和显著的强非线性半主动控制。因而其具有一定的工程应用价值。     

加筋土挡墙集中质量模型分析与应用

以前人对土层地震反应分析方法的研究为基础,将加筋土挡墙结构简化为一个集中质量的多自由度体系。通过考虑筋材对土层的刚度和土层间摩擦的影响,形成加筋土结构集中质量模型。通过数值计算软件MATLAB,得到挡墙运动方程的数值解,完成加筋土挡墙地震反应分析。用集中质量模型分析的结果与试验结果吻合良好,从而说明所建议的挡墙集中质量模型和推导的数学公式是有效的。这为系统的研究加筋土挡墙地震反应分析方法揭开了序幕。     

黄土的地震反应分析

用振型分解法对黄土场地地层的地震反应进行了分析,推导建立了地层剪切模量随深度呈线性变化时黄土场地地层地震反应的一般解,并用MATLAB对该方法进行了编程和实例计算。算例结果表明,黄土地层的地震反应具有明显的放大作用。     

MATLAB在复杂化学反应优化中的应用

MATLAB是可以完成各种化工计算和数据处理可视化的、强有力的计算程序。本文结合基于MATLAB化工工具箱的开发,分析MATLAB在复杂反应优化中的应用,对间歇反应釜中发生的多级平行-连串反应中的一些可优化问题进行了数值计算。     

轨道交通高架桥梁(65+110+65)m连续梁抗震性能分析

在轨道交通高架桥梁建设中,大跨度的连续梁结构频繁出现,其抗震性能的分析计算成为控制设计的主要因素。本文结合某轨道交通高架桥梁(65+110+65)m连续梁结构设计,在多遇地震作用下采用反应谱法、时程分析法对桥梁结构进行了弹性地震反应分析,在罕遇地震作用下进行了弹塑性时程反应分析,并对部分钢筋混凝土桥墩进行了延性验算,比较了在不同行车工况下的结构反应,并总结相应的抗震分析设计经验,为同类轨道交通高架桥梁的两阶段分析提供一定的工程实际数据参考。     

MATLAB在结构振动控制中的应用与实例分析

土木工程建筑结构除了承受静荷载以外,同样承受着包括风、浪、地震等动荷载。这些动荷载会引起严重且持续的振动并影响结构的可靠性。MATLAB作为一种数值分析软件,在结构振动控制方面的计算具有较大优势,本文简要介绍了MATLAB软件的特点以及原理,并通过主动控制算例简要阐述了其在结构控振方面的应用。     

确定桥梁半主动控制阻尼器位置的简便方法

提出了按照主动控制力的大小数值来确定桥梁半主动控制阻尼器位置的方法,并通过一座大跨桥梁纵向地震反应半主动控制计算分析,验证了该方法的有效性,在分析和总结计算结果的基础上,提出了一些关于桥梁减震控制中阻尼器位置的建议。     

应用MRF-04K阻尼器的大跨连续刚构桥地震反应的半主动控制

应用最近设计制作的MRF-0 4K型磁流变(MR)阻尼器对大跨连续刚构桥的地震反应实施半主动控制。首先建立了多支承不同步地震激励下大跨连续刚构桥的运动方程,并基于瞬时最优控制算法建立了大跨连续刚构桥地震反应控制的计算方法,数值仿真分析了某四跨预应力混凝土连续刚构桥在不同控制策略下地震反应的控制效果,结果表明当在该连续刚构桥的两端各安装5 0个MRF-0 4K阻尼器,中墩墩顶水平位移降低7 0.4%,中跨跨中竖向位移降低7 7.7%,边跨跨中竖向位移降低6 6.0%。最后得出结论:应用MRF-0 4K阻尼器能使多支承不同步地震激励下大跨连续刚构桥的地震反应得到有效的控制,主动控制效果明显地高于被动控制效果,且半主动控制能取得理想的控制效果,即使地震发生时半主动控制系统失效,同样可以取得理想的控制效果,从而为MRF-0 4K阻尼器的工程应用提供了理论依据。     

超大跨度斜拉桥的地震位移控制

对于千米级的超大跨度斜拉桥 ,一般要求塔柱在强震下基本保持弹性 ,因此往往选择隔震体系 (全飘浮或支承 )来减小地震反应。但是采用隔震体系的超大跨度斜拉桥在强震下会产生很大的梁端位移 ,必须加以控制才能保证整个结构的抗震安全性。本文从地震位移控制的机理出发 ,探讨了控制地震位移的方法、具体的装置及参数选择 ,最后介绍了超大跨度斜拉桥地震位移控制的实例。实例分析表明 ,只要合理选取参数 ,在塔、梁间设置弹性连接装置或阻尼器均能有效地控制梁端的地震位移 ,但阻尼器的效果更为理想。     

Computational studies on the seismic response of the State Route 99 bridge in Seattle with SMA/ECC plastic hinges

This paper reports a computational study on the seismic response of a three-span highway bridge system incorporating conventional and novel substructure details for improved seismic performance. The bridge has three continuous spans supported by two single-column piers and integral abutments founded on drilled shafts. It will be the first full-scale highway bridge to use superelastic shape memory alloy bars (SMA) and engineered cementitious composite (ECC) to mitigate column plastic hinge damage and minimize residual displacements after a strong earthquake. A three-dimensional computational model capturing the nonlinear constitutive response of the novel materials and the effects of dynamic soil-structure interaction was developed to assess the seismic response of the bridge in finite-element software OpenSees. Two versions of the same bridge were analyzed and compared, one with conventional cast-in-place reinforced concrete columns, and the other with top plastic hinges incorporating Nickel-Titanium (NiTi) SMA reinforcing bars and ECC. The novel SMA/ECC plastic hinges were found to substantially reduce damage and post-earthquake residual displacements in the bridge substructure, but led to larger maximum drifts relative to the bridge with conventional reinforced concrete plastic hinges. The analysis results suggested that the novel plastic hinges could lead to improved post-earthquake serviceability of bridges after intense earthquakes.     

Control of Traffic-Induced Vibrations of Elevated Urban Highways

Abstract: This paper studies the active control of traffic-induced vibrations of elevated highway bridges. In order to suppress the vibration, an active control device (AMD or ATMD) is installed beneath the bridge girder at the center. Three different feedback control algorithms are studied, depending on different levels of vehicle information used in control design, namely, (1) full-state feedback, (2) output feedback, and (3) constant-gain output feedback. The gains of the algorithms 1 and 2 are time-varying, while the gain of algorithm 3 is time-invariant. The numerical examples of bridge-control system responses, subjected to the moving vehicle, are computed. The results demonstrate the effectiveness of the active control in reducing the bridge responses. However, for the control design, the information of passing vehicles is found to be almost unnecessary for inclusion in the feedback, although for the response analysis, it is known that the vehicles form an essential part that should be incorporated in the system dynamic model. It is also found that the control performance of ATMD is higher than that of AMD. Finally, based on the understanding of the control characteristic, a new control concept is proposed. It is shown that the ATMD's performance can be further improved by the proposed control.     

Seismic performance of benchmark highway bridge installed with piezoelectric friction dampers

Dynamic response of the benchmark highway bridge installed with semi-active piezoelectric friction dampers (PFDs) is investigated under six bidirectional earthquake ground motions. PFD utilises the response of the structure to develop control actions by adjusting frictional damping characteristics of the system. Conventional friction dampers abruptly fluctuate between stick-slip states. On the other hand, PFDs change the friction force continuously and smoothly. The study is based on the simplified lumped mass finite-element model of the 91/5 highway bridge, located in Southern California. The parameters affecting the performance of PFDs are gain factors, coefficient of friction and the preload on damper. Exhaustive studies are carried out to determine the most optimum values of these parameters. Eight dampers are installed at each deck-end and abutment junction (phase I). Additional four dampers are installed at the centre (phase II), at the junction of bent beam and piers of the bridge. In each case, the response of the bridge is compared with the corresponding uncontrolled case and that controlled by the alternate sample semi-active control strategy, using magnetorheological (MR) dampers. It is concluded that with the installation of PFDs, the seismic response of the bridge under near-fault motions can be controlled significantly. The PFDs are quite effective in reducing the peak response quantities of the bridge to a level comparable to or superior to that of the MR dampers.     

Seismic analysis incorporating detailed structure–abutment–foundation interaction for quasi-isolated highway bridges

The Illinois Department of Transportation has adopted an economical and pragmatic methodology for designing earthquake-resistant highway bridges in the Midwestern United States. These so-called quasi-isolated bridges employ low-cost non-seismically designed bearing components as sacrificial structural fuses. During seismic events, fusing actions of these components and subsequent sliding of superstructures on substructures are intended to achieve response characteristics similar to those of conventionally isolated bridges that employ specially designed isolators. This study explores seismic structure-abutment-foundation interaction for quasi-isolated bridges in Illinois, employing a detailed yet efficient non-linear finite-element model for seat-type bridge abutments. The abutment model incorporates many structural components and geotechnical mechanisms that are critical to seismic response of the structure-abutment-foundation (SAF) system. Through non-linear static analyses performed on a complete bridge model, the force-transfer mechanisms, component fusing performance, and potential failure modes of the SAF system were explored. Using earthquake ground motions, non-linear dynamic analyses were conducted to evaluate seismic characteristics of the quasi-isolated bridge, sequences of critical limit state occurrences, and effects of abutment attributes on bridge seismic performance. The influence of abutment model sophistication on simulated bridge response was also highlighted by direct comparison of simulation results obtained from different models.     

轨道交通莘闵线高架桥抗震研究

结合上海市轨道交通莘闵线独柱墩设计 ,针对高架上铺设无缝线路的实际情况 ,建立了高架桥梁结构一桩基—土动力相互作用力学模型 ,采用工程场地波计算了高架桥的弹性、非线性地震响应 ,并对其进行抗震延性分析 ;重点探讨了高架桥上长钢轨对桥梁的纵向约束作用及后继结构对桥梁抗震性能的影响 ,分析了橡胶支座对高架桥的减隔震作用 ;提出了莘闵线高架桥合理抗震设计参数及抗震措施