Authors: Wei Guo, Chao Fan, Yao Cui, Chen Zeng, Lizhong Jiang and Zhiwu Yu
Abstract: Piers are the main lateral force-resisting members of high-speed railway (HSR) bridges used in China and are characterized by low axial load ratios, low longitudinal reinforcement ratios, low stirrup ratios, and high shear span ratios. It is well known that flexural, flexural-shear, and shear failures of piers may occur during an earthquake. In this study, a new shear strength model was developed to simulate the seismic failure of HSR solid piers accurately. First, low cyclic-loading test data of solid piers obtained in recent years were collected to set up a database for model verification. Second, based on the test database, the applicability of existing shear strength models was evaluated. Finally, a new shear strength model for HSR solid piers with round-ended cross-sections was derived based on the truss model and ultimate equilibrium theory. In comparison with existing models, it was demonstrated that the proposed model could be used to predict the shear strength of HSR piers more accurately.
Keywords: High-speed railway; Round-ended cross-sectional solid piers; Seismic failure; Shear strength model; Cyclic loading test
Original download: http://www.techno-press.org/content/?page=article&journal=sem&volume=78&num=4&ordernum=4#
Authors: Ping Shao, Wei Guo, Qi Lei, Chen Zeng
Summary: The real-time hybrid simulation (RTHS), which combines experiment with numerical simulation, is an effective method to study the dynamic characteristic of high-speed railway train–bridge coupling vibration. In this paper, a simplified virtual RTHS platform of train–bridge coupling vibration is developed to illustrate the test logic and the feasibility of carrying out the physical test of moving train on bridge in a limited laboratory space. The accuracy and stability of the RTHS platform are highly dependent on the time delay caused by experimental loading device. The adaptive compound control composed of adaptive state feedback control (ASFC) and interpolation prediction algorithm is proposed to compensate for the time delay. Its adaptive control framework ensures the applicability by avoiding the need for prior knowledge of experimental substructure. The feedback control parameters are adjusted automatically, and the time delay is dynamically compensated according to the characteristics of the on-line estimated model of loading device and experimental substructure. The simulation results show that the proposed control is an effective approach for time delay compensation compared with the proportional control, the state feedback control, and the adaptive time-series control.
Keywords: Adaptive state feedback control; High-speed railway; On-line model estimation; Real-timehybrid simulation; Train–bridge coupling vibration
Original download: https://onlinelibrary.wiley.com/doi/full/10.1002/stc.2816
Authors：Wei Guo，Xueyuan Chen，Yujie Yu，Dan Bu，Shu Li，Wenbin Fang，Xingye Wang，Chen Zeng，Wang Wang
Abstract: In this paper, a modified pipe damper design which called X-shaped pipe damper (XPD) is proposed. The damper is fabricated by connecting two oppositely positioned pipe halves to form a X-shaped core, which is then bolted to connecting plates. The bolted XPDs are replaceable and can be conveniently fabricated at low costs. Cyclic tests were performed on 5 bolted XPDs and 2 welded XPDs to investigate the strength development patterns, hysteretic performances, energy dissipation abilities and failure modes. The bolted and welded XPDs were also applied to the seismic retrofit of a 6-story steel frame to investigate the performance of new dampers on the seismic response control. Experimental results indicated that the bolted XPDs can provide good ductility and stable hysteretic relations under both standard cyclic protocol and fatigue cyclic protocol. The connected pipe halves can successfully form tensile bracing modes and induced secondary strength increases at large lateral displacements. The welded XPDs possessed weaker energy dissipation capacity due to early fracture failures, but they can provide higher stiffness and yielding strength. The bolted XPDs presented good dynamic response controlling performance under both medium level and high intensity level earthquakes.
Keywords：Steel damper；Cyclic test；Hysteretic behavior；Seismic retrofit；Dynamic analysis
Original download: https://www.sciencedirect.com/science/article/pii/S0141029621004776
Authors:Wei Guo，Chen Zeng ，Hongye Gou ，Quan Gu ，Tao Wang ，Huimeng Zhou ，BoZhang ，Jiliang Wue
Abstract: Train-track-bridge interactions (TTBIs) in high-speed railways affect the response of the train on the bridge and involve complicated dynamics. This study introduced an improved real-time hybrid simulation (RTHS) method, wherein a physical train model was tested on a shake table, while the dynamics of the track-bridge structure were determined numerically. The moving load convolution integral method (MLCIM) was proposed for the real-time calculation of the track-bridge structure dynamics independent of the complexity of the numerical model. The results obtained using the MLCIM were compared to those obtained using the traditional finite element method to verify its accuracy and efficiency. Next, the TTBI characteristics of a train moving across a seven-span simply supported bridge with the track structure were analyzed for cases of different girder stiffnesses and train speeds. The results demonstrated that the improved RTHS method using the MLCIM effectively represented the TTBI dynamics. The girder stiffness and train speed were shown to substantially influence the responses of the moving train. Further, a ride comfort evaluation confirmed the operational performance of a train on the studied track-bridge structure.
Keywords: Real-time hybrid simulation；High-speed railway；Train-track-bridge interaction；Moving load convolution integral method；Ride comfort
Original download:https://www.sciencedirect.com/science/article/pii/S0141029620341389
Authors: Wei Guo , Zhenyu Bai , Xiaobo Wang , Hanyun Liu , Dan Bu , Zhen Guo , Wenqi Hou , Zhiwu Yu
Abstract:With the rapid development of high-speed railway (HSR) in China, the problem of environmental vibration induced by HSR train has attracted critical concern. In this paper, a combination vibration reduction (CVR)
strategy of hollow-closed-wall in-filled trench (HIT) and elastic bearing (EB) is proposed to decrease environ-mental vibration induced by HSR train, in which the depth of HIT could be well controlled to benefit the practical construction and economic cost. Based on the multi-body dynamics and finite element theory, HSR environ-mental vibration system is established and then divided into two sub-models including the ‘train-track-bridge’ vibration source sub-model and the ‘pile-soil’ vibration propagation sub-model. The two sub-models are con-nected via the force balance condition of the pier bottom. The verification of numerical models is conducted by comparing with the empirical formula and the ground data in the references. Then the attenuation law of environmental vibration is analyzed, and the vertical component is shown to be dominant in the HSR envi-ronmental vibration. On this basis, numerical simulations are performed to analyze the environmental vibration reduction under three strategies, namely the HIT, EB, and CVR. The results show that the HIT presents a distinct vibration reduction effect in the frequency range above 4 Hz and the vibration reduction becomes more obvious as the HIT’s depth increases. However, the depth should be larger than 8 m to satisfy the code requirement; the EB presents an obvious reduction in the frequency range above 8Hz; the CVR strategy not only further decrease the environmental vibration, but also effectively reduce the HIT’s depth. By numerical analysis, the combination strategy of 6 m deep HIT and 2200 kN/mm vertical stiffness EB is recommended in the HSR environmental vibration reduction, which could also satisfy the limit of Chinese railway code.
Keywords: Environmental vibration；High-speed railway；Combination vibration reduction strategy；Hollow-closed-wall in-filled trench；Elastic bearing；Train-track-bridge coupled system
Original download:
Authors: Wei Guo , Qiandan Du , Zhe Huang , Hongye Gou , Xu Xie , Yong Li
Abstract:The high-speed railway (HSR) in China has developed rapidly in recent years. However, HSR bridges have to face the challenge of earthquakes since China is one of the most earthquake-prone countries in the world. Bearing is the key component in the HSR bridge, and using isolation bearing instead of common bearing (non isolation bearing) can provide bridge the better seismic performance. To improve seismic performance of HSR bridges at different earthquake intensities, in this paper the friction pendulum bearing (FPB) is used, and an improved equivalent energy-based design procedure (EEDP) based on the principle of energy conservation is proposed.This method has the advantages of simple calculation and avoiding complicated iterations, which can also take into account the post-yield stiffness of the structural members and is capable of designing three performance objectives simultaneously. Meanwhile, based on the analysis of experimental data, the improved performance objectives applicable to the isolated HSR bridges are proposed. The FPB of an isolated HSR bridge is designed by the improved EEDP to verify the applicability of the proposed method. Then the finite element model of the designed isolated HSR bridge is built, and nonlinear dynamic responses at different earthquake intensities are analyzed to examine the structural seismic performance. Results show that the designed structure can achieve the prescribed performance objectives at three earthquake intensities which proves the practicability and effec-tiveness of the proposed improved EEDP method.
Keywords: High-speed railway bridge；Earthquake；Friction pendulum bearing (FPB)；Isolation；Energy-based design procedure (EEDP)；Seismic performance
Original download:/editor/attached/file/20210202223647674767.pdf
作者：翟治鹏、国巍、余志武
摘要: 提出一种易制作易安装易更换的S型钢板阻尼器，设计制作3组试件，通过开展拟静力试验，对其变形和破坏模式 滞回特性及耗能能力进行研究 基于试验结果提出一种改进的 BWBN 滞回模型，建立 Simulink模型并开展试件参数识别研究 结果表明: S 型钢板阻尼器的滞回曲线饱满，具有较大的变形能力，良好稳定的耗能能力，较高的延性系数和超强系数; 阻尼器通过弯曲和轴向变形耗能，变形包括弯曲弹性段 弯曲屈服段及弯-拉屈服段，由于弯-拉强化效应，第三段刚度和强度逐渐增大，可提高结构承载能力并降低残余变形; 所提出的滞回模型可以反映 S 型钢板阻尼器的弯-拉强化效应，能够较精确地模拟阻尼器的滞回曲线 恢复力变化以及累积能量耗散。
关键词: 型钢板阻尼器; 拟静力试验; 弯—拉强化效应; 滞回模型; 参数识别
Authors: Zhipeng Zhai , Wei Guo , Zhiwu Yu , Chongjian He , Zhefeng Zeng
Abstract: In this paper, a new metallic structural fuse named S-shaped steel plate damper (SSPD) is proposed for seismic resilient application. The SSPD consists of two S-shaped plates fabricated by normal steel, which is convenient for fabrication, installation, inspection and replacement. In small and medium displacement, seismic energy is dissipated through flexural plastic deformation of the S-shaped arc plate. The deformation shifts from flexural behavior to tensile behavior in relative large displacement. To investigate the failure mode and seismic performance, a total of ten specimens were tested by monotonic and cyclic loading. The results indicate that the SSPD exhibits stable hysteresis loops, good energy dissipation, large deformation and ductility capacity; the damper has characteristics of large strength-mass ratio, secondary stiffness, over-strength coefficient and stable flexural-tensile behavior; the failure mode is dominated by fracture of end plate and squeezed indentation; the fatigue performance is more vulnerable in large displacement. Moreover, the mull-linear theoretical model was proposed to represent the SSPD, and the corresponding finite element model was established and validated by experimental results. Based on the numerical simulation, accuracy of theoretical derivation was verified, and improvements of SSPD were recommended. Finally, parametric studies considering different geometric dimensions were conducted, which reveals that the height-thickness ratio is crucial to the damper`s stiffness and ductility. Practical formulas were suggested to facilitate the damper`s design and application.
Keywords: Steel plate damper; Flexural-tensile behavior; Seismic resilience; Cyclic test; Finite element analysis
Original download:https://apps.webofknowledge.com/full_record.do?product=WOS&search_mode=GeneralSearch&qid=4&SID=5CksLBHyNL6KXmHtjAH&page=1&doc=1
Authors: Zhipeng Zhai , Wei Guo , Zhiwu YU , Yao Hu , Chenzhi Ma
Abstract: This paper aims to utilize a novel steel strip damper to enhance seismic resilience of high-rise steel frame in high seismic intensity regions. The developed damper is composed of external casing, internal casing and steel strip fuses dissipating seismic energy via bending-dominated deformation throughout the entire section, which is convenient for post-earthquake replacement. A series of cyclic loading tests have shown the damper`s good energy dissipation capacity with features of stable and full hysteretic loops. A numerical model for the damper is proposed and validated by the experimental results. Then a 20-story steel frame is adopted as the representative building and retrofitted using a design procedure based on the stiffness and displacement demands. Nonlinear dynamic analysis considering damper failure is performed to evaluate seismic responses of the steel frames. And incremental dynamic analysis is employed to discuss the seismic fragility. Finally, seismic losses of the steel frames are assessed through the story-based loss estimation method in which the demolition-related economic losses are included. The analyses indicate that the presented damper can obviously mitigate the roof displacement, inter-story drift, plastic damage and soft story deformation mechanism; the damper-fused frame has much lower probability to collapse; the expected total losses, expected annual losses and expected life-cycle losses are significantly decreased by retrofitting with the novel dampers.
Keywords: Steel strip damperSeismic resilienceIncremental dynamic analysisSeismic fragilitySeismic loss assessment
Original download:https://www.sciencedirect.com/science/article/pii/S0143974X20309895
祝贺中南大学土木工程学院与厦门大学建筑与土木工程学院合作论文《一种基于非线性接触关系的新型二维轮轨耦合单元及OpenSees实现》（古泉、国巍）在《铁道学报》得以发表。
论文主要内容为：基于轮轨竖向非线性接触关系，作者提出一种新型通用的二维轮轨耦合单元模型，并在有限元OpenSees软件平台上实现。所提单元由轮节点和与之接触的梁单元节点组成，通过建立和求解轮轨作用力的一元三次方程，从而可以得到轮轨之间的接触力，继而计算由于轮轨相互作用产生的耦合单元各节点力，定义为单元内力，其中不包括梁单元内力。通过与文献中计算结果对比，本文验证了该单元模型的准确性和可靠性，并基于此模型分析了高速列车通过桥梁时在轨道不平顺激励和地震作用下的动力响应。此耦合单元模型易于集成到有限元计算平台中，和已有的列车模型、轨道和桥梁等模型联合使用，能够考虑轨道不平顺和轮轨脱离等情况，可以用来分析复杂的竖向车桥耦合系统的动力问题。
祝贺课题组毛建锋博士在期刊 《Journal of Sound and Vibration》发表论文：Zhi-wu Yu, Jian-feng Mao*, Feng-qi Guo, Wei Guo，Non-stationary random vibration analysis of a 3D train–bridge system using the probability density evolution method。论文主要内容为：“Rail irregularity is one of the main sources causing train–bridge random vibration. A new random vibration theory for the coupled train–bridge systems is proposed in this paper. First, number theory method (NTM) with 2N-dimensional vectors for the stochastic harmonic function (SHF) of rail irregularity power spectrum density was adopted to determine the representative points of spatial frequencies and phases to generate the random rail irregularity samples, and the non-stationary rail irregularity samples were modulated with the slowly varying function. Second, the probability density evolution method (PDEM) was employed to calculate the random dynamic vibration of the three-dimensional (3D) train–bridge system by a program compiled on the MATLAB software platform. Eventually, the Newmark-β integration method and double edge difference method of total variation diminishing (TVD) format were adopted to obtain the mean value curve, the standard deviation curve and the time–history probability density information of responses. A case study was presented in which the ICE-3 train travels on a three-span simply-supported high-speed railway bridge with excitation of random rail irregularity. The results showed that compared to the Monte Carlo simulation, the PDEM has higher computational efficiency for the same accuracy, i.e., an improvement by 1–2 orders of magnitude. Additionally, the influences of rail irregularity and train speed on the random vibration of the coupled train–bridge system were discussed.”原文请参见附件。
毛建锋博士的主要研究方向为基于概率密度演化理论的车-线-桥耦合随机振动分析。他引入（广义）概率密度演化理论，基于物理本质的思想，发展了基于输入激励随机性和结构参数随机性的列车-轨道-桥梁结构耦合系统随机振动模型，分别建立了列车-桥梁垂向系统随机振动模型、列车-桥梁空间系统随机振动模型和基于轮轨关系精细化的高速列车-无砟轨道-桥梁三维空间耦合随机振动模型，逐步验证了应用广义概率密度演化理论进行车桥耦合随机振动分析的适用性、高效性和高精度性，并进行了大量高速列车-无砟轨道-简支桥梁随机动力系统的随机振动仿真计算和结果分析，为我国高速铁路建设提供了全新、可靠的研究思路和技术支撑。并且发展了一系列高速列车-桥梁随机输入激励参数和结构随机参数离散代表样本点集的选取方法，有效提升了车桥耦合随机动力系统响应的计算效率和计算精度。更多关于基于概率密度演化理论的车-线-桥耦合随机振动分析内容请参见附件。
祝贺课题组刘汉云博士在期刊《Engineering Structures》发表论文：A General Spectral Difference Method for Calculating the Minimum Safety Distance to Avoid the Pounding of Adjacent Structures during Earthquakes [J]. Engineering Structures. Zhi-wu Yu(余志武) , Han-yun Liu(刘汉云), Wei Guo*(国巍), Qun Liu(刘群) （accepted）. 本文的主要研究内容为：With the development of cities, buildings have become increasingly concentrated. Therefore, there are serious potential collision dangers between the adjacent buildings or the building partitions under earthquakes, hence buildings need to set the appropriate safety distance to avoid pounding. However, the calculation of the minimum safety distances (MSD) of the adjacent buildings in Chinese Code is rough and arbitrary, while the traditional response spectrum method is derived based on the assumption of proportional damping and it is difficult to consider the non-proportional damping characteristics for large and complex building systems. Based on the above, this paper proposes a new general spectral difference method (gSDM) to calculate the MSD. First, the pseudo-excitation method is used to derive the relative displacement random expression of adjacent buildings during earthquakes. Then, combined with the response spectrum method, the gSDM formula is established, in addition, the explicit expressions of combination coefficient in the gSDM formula are given. Finally, the examples of two adjacent multi-storey shear-buildings are used to illustrate the accuracy and wide adaptability of the gSDM during the El-Centro earthquake. The results compared and discussed in detail with the classical spectral difference method (cSDM), SRSS method and time history analysis.
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