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欧智菁俞杰林上顺王金泽 《福建工程学院学报》2019,(6):511-517
以黄桷湾特大桥为工程背景,选取轴压比、梁墩刚度比、系梁布置形式及柱肢混凝土强度等级为设计参数,应用Midas Civil有限元软件构造了20座三跨对称桥梁计算模型。研究E1地震作用下钢管混凝土双肢格构墩连续梁桥主要控制截面参数地震响应,探讨各设计参数对钢管混凝土双肢格构墩连续梁桥抗震性能的影响规律,并对全桥进行优化验证。研究结果表明:轴压比对地震作用下结构内力和位移有一定影响,建议控制在0.15~0.25;梁墩刚度比对结构的抗震性能影响较大,控制在4.08~10.90时结构的内力分布更加合理;核心混凝土的强度在C40~C50时取值较为合理。 相似文献
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The dynamic stress path of a rock and soil mass under seismic action has a crucial influence on its catastrophic behavior. In soil dynamics, earthquakes are commonly simplified as vertically incident shear waves and the seismic stresses in soil are estimated based on rigid foundation models. However, the great effect of P-waves should not be overlooked in strong earthquakes, which have happened frequently in recent years. The characteristics of the dynamic stress path under longitudinal waves with significant oblique incidence are still unclear. Analytical formulas for the seismic stresses at any depth of a semi-infinite elastic space under obliquely incident P-waves are derived, which degenerate into the traditional rigid foundation method in soil dynamics when both the incident angle and Poisson’s ratio are taken as zero. Here, we reveal the fundamental characteristics of a dynamic stress path under obliquely incident P-waves. The stress path is proved mathematically to be an oblique ellipse in the plane of normal stress difference and horizontal shear stress. We identify factors affecting the stress path, including the incident angle, Poisson’s ratio, and depth corresponding to unit wavelength. The possible variation in the range of an oblique elliptic stress path is systematically analyzed, which lays a theoretical foundation for further study of the dynamic response of sites under obliquely incident seismic waves. 相似文献
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Brittle cracks were observed in the welded beam-to-column connections of steel frames during an earthquake. The crack propagation and accumulated damage to the connections can lead to fractures at much lower ductility ratios. Understanding the connections’ damage behavior during an earthquake is crucial for the design of steel moment frames in seismic areas. Nine full scale beam-to-column connections were tested under constant amplitude and variable amplitude cyclic loading. The effects of loading amplitude, loading history, and peak load on the connection damage were analyzed. The damage characters were studied and three damage evolution models were calibrated and validated based on test results. The damage mechanism was investigated and an effective plastic strain index was developed to evaluate connection damage based on a ductile fracture mechanism. A fatigue fracture mechanics-based model, for evaluating the damage process of beam-to-column connections under cyclic loading, was proposed. 相似文献
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对国内外城市地下线形结构（地下管道、地下铁道和隧道等）震害的形式、成因及外部影响因素，如地震烈度、场地土条件、埋深、结构构造特点及尺寸等进行了综合分析．并就不同地下线形结构抗震措施的制订发表了见解。综合有关文献资料和工程实例．对盾构隧道进行纵向抗震分析，总结了地震区隧道结构的震害特点以及目前所采用的抗震措施，以供地震区隧道结构的设计、施工、加固作参考。 相似文献
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The seismic analysis of a rigid-framed prestressed concrete bridge in Tianjin Light Railway is performed. A 3-D dynamic finite element model of the bridge is established considering the weakening effect caused by the soft soil foundation. After the dynamic characteristics are calculated in terms of natural frequencies and modes, the seismic analysis is carried out using the modal response spectrum method and the time-history method, respectively. Based on the calculated results, the reasonable design values are finally suggested as the basis of the seismic design of the bridge, and meanwhile the problems encountered were also analyzed.Finally, some conclusions are drawn as ：1 ) Despite the superiority of rigid-framed prestressed concrete bridge,the upper and lower ends of the piers of the bridge are proved to be the crucial parts of the bridge, which are easily destroyed under designed earthquake excitations and should be carefully analyzed and designed; 2) The soft soil foundation can possibly result in rather weakening of the lateral rigidity of the rigid-framed bridge, and should be paid considerable attention; 3) The modal response spectrum method, combined with time-history method, is suggested for the seismic analysis in engineering design of the rigid-framed prestressed concrete bridge. 相似文献
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通过基于随机振动理论的虚拟激励法,分析了具有非比例阻尼特性、安装有结点阻尼器的半刚性结点框架.用建立在半刚性节点单元的动力分析有限元程序分析半刚性结点框架的地震响应.结果表明,结点阻尼器能有效地减小半刚性结点框架的地震响应. 相似文献
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夯实动力学课程的理论水平与数值分析技能,是开展水工抗震领域相关研究的重要基础。然而,动力学概念与分析手段对于许多高年级本科生或硕士研究生来说,都显得过于复杂,难以在短时间内领悟,一定的怠学情绪存在于课堂教学中。本文拟从拓展教学手段的角度出发,尝试探讨网络平台教育的可行性,对该问题做一分析,在生动地拓展同学知识面的同时,激发学习热情,为实现教育教学资源的高水平立体化而服务。 相似文献
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Reinforced concrete （RC） columns lacking adequately detailed transverse reinforcement do not possess the necessary ductility to dissipate seismic energy during a major earthquake without severe strength degradation. In this paper, a new retrofit method, which utilized fiber-reinforced plastics （FRP） confinement mechanism and anchorage of embedded bars, was developed aiming to retrofit non-ductile large RC rectangular columns to prevent the damage of the plastic hinges. Carbon FRP （CFRP） sheets and glass FRP （GFRP） bars were used in this test, and five scaled RC columns were tested to examine the function of this new method for improving the ductility of columns. Responses of columns were examined before and after being retrofitted. Test results indicate that this new composite method can be very effective to improve the anti-seismic behavior of non-ductile RC columns compared with normal CFRP sheets retrofitted column. 相似文献
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Retrofitting of RC Slabs Against Explosive Loads 总被引：1，自引：0，他引：1
OEHLERS Deric John 《天津大学学报(英文版)》2006,12(Z1)
With the increase of terrorist bomb attacks on buildings, there is a need to develop advanced retrofitting techniques to strengthen structures against blast loads. Currently, several guidelines including an Australian version for retrofitting reinforced concrete (RC) structures are available for the design of retrofitting systems against seismic and monotonic loads using steel or fibre reinforced polymer (FRP) plates that can be either adhesively bonded to the surface or near surface mounted to the concrete cover. However, none of these guidelines provide advice suitable for retrofitting structures subjected to blast loads. In this paper, numerical models are used to simulate the performance of retrofitted RC slabs subjected to blast loads. Airblast pressure distributions on the surface of the slabs estimated in a previous study are used as input in the analysis. A material damage model developed previously for concrete and an elastoplastic model for steel bars are employed in this research for modelling reinforced concrete behaviour due to explosive loads. The material models and blast loading are coded into a finite element computer program LS-DYNA3D to do the analysis. With the numerical model, parametric studies are conducted to investigate RC slabs retrofitted by either externally bonded or near-surface mounted plates or GFRP sheets subjected to blast loads. Discussion is made on the effectiveness of the retrofitting system for RC slabs against blast loads. 相似文献
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Seismic force modification factor for ductile structures 总被引：3，自引：0，他引：3
INTRODUCTION In codes for seismic design of buildings of many developed countries, elastic response spectra are adopted to calculate the base shear forces. For exam-ple, the base shear defined in Japan code 1997 is: FEK=DsFesC0ZAiRtW (1) where Rt is the elastic design spectrum; Ds is the structural coefficient changing among 0.25 to 0.50 to take account of different ductility of different struc-tures; W is the total weight of a structure; the others are site coefficient, irregular… 相似文献
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抗震支架可在地震中对建筑机电工程设施给予有效保护,降低震后二次灾害的破环。为探究吊杆对抗震支架抗震性能的影响程度,基于螺杆式抗震支架模型,运用ANSYS Workbench与高性能计算（HPC）技术进行模态分析及反应谱分析。通过研究吊杆直径、吊杆安装长度、吊杆有无紧固C槽钢及紧固C槽钢的安装尺寸4个因素,探究悬吊部分对抗震支架抗震性能的影响程度。研究发现吊杆直径与吊杆安装长度对螺杆式抗震支架悬吊部分性能有较大影响,吊杆处增加紧固C型槽钢可提高吊杆的抗震性能。运用HPC技术进行抗震仿真运算,为ANSYS Workbench与HPC技术在抗震工程中的应用提供范例,也为螺杆式抗震支架的实践应用提供了理论依据。 相似文献
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刘如月薛潘荣颜桂云 《福建工程学院学报》2020,(6):553-559
为实现装配式结构震损后能快速修复以恢复使用功能,提出一种带可恢复功能节点的装配式框架结构体系。利用ABAQUS 有限元软件对可恢复功能节点进行数值模拟,探讨可恢复功能节点的作用机理,并将可恢复功能节点布置到装配式框架结构中形成可恢复功能装配式框架结构,考察整体结构的受力机理,可更换耗能铰、装配式节点核心区与梁柱部件的失效演化规律。结果表明,节点的失效主要是由于可恢复功能节点在削弱钢板处的损伤累积引起的断裂导致?与现浇混凝土框架及节点加强型现浇混凝土框架相比,可恢复功能装配式框架的承载能力更高、延性更好,通过可更换耗能铰的塑性变形耗散能量大幅度提高了结构的耗能能力,且结构的损伤破坏集中在削弱钢板上,有效地避免了预制梁柱和节点核心区的损伤。震后通过更换损伤耗能元件即可恢复结构的使用功能,实现了损伤可控和震后功能可恢复的抗震设防理念,具有广泛的应用前景。 相似文献
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根据 Ed和 Ie动力系统的分形与混沌内在属性——短期演化行为的可预测性和长期演化行为的概率特征 ,分别探讨其长短期行为演化规律 .根据短期行为的预测结果 ,探讨了实际工程结构中的主被动抗震参数控制、在役维护的确定以及系统输入能量优化等问题 ;根据长期行为的概率预测结果 ,对实际工程结构中的抗震设计概率、在役维护概率、地震危险性与地震危害性进行了分析 ,为抗震理论和分析方法以及控震减震规律的实际应用提供了一定的参考价值 相似文献
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研究目的：通过非线性动力有限元分析,模拟多塔斜拉桥在多点激励下的地震响应以及揭爪其在强震下的倒塌破坏模式。创新要点：解决了多塔斜拉桥的非线性动力数值模拟技术,并首次模拟了多塔斜拉桥在强震下的破坏模式。研究方法：首先采用隐式的Newmark-β法求解多点地震激励下的非线性动力方程（图3）,随后采用显式的中心差分格式对强震作用下桥梁的倒塌破坏过程进行数值仿真（图4）。重要结论：1．单主梁模犁的数值结果可以很好地反映地震模拟振动台试验的地震响应结果;2．在加速度峰值为4．0m／s2的E1。Centro波时,多塔斜拉桥模型只出现了中塔支座的破坏;3．在加速度峰值为4．0m／s2的江心波时,多塔斜拉桥模型先后出现了支序破坏、拉索与塔的连接破坏以及中塔上塔柱段的单元失效。 相似文献
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鉴于矮塔斜拉桥受力性能的特殊性,引入增量动力分析（IDA）和拉丁超立方体抽样（LHS）评估该结构在地震激励下发生损伤的风险概率。首先采用LHS考虑桥梁构件材料的随机性,与事先选取的地震波相结合形成桥梁-地震动样本集合;其次在确定桥梁有限元模型主要构件损伤指标的基础上采用基于蒙特卡罗（MC）抽样的IDA进行地震易损性分析和地震风险概率评估。为验证方法的正确性和有效性,对一预应力混凝土独塔双索面矮塔斜拉桥结构模型进行地震风险概率评估,结果表明:该方法既充分考虑了材料和地震输入双重随机性又避免了繁琐的积分过程,同时也提高了工程计算的效率及精度。 相似文献
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为了分析塔式起重机的动力特性及在不同水平下的地震响应,首先借助ANSYS有限元分析软件,对塔式起重机进行模态分析;其次对塔式起重机的有限元模型分别输入EI Centro、Taft及汶川什邡八角站三种激励地震波,分析塔身和水平横梁节点地震响应,最后讨论塔式起重机的抗震设计要点及隔震措施。结果表明：塔式起重机的塔臂疲劳主要由地震反应谱中的窄带过程控制,反之,塔臂的折断破坏是由宽带过程起主要作用。 相似文献
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试论推进地震监测预报体系建设 总被引：1，自引：1，他引：0
我国是世界上地震灾害最为严重的国家之一.切实建立健全地震监测预报工作体系,把地震监测预报这个基础工作做好,才能最大限度地减轻地震灾害损失,保障我国经济、社会的健康和可持续发展.本文从提高地震监测预报水平,提高防震减灾综合能力,树立科学的防震减灾发展观等三个方面讨论了推进地震监测预报体系建设的有关问题. 相似文献