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为提高梁式结构损伤诊断的效率,提出一种基于类柔度差曲率和频率摄动的结构损伤识别方法。首先根据结构振动理论,研究广义柔度矩阵计算公式;再利用模态柔度对结构损伤灵敏性高的优点,改进基于柔度差曲率的损伤定位指标,定义类柔度差曲率LCFC损伤指标,并初步识别损伤;最后基于矩阵摄动进行结构损伤识别结果确认。考虑多种损伤工况,对一简支梁结构进行损伤识别数值模拟验证。结果表明:仅使用一阶模态,建立的类柔度差曲率LCFC指标对梁式结构损伤定位具有良好的诊断效果,且计算工作量小;对于含边界损伤单元的多损伤工况,当损伤程度大于10%时,LCFC指标识别有效;当损伤程度不大于25%时,各工况二阶摄动识别结果精度较高,相对误差较一阶摄动结果明显降低,证明了该方法的实用性、有效性和精确性。 相似文献
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《地震工程与工程振动》2017,(6)
为了采用结构柔度矩阵进行损伤识别,由均匀荷载面曲率差指标推导出一种加权柔度矩阵指标构造方法,权值分别取振型、振型曲率和、振型曲率符号函数构造出三个新的损伤指标。基于结构损伤前后指标的相对变化及节点损伤程度和单元损伤程度的关系,提出了指标的结构损伤程度计算方法。采用一简支梁和一三跨连续梁算例,考虑多种损伤情况,与均匀荷载面曲率差指标进行了对比分析,表明振型曲率符号函数加权损伤指标仅需前几阶模态便能进行损伤检测,具有良好的损伤定位能力,并能准确识别损伤程度。 相似文献
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结构健康监测和结构状态评估的主要前提之一是结构损伤识别。基于曲率模态对结构局部损伤比较敏感和频率指标测试简单方便、精度高的特点,本文提出了一种以结构的曲率模态为基础,综合考虑频率的变化的改进的结构损伤识别方法。随机子空间方法是一种行之有效的基于环境激励的结构状态识别方法。该方法的主要优点是无需人工激励,不中断桥梁的运营。为此,论文提出了一种不中断桥梁运营的基于改进曲率模态的桥梁结构损伤识别方法。最后用一三跨连续梁的有限元模型对该改进方法进行了验证。结果表明,采用随机子空间结合改进的曲率模态方法可以在不中断桥梁运营的前提下有效地识别出桥梁的损伤状况。 相似文献
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基于应变模态的钢结构构件焊缝损伤定位方法的研究 总被引：15，自引：1，他引：15
本文探讨了用应变模态对钢结构焊缝损伤进行识别与定位的方法。应变模态对结构局部损作斩反应敏感，是对结构进行微小损伤诊断的较理想的损伤识别指标。文中以一简支工字型梁为研究对象，分别采用基于应变模态差的三种定位准则和神经网络方法，对其进行了单处和两处焊缝损伤定位的研究。结果表明，基于应变模态差的定位准则对于这两种情况的损伤都具有较高的定位识别率，但不能区别出单处和两处损伤；而采用神经网络方法不仅可以区别出单处和两处损伤，而且训练好的网络对受噪声污染的测试样本也具有较好的识别效果。 相似文献
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曲率模态在结构损伤识别中有很好的应用。针对模态分析中某几阶曲率模态曲线未能有效地反映损伤的情况,本文提出对曲线进行一次数值微分的处理方法,计算结果表明这种方法能进一步提高曲率模态对损伤的敏感性,是一种很好的辅助处理数据方法。 相似文献
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对损伤部位向量(DLV)法作了简单介绍,并用该方法对钢框架进行了损伤识别和损伤定位。该方法假定结构损伤前后为线性,对结构损伤前后柔度矩阵差进行奇异值分解,将奇异值为零所对应的向量,作为静荷载施加在无损结构的测点位置,则应力为零的单元为可能损伤的单元。对3种不同工况的钢框架进行了振动模态试验,用前3阶模态参数构造框架的柔度矩阵,按照DLV法对其进行了损伤识别,识别结果与已知损伤情况相一致。从测试自由度不完备、噪声和振型质量归一化系数这3个方面对识别效果进行了分析,结果表明:当损伤使结构动力特性有微小改变时,使用该方法不易定位损伤,应结合局部损伤识别方法进行判定;当损伤使结构动力特性有较大改变时,该方法能有效识别损伤的单元。DLV方法概念简单,理论明确,不受结构类型的限制,不需要结构的数学模型和模型缩聚或扩展技术,只需获得结构损伤前后的前几个低阶模态参数,即可识别结构一处或多处损伤,实际应用时可操作性强。 相似文献
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曲率模态小波法用于网壳结构损伤的识别和定位 总被引：1，自引：0，他引：1
工程结构损伤的识别与定位研究以往主要针对梁、框架等结构形式,根据大跨度空间结构杆件和节点繁多等特点,提出用曲率模态和小波混合方法对空间结构的损伤进行识别和定位.以跨度100 m的Schwedler网壳结构损伤前、后的曲率模态作为标识量,分别通过离散和连续小波变换,判断网壳结构有无损伤和损伤位置,统计了小波系数差与结构损伤的图形关系,计算了各种损伤工况下该方法判断损伤的准确程度.结果发现基于曲率模态和小波方法的大跨度网壳结构损伤定位精度很高,充分证明该方法对此类结构损伤定位具有有效性和实用性. 相似文献
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为快速识别地震导致的框架结构损伤，采用一种新的损伤识别方法，即振型曲率演化法。该方法采用S变换对结构顶部的加速度进行分析，进而得出地震前与地震期间的两个重要时刻，然后通过计算这两个时刻的振型曲率差识别结构薄弱层位置。为验证该方法的合理性和有效性，以6层3跨RC框架结构为例，在不同地震波和不同调幅工况下，分别对比振型曲率演化法与单参数层间位移角、双参数损伤指数两种损伤指标识别的结构薄弱层位置。在此基础上进一步研究了振型曲率差与两种损伤指标之间的相关性，并建立了线性关联模型来识别薄弱层损伤程度。结果表明：振型曲率演化法与两种损伤指标在不同地震工况作用下识别的薄弱层有很好的一致性，说明该方法能够准确识别结构薄弱层位置。振型曲率差与两种损伤指标之间的拟合公式的相关系数均在0.8以上，相关性都很高，通过分析这种相关性，可以利用振型曲率差获得结构薄弱层的损伤程度。 相似文献
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基于曲率模态和小波变换的结构损伤位置识别 总被引：12，自引：3，他引：9
小波变换具有在时域和频域内表征信号局部特性的能力,能够在不同尺度下对结构响应中的突变信号进行放大和识别.在结构曲率模态基础上,本文提出了一种基于小波变换的结构损伤检测和定位方法.利用双正交小波函数对损伤前后结构的曲率模态进行小波变换,用损伤前后小波变换系数残差建立了结构损伤指标,通过小波变换系数残差的分布统计情况判定损伤的存在并确定其位置.应用简支梁数值模拟结果对该方法进行了验证. 相似文献
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为方便地检测梁桥支座损伤,提出了利用运营桥梁实测模态位移结合其无损状态的模态位移判断支座损伤的高斯曲率模态相关系数法。通过简支梁桥的室内试验,验证了利用高斯曲率模态相关系数判定支座损伤的合理性以及该方法中无损状态下的模态位移可以通过模态试验和有限元模拟两种方法获得。利用该方法对实际简支梁桥和连续梁桥进行的支座损伤识别结果表明:高斯曲率模态相关系数法可准确识别出单支座和多支座损伤的支座损伤位置,具有较强的鲁棒性,可将此方法应用于实际工程中的支座损伤识别。 相似文献
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多次强震震害表明,梁破坏时梁端截面并未能形成理想塑性铰,而是在梁柱连接处发生脆性破坏。提出了改进钢框架梁连接设计的具体作法,即局部加大梁端焊缝截面的同时,在梁端一定距离处又适当削弱梁翼缘尺寸,合理确定梁端塑性铰弯矩,按梁两端出现同向塑性铰求出钢框架梁柱连接、梁的拼接处的内力(M、V)作为多遇地震作用下的调整内力设计值,改进梁柱连接、梁拼接的设计,供工程设计和修订相应规范作参考。 相似文献
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进行了4根GFRP筋混凝土简支梁在ISO834标准升温曲线下的火灾实验,试件依据ACI440.1R-06进行截面设计,分别考虑了不同荷载比、保护层厚度、端部锚固方式对梁耐火性能的影响。试验结果表明,GFRP筋混凝土梁在火灾中的裂纹开展深度较传统的钢筋混凝土结构明显偏大。由于GFRP筋横向膨胀大更易造成梁底混凝土的开裂与剥落,建议在满足纵筋锚固性能要求的前提下,尽量减少端部J型锚固筋。GFRP筋在高温下的材料性能衰减严重,合理的设计保护层厚度和限制GFRP筋的使用内力,可使GFRP筋混凝土梁的耐火性能满足实际工程的需要。 相似文献
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在海岸与近海结构工程中被广泛应用的钢筋混凝土构件,由于长期处在有海水腐蚀、干湿交替和循环荷载的严酷环境中,导致钢筋因侵蚀结构严重损伤。本文对6根钢筋混凝土试验梁进行了腐蚀与循环荷载作用下的疲劳试验研究,循环荷载幅值设计为2%～40%P_u和2%～60%P_u两种,对试验梁在大气环境中、淡水环境中和海水腐蚀环境中疲劳破坏情况进行试验探索,研究在三种环境与循环荷载作用下钢筋混凝土构件的力学性能及刚度损伤演化规律,同时分析了破坏形态、裂缝宽度、挠度的发展规律和疲劳寿命。结果表明:腐蚀与循环荷载共同作用下,短期内腐蚀溶液不会对梁内部钢筋造成显著影响从而降低耐久性;在循环次数达到一定范围内,试验梁耐久性降低42%,其中两个试验梁在循环荷载上限为0.6P_u时的耐久性分别降低54%和37%。 相似文献
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Plate structures are employed as important structural components in many engineering applications. Hence, assessing the structural conditions of in-service plate structures is critical to monitoring global structural health. Modal curvature-based damage detection techniques have recently garnered considerable attention from the research community, and have become a promising vibration-based structural health monitoring solution. However, computing errors arise when calculating modal curvatures from lateral mode shapes, which result from unavoidable measurement errors in the mode shapes as identified from lateral vibration signals; this makes curvature-based algorithms that use a lateral measurement only theoretically feasible, but practically infeasible. Therefore, in this study, long-gauge fiber Bragg grating strain sensors are employed to obtain a modal curvature without a numerical differentiation procedure in order to circumvent the computing errors. Several damage indices based on modal curvatures that were developed to locate beam damage are employed. Both numerical and experimental studies are performed to validate the proposed approach. However, although previous studies have reported relative success with the application of these damage indices on a simple beam, only one damage index demonstrated the capability to locate damage when the stiffness of the local region changed near the sensor. 相似文献
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Chao‐Hsien Li Keh‐Chyuan Tsai Jing‐Tang Chang Chih‐Han Lin Jia‐Chian Chen Te‐Hung Lin Pei‐Ching Chen 《地震工程与结构动力学》2012,41(9):1277-1299
Coupled steel plate shear wall (C‐SPSW) consists of two or more steel plate shear walls interconnected by coupling beams at the floor levels. In this study, a six‐story C‐SPSW prototype building was designed. A 40% scale C‐SPSW specimen, which is representative of the bottom two‐and‐half‐story substructure of the prototype, was cyclically tested using Multi‐Axial Testing System at the National Center for Research on Earthquake Engineering in 2009. In addition to a constant vertical force representing the gravity load effects, cyclic increasing displacements and the corresponding overturning moments transmitted from the upper stories were computed online and simultaneously applied on the substructural specimen. This paper firstly introduces the designs of the prototype C‐SPSW and the test specimen. Then, the test results and the numerical simulation are discussed in detail. Test results confirm the effectiveness of the proposed column capacity design method, which aims at limiting the plastic hinge formation within the bottom quarter height of the bottom column. Test and analytical results suggest that the coupling beam rotational demands can be estimated as the design story drifts when the formation of desirable plastic mechanism of the C‐SPSW is expected. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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Vibration-based structural identification is an essential technique for assessing structural conditions by inferring information from the dynamic characteristics of structures. However, the robustness of such techniques in monitoring the progressive damage of real structures has been validated with only a handful of research efforts, largely due to the paucity of monitoring data recorded from damaged structures. In a recent experimental program, a mid-rise cold-formed steel building was constructed at full scale atop a large shake table and subsequently subjected to a unique multi-hazard scenario including earthquake, post-earthquake fire, and finally post-fire earthquake loading. Complementing the simulated hazard events, low-amplitude vibration tests, including ambient vibrations and white noise base excitation tests, were conducted throughout the construction and the test phases. Using the vibration data collected during the multi-hazard test program, this paper focuses on understanding the modal characteristics of the cold-formed steel building in correlation with the construction and the structural damage progressively induced by the simulated hazard events. The modal parameters of the building (i.e., natural frequencies, damping ratios, and mode shapes) are estimated using two input–output and two output-only time-domain system identification techniques. Agreement between the evolution of modal parameters and the observations of the progression of physical damage demonstrates the effectiveness of the vibration-based system identification techniques for structural condition monitoring and damage assessment. 相似文献
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Modeling of the composite action in fully restrained beam‐to‐column connections: implications in the seismic design and collapse capacity of steel special moment frames 
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下载免费PDF全文 This paper investigates the effect of the composite action on the seismic performance of steel special moment frames (SMFs) through collapse. A rational approach is first proposed to model the hysteretic behavior of fully restrained composite beam‐to‐column connections, with reduced beam sections. Using the proposed modeling recommendations, a system‐level analytical study is performed on archetype steel buildings that utilize perimeter steel SMFs, with different heights, designed in the West‐Coast of the USA. It is shown that in average, the composite action may enhance the seismic performance of steel SMFs. However, bottom story collapse mechanisms may be triggered leading to rapid deterioration of the global strength of steel SMFs. Because of composite action, excessive panel zone shear distortion is also observed in interior joints of steel SMFs designed with strong‐column/weak‐beam ratios larger than 1.0. It is demonstrated that when steel SMFs are designed with strong‐column/weak‐beam ratios larger than 1.5, (i) bottom story collapse mechanisms are typically avoided; (ii) a tolerable probability of collapse is achieved in a return period of 50 years; and (iii) controlled panel zone yielding is achieved while reducing the required number of welded doubler plates in interior beam‐to‐column joints. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献