【作者】 聂桂波；

【导师】 沈世钊； 范峰；

【作者基本信息】 哈尔滨工业大学 ， 结构工程， 2012， 博士

【摘要】 以网壳为代表的大跨空间结构由于其受力合理、重量轻、刚度大以及形式活泼新颖等优点，在近三十年取得了飞速发展。我国是世界上地震灾害最为严重的国家之一，地震区域广阔分散，地震频繁强烈。由于网壳结构的重要性和特殊性，遭遇地震发生破坏所带来的影响以及修复费用都相当巨大，这些都对该类结构的抗震设计理论提出了更高的要求。然而，目前对于网壳结构强震下失效机理的研究仍存在欠缺，也还没有形成合理高效的抗震设计理论。正是基于这些问题，本文基于损伤累积材料本构模型的研究，对网壳结构强震下失效机理进行了讨论；在此基础上了开展网壳结构抗震性能评估的理论研究工作，主要研究内容和成果如下：1、圆钢管空间滞回性能试验和考虑材料损伤累积本构模型设计了适用于圆钢管试件空间三维加载的试验装置，通过对比试验验证了该装置的稳定性。考虑10组加载方案，系统考察了50根网壳结构常用圆钢管杆件的空间滞回性能；通过有限元软件ABAQUS编制了能够考虑材料损伤累积效应的用户子程序，实现对试验的数值模拟，并以数值曲线和试验曲线在峰值点的吻合程度来得到材料考虑损伤累积本构模型中的各个参数；对50组参数结果进行最小二乘法拟合，得到了圆钢管考虑损伤累积的材料本构模型。通过不同的本构模型对试验试件进行模拟比较可以发现，理想弹塑性本构模型仅能较为精确地模拟试件在弹性阶段内的力学行为，考虑材料损伤累积效应后，随着构件塑性发展的不断深入，其影响逐渐增大，并且采用本文获得的考虑材料损伤累积本构模型得到的数值模拟曲线与试验曲线拟合最好，说明该模型具有较好的精度，这为后续研究奠定了基础。2、基于损伤累积本构的强震失效模式及强度破坏振动台试验应用本文提出的材料本构模型和开发的用户材料子程序，利用有限元软件ABAQUS，对单层网壳结构在动力荷载作用下的失效模式进行了分析，详细描述了网壳结构在动力荷载作用下存在的两种可能的失效模式，即由于几何非线性起主要作用导致的动力失稳和由于材料非线性起主要作用导致的动力强度破坏；考虑损伤累积后，网壳结构的地震响应发生了明显变化，结构的失效极限荷载显著降低。为验证单层球面网壳的动力强度破坏，开展了单层球面网壳缩尺模型的振动台试验，试验同时测定网壳结构的动力特性及结构在弹性阶段的动力响应。强震试验结果表明：在1500cm s2的地震作用下，模型中的塑性得到了充分发展，结构的受力性能已经严重削弱，结构变形较大，表明结构在此时应已发生了材料塑性充分发展的动力强度破坏。在对该试验进行数值模拟重现的过程中也能发现，采用本文本构模型获得的数值模拟曲线与试验曲线吻合程度最好。3、网壳结构强震失效机理参数分析及结构损伤模型通过本文提出的材料本构模型和基于荷载域的全过程分析方法对网壳结构在强震下的响应进行了大规模的参数分析；考察了单层球面网壳、单层柱面网壳在不同的矢跨比、杆件截面、屋面质量、长宽比、初始缺陷下结构响应的变化规律，分析了地震变异性对结构响应的影响。通过对这些算例在失效极限状态时的响应进行统计，掌握了网壳结构在地震荷载下的失效特点和规律；在此基础上，拟合获得了基于多项特征响应和基于变形能量的结构损伤模型，实现对结构强度破坏极限及不同损伤程度的判别。4、网壳结构地震易损性分析及抗震性能评估根据网壳结构的特殊特点，定义了它的性能水准，应用结构损伤因子对性能水准进行了量化。通过考虑地震动的差异性开展网壳结构基于不同性能水准的易损性分析；结合地震危险性分析和结构地震易损性分析，获得网壳结构地震下失效概率，讨论了结构失效概率与经济损失及人员伤亡之间的关系，开展了结构地震损失风险评估工作。更多还原

【Abstract】 As a major form of large span space structures, reticulated shells developed fastin last30years for its excellent shape and mechanical behavior. China spans Circum-Pacific seismic zone and Eurasia seismic zone with frequent strong earthquakes.Huge amount of money needed for building or repairing before or after earthquakejustify the great necessity to evaluation the anti-seismic performance of reticulatedshells. However, the failure mechanism of reticulated shells under seismic motion, isnot well understood. Based on the mentioned above, this paper take a deeplyinvestigation on the failure mechanism of reticulated shells under seismic motionsbased on the damage cumulative constitutive model. And then the evaluation of anti-seismic performance of reticulated shells is completed. The main contents in thispaper are shown as following.1. Test on the hysteretic behavior of circular steel pipe and materialconstitutive model considering material damage cumulationThe setup applicable for three-dimensional loading is designed and then itsstability is verified by comparing test. Test is conducted on fifty circular steel tubeswith10groups of load schemes and their hysteretic behavior is investigated. Finite-element model is developed using a user-defined material sub-routine UMATencoded incorporating ABAQUS to consider material damage cumulation. Then, theparameters in the constitutive model is developed using the goodness of fit betweennumerical simulation and test results. Finally, a generalized constitutive modelconsidering damage cumulation is developed using the least square method with50groups of results. The numerical simulation using different material constitutivemodels is conducted. It is found through comparison that the perfect elasto-plasticcan only simulate the mechanics behavior in the range of elastic. Effect of damagecumulation becomes more and more obvious with increase of plasticity. The simulatecurves using the damage cumulative constitutive model are in good agreement withtest curves which proves not only the constitutive model is accurate but also the user-defined material sub-routine is applicable for theoretical analysis.2. Failure pattern of reticulated shells under severe seismic motion and ashaking table test on dynamic strength failureThe failure mechanism of single-layer reticulated shells considering damagecumulation under dynamic load is investigated by the material constitutive model and the UMAT using finite element software ABAQUS.The failure mechanism of single-layer reticulated shells considering damage cumulation under dynamic load isinvestigated. It is found that two failure patterns of the structure, dynamic instabilitydue to geometrical non-linearity and dynamic strength failure due to material non-linearity under dynamic load, are described. What is more, the performance ofstructure changes obviously especially its failure load decreases obviously whenconsider material damage cumulation. A shaking table test of single-layer reticulateddome is conducted to understand dynamic strength failure of single-layer reticulateddome under seismic motion. The free vibration property and the dynamic responsesof the single-layer reticulated dome under small or strong seismic motions areobtained; the performance of this model presents large deformation and obviousmaterial plasticity under seismic motion with an amplitude of1500cm s2whichindicates dynamic strength failure is appeared due to severe plastic development. Thenumerical simulation using different material constitutive models are conducted，the results show that the simulate curves using the damage cumulative constitutivemodel are in good agreement with test curves.3. The parametric analysis of failure mechanism of reticulated shells andstructrue damage modelThe vast scale parametric analysis of the failure mechanism of reticulated shellsis conducted by whole-course analysis method using the damage cumulative materialdamage model. The responses regularity of reticulated shells is investigated underdifferent ratio of rise to span, member cross-section, roof mass, length-width ratioand seismic motions. And then the failure characteristic and regularity of reticulatedshells under seismic motion is investigated by statistic analysis of the responsesunder different damage level. Based on the mention above, the damage state of thestructures under seismic motions is quantified using two structural damage models,one is based on multiple structural responses and another is based on deformationand energy.4. The seismic vulnerablity analysis of reticulated shells and anti-seismicperformance evaluation methodThe performance levels of reticulated shells are defined by its characteristic.And then the graded performance levels are quantified using structural damagemodel. The seismic vulnerability of the graded performance levels is conducted byconsidering the variance of different seismic motions. The exceeded probability ofearthquake with different intensities in a given design period is calculated using seismic hazard analysis. The failure probability of reticulated shells under earthquakeis calculated using the seismic hazard analysis and seismic vulnerability analysis.The anti-seismic performance evaluation of reticulated shells is completed using therelationship between structural failure probability and economic loss as well ascasualty loss.更多还原