铝合金单层球面网壳结构弹塑性稳定性及强震失效机理研究

Compared to carbon steel, aluminum alloy has the advantages of light weight, corrosion resistance and easy processing. There have been built several aluminum alloy single-layer spherical reticulated shells in China recent years with a rapid development trend. However, at present, the research on the shell structures of the aluminum alloy with low elastic modulus and no obvious yield plateau is far less from that of the steel reticulated shells. This study intends to carry out the stability and failure mechanism under seismic motions of aluminum alloy spherical reticulated shells. Firstly, based on the theoretical analysis and experimental study, a refined constitutive model of 6061-T6 aluminum alloy with strain hardening characteristics will be established. Secondly, based on the stability experiment of a 9m diameter reticulated shell with H-shape elements and plate joints, the instability mode of the reticulated shell will be studied. Based on this, the performance of different types of reticulated shells will be studied by large scale parametric analysis under different span, rise-span ratio and initial geometric imperfection. The influence of each factor will be analyzed, and the appropriate initial imperfection value and the coefficient of stability bearing capacity will be recommended. Thirdly, based on the shaking table test of the shell model with the same size, the dynamic failure mechanism under strong earthquake is studied. The dynamic response analysis of different types of reticulated shells is to be carried out, and the criterion of dynamic instability and strength failure will be proposed, and corresponding anti-seismic measures will be given.

与钢材相比，铝合金具有重量轻、耐腐蚀、加工方便等优点，近年我国已建成多项百米级铝合金网壳，并呈快速发展趋势。然而，目前对弹性模量低且没有明显屈服台阶的铝合金材料的网壳结构研究远没有钢网壳那样深入和系统。为此，本课题拟开展铝合金球面网壳稳定性及强震失效机理研究。首先，作为基础，通过理论推导和试验研究，建立常用的具有应变硬化特征的6061-T6铝合金材料精细化本构模型。其次，通过直径9m的H型杆件、板式节点球面网壳稳定性试验，深入研究其失稳模式；在此基础上对不同类型、跨度、矢跨比、几何初始缺陷、杆件初弯曲、节点刚度等网壳进行大规模全过程稳定性分析，得出各因素影响规律，揭示失稳机制，给出网壳结构合适的最大初始缺陷值及稳定承载力安全系数。第三，基于同规格网壳模型的振动台试验，深入分析其动力失效机理；对不同类型网壳进行大规模考虑材料损伤累积的动力响应分析，分析强震失效机理并给出动力失效判断准则。

该项目经过4年、11位成员的努力，完成了下列工作。. 1.材料本构关系研究：基于材性试验研究了6061-T6铝合金材料的单向拉伸本构关系，通过比较得出拟合结果最优的Ramberg-Osgood模型的各项参数值；基于材性试验和有限元分析，得出了材料滞回性能的Chaboche混合强化模型的各项参数取值；可用于铝合金结构的静力及抗震性能分析。. 2.H型杆件的滞回性能研究：通过构件和精细化有限元分析，得出了H性构件在轴心和偏心荷载作用下的滞回性能及破坏形式；为铝合金结构的抗震分析奠定基础。. 3.板式节点性能研究：通过模型试验和精细化有限元分析，研究了起拱节点的弯矩-转角曲线、极限承载力、滞回性能、耗能能力和破坏形式，为考虑节点性能的铝合金网壳的分析奠定基础。. 4.铝合金单层球面网壳静力稳定性能研究：基于网壳模型试验和精细化有限元分析，研究了网壳的失效模式、静力承载力的影响因素、稳定系数取值等，研究表明，整体缺陷、杆件长细比和节点刚度对网壳稳定承载力均有明显影响，为铝合金网壳的分析与设计提供理论基础。. 5.铝合金单层柱面网壳抗震性能及强震倒塌机理研究：通过网壳模型振动台试验和精细化有限元分析，研究了柱面网壳的抗震性能、破坏形式、强震倒塌机理以及抗震设计建议等。. 6.铝合金单层球面网壳抗震性能及强震倒塌机理研究：通过模型试验和精细化有限元分析，研究了单层球面网壳的弹塑性地震响应、破坏形式、强震倒塌机理、抗震设计建议等。. 基于上述研究和成果，可为铝合金网壳结构的设计和分析提供实验和理论基础，促进我国铝合金结构的发展。