基于塑性极限分析的渡槽结构抗震安全评估

Large amount aqueducts are used for urban water supply and agricultural irrigation in our country, and more aqueducts will be built following with implementation of the equilibrium policy of water resources at space and time. Many aqueduct structures are space think shell structure systems with high piers, and lie in the area with seismic intensity of 7 degree and more than 7 degree, so it is very important that the aqueduct structure seismic safety impacting on the safety operation of the whole water delivery lifeline engineering. .This project will reveals the main failure mode of the aqueduct structures and the corresponding failure mechanism based on a large amount of research materials and vibration table model test; it will establish a beam-shell model considering fluid-solid coupling, bearings role of the aqueduct structures, aquire the section generalized yield criterion of the beam-shell membe; In this project, a elastic iterative algorithm used for the seismic plastic limit analysis of aqueduct structures will proposed, which is combined with plastic ultimate analysis and vibration mode decomposition theory, and then to build a limit state equation of aqueduct structures that based on the evaluation index of seismic limit bearing capacity, determine its limit of seismic ultimate bearing capacity. Thus, the seismic safety evaluation theory of the aqueduct structures under the theory can be build systematically, which can also provide the theory basis and the application method for health diagnosis and disaster prevention and mitigation measures of the structures.

我国在城市供水与农业灌溉中有大量渡槽，同时随着水资源空间和时间平衡政策的实施，将会建设更多渡槽。渡槽结构多为高墩空间薄壁壳体结构体系，且很多位于地震烈度为7度及以上的地区，其抗震安全对保障输水生命线工程的正常运行有着十分重要的意义。.本项目将在大量调研资料及振动台模型试验基础上，揭示渡槽结构的主要破坏模式和相应破坏机理，建立考虑流固耦合、隔震支座作用时的渡槽结构极限分析的梁壳模型，获得梁壳构件截面的广义屈服准则，结合塑性极限分析与振型分解理论，提出渡槽结构抗震塑性极限分析的弹性迭代算法，进而构建以渡槽结构抗震极限承载力为评价指标的极限状态方程，确定其抗震极限承载力的限值，系统地建立地震作用下渡槽结构的安全评价理论，为结构的健康诊断和防灾减灾措施提供理论依据和应用方法。

渡槽结构往往涉及到输水生命线工程，很多也处于地震高烈度区域，一旦发生事故，危害性极大。此外，我国仍有数以万计的渡槽结构存在各种严重缺陷，现实中不可能对这些渡槽结构全部予以报废更新或彻底修复，因此，必须对地震作用下渡槽结构的破坏机理和安全评估进行深入研究，提出科学、安全、经济、实用的预防渡槽震害的技术和方法。本项目主要是开展了渡槽结构抗震极限承载力分析的计算模型、数值分析方法和安全评估方法的研究。研究内容包括：开展了渡槽结构的试验研究；结合试验数据，基于板壳理论、曲梁模型，建立了渡槽结构抗震塑性极限分析的梁壳模型，提出一种钢筋混凝土结构塑性极限分析的弹性迭代算法，确定渡槽结构的抗震极限承载力；并以此建立以抗震极限荷载为评估指标的安全评估方法。该成果对确保结构能够抵御地震灾害的侵袭具有重要的工程意义和科学研究价值，是渡槽结构安全评估中的关键技术问题。