型钢混凝土结构多尺度损伤性能优化设计理论与试验研究

Oriented to the strategy of future structures with high-performance, this project aims to propose the multi-scale damage performance-based optimum design methodology and performance-optimized techniques by using steel fibre concrete or steel tube confinement in the plastic regions of steel reinforced concrete (SRC) structures. It firstly aims to reveal the impact mechanism of steel fibres and different type confinement actions on the micro-scale damage evolution mechanism of concrete, and to propose a generalized damage constitutive model for confined concrete and steel fibre concrete. Secondly, the multi-scale damage evolution correlativity analysis method will be proposed by the realationships between the finite element method, damage mechanics and dynamic mechanics. Based on the experimental research and numerical analysis, it aims to establish the multi-scale damage performance levels of structure with the reliability-based limit damage threshold values. According to the seismic design level, the multi-level damage performance design goals of SRC structures will be proposed. Moreover, the impact mechanism of plastic-region's performance-optimized techniques on the structural performance will be analyzed and its controlling index will be proposed. Finally, the optimization objective function could be defined by the criteria of damage homogeneous distributions on the structural multi-levels, and the optimization constraint functions could be defined by the multi-level damage performance design goals. Thus, the multi-scale damage performance-based optimum design methodology will be established in order to achieve the structural high-performance. This project agrees well with the future development requirements of our country's civil engineering constructions. It is valuable both in theoretical research and engineering application.

面向未来高性能结构发展战略，本项目针对型钢混凝土结构，提出多尺度损伤性能优化设计方法和塑性区采用钢纤维混凝土及外置钢管约束的性能优化技术。本项目首先试验研究钢纤维及不同类型约束作用对混凝土微观损伤演化影响的物理机制，建立统一形式的约束混凝土/钢纤维混凝土损伤本构模型。其次，结合有限单元法、损伤力学与动力学原理，建立多尺度损伤演化相关性分析方法。利用试验与数值分析方法，研究结构多层次损伤性能水准和基于可靠度的临界损伤阈值。结合地震动设防水准，建立型钢混凝土结构多层次损伤性能设计目标。同时，试验研究塑性区优化技术对结构/构件性能的影响机理，并提出相应的性能控制指标。最后，以多层次损伤分布均匀为准则定义优化目标方程，以多层次损伤性能设计目标定义优化约束方程，从而建立结构多尺度损伤性能优化设计方法以实现结构的高性能。本项目研究方向契合我国土木工程建设未来发展要求，具有理论意义和工程应用价值。

发展高性能结构是提升我国城市韧性和保障人民生命安全的重要途径。面向高性能结构发展需求，本项目首先开展了箍筋约束、钢管约束、型钢约束三类约束形式混凝土轴压试验，提出了不同约束形式混凝土轴压塑性损伤本构模型。开展了素混凝土和钢纤维混凝土断裂性能试验，提出了素混凝土和钢纤维混凝土基于断裂过程的单轴受拉塑性损伤本构模型。发明了基于声发射特性判别微观开裂模式的机器学习算法和混凝土单轴受拉应力-应变关系和损伤演化方程试验方法。为准确分析高性能结构非线性力学行为提供了有力的本构理论。其次，开展了型钢混凝土构件和钢管混凝土构件的损伤性能试验，建立构件基于概率统计的损伤性能水准和判别准则，提出了构件抗震性能优化和韧性提升技术。发明了塑性区增韧的型钢混凝土节点、内部具有负泊松比约束效应的钢管混凝土柱和海绵夹层外包碳纤维布钢管混凝土柱。为实现高性能结构提供了合理的构件损伤性能设计水准和性能优化技术。最后，提出了基于累积塑性应变能的结构多尺度损伤评估模型，提出了结构多尺度损伤演化相关性和优化方法，建立了结构多尺度损伤性能水准，提出了结构塑性区钢纤维增韧的优化技术方法。本项目在材料本构、韧性构件和结构多尺度优化方面取得了系列成果，对实现高性能结构具有理论意义和工程应用价值。