ECC和抗拔不抗剪连接件用于组合框架结构抗裂性能提升应用研究

Nowadays, steel-concrete composite frame structure is widely used in building structures. However, under severe structural load conditions or requirements for more complex applications of structures, cracking in negative moment is one of the bottleneck problems in the popularization and application of the composite structures. Therefore, it is imperative to solve the cracking problem. Engineered cementitious composites (ECC) are a type of new materials with excellent performance, the uplift-restricted and slip-permitted connector is a new connection method to improve the performance by releasing the combined action. The proper application of both in the negative moment area will provide a new efficient and economic technique to solve the crack resistance problem of steel-concrete composite structure. This project intends to focus on the composite frame with ECC and uplift-restricted and slip-permitted connectors. Firstly, the theoretical solution of composite beams in frames is obtained by theoretical analysis, and the mechanical performance, cracking mechanism and failure mode of composite frame are revealed by experimental study. Then, the influences of key parameters on the mechanical performance are analyzed by establishing elaborate finite element models. Finally, the efficient fiber beam-column model of steel-concrete-ECC beams with uplift-restricted and slip-permitted connectors is developed, the seismic elasto-plastic time history analysis of the composite frame system under various parameters changes is carried out, and application methods and design suggestions are proposed. The research findings of this project will provide guidance for the application of ECC and uplift-restricted and slip-permitted connectors in improving the crack resistance of composite frame system.

目前，钢-混凝土组合框架结构已被广泛应用于建筑结构中。而在苛刻的结构荷载条件或对结构有复杂应用需求下，负弯矩开裂问题是组合结构推广应用的瓶颈问题之一，因此解决开裂问题非常重要。纤维增强水泥基复合材料(ECC)是性能优异的新材料，抗拔不抗剪连接件是通过释放组合作用提升性能的一种新型连接方式，两者合理应用于负弯矩区，将为解决钢-混凝土组合结构抗裂难题提供一种新的高效而经济的技术手段。本项目拟针对应用ECC和抗拔不抗剪连接件的组合框架，首先通过理论分析得到框架组合梁的理论解，试验研究揭示组合框架的受力性能、开裂机理、破坏模式等；随后建立精细有限元模型分析关键影响参数对其受力性能的影响；最后开发抗拔不抗剪钢-混凝土-ECC高效纤维梁模型，对组合框架体系进行各参数变化下的地震弹塑性时程分析，并提出应用方法和设计建议。本项目研究将为ECC和抗拔不抗剪连接件在组合框架体系中抗裂性能提升的应用提供指导。

为提升钢-混凝土组合框架结构的抗裂性能，本研究提出将纤维增强水泥基复合材料(ECC)和抗拔不抗剪连接件两者合理应用于结构负弯矩区，从子结构和框架体系层面开展了理论、试验和数值模拟分析，探究了受力机理并提出了设计建议。理论分析了抗拔不抗剪连接钢-混凝土组合框架的基本受力机制、抗侧刚度和采用ECC后的框架梁弯矩承载力，试验揭示了抗拔不抗剪连接钢-混凝土-ECC组合框架在竖向堆载和水平低周往复加载工况下的开裂机理、承载能力、破坏形态等，对比分析了连接件布置方案和楼板材料对组合框架受力性能的影响规律。建立了考虑复杂界面行为的抗拔不抗剪连接钢-混凝土-ECC组合框架壳-实体精细有限元模型，探究了影响该组合框架结构性能的一系列关键因素。提出了用于分析抗拔不抗剪连接钢-混凝土-ECC组合框架体系受力的梁-壳高效模型，并对比分析了采用不同连接件和不同楼板材料的结构体系的自振频率、振型等。ECC和抗拔不抗剪连接件在显著减小楼板裂缝宽度的同时，几乎不影响框架的刚度、承载力和体系自振特性。研究成果对实际工程中ECC和抗拔不抗剪连接件在组合框架体系中抗裂性能提升的应用具有重要的指导意义。