新型多层钢木混合结构抗震性能与设计方法研究

Wood is a renewable and environmentally friendly building material. Wood and steel can both be recycled and prefabricated, which is a premise for energy efficient buildings and green construction. Due to the material's high strength-weight ratio and ductile behavior, desirable seismic performance is expected for timber and steel structures. A concept of green multi-storey timber-steel hybrid structure which is composed of steel frame and wood diaphragms and shear walls is proposed in this project. In such structures, wood diaphragms combined with steel beams serve as the floor system to resist vertical loads and transfer lateral loads, and wood shear walls are used as in-fills between steel columns to form a timber-steel hybrid system to resist lateral loads of the structure. Theoretical analysis will be conducted to study the lateral performance of timber-steel hybrid structures with different structural configurations. Then the load sharing effect between the timber and steel subsystems in the hybrid structure will be studied through dynamic tests and numerical simulation, at the same time, the lateral force resisting characteristics, seismic failure modes and failure mechanisms of this kind of hybrid structures will be studied. The structural performance function will be formulated and seismic reliability analysis will be conducted to evaluate the seismic reliabilities of timber-steel hybrid structures, which can then serve as the fundamental theories for performance-based seismic design for this kind of structures. This project will have an important significance on the aspects of ecological civilization of constructional industry, utilization of renewable resources, green construction and building industrialization, as well as the development of performance-based design procedures for new structures.

木材资源最可再生，墙体保温性能好；钢木材料均可循环利用、工厂预制和现场组装、可实现绿色施工；且钢木结构重量轻、韧性好，抗震能力强。本课题充分利用钢木结构的优点，以钢作框架、木作楼盖和墙体，构建新型绿色多层钢木混合结构体系。通过对木楼屋盖与钢框架梁组成的水平抗侧力体系、木剪力墙与钢框架组成的竖向抗侧力体系的理论分析，研究影响水平结构体系、竖向结构体系的刚度和抗侧能力的因素。通过结构整体动力试验和数值模拟，阐明钢框架与木楼屋盖、木剪力墙的协同工作机理，揭示该类结构抗侧力性能与特点，提出结构地震破坏模型和失效机理。建立结构性能目标函数，基于结构地震可靠度分析，为该类新型混合结构基于性能的抗震设计方法奠定理论基础。本研究成果对推动建筑业生态文明建设、利用再生资源、实现绿色施工、提高建筑产业化和发展新型结构基于性能的设计方法均具有重要理论意义和实用价值。

钢木混合结构利用绿色环保、轻质高强的木材和钢材作为建筑材料，预制装配化程度高，符合我国多高层建筑发展的需要。为了全面深入地了解这一新型结构体系的整体抗侧性能，对钢木混合结构体系进行了一系列的研究。本课题首先完成了单层钢木混合结构拟静力试验，揭示了钢木混合结构中钢框架和木剪力墙的协同工作机理；完成了钢木混合楼盖拟静力试验，获得了钢木混合楼盖的平面内抗侧力性能；进行了不同连接方式下钢木混合墙体试验，研究了不同连接形式对钢木混合墙体抗侧性能的影响；完成了四层钢木混合结构振动台试验，全面深入地了解了钢木混合结构抗侧力体系从弹性状态到极限状态全过程的受力机理和协同工作特性。研究结果表明，当结构侧移较小时，轻木剪力墙承担大部分剪力，随着位移增大，剪力墙强度与刚度发生退化，承载力主要由钢框架提供。侧向荷载下，钢木混合抗侧力体系的破坏都始于木剪力墙面板钉连接的破坏，且木剪力墙先于钢框架屈服。在试验研究成果的基础上，采用“HYST”算法模拟轻木剪力墙抗侧性能，建立了钢木混合结构的有限元模型，该模型可以很好模拟钢木混合结构中轻木剪力墙的捏缩特性。对不同条件的钢木混合结构进行参数化分析，结果表明木剪力墙与钢框架的抗侧刚度比对混合体系协同工作性能有重要影响，应使木剪力墙和钢框架的抗侧刚度比不小于 0.5；研究得到了混合结构自振周期的估算公式和剪力分配系数的拟合公式；通过易损性分析和响应面分析的方法，对钢木混合抗侧力体系进行了地震可靠度评估。综合钢木混合结构抗震性能的研究成果，提出了直接位移抗震设计方法，为混合结构的合理设计提供了依据。课题研究为钢木混合结构这一新型、环保、预制化体系的工程应用和推广奠定了可靠的研究基础，对于发展生态文明，倡导绿色建筑，促进多高层建筑抗震技术发展，都有着重要的意义。