低碳绿色的轻型钢木混合楼盖及其结构体系抗震性能

A new type of light wood-steel hybrid diaphragm has been proposed with high degree of precast production composed by renewable wood and recycled steel, addressing high energy consumption and resources shortage of construction industry. Significantly reducing structure deadweight, earthquake action and foundation load thereby decreasing material consumption on foundation and structural members, the diaphragm is an exploration of low-carbon and energy-conserving buildings and in according with strategic development goal of national building industry. However, different from traditional fully rigid concrete floor and completely flexible timber diaphragm, the light wood-steel hybrid diaphragm possesses certain in-plane stiffness depending mainly on its nail connection, which influences horizontal load distribution, seismic performance of structure and forces on itself. Nevertheless, existing nail joint elements lose sight of its behavior difference between parallel and perpendicular to grain and few research is involved in seismic performance of timber composite floor and its structure system. Therefore, based on test of the diaphragm and its nail connection, a new nail joint element overcoming limits described above will be programmed and the diaphragm’s detailed model be built for parametric study, aiming to obtain working mechanism and seismic performance of the diaphragm. Then taking into account several parameters, timber-steel hybrid structure models are to be conducted to study the influence of diaphragm’s in-plane stiffness on the seismic behaviors of structures. Subsequently, some seismic design suggestions are about to be given for the light wood-steel hybrid diaphragm and timber-steel hybrid structure. Eventually, supplying scientific basis for aseismic analysis and numerical simulation of timber and its hybrid structure, this project will be of significance for promoting low-carbon buildings and architectural industrialization.

针对建筑业能耗高、资源匮乏问题，将可再生的木材、可循环利用的钢材组成一种预制装配化程度高的绿色轻型钢木混合楼盖，它较大地减少了结构自重、地震作用及基础受力，从而节约材料，是对低碳节能建筑的一种探索，符合国家建筑业战略发展目标。不同于传统的混凝土楼盖和木楼盖，其平面内刚度受钉节点影响很大，并非完全刚性或柔性，影响着水平力分配、结构抗震性能及楼盖自身受力。现有钉节点单元不能考虑钉节点顺纹及横纹向性能差异，木混合楼盖及其结构体系抗震性能研究缺乏。基于钉节点及楼盖试验，考虑钉节点顺纹及横纹向性能差异，编制钉节点单元，建立楼盖模型进行参数研究，获得其水平荷载作用下的工作机理及抗震性能；建立钢木混合结构模型，考虑楼盖平面内刚度影响进行结构抗震性能参数研究，对该楼盖及其结构体系抗震设计提出建议。研究成果将为木及木混合结构抗震、数值模拟方面提供科学依据，对推动低碳节能建筑及建筑产业化具有重要意义。

我国日益匮乏的资源与人口众多的矛盾愈加严重，亟需寻找低碳绿色建材及建筑。增加木材和钢材在结构中的利用、形成钢木混合构件及其结构体系是一种解决问题的途径。本项目提出一种新型绿色的轻型钢木混合楼盖。其搁栅为轻型C型钢，SPF（云杉-松木-冷杉）木规格材面板与搁栅通过螺钉连接，然后面板上铺设细钢筋网，用骑马钉固定，最后铺设薄层聚酯砂浆面层。楼盖质量是混凝土楼盖的1/3，质轻利于抗震，它绿色节能，预制装配化程度高、现场湿作业少、施工迅速。但它平面内刚度并非完全刚性和柔性，其大小影响整体结构水平地震荷载的分配及其抗震性能。因此本项目研究主要内容是轻型钢木混合楼盖平面内抗震性能，特别是其刚度的研究，以及其刚度对由该楼盖及钢框架内填轻型木剪力墙组成的钢木混合结构抗震性能的影响。本项目基于实验与数值模拟相结合的方法，揭示了其结构体系在整个弹塑性状态下的抗震性能及其楼盖水平荷载分配能力。提出了水平荷载转移能力系数β概念及公式以衡量楼盖转移水平荷载的具体大小；揭示了楼盖与竖向抗侧力构件平面内刚度比值α对β的影响，提出了如何对轻型钢木混合楼盖进行刚柔分类；得到如下结论：结构弹性及塑性层间位移角建议取为1/250及1/50,破坏模式为墙体破坏，楼盖很少破坏；α＞3时，楼盖为刚性; 0.2 ≤α≤3时，楼盖为半刚性；α＜0.2时楼盖为柔性；随着结构侧移增大，α及β不断增大，楼盖不断调节各竖向抗侧力墙体水平荷载的分配，在结构破坏前，各墙体剪力、刚度及侧移趋向于均匀；结构初始状态时，楼盖并非需要完全刚性，只需达到某门槛值时，随着结构侧移增大，楼盖刚度会迅速增大从而转变为刚性。结构设计时，需对该类结构体系的中部抗侧力构件强度适当放大，以避免楼盖在达到刚性前其就破坏。轻型钢木混合楼盖具有较大的平面内刚度，初始水平荷载转移能力在75%以上，使结构具有很好的整体抗震性，它及其结构体系适合我国战略发展目标。