开洞冷弯薄壁型钢—石膏基自流平砂浆组合楼盖受力性能及设计方法研究

Cold-formed thin-walled steel composite floor is a kind of composite structure system, which is composed of cold-formed thin-walled steel joists and lightweight floor slab to force together and ensure collaborative deformation. The floor slab of gypsum based self-leveling mortar has the advantage of easy construction and good comfort, which is prepared by industrial waste desulphurization gypsum for the sake of making waste profitable as well as conforming to the requirements of the green building development in China. The opening of the floor can destroy the continuity of the structure and has a great influence on the mechanical performance of composite floor. And the relevant research has not been carried out yet. The in-plane and out-plane mechanical behavior and working mechanism of composite floors with different loading direction, floor slab type, opening size and opening position will be investigated through quasi-static experimental study, finite element numerical simulation and theoretical analysis in this project. The failure characteristics of floor openings can be revealed. Furthermore, the refined elasto-plastic analysis model and mechanical model of orthogonal anisotropic plate rib system will be established and verified. The flexural capacity and flexural stiffness calculation theory of composite floor with opening will be proposed along with the in-plane capacity and in-plane stiffness calculation method. Moreover, the design limit of floor opening rate and construction measures of the opening reinforcement will be put forward. The research achievements of this project are the improvement and development of the design method of composite floor in cold-formed thin-walled steel structural system, which will provide a scientific basis for improving the technical standard of multi-storey cold-formed steel residential buildings and lay a theoretical foundation for the extensive application of cold-formed thin-walled steel structural system.

冷弯薄壁型钢组合楼盖是由冷弯薄壁型钢梁和轻质楼板形成的共同受力、协同变形的组合结构。以工业废弃物—脱硫石膏为原材料制备石膏基自流平砂浆作为楼面板，施工方便，舒适性佳，既实现变废为宝，又符合我国绿色建筑发展要求。楼盖开洞会破坏结构的连续性，对结构的受力性能有较大影响，相关研究尚未开展。本项目采用拟静力试验研究、有限元数值模拟和理论分析相结合的方法，研究不同加载方向、楼板类型、开洞尺寸及开洞位置的楼盖面内和面外的受力性能及工作机理，揭示楼盖洞口处的破坏特征，建立并验证精细化弹塑性分析模型和正交各向异性板肋体系力学模型，提出开洞组合楼盖抗弯承载力和抗弯刚度计算理论，以及面内承载力和面内刚度计算方法，提出楼盖开洞率设计限值以及洞口加固的构造措施。本项目研究成果是对冷弯薄壁型钢结构体系中组合楼盖设计方法的完善和发展，可为完善多层冷弯型钢住宅技术标准提供科学依据，为该体系的广泛应用奠定理论基础。

冷弯薄壁型钢组合楼盖作为冷弯薄壁型钢结构住宅体系中主要竖向承重和水平传力构件，应具备良好的面外和面内受力性能。设计中为布置楼梯及电梯井道需要在楼盖开洞，其破坏了结构的连续性，局部切断了原有的传力路径，对结构的承载力及刚度产生不利影响。基于此，本项目对开洞冷弯薄壁型钢—石膏基自流平砂浆组合楼盖的受力性能和设计方法开展了系统研究。在材料层面，按照水：自流平材料：细砂=0.5：1：1.5的配合比配置石膏基自流平砂浆，对立方体试块进行抗压强度试验及对棱柱体试块进行弹性模量试验，测得材料的实测力学性能指标，为石膏基自流平砂浆的损伤本构模型提供材料参数。在连接层面，对冷弯薄壁构件与组合板采用自攻螺钉连接的推出试件进行了推出试验，研究了不同抗剪构造措施和不同楼板面材料对推出试件抗剪刚度、抗剪承载力及粘结性能的影响，获取了单颗自攻螺钉的抗剪承载力和自攻螺钉荷载—滑移曲线。依据规范，建立了推出试件中单颗螺钉的抗剪承载力计算方法。在结构层面，以试验研究、数值模拟和理论分析相结合的方法，对开洞冷弯薄壁型钢组合楼盖面内、外的受力性能进行了系统研究。结果表明：组合楼盖面外最终破坏模式为C形楼盖梁在最外侧加载点处压屈破坏，面内最终破坏模式为两侧C形楼盖梁与压型钢板间自攻螺钉连接破坏，冷弯薄壁型钢组合楼盖属于部分抗剪连接的组合楼盖。建立精细化的开洞组合楼盖有限元分析模型，分析了洞口尺寸、开洞加固措施、洞口周边螺钉间距、洞口位置以及楼面板材料对组合楼盖抗弯性能和面内受力性能的影响规律。推导了部分抗剪连接T形截面组合梁的等效抗弯刚度来计算开洞楼盖的抗弯刚度；借鉴规范，提出了考虑楼盖梁腹板剪切应力的开洞楼盖抗弯承载力计算公式；建立宽翼缘深梁受力分析模型，推导出开洞组合楼盖面内刚度以及面内极限承载力的计算方法。项目研究成果为完善冷弯薄壁型钢多层住宅体系中组合楼盖的设计计算理论提供了科学依据，可用于解决工程应用的关键问题。