冷弯型钢-微硅粉高强泡沫混凝土组合剪力墙破坏机理与设计方法研究

As one of the best structures of green buildings, cold-formed steel (CFS) structure has several remarkable advantages, such as light weight, easy installation and environmental friendliness. However, the CFS structure is limited to being utilized for low-rise buildings, due to its low seismic performance. To improve seismic behavior of CFS wall, this project proposes a new type of silica fume high-strength foamed concrete-filled cold-formed steel composite shear wall. The composite shear wall is composed of silica fume high-strength foamed concrete (SHFC) developed independently and existing CFS composite wall. Firstly, the damage evolution and failure mechanism of the shear walls under cyclic loading are investigated by experiment and numerical simulation to establish the failure criterion considering the enhancement effect of SHFC on the composite shear walls. Then, numerical simulation and theoretical analysis are used to investigate the distributions of principal stress in the composite shear walls. Therefore, the shear strength and flexural strength of the walls are established by the principal stress trace method, and then the corresponding calculate formulas are obtained. Finally, through theoretical analyzing the variation of the wall’s each deformation component in test loading process, a deformation analysis model considering the axial-flexure-shear coupling effect is established, and thus a formula for calculating the wall deformation is proposed. This research expands new ideas for improving the seismic behavior of CFS walls and provides theoretical supports for the seismic design of SHFC-filled CFS composite shear walls.

冷弯型钢结构是绿色建筑的最佳结构形式之一，具有自重轻、装配化程度高和绿色环保等优点，但因其抗震性能较差，故主要用于低层建筑。为了提高冷弯型钢墙体的抗震性能，本项目提出一种新型的冷弯型钢-微硅粉高强泡沫混凝土组合剪力墙，是由自主研发的最新型微硅粉高强泡沫混凝土与现有冷弯型钢组合墙经构造组合而成。首先，通过试验和数值模拟揭示水平地震作用下剪力墙的损伤演变规律和破坏机理，建立考虑微硅粉高强泡沫混凝土增强效应的剪力墙失效破坏准则。其次，通过数值模拟和理论分析揭示剪力墙主应力分布规律，采用应力迹线法建立剪力墙的受剪和压弯承载力计算模型，提出相应的实用计算公式。最后，通过试验和理论分析揭示水平地震作用下剪力墙的弯曲、剪切和滑移变形分量的变化规律，构建考虑压、剪和弯耦合效应的墙体变形能力分析模型，并提出位移计算公式。本研究开拓了冷弯型钢墙体抗震性能提升的新思路，为该新型组合剪力墙的抗震设计提供理论依据。

以微硅粉泡沫混凝土作为冷弯型钢组合剪力墙的填充承重材料，可以提高剪力墙的刚度和强度、保温隔热性能和解决墙体 “空鼓效应”。本项目以冷弯型钢-微硅粉泡沫混凝土组合剪力墙为研究对象，采用试验研究、数值模拟和理论分析相结合的方法，系统性研究了该组合剪力墙的破坏机理、抗震性能、承载力和变形能力计算方法。结果表明：①微硅粉泡沫混凝土通过自身抗压承载力和对冷弯型钢骨架变形的约束作用，使得冷弯型钢组合剪力墙的破坏模式由冷弯型钢局部畸变屈曲的脆性破坏转变成以混凝土斜裂缝和冷弯型钢整体屈曲为主的延性破坏，进而提高了剪力墙的滞回性能、承载能力、抗侧刚度、延性和耗能能力，在此基础上增加冷弯型钢立柱开孔和水平钢拉条的数量均能显著提高剪力墙的抗震性能，其次是钢斜撑、增强端立柱和泡沫混凝土强度，最后是增强中立柱、增加轴压比；②基于组合剪力墙的裂缝分布规律和应力流传递路径，提出了适用于此剪力墙的软化拉-压杆模型承载力计算模型，给出了计算公式与求解流程，并通过节点处力平衡理论，推导出该组合剪力墙的斜截面抗剪承载力的计算公式；③基于承载力叠加原理和影响因素对承载力的定量分析结果，确定影响组合剪力墙受剪承载力的主要因素，并建立表征各部分的承载力计算模型，进而提出符合JGJ383-2016《轻钢轻混凝土结构技术规程》要求的冷弯型钢-泡沫混凝土组合剪力墙抗剪承载力计算公式；④弯曲变形、剪切变形和滑移变形占剪力墙总变形的比例分别为51.8%~67.8%、38.8%~23.2%、5.9%~11.0%，进而建立上述变形分量计算方法，并采用叠加原理建立该剪力墙考虑剪切、滑移和弯曲贡献的变形能力计算模型。本项目的研究成果对冷弯型钢-微硅粉泡沫混凝土组合剪力墙的抗震设计和性能评估具有重要的参考价值。