高温后钢骨-方钢管混凝土组合短柱轴压性能研究

Study on Axial Compression Behavior of Steel Reinforced Concrete-Filled Square Steel Tubular Short Columns after High Temperature

目的对钢骨方钢管混凝土短柱施加火灾作用,进而研究火灾后试件的轴压力学性能。方法通过数值模拟分析方法,建立温度场分析模型,明确试件各组分温度场分布规律,研究高温后试件在轴向荷载作用下的破坏形态,并分析受火时间、内置钢骨形式、钢管壁厚以及混凝土强度等参数对试件力学性能的影响。结果是否内置钢骨对试件破坏形态具有一定影响,无内置钢骨的试件破坏时主要表现为中部发生鼓曲,钢管褶皱,内置钢骨的试件在破坏时呈双波型鼓曲;受火时间增加,试件劣化程度加剧,钢管壁厚为6 mm和7.5 mm的试件极限承载力相对于厚度为4.5 mm的试件分别提高了25.6%和30.1%,混凝土强度等级的变化对试件极限承载力影响较小。结论内置钢骨的存在使得试件各组分协同作用,试件受力性能良好,且在高温后仍具有足够的安全储备空间。

The objective is to study the axial compressive performance of the specimens after fire,through exerting fire effect to square steel tube concrete short column with steel bone.Establish the temperature field analysis model through numerical simulation analysis method,to identify the temperature field distribution rule of each component of the specimen,to study the failure mode of the specimen under axial load after high temperature,and to analyze the influence of the parameters such as the fire time,the form of the embedded steel bone,the thickness of the steel tube and the concrete strength on the mechanical properties of the specimen.Whether the concrete short column is embedded with steel bone or not has certain influence on the failure mode of specimen.The failure of the specimen without embedded steel bone is mainly manifested as buckle in the middle and steel tube wrinkle.The failure of the specimen with embedded steel bone is manifested as double wave buckle.With the increase of fire exposure time,the deterioration of the specimens was intensified.The specimens with the wall thickness of 6 mm and 7.5 mm have the ultimate bearing capacity 25.6%and 30.1%higher than that of the specimens with the thickness of 4.5 mm.The change of the strength grade of concrete had little effect on the ultimate bearing capacity of the specimens.The embedded steel bone makes the components of the specimen cooperate with each other,makes the specimen have good mechanical performance and have enough safe reserve space after high temperature.