高强度Q460钢高温蠕变性能

Creep Behavior in High Strength Q460 Steel

摘要:

为了研究高强度Q460钢的高温蠕变对钢结构抗火性能的影响，采用高温蠕变试验装置测试了高温下高强度Q460钢材在不同应力水平下的蠕变应变随时间的变化曲线.根据试验数据，在现有蠕变模型的基础上拟合了高强度Q460钢材的高温蠕变模型.在有限元结构分析中引入钢材高温材料力学性能和蠕变参数，分析了考虑高温蠕变后轴心受力Q460钢柱的抗火性能.研究表明，高强度Q460钢材在高温和应力作用下具有明显的蠕变变形，在同一温度和时间下，蠕变应变随应力水平的提高明显增加；考虑蠕变效应后，在标准（ISO834）的升温条件下，钢柱的耐火极限明显降低；在恒定温度下，钢柱的极限承载力随着时间的增加急剧降低，因而结构的抗火承载力设计需要考虑受火时间的影响.

关键词:高强度Q460钢; 蠕变; 抗火性能; 有限元分析

Abstract:

In order to investigate the effect of creep in high strength Q460 steel on the fire resistance of structures, creeptime curves for high strength Q460 steel under various temperature and stress was tested by using creep testing setup. According to the test data, creep models for high strength Q460 steel were proposed based on current creep models. The fire resistance of axially compressed high strength Q460 steel column was analyzed by employing finite element modeling after taking material properties and creep at elevated temperatures into consideration. The study shows that the creep deformation under the action of temperature and stress in high strength Q460 steel is significant, and at the same temperature and time, the creep increase obviously with rise of stress. After considering the effect of creep, fire duration of steel column decrease seriously under the fire exposure to ISO834 standard temperature curve. At a certain temperature, there is a pronounced reduction in load bearing capacity of steel column with the increase of time for fire exposure. Therefore, in the design of load bearing capacity of steel column, the time lasting in fire should be taken into consideration.

Key words:high strength Q460 steel; creep; fire resistance; finite element analysis