火灾下超高强钢S960力学性能与抗火设计建议

Fire Performance and Design Recommendations of Very High Strength Steel S960

摘要:

为研究超高强钢S960在火灾下的材料力学性能，分别采用稳态火灾试验方法和瞬态火灾试验方法对超高强钢S960进行高温力学性能试验，得到超高强钢S960在火灾下的弹性模量、屈服强度、极限强度、应力-应变关系曲线以及钢材破坏模式等。将试验研究结果同现行钢结构规范EC3、ASCE、AISC、AS 4100和BS 5950等进行对比分析，以验证规范对于高强钢的适用性。同时，为研究不同种类高强钢火灾下力学性能差异，将试验结果与现有文献中欧标高强钢S460、S690以及国产高强钢Q460、Q550、Q690和Q890的火灾下材料力学性能进行对比。此外，提出超高强钢S960在火灾高温作用下钢材力学性能的拟合公式，并验证其准确性。研究结果表明，现行各国规范不能安全可靠地指导超高强钢S960及其他高强钢的抗火设计，对规范进行针对高强钢的修订势在必行。

Abstract:

In order to reveal the high temperature mechanical properties of very high strength steel （VHSS)S960, tensile tests were conducted under both steady state and transient state fire conditions. The elastic modulus, yield strength, ultimate strength, stress-strain curve as well as failure mode of S960 were obtained. The test results were compared with current steel structure codes, such as EC3, ASCE, AISC, AS 4100 and BS 5950, to verify the applicability of standards for high strength steel (HSS). For comparison, the available research results in literature on S460, S690, Q460, Q550, Q690 and Q890 were compared with the test results of S960.Besides, the fitting formula of the mechanical properties of the VHSS S960 under the action of high temperature of fire was put forward, and its accuracy was verified. It is shown that fire-resistance design of steel structures with S960 is unsafe according to the current design standards, and differences of mechanical properties of HSS exist in different kinds of HSS. Moreover, the fitting formula for the deterioration of S960 at high temperatures was validated for practical engineering design.