高温影响的钢管混凝土柱抗爆性能研究

火灾与爆炸通常相伴发生，对工程结构安全造成了严重威胁。为研究高温下钢管混凝土柱抗爆性能，采用ABAQUS有限元软件建立了ISO 834标准火灾作用下钢管混凝土柱抗爆模型。在验证有限元模型可靠性基础上，首先分析了标准火灾作用下钢管混凝土柱抗爆工作机理；其次重点研究了受火时间、材料强度、含钢率以及爆炸当量对构件在标准火灾下抗爆性能的影响。研究结果表明:火灾作用下两端固结的钢管混凝土柱受爆炸荷载时，柱两端首先发生剪切破坏，随后整体发生受弯破坏；随着受火时间增加，钢管耗能占比降低，混凝土塑性变形逐渐成为主要耗能机制；混凝土强度、爆炸当量与轴压比对钢管混凝土柱高温下抗爆性能影响明显，当混凝土立方体抗压强度从30 MPa增加到50 MPa，常温与受火90 min构件抗爆性能分别提高约21%与42%。

Study on explosion-resistance performance of concrete-filled steel tubular columns considering the influence of elevated temperatures

Fire and explosion often occur together that seriously threatens the safety of engineering structures. In order to investigate the explosion resistance of concrete-filled steel tubular (CFST) columns at elevated temperatures, the finite element (FE) model of explosion resistance performance for circular CFST columns at elevated temperatures was established using the ABAQUS software. The fire and blast loads were simulated using ISO 834 standard fire and ConWep model, respectively. In the model, the static implicit and dynamic explicit analysis was coupled using “Restart” and “Import” commands and the strain-rate effect was considered. The experiment results of related literatures, including the temperature field, fire resistance duration and explosion resistance of CFST columns, were used to verify the feasibility of the method. Based on the validated FE models, the explosion mechanism of CFST columns subjected to standard fire was analyzed, including the failure modes, full-range analysis, development of stress and strain, interaction between steel tube and concrete and energy consumption. The influence of duration time, material strength, steel ratio and explosion equivalent on the explosion resistance were studied. The maximum mid-span deflection (Δ_peak) was employed to quantitatively analyze the explosion-resistance performance of the CFST columns. The results show that shear failure firstly occurs at both fixed ends, and then the whole column presents flexural failure mode when subjected to explosion load under fire condition. With the increase of duration time, the proportion of energy consumption of steel tube decreases, and plastic deformation of concrete gradually becomes the main energy consumption mechanism. The concrete strength, explosion equivalent and axial load ratio have significant influence on the explosion resistance of CFST at high temperatures. After 0 min and 90 min fire duration, the explosion resistance is improved by approximately 21% and 42% respectively when the concrete cubic compressive strength increases from 30 MPa to 50 MPa.