不同高温作用后混凝土劣化损伤性能

doi:10.12382/bgxb.2023.0731

摘要/Abstract

摘要：

混凝土作为普遍使用的建筑材料,为进一步探索其在受到高温冷却后劣化损伤性能,使用ϕ74mm大口径分离式霍普金森压杆对不同温度冷却处理后的C30混凝土材料进行动态力学性能试验,得到其不同温度后、不同应变率下的应力-应变曲线,并针对其动态抗压强度、损伤变量及破碎形态进行了探讨。结果表明:在100~200℃范围内,混凝土的动态抗压性能下降有限,但当温度达到400℃及以上时,其力学性能下降明显,破碎形态严重。过高的温度会对混凝土材料造成损伤,高温冷却会使混凝土产生应变软化效应,高应变率下混凝土材料也体现出了应变率强化效应。过多的裂缝扩展也一定程度上抑制了损伤变量的增长。在相同温度处理后,应变率越高会使混凝土试样破碎越严重。且过高的温度会加剧混凝土的劣化损伤。

关键词: 高温冷却, 混凝土, 霍普金森压杆, 应力-应变关系, 应变率效应, 损伤变量

Abstract:

Concrete is a commonly used building material. In order to further explore its degradation and damage performance after high-temperature cooling, the dynamic mechanical properties of C30 concrete material after cooling at different temperatures were tested through the ϕ74mm split Hopkinson pressure bar, and the stress-strain curves at different temperatures and different strain rates were obtained. The dynamic compressive strength, damage variables and crushing morphology of concrete are discussed. The results show that the dynamic compressive performance of concrete decreases limitedly in the range of 100~200℃, but its mechanical properties decreases significantly and its broken form is serious when the temperature reaches 400℃ and above. Too high temperature can cause damage to the concrete material, the high temperature cooling causes the concrete to produce a strain softening effect, and the concrete material also shows the strain rate hardening effect under high strain rate. Excessive crack propagation inhibites the growth of damage variables to a certain extent. The higher strain rate makes the concrete sample be broken more seriously after the same temperature treatment. And the excessively high temperatures would aggravate the deterioration and damage of concrete.

Key words: high temperature cooling, concrete, SHPB, stress-strain relationship, strain rate effect, damage variable

中图分类号:

O347.3

张仲昊, 汪维, 张国凯, 王振, 吴汩. 不同高温作用后混凝土劣化损伤性能[J]. 兵工学报, 2023, 44(S1): 152-159.

ZHANG Zhonghao, WANG Wei, ZHANG Guokai, WANG Zhen, WU Gu. Study on Deterioration and Damage Performance of Concrete at Different High Temperatures[J]. Acta Armamentarii, 2023, 44(S1): 152-159.

图/表 13

表1 混凝土配合比

Table 1 Concrete mix ratio kg/m3

成分	水泥	砂	碎石	水	粉煤灰
配合比	515	782	1271	175	57

图1 SHPB装置

Fig.1 Split Hopkinson pressure bar

图2 SHPB装置示意图

Fig.2 Schematic diagram of split Hopkinson pressure bar

图3 高温箱式电炉

Fig.3 High temperature box-type electric furnace

表2 混凝土试样测试相关结果

Table 2 Test results of concrete sample

温度/℃	应变率/s^-1	峰值应力/MPa
	66.2	27.97
20	87.5	31.51
	104.5	33.32
	69.5	26.82
100	91.2	28.66
	106.9	32.11
	72.1	24.49
200	92.6	25.61
	113.6	31.32
	73.7	24.91
400	93.7	25.21
	112.2	28.99
	70.9	15.48
600	87.3	19.65
	113.3	21.39

图4 混凝土试样高温冷却后外观图

Fig.4 Appearance of concrete sample after high temperature cooling

表3 不同加热温度及冷却条件下混凝土试样外观对比

Table 3 Comparison of the appearances of concrete samples under different heating temperatures and cooling conditions

温度/℃	自然冷却
温度/℃	颜色	裂纹	破损
20	灰
100	灰、淡黄
200	灰、黄
400	灰白、淡红	细裂纹
600	灰白、红	明显裂纹	少量剥落

图5 不同温度冷却后混凝土试样各应变率下的应力应变曲线

Fig.5 Stress-strain curves of concrete samples at different strain rates after cooling at different temperatures

图6 不同温度冷却下混凝土试样的峰值应力

Fig.6 Peak stress of concrete samples cooled at different temperatures

图7 不同温度冷却下混凝土试样的弹性模量

Fig.7 Elastic modulus of concrete samples cooled at different temperatures

图8 相同应变率不同温度冷却后混凝土试样损伤变量与塑性应变的关系

Fig.8 Relationship between damage variable and plastic strain of concrete samples cooled at different temperatures with the same strain rate

图9 应变率为70s-1左右时混凝土试样破碎形态

Fig.9 Broken forms of concrete sample with strain rate of about 70s-1

图10 400℃冷却后混凝土试样破碎形态

Fig.10 Broken forms of concrete samples after heating at 400℃ and cooling

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