高温后高强混凝土剪切强度与细观结构

Shear Strength and Meso structure of High Strength Concrete after Elevated Temperatures

关键词:  高强混凝土  高温  剪切强度  细观结构  骨料断裂率  骨料咬合

Key words:  high strength concrete(HSC)  elevated temperature  shear strength  meso structure  aggregate fracture rate  aggregate interlock

摘要:

通过高温后高强混凝土（HSC）试件的push off试验，研究了温度和混凝土抗压强度对HSC剪切强度的影响.基于剪切面细观结构的变化，分析了高温后HSC剪切强度变化的机理,研究了高温后HSC骨料断裂率与剪切强度的关系.结果表明：常温下HSC抗压强度为647，940MPa时，200℃后HSC剪切强度较常温时分别略有减小和略有增大；超过200℃后，HSC剪切强度随温度的升高而降低；无论经历多高的温度，混凝土的抗压强度越高，则HSC剪切强度越大；HSC试件剪切面上的骨料断裂率随温度的升高而减小，随混凝土抗压强度的增加而增大.最后，建立了高温后HSC的骨料咬合模型.

Abstract:

Push off tests for high strength concrete(HSC) specimens after elevated temperatures were carried out to study the effect of elevated temperature and concrete compressive strength on shear strength of HSC. Based on the variation of the meso structure of HSC shear plane, the mechanism for shear strength change of HSC after elevated temperatures was investigated. The relationship between aggregate fracture rate and shear strength of HSC after elevated temperatures was discussed. Results show that when the compressive strengths are 647,940MPa at room temperature, the shear strengths of HSC after 200℃ have a little decrease and a little increase compared with that at room temperature, respectively. When the elevated temperature exceeds 200℃, the shear strength of HSC reduces with the increase of the elevated temperature. The higher the compressive strength of concrete (at any temperature) is, the greater the shear strength will be. The aggregate fracture rate of HSC shear plane decreases as the elevated temperature rises and it will increase as the concrete compressive strength increases. At last, the aggregate interlock model for HSC after elevated temperatures is proposed.