摘要
针对混凝土的重要组成材料水泥砂浆,在MTS试验机上对其进行不同应变速率、不同预静载下的冲击加载以及变幅三角波荷载下的动态轴向拉伸系列试验。试验结果表明:①砂浆的抗拉强度随应变率变化敏感性较强,在10-6～10-2 s-1应变率范围内,强度可提高2倍以上;②弹性模量随应变率增加成比例增长,但幅度不大;③峰值应变随应变率的提高有所提高,但离散性较大。极限应变值没有明显率敏感性;④由应变片值获得的名义轴拉应力应变曲线可简化为三段折线,上升段可近似看为直线段,下降段可看成两段折线,卸载至约25%强度时,出现拐点,应变约为200με;⑤65%以下预静载没有对砂浆的动载强度产生不利,反而有所增强;⑥在加载上升段进行地震作用频率范围的往复加载,对水泥砂浆造成的损伤累计较小。
A series of dynamic axial tensile tests of mortar were carried out on MTS, considering the impact load with different strain rates, different initial static loads and the cyclic variable amplitude loads. The results indicate that： （1） the tensile strength of mortar is so sensitive to the strain rate that the dynamic tensile strength can be more than doubled with the strain rate ranging from 10^-6s^-1 to 10^-2s^-1, and mortar is more sensitive to the strain rate than concrete; （2） the modulus of elasticity is also increased proportionally with increasing strain rate, but not as significant as the increment of the strength ; （3） the strain at peak stress is increased slightly with the increase of strain rate but the results are discrete. the ultimate strain is not sensitive to the stain rate ; （4） The ascending portion of the stress-strain curve for mortar can be taken as straight line and the descending portion can be divided into two segments, an inflexion point appears when the load decreases to 25% of the tensile strength with a strain about 200ire; of the strength will not affect but benefit the dynamic tensile strength; （5） the initial static load roughly less than 65% （6） the fatigue damage of mortar by the cyclic variable amplitude load at upward loading section is relatively small.
出处
《土木工程学报》
EI
CSCD
北大核心
2012年第1期13-22,共10页
China Civil Engineering Journal
基金
国家自然科学基金重点项目资助(90510017)
国家自然科学基金面上项目资助(50979032)
关键词
水泥砂浆
动态轴向拉伸
本构关系
冲击荷载
预静载
mortar
dynamic axial tension
constitutive relation
impact load
initial static load
