不同环境下混凝土动态直接拉伸特性研究

在MTS810电液伺服万能试验机上对47个哑铃形混凝土试件进行了不同应变速率(10-5～10-0.3s-1)下的直接拉伸试验,系统研究了两种湿度、两种温度混凝土在不同加载速率下抗拉强度、初始弹性模量、泊松比、临界应变,以及吸能能力与应变速率之间的关系.试验结果表明,混凝土速率敏感性是由混凝土中自由水产生的粘滞性以及破裂形式的改变引起的;随着含水量的增加,混凝土的拟静态强度有降低的趋势,对应变速率的敏感性有所提高;在低温条件下混凝土的拟静态强度较室温条件下有所提高,对应变速率的敏感性却有所降低.

Research on dynamic direct tensile properties of concrete under different environments

Direct tensile experiments were conducted through the MTS810 electro-fluid servo-universal machine to investigate the effect of moisture content and temperature variation on the rate sensitivity of concrete, in which the range of strain rate varied from 10~(-5)/s to 10~(-0.3)/s. Dynamic strength, initial modulus, critical strain, Poison ratio and energy absorption capacity properties were studied systematically. It is concluded that the effect of rate sensitivity is attributed to both the viscosity caused by free water and the transformation of fracture pattern subjected to higher strain rate. With the increasing amount of water content, the static strength of concrete tends to decrease whereas its strain-rate dependency seems to increase. In low temperature environment the concrete has a slightly higher static strength than that of concrete under room temperature condition while its strain-rate sensitivity tends to decrease.