不同温度下改性聚氨酯混凝土单轴拉伸试验及本构关系

Tensile properties and constitutive relation of modified polyurethane concrete at different temperatures

钢桥面铺装材料易受温度影响而产生破坏,其中拉伸破坏最为常见。改性聚氨酯混凝土是一种新型钢桥面铺装材料,为研究温度对其拉伸性能的影响,在-10℃、0℃、15℃、40℃和60℃这5组温度环境下分别进行单轴拉伸试验研究。为保证拉伸试验成功,率先设计并制作了两种拉伸试件(哑铃形试件、经圆弧过渡的哑铃形试件)。同时设计用于匹配试件的拉伸试验新型夹具,开展两种试件的对比试验。通过拉伸试验,测得该材料在单轴受拉时的应力-应变曲线,依据该曲线计算得到各拉伸性能指标。研究结果表明:使用经圆弧过渡的哑铃形试件与新夹具的组合方案的拉伸效果更优。新型夹具可通过增设螺栓约束夹具的变形,从而有效改善加载过程中试件的局部应力集中效应。随温度的升高,改性聚氨酯混凝土的抗拉强度、拉伸弹性模量均呈减小趋势;峰值应变、断裂能密度和拉压比均呈增大趋势。提出了各拉伸性能指标的温度相关计算式。构建适用于改性聚氨酯混凝土的单轴拉伸本构关系,计算与试验结果吻合良好,为该材料未来的工程应用提供参考。

The steel bridge deck pavement materials are susceptible to damage caused by temperature,among which tensile damage is the most common.Modified polyurethane concrete is a new type of steel bridge deck pavement material.In order to study the effect of temperature on its tensile properties,uniaxial tensile experiments were carried out at-10℃,0℃,15℃,40℃and 60℃.In order to ensure the success of the experiment,two kinds of experimental specimens(dumbbell-shaped specimen and dumbbell-shaped specimen with circular arc edge)were first designed.Meanwhile,a novel tensile testing fixture used to match the specimen was designed,and the experiment comparison of the two specimens was carried out.Through the uniaxial tensile experiment,the stress-strain curves were obtained and the tensile performance indexes were calculated according to the curve.The results show that using the dumbbell-shaped specimen with circular arc edge and the new tensile testing fixture has better effect.The new fixture can restrain the deformation of the fixture by adding bolts,so as to effectively reduce the stress concentration in the loading process.With the increase of temperature,the tensile strength and tensile elastic modulus of modified polyurethane concrete decrease.The peak strain,fracture energy density and tension-compression ratio all increase.The temperature related expressions of the tensile performance indexes are proposed.The uniaxial tensile constitutive relation of modified polyurethane concrete is constructed,and the calculation is in good agreement with the experimental results.The results can serve as basic references for the future engineering application of this material.