钢筋增强超高韧性水泥基复合材料(RUHTCC)梁弯曲性能影响的几何参数分析

PAPAMETERIC STUDY ON THE EFFECT OF BEAM GEOMETRY ON FLEXURAL BEHAVIOR OF STEEL REINFORCED ULTRA HIGH TOUGHNESS CEMENTITIOUS COMPOSITES (RUHTCC) BEAMS

具有超高韧性新型随机PVA短纤维增强的水泥基复合材料(UHTCC)代替传统的具有准脆性应力软化特征的混凝土或纤维混凝土材料制作的钢筋(RUHTCC)受弯梁,可提高承载力,改善构件的延性,并具有良好的损伤演变能力,被认为是一种抗震性能较好的新型构件形式。除了配筋率和UHTCC拉压材料性能外,截面几何尺寸是影响其弯曲性能的一个重要因素。基于受弯理论分析和试验验证,采用该理论公式对截面几何尺寸(截面高度、宽度以及面积)的影响规律进行了系列分析。结果发现:对承载力,梁高度比宽度影响明显,而对承载力提高幅度和变形而言,随梁高的增加而减小,梁宽没有影响;对裂缝控制来说,只要梁下边缘的极限拉应变小于UHTCC材料的极限拉应变,截面尺寸的变化几乎不影响裂缝宽度的大小。并进一步针对RUHTCC梁的受弯设计提出了一些设计建议。

In steel reinforced ultra high toughness cementitious composites （RUHTCC） flexural beam, the random-oriented PVA short fiber reinforced cementitious composite with ultra high toughness （UHTCC） is used to replace conventional plain concrete or fiber-reinforced concrete materials which behave in strain-softening quasi-brittle manner, thus the ductility and damage tolerance of RUHTCC structures are enhanced and thereby they are regarded as a new form of structural member with excellent seismic resistance behaviors. Apart from the reinforcement ratio and the tension and compression mechanical properties of UHTCC, cross-sectional size of the beam also is an important parameter influencing the flexural behavior of RUHTCC beam. Based on previous research achievements, beams with various cross-sectional sizes with varying beam depth, width and cross-sectional area were investigated to study their flexural responses. The results revealed that the depth of beam has more significant influence on the flexural capacity than the beam width, and that the degree of improvement on flexural capacity and deformation decreases with the increase in the depth of beam but unchangeable with the increase in the beam width. It was also discovered that cross sectional size of beam has almost no impact on the crack width as long as the strain in the bottom surface of beam is below the ultimate tensile strain of UHTCC materials used. Subsequently, some suggestions for the flexural design of RUHTCC beam were recommended.