RPC-NC组合梁弯曲承载力的影响因素

Factors Influencing Bearing Capacity of RPC-NC Composite Beam

活性粉末混凝土(RPC)因其高强度、高韧性、高耐久性得到广泛应用。但预制RPC构件整体性、抗震性差;全截面采用RPC会造成材料浪费、增加工程成本。RPC-NC叠合构件的使用可避免上述问题。为研究RPC水胶比、界面粗糙度及RPC厚度对RPC-NC叠合构件承载力的影响,根据正交试验设计了9组27个RPC-NC叠合梁试件,进行四点弯曲试验,并进行极差分析研究各因素对承载力的影响,基于本构关系推导叠合试件开裂弯矩计算公式。试验结果表明:RPC-NC叠合试件承载力明显高于C30混凝土弯曲试件,承载力提高了74.33%~157.76%,且RPC表现出良好的控裂能力;界面粗糙度对承载力影响最大,RPC厚度次之,RPC水胶比影响最小;试验得到最优配合为界面切槽处理、RPC厚度为0.5倍梁高、RPC水胶比为0.22。开裂弯矩公式计算所得弯矩值与试验值吻合较好,可作为叠合构件开裂弯矩计算公式。

Reactive Powder Concrete is widely used for its high strength,toughness and durability.But the prefabricated RPC components are poor in integrity and seismic performance;full-scale use of RPC will cause material waste and increase the cost of the project.The use of RPC-NC stacking components can avoid these problems.In order to study the factors influencing the bearing capacity of RPC-NC composite specimens,selected RPC water-binder ratio,interfacial roughness and thickness of the RPC as the research factors.According to the orthogonal experiment designed nine groups of 27 RPC-NC composite beam specimens,four-point bending test was conducted and studied the effect of various factors on the adhesive power by gradation analysis.Based on constitutive relation deduced the calculation formula of cracking moment of composite specimen.The results showed that the RPC-NC bearing capacity of composite specimens were significantly higher than C30 concrete bending specimen,the bearing capacity improved 74.33% to 157.76%,and RPC showed good ability to control crack.The interface roughness was the biggest factor influencing the bearing capacity,RPC thickness followed,RPC water-binder ratio was the minimum.The interface with slotting treatment,RPC thickness of 0.5 times of the beam height and RPC water-binder ratio of 0.22 was the optimal combination.The bending moment calculated from the formula was in good agreement with the experimental value and could be used as the formula for calculating the cracking moment of the composite specimen.