考虑应变软化纤维增强混凝土圆管极限荷载统一解

纤维增强混凝土通常通过在混凝土中掺入少量的钢纤维、合成纤维等制成，能有效地改善混凝土的抗拉、抗弯性能，近年来纤维增强混凝土越来越多地应用到厚壁圆筒的制造中．由于Mohr-Coulomb、Mises、Tresca等屈服准则只适合拉、压强度相等的金属类材料，不适用于纤维混凝土，因此本文在讨论纤维增强混凝土软化特性的基础上，基于俞茂宏提出的能考虑中间主应力影响的统一强度理论和材料应变软化特性，得到了适合应变软化材料的统一强度准则，分析了受内压作用纤维增强混凝土厚壁圆管的受力特性，导出了其弹性与塑性极限荷载统一解形式．利用此解，可以很容易得到具有应变软化特性的各种拉、压强度不等材料以及不同纤维增强混凝土材料的厚壁圆管极限荷载解，同时，由于此解既考虑了材料的软化特性的影响又考虑了中间主应力的影响，因此它更符合实际情况。

The Unified Limit Load Solution of Fiber-reinforced Concrete Cylinders Considering the Strain Softening of Material

In recent years,fiber reinforced concrete(FRC),which is produced by adding strengthening intensifier such as steel fiber,synthetic fiber into plain concrete,so as to improve the tensile and bending strengths of concrete effectively,has been applied more and more in the production of the thick wall cylinder.Since Mohr-Coulomb criterion,Tresca or Mises criterions are all only applicable to materials having equal tensile and compressive strength,these criterions are not applicable to FRC.In this paper,based on the discussion of the softening characteristic of FRC and the unified strength theory(YU Mao Hong and HE Li Nan,1991),which can take the intermediate principle stress and the softening characteristic of material strain into consideration,the uniform strength principle which is applicable to strain softening material was derived.In addition,the stress characteristic of thick wall cylinder made of FRC was analyzed,and its unified solutions of the elastic and plastic limit loads were derived.The solution could be more practical to the calculation of the limit compression loads of materials with different tensile and compression strength and the thick wall cylinder made of different FRC by taking into account of both the materials' strain softening and the intermediate principal stress.