It is essential to predict the long-term deformation of partially enclosed steel reinforced concrete (PSRC) columns employed extensively in modern high-rise buildings. This study aims to evaluate the differences of drying shrinkage deformation between PSRC and plain concrete (PC) columns due to their different moisture diffusion, and propose a modified B3 model to predict the dry shrinkage of PSRC columns considering the hindrance of section steel to moisture diffusion. First, the numerical simulation is conducted to estimate the differences between the PC and PSRC column behaviors by the finite element analysis method, focusing on moisture diffusion. The prediction results indicate that the section steel delays the drying shrinkage deformation of concrete due to its obstruction to moisture diffusion. Then, the B3 model is adjusted to fit the long-term deformation of PSRC columns by introducing two modified coefficients, which are determined by parametric analysis. The analytical results show that the geometry of section steel and the ambient relative humidity are the dominant factors to control the variation of the two modified coefficients. Finally, an experiment is performed to grasp the variation law of moisture in concrete and verify the rationality of the proposed model for predicting the drying shrinkage deformation of PSRC columns.

预测在现代高层建筑中广泛使用的部分封闭的钢筋混凝土（PSRC）柱的长期变形至关重要。这项研究旨在评估PSRC和普通混凝土（PC）柱由于水分扩散不同而引起的干燥收缩变形的差异，并提出一种改进的B3模型，以考虑型钢对水分扩散的阻碍来预测PSRC柱的干收缩。首先，通过有限元分析方法进行了数值模拟，以估计PC和PSRC色谱柱行为之间的差异，重点是水分扩散。预测结果表明，型钢由于阻碍了水分的扩散而延迟了混凝土的干缩变形。然后，通过引入两个修正系数来调整B3模型以适应PSRC柱的长期变形，参数分析。分析结果表明，型钢的几何形状和环境相对湿度是控制两个修正系数变化的主要因素。最后，通过实验掌握了混凝土中水分的变化规律，验证了所提出的预测PSRC柱干缩变形的模型的合理性。