论文部分内容阅读
本文从理论上分析了钢管核心混凝土的变形机理,指出在水化过程中存在收缩变形和膨胀变形两种变形趋势,最终的变形表现为收缩还是膨胀取决于两种变形趋势谁占优势。并通过对7组钢管混凝土构件的变形测定来分析水胶比、外掺料、截面尺寸等因素对核心混凝土自收缩的影响以及钢管混凝土作为一种组合构件自身的一些特点。通过试验发现核心混凝土的自收缩随着水胶比的增大而减小,水胶比大的普通混凝土会表现为膨胀;掺硅粉可增大自收缩,掺粉煤灰可减小自收缩;自收缩值与构件尺寸关系不大。核心混凝土的收缩是在外围钢管约束下的收缩,收缩会使钢管产生压应力,混凝土产生拉应力,由于粘结强度较小,收缩引起的应力达到一定值后会使钢管与混凝土脱离,但一般会保持一定的应力余量,说明钢管与混凝土没有完全脱离。最终混凝土收缩的影响表现为使钢管与混凝土产生初应力,同时使混凝土与钢管有相对位移,纵向的相对位移使核心混凝土上表面低于钢管的上表面。
In this paper, the deformation mechanism of steel core concrete is theoretically analyzed. It is pointed out that there are two deformation trends of shrinkage deformation and expansion deformation in hydration process. Whether the final deformation is shrinkage or expansion depends on who has the predominance of two deformation trends. The influence of water-cement ratio, external admixture and cross-section size on the self-shrinkage of core concrete and the characteristics of CFST as a composite member were analyzed by measuring the deformation of 7 CFST members. It is found through experiment that the self-shrinkage of core concrete decreases with the increase of water-cement ratio, and the ordinary concrete with large water-cement ratio will show expansion; silicon powder can increase self-shrinkage and fly ash can reduce self-shrinkage ; Self-shrinkage value has little to do with the size of the component. The shrinkage of core concrete is the contraction under the restraint of the steel pipe. The shrinkage will make the steel pipe produce compressive stress and the concrete produce tensile stress. Since the bond strength is small, the stress caused by shrinkage reaches a certain value, the steel pipe will be separated from the concrete. However, Will maintain a certain amount of stress, indicating that steel and concrete are not completely separated. The final concrete shrinkage is manifested by the initial stress of the steel pipe and concrete and the relative displacement of the concrete and the steel pipe. The longitudinal relative displacement causes the upper surface of the core concrete to be lower than the upper surface of the steel pipe.