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对由钢和玻璃纤维增强复合管制作的矩形混凝土填充管进行三点弯曲试验,考察剪跨比为1~5情况下的断裂模式、强度和破坏方式。研究显示:带有玻璃纤维增强复合管的矩形混凝土填充管弯矩下降时的临界比为4~5,带有钢管的矩形混凝土填充管弯矩下降时的临界比为1~2。另一方面对于钢管,当临界比低于3时,延性急剧下降。断裂的模式与尺寸取决于混凝土和钢管之间的滑移大小。所有带有玻璃纤维增强复合管的矩形混凝土填充管都产生大的纵深弯曲裂缝,即使在临界比为1的情况下。然而,当内部增加钢筋时,除了细小的弯曲裂缝外,还产生了主要的斜裂缝。带有钢管的矩形混凝土填充管,除了临界比为1时主要产生斜裂缝外,均产生细小的弯曲裂缝。通过建立拉压杆模型预测矩形混凝土填充管梁的强度,为试验结果提供一个合理的解释。
A three-point bending test was conducted on a rectangular concrete filled tube made of steel and fiberglass-reinforced composite pipe to examine the fracture mode, strength and failure mode under a shear-span ratio of 1 to 5. The results show that the critical ratio of rectangular concrete filled tube with glass fiber reinforced composite pipe decreases from 4 to 5, and the critical ratio of rectangular concrete filled tube filled with steel tube decreases from 1 to 2. On the other hand, for the steel pipe, when the critical ratio is lower than 3, the ductility decreases sharply. The mode and size of the fracture depend on the size of slip between the concrete and the pipe. All rectangular concrete filled tubes with glass fiber reinforced composite tubes produced large deep flexural cracks, even at a critical ratio of 1. However, with the addition of rebar internally, there were major diagonal cracks in addition to the small curved cracks. Rectangular concrete filled tubes with steel tubes, except for the critical ratio of 1, mainly produce diagonal cracks, resulting in small, curved cracks. Through the establishment of tension and compression rod model to predict the strength of rectangular concrete filled tube beam, the test results provide a reasonable explanation.