缓粘结预应力混凝土梁极限承载力试验

Ultimate Bearing Capacity Test of Retard-bonded Prestressed Concrete Beams

通过4根预应力混凝土梁的极限承载力试验,分别对其开裂荷载、破坏荷载、控制截面应力、裂缝与变形进行了测试,对比了缓粘结与普通预应力混凝土梁的受力性能差异。从试验结果来看,缓粘结预应力混凝土梁具有较好的受力性能,缓粘结与普通预应力混凝土梁的挠度、应变实测数据变化规律基本一致。跨中截面体内应变测试结果表明,缓粘结与普通预应力混凝土梁的体内应变变化规律吻合较好。跨中截面钢筋应变与混凝土应变测试结果表明,缓粘结与普通预应力混凝土梁的应变变化规律基本一致,缓粘结预应力混凝土梁的实测值相对较大。缓粘结预应力混凝土梁的实际开裂荷载、破坏荷载大于普通预应力混凝土梁,矩形、T形缓粘结预应力混凝土梁的开裂荷载实测值较普通预应力混凝土梁偏大6%、10%,矩形、T形缓粘结预应力混凝土梁的破坏荷载实测值较普通预应力混凝土梁偏大4%、3%。缓粘结预应力混凝土梁裂缝宽度实测值较普通混凝土梁相对较小,表明缓粘结预应力筋与混凝土之间具有足够的粘结力。

Through testing the ultimate bearing capacities of 4 prestressed concrete beams, the mechanical behavior differences between retard-bonded and ordinary prestressed concrete beams are contrasted by measuring cracking load, failure load, stress of control section, crack and deformation. The test result shows that the retard-bonded prestressed concrete beam has good mechanical behavior, the change regularities of the measured deflections and strains of retard-bonded and ordinary prestressed concrete beams are basically the same. The measured internal strains at mid-span cross-section show that the change regularities of internal strains of retard-bonded and ordinary prestressed concrete beams are basically the same. The measured strains of steel rebars and concrete at mid-span cross-section show that （ 1 ） the change regularities of strains of retard-bonded and ordinary prestressed concrete beams are basically the same and the measured values of retard-bonded prestressed concrete beams are relatively larger; （2） the actual cracking loads and failure loads of retard-bonded prestressed concrete beams with rectangular section and T-shaped section are 6% and 10% higher than those of ordinary prestressed concrete beams respectively ; （3） the failure loads of retard- bonded prestressed concrete beams are 4% and 3% higher than those of ordinary prestressed concrete beams respectively; （4） the measured values of crack width of retard-bonded prestressed concrete beams are relatively smaller than those of ordinary concrete beams, which proves that the former has sufficient bonding force between retarded-bond prestressed reinforcement and concrete.